Through what medium does EM propagate in empty space?

[Nereid]

Am moving this to Quantum Physics. Other than that the 'astronomical' or 'cosmological' domain may be where some of the (important) tests of concepts, theories, and ideas related to the OP are conducted, I feel the content of this thread has far more to do with quantum physics than GA&C (as ST pointed out, very early on).

 

[selfAdjoint]

have seen no research to back up that assertion. In fact, if the Scharnhorst effect is real, light MUST interact with the EM field of the quantum vacuum.

I apologize, I did not know about the Scharnhorst effect. The photon does interact with the quantum vacuum by sometimes creating virtual electron-positron pairs. After their brief candle is out it procedes as a photon till it creates another pair. It cannot create real ones because that would violate conservation of energy and momentum, but it can create virtual ones, "off the mass shell". No names, no pack drill.

But far from supporting the radiation this quantum process slows it down! It is precisely the point of Scharnhorst's theory that by intervening with plates a la Casimir we can cause fewer of these transitions and hence increase the speed of the photon above ordinarily measured c. So invoking Scharnhorst, and the active QED vacuum generally, as a "modern ether" is exactly in the wrong direction.

 

[member 11137]

Now I'm confused. If EM propagates as waves, not corpuscular entities traveling through empty space, how does EM propagate? Without a transmissive medium, waves go nowhere.

Think at the ocean and at some waves propagating at the surface of it; it is not always the water that moves, but the ondulation of the surface going up and down without any lateral motion that give us the sensation of a "propagation". Can we not imagine a similar picture for EM waves and vacuum? Or going further can we not imagine that infinitesimal variations of the metric are only giving us the illusion that something is propagating ?

 

[turbo]

I apologize, I did not know about the Scharnhorst effect. The photon does interact with the quantum vacuum by sometimes creating virtual electron-positron pairs. After their brief candle is out it procedes as a photon till it creates another pair. It cannot create real ones because that would violate conservation of energy and momentum, but it can create virtual ones, "off the mass shell". No names, no pack drill.

Do not apologize. Nobody can be familiar with all the research done by everyone in physics. In fact, I had been trying to determine the optical properties of the quantum vacuum for nearly a year when one of the most prominent researchers in that field tipped me off to the Scharnhorst effect in an email. I was coming at this from the viewpoint of an optician and was not as familiar with the theoretical/experimental work in quantum physics as I could have been.

But far from supporting the radiation this quantum process slows it down! It is precisely the point of Scharnhorst's theory that by intervening with plates a la Casimir we can cause fewer of these transitions and hence increase the speed of the photon above ordinarily measured c. So invoking Scharnhorst, and the active QED vacuum generally, as a "modern ether" is exactly in the wrong direction.

No, it's exactly the right direction for my purposes. Now let's think through the implications of this: If the Sharnhorst effect is real, and the quantum vacuum is the dynamical gravitational ether envisioned by Einstein, we have something to work with. The gravitational densification/polarization of the vacuum field would cause an increase in these reactions, resulting in a slowing of the propagation speed of light, while rarification/relaxation of this field would result in faster propagation of light (a la the Scharnhorst effect between the plates of a Casimir device). This is a real mechanical explanation of "gravitational lensing" that makes sense in classical optics.

I am trained as an optician and have been studying the quantum vacuum field as if it were a refractive medium. If the Scharnhorst effect is confirmed, then the quantum vacuum is definitely a refractive medium, and optical effects will give us powerful probes into the qualities of the vacuum fields around galaxies and clusters.

 

[selfAdjoint]

The gravitational densification/polarization of the vacuum field would cause an increase in these reactions, resulting in a slowing of the propagation speed of light, while rarification/relaxation of this field would result in faster propagation of light (a la the Scharnhorst effect between the plates of a Casimir device)

Quantum polarization is not densification. The optical consequences of the Scharnhorst effect were shown by Visser to be unobservable. The quantum vacuum as a medium does nothing but resist and slow the photon, it did not create it and does not support its momentum.

 

[turbo]

Quantum polarization is not densification. The optical consequences of the Scharnhorst effect were shown by Visser to be unobservable. The quantum vacuum as a medium does nothing but resist and slow the photon, it did not create it and does not support its momentum.

References please...

 

[selfAdjoint]

References please...

This is the slides from a talk Visser gave in Brazil. Warning - it's postscript.

www.physics.wustl.edu/~visser/Analog/casimir-rio.ps[/URL]

 

[turbo]

Quantum polarization is not densification. The optical consequences of the Scharnhorst effect were shown by Visser to be unobservable. The quantum vacuum as a medium does nothing but resist and slow the photon, it did not create it and does not support its momentum.

If the quantum vacuum is densified by the presence of large masses, we might expect EM to move more slowly near massive bodies and faster in less-dense domains. This could be the explanation for the unexplained sunward acceleration of the Pioneer probes. They are moving along nicely on they original trajectories, but since they are traveling though less and less dense regions of vacuum, EM from them gets to Earth a little faster than we might expect, leading us to believe that they are slowing down.

 

[selfAdjoint]

If the quantum vacuum is densified by the presence of large masses, we might expect EM to move more slowly near massive bodies and faster in less-dense domains. This could be the explanation for the unexplained sunward acceleration of the Pioneer probes. They are moving along nicely on they original trajectories, but since they are traveling though less and less dense regions of vacuum, EM from them gets to Earth a little faster than we might expect, leading us to believe that they are slowing down.

Your ideas of scale are all off. The vacuum isn't more or less dense except at submicroscopic distances near charged bodies like electrons. which polarize it.

 

[turbo]

Your ideas of scale are all off. The vacuum isn't more or less dense except at submicroscopic distances near charged bodies like electrons. which polarize it.

I don't think my ideas of scale are "off". In Einstein's Leyden address, he expressed the opinion that the ether (the vacuum) is dynamical. It does not simply sit there as a background on which the universe is played out, but is affected by the matter embedded in it.

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.

There is a possible mechanism by which the particle-antiparticle pairs of the vacuum can be polarized and densified, and that mechanism will be put to the test at CERN, as soon as they can make and contain experimentally-useful quantities of neutral anti-hydrogen. That test (a critical part of the Athena project) is to measure the gravitational infall rate of antihydrogen and compare it to the gravitational infall rate of hydrogen. It has been assumed but never proven that these infall rates are equivalent. The problem is that all previous measurements have involved charged antiparticles, and the electromagnetic effects absolutely swamp any detectable gravitational effects.

 

[selfAdjoint]

You evidently won't be persuaded by any modern science, you continually revert to what Einstein said in the 1920's, which to my mind has no force at all. and you interpret everything according to your preconceptions. I am through with this discussion.

 

[turbo]

You evidently won't be persuaded by any modern science, you continually revert to what Einstein said in the 1920's, which to my mind has no force at all. and you interpret everything according to your preconceptions. I am through with this discussion.

I refer to Einstein's Leyden address because in it he puts his view of the "ether" in historical context. He was convinced that GR was incomplete and that he had to explain the interaction of matter with the vacuum before he could unite gravity with the fundamental forces. It is a critical concept.

Have you read this paper? Is this modern enough?

http://arxiv.org/PS_cache/hep-th/pdf/9810/9810221.pdf

Relativistic quantum field theory can be understood as having emerged, historically, from a combination of special relativity and quantum mechanics, but as its very fathers have always been very aware it is not a synthesis of these two theories. In standard relativistic quantum field theory, space-time is considered as a fixed arena in which the physical processes take place. The characteristics of the propagation of light are considered as classical input to the theory. This entails the view that there exists a single universal vacuum velocity of light c. However, starting in the early 1950’s [1] research in quantum electrodynamics (QED) has revealed that higher conceptional sophistication in discussing the propagation of light in a vacuum is required. This more advanced insight derives from studies of QED vacua which have been modified by means of external conditions [background fields (electromagnetic, gravitational), finite temperature (heatbath), boundary conditions]. These modified vacua can be explored by studying the behaviour of particles immersed into the vacuum. One particular method, which is of special conceptional significance, consist in the investigation of the propagation of photons (light) in the vacuum modified by external conditions. The characteristics of the propagation of light then describe certain aspects of the vacuum structure. As a result, it has been found that
modified QED vacua are complicated dispersive media which exhibit almost every phenomenon which is well known from ordinary condensed matter media in this respect. This is a quantum effect which is caused by the phenomenon
of vacuum polarization.

Extrapolating from this work and others relating to the behavior of light in modified vacua, we may expect to see observable effects in the manner in which EM propagates through the vacuum. If the vacuum exhibits gravitational dynamic behaviour as Einstein's Machian ether demands, the optical effects of EM traversing vacua of different densities should be apparent. We may discover that we do not need lots of dark matter to explain excess cluster lensing. We may have a solution to the Pioneer acceleration riddle.

 

[Nereid]

That test (a critical part of the Athena project) is to measure the gravitational infall rate of antihydrogen and compare it to the gravitational infall rate of hydrogen. It has been assumed but never proven that these infall rates are equivalent.

Other than to test the Standard Model, and pick up on anything that looks interesting, do you know if these experiments will have the sensitivity (etc) to test various non-mainstream 'EM propogation through vaccua' models/theories/ideas (e.g. LQG)?

Extrapolating from this work and others relating to the behavior of light in modified vacua, we may expect to see observable effects in the manner in which EM propagates through the vacuum.

Such as? To what extent have these been quantified?

If the vacuum exhibits gravitational dynamic behaviour as Einstein's Machian ether demands, the optical effects of EM traversing vacua of different densities should be apparent.

How? To what extent? Why haven't these been detected so far?

We may discover that we do not need lots of dark matter to explain excess cluster lensing.

Is this an example? Or does 'galactic DM' and 'cosmological DM' get swept up here too?

We may have a solution to the Pioneer acceleration riddle.

Indeed.

However, it sure would be nice if something specific could be predicted ahead of time (akin to Garth and SCC, re GPB)!

 

[turbo]

However, it sure would be nice if something specific could be predicted ahead of time (akin to Garth and SCC, re GPB)!

You want predictions relating to observable effects of vacuum polarization/densification? Here is a list I made some time ago.

1) Testing the Gravitational Mass of Matter vs. Antimatter

The Athena Project is designed to produce experimentally usable quantities of anti-hydrogen. One experiment is of particular interest – the measurement of the gravitational mass-equivalence of matter vs. antimatter. In my model, the quantum vacuum is polarized due to a differential in the gravitational infall rates of matter vs. antimatter. Particle-antiparticle pairs of the vacuum preferentially arise in the orientation that requires the least amount of energy, and if antiparticles are more strongly attracted to nearby mass than their partner particles, we have a mechanism by which the quantum vacuum (Einstein's gravitational ether) is polarized. The Polarized ZPE model is falsifiable by this mass-equivalence experiment, for without this gravitational mass differential, I cannot conceive of a simple universal mechanism by which the gravitational ether can interact with embedded masses.

2) Testing for the Existence of ZPE Field Polarization in Earth Orbit

I propose adding an experiment to an Earth-orbiting platform to test the strength of the Casimir effect in various orientations. Using a conventional Casimir device with parallel conducting plates, the device should be oriented with the plates parallel to an imaginary line drawn from the orbiter to earth. A second data run should be made with the conducting plates oriented perpendicular to that line. Each data run should consist of a large enough number of orbits to allow the effects of ZPE field fluxes caused by the Sun and the Moon to be extracted and compared. The Polarized ZPE field model predicts measurable differences in Casimir force as the device traverses gradients in the ZPE field caused by these massive bodies. Subject to instrument sensitivity, the Polarized ZPE model is falsifiable by this test.

3) Measuring the Speed of Light in a Casimir “Vacuum”

Casimir devices produce ZPE fields that are slightly under the local ground state by using very small gaps to physically suppress the appearance of some frequencies of the ZPE spectrum. This suppressed field is somewhat below the local ZPE ground state, although it is by no means a true quantum vacuum. I propose an experiment using interferometry to compare the speed of light across a Casimir gap to that of a beam crossing an equivalent vacuum with no ZPE suppression. The Polarized ZPE model’s concept that the speed of light is dependent on the density of the ZPE field through which is propagates is falsifiable by this test. GR’s invariable speed of light in a vacuum is also falsifiable by this test. (Note: A ZPE researcher kindly pointed out to me that this effect had already been predicted by Klaus Scharnhorst in 1990. My newness to the field has resulted in several such surprises, though I find it encouraging to have deduced a concept only to find that someone else has come to the same conclusion, often through another line of reasoning.)

4) WMAP Anisotropies Resulting from Motion Relative to the Vacuum Fields

WMAP's first year data contains interesting anisotropies. The dipole anisotropy is oriented with respect to our galaxy, and there are several strong multipole anisotropies. These anisotropies are due to our motion relative to the vacuum. Contributory motions include the passage of the MW through the vacuum (responsible for the large dipole anisotropy), the rotation of our spiral arm, the motion of the Sun through the spiral arm, and the motion of the Earth (and the WMAP probe at L2) around the Sun. When WMAP's second year is finally released, I predict that the dipole anisotropy and larger-scale anisotropies will be consistent with the first year data. The smaller anisotropies will not overlay properly, and when studied, they will be seen as artifacts of the WMAP probe's motion relative to the reference frame of the vacuum field. An antenna oriented in the direction of the probe's motion will sense a higher temperature, and one oriented toward the rear will sense a lower temperature. Even the very smallest anisotropies cover vast areas when projected to cosmological distances, as in the CMB. These vast areas cannot have conspired to change from one year to the next. If these small-scale anisotropies have not changed from WMAP1 to WMAP2, my ZPE model is falsified. If they have changed, the CMB is local, not cosmological.

5) Frequency-dependent Effects of the ZPE Fields on Light

Light propagating through ZPE fields should exhibit effects that are frequency-dependent. High frequency, short wavelength EM will be found to interact more strongly with the ZPE fields and will be slowed more than low-frequency, long wavelength EM. Observationally, the light curve of a distant astronomical source like a supernova should exhibit a stretched light-curve, with the low frequency EM arriving sooner on average than the high frequency EM. The spectra of long-lived objects of steady luminosity will appear normal, and frequency-dependent arrival times will not be measurable. The spectra and luminosity curves of objects that exhibit rapid changes in luminosity will be spread by the interactions of the EM with the ZPE fields. Perhaps the best objects to study for confirmation of this effect are gamma-ray bursters. Their light curves should exhibit a spectral smear in which long wavelength "forerunner" EM precedes gamma rays by an amount proportional to the distance from the source to Earth and the density of the ZPE fields traversed on that path.

 

[turbo]

That test (a critical part of the Athena project) is to measure the gravitational infall rate of antihydrogen and compare it to the gravitational infall rate of hydrogen. It has been assumed but never proven that these infall rates are equivalent.

Other than to test the Standard Model, and pick up on anything that looks interesting, do you know if these experiments will have the sensitivity (etc) to test various non-mainstream 'EM propogation through vaccua' models/theories/ideas (e.g. LQG)?

The Athena project is not going to test EM propagation rates, to my knowledge. The mass-equivalence experiment is absolutely critical to our understanding of gravitation, however, since it will employ neutral antihydrogen, which will make it possible to screen for EM effects and accurately measure gravitational effects on antimatter for the first time.

Extrapolating from this work and others relating to the behavior of light in modified vacua, we may expect to see observable effects in the manner in which EM propagates through the vacuum.

Such as? To what extent have these been quantified?

If my quantum vacuum=ether model is correct, the quantification of the effects of EM propagation through vacua of varying density has already been accomplished by the Pioneer telemetry studies. The puzzling sunward acceleration is not real - we interpret the shorter-than expected EM return times as if the probes are slowing because we believe that EM travels at the same speed through all vacua. If the Scharnhorst effect is real, this rule about the absolute nature of the speed of light is wrong, and we should consider that the Pioneer probes are traversing vacua that are less polarized and densified than we experience near Earth, and EM can traverse those vacua more quickly than here.

If the vacuum exhibits gravitational dynamic behaviour as Einstein's Machian ether demands, the optical effects of EM traversing vacua of different densities should be apparent.

How? To what extent? Why haven't these been detected so far?

Perhaps they have been detected, but have been misinterpreted. If you believe that "empty" space is truly empty, and that the vacuum cannot interact with matter and EM, you might look at strong cluster lensing, and decide that we are only seeing a tiny fraction of the mass in the cluster. You probably would not consider that the vacuum could be gravitationally densified or that EM waves encountering these fields could be refracted by them. You would simply refer back to Einstein's curved space-time model and infer lots of missing mass.

Is this an example? Or does 'galactic DM' and 'cosmological DM' get swept up here too?

If there is a dynamic gravitational ether comprised of the fields of the quantum vacuum, the simple inverse square relationship that works so well for simple systems like the Solar system may not apply very well at galactic and cluster scales. If mass, gravitation, and inertia are emergent (arising from matter's interaction with the vacuum) and not fundamental, the effects (cluster binding, excess cluster lensing, flat galactic rotation curves) that prompt the invocation of dark matter may be explainable by other means. I do not expect that it will be clean and easy to quantify gravitational forces with a dynamic vacuum field, but I believe that it is the only way that gravitation is going to be compatible with quantum theory.

 

[Chronos]

It still has a steep hill to climb:

Quantum Foam and Quantum Gravity Phenomenology
http://www.arxiv.org/abs/gr-qc/0405078

Modern tests of Lorentz invariance
http://www.arxiv.org/abs/gr-qc/0502097

Probing spacetime foam with extragalactic sources
http://www.arxiv.org/abs/gr-qc/0508121

Shortly after the original Scharnhorst paper, several papers quickly followed that raised objections. Unfortunately, they are not freely available.

John Baez said:

"However, further theoretical investigations have shown that once again there is no possibility of FTL communication using this [Scharnhorst] effect."

http://math.ucr.edu/home/baez/physics/Relativity/SpeedOfLight/FTL.html#12

 

[turbo]

You may wish to trace this thread re the Scharnhorst effect.

http://www.lns.cornell.edu/spr/1998-12/msg0013670.html

 

[Jonny_trigonometry]

when I think of the quantum vacuum, I get this picture of a bunch of em waves going all directions, frequencies, and present at every point with an overall energy-density (all frequencies have different energy densities). They mostly all cancel each other due to superposition, but every once and a while, like a chaotic system, there will be an emergant pattern that moves through due to the mutual seemingly serindipitous cooperation of all needed waves to make the emergant structure (ie, a photon). Later, if you view where the photon came from, then it's not so serindipitous when you see it was caused by an interaction of matter at some other point in space.

I think of matter waves in this way too, because a wave group is composed of an infinate number of superposed wavelegths, and I just imagine the same picture, only with matter waves, and the same properties result like in a chaotic dynamical system. This is what suits me as an answer to particles that pop out of nowhere and then disappear (emergant property of the chaotic dynamical system of matter waves).

So I would say that the quantum vacuum is in a way, an aether made of both matter and EM waves in a chaotic system of interaction.

 

[Nereid]

You want predictions relating to observable effects of vacuum polarization/densification? Here is a list I made some time ago.

1) Testing the Gravitational Mass of Matter vs. Antimatter

The Athena Project is designed to produce experimentally usable quantities of anti-hydrogen. One experiment is of particular interest – the measurement of the gravitational mass-equivalence of matter vs. antimatter. In my model, the quantum vacuum is polarized due to a differential in the gravitational infall rates of matter vs. antimatter. Particle-antiparticle pairs of the vacuum preferentially arise in the orientation that requires the least amount of energy, and if antiparticles are more strongly attracted to nearby mass than their partner particles, we have a mechanism by which the quantum vacuum (Einstein's gravitational ether) is polarized. The Polarized ZPE model is falsifiable by this mass-equivalence experiment, for without this gravitational mass differential, I cannot conceive of a simple universal mechanism by which the gravitational ether can interact with embedded masses.

Quantification (even OOM levels would do fine)?

2) Testing for the Existence of ZPE Field Polarization in Earth Orbit

I propose adding an experiment to an Earth-orbiting platform to test the strength of the Casimir effect in various orientations. Using a conventional Casimir device with parallel conducting plates, the device should be oriented with the plates parallel to an imaginary line drawn from the orbiter to earth. A second data run should be made with the conducting plates oriented perpendicular to that line. Each data run should consist of a large enough number of orbits to allow the effects of ZPE field fluxes caused by the Sun and the Moon to be extracted and compared. The Polarized ZPE field model predicts measurable differences in Casimir force as the device traverses gradients in the ZPE field caused by these massive bodies. Subject to instrument sensitivity, the Polarized ZPE model is falsifiable by this test.

But if there were a null result, how could that rule out your ideas? I mean, you've proposed nothing quantitative (or did I miss it?), so a null result gets you nowhere (except, perhaps, a request for a repeat, way out in an Oort orbit, with sensitivity increased by 10^5 (or maybe way inside Mercury's orbit?).

3) Measuring the Speed of Light in a Casimir “Vacuum”

Casimir devices produce ZPE fields that are slightly under the local ground state by using very small gaps to physically suppress the appearance of some frequencies of the ZPE spectrum. This suppressed field is somewhat below the local ZPE ground state, although it is by no means a true quantum vacuum. I propose an experiment using interferometry to compare the speed of light across a Casimir gap to that of a beam crossing an equivalent vacuum with no ZPE suppression. The Polarized ZPE model’s concept that the speed of light is dependent on the density of the ZPE field through which is propagates is falsifiable by this test. GR’s invariable speed of light in a vacuum is also falsifiable by this test. (Note: A ZPE researcher kindly pointed out to me that this effect had already been predicted by Klaus Scharnhorst in 1990. My newness to the field has resulted in several such surprises, though I find it encouraging to have deduced a concept only to find that someone else has come to the same conclusion, often through another line of reasoning.)

OK, but again, without at least an OOM quantification, doing such an experiment tells you nothing, right?

4) WMAP Anisotropies Resulting from Motion Relative to the Vacuum Fields

WMAP's first year data contains interesting anisotropies. The dipole anisotropy is oriented with respect to our galaxy, and there are several strong multipole anisotropies. These anisotropies are due to our motion relative to the vacuum. Contributory motions include the passage of the MW through the vacuum (responsible for the large dipole anisotropy), the rotation of our spiral arm, the motion of the Sun through the spiral arm, and the motion of the Earth (and the WMAP probe at L2) around the Sun. When WMAP's second year is finally released, I predict that the dipole anisotropy and larger-scale anisotropies will be consistent with the first year data. The smaller anisotropies will not overlay properly, and when studied, they will be seen as artifacts of the WMAP probe's motion relative to the reference frame of the vacuum field. An antenna oriented in the direction of the probe's motion will sense a higher temperature, and one oriented toward the rear will sense a lower temperature. Even the very smallest anisotropies cover vast areas when projected to cosmological distances, as in the CMB. These vast areas cannot have conspired to change from one year to the next. If these small-scale anisotropies have not changed from WMAP1 to WMAP2, my ZPE model is falsified. If they have changed, the CMB is local, not cosmological.

You've said this before too ... but at what quantitative levels? How much 'relative motion' will produce how much 'not overlay properly'?

5) Frequency-dependent Effects of the ZPE Fields on Light

Light propagating through ZPE fields should exhibit effects that are frequency-dependent. High frequency, short wavelength EM will be found to interact more strongly with the ZPE fields and will be slowed more than low-frequency, long wavelength EM. Observationally, the light curve of a distant astronomical source like a supernova should exhibit a stretched light-curve, with the low frequency EM arriving sooner on average than the high frequency EM. The spectra of long-lived objects of steady luminosity will appear normal, and frequency-dependent arrival times will not be measurable. The spectra and luminosity curves of objects that exhibit rapid changes in luminosity will be spread by the interactions of the EM with the ZPE fields. Perhaps the best objects to study for confirmation of this effect are gamma-ray bursters. Their light curves should exhibit a spectral smear in which long wavelength "forerunner" EM precedes gamma rays by an amount proportional to the distance from the source to Earth and the density of the ZPE fields traversed on that path.

Same comment - what size is the effect you predict? Within an OOM of what the best experimental setup we could construct today would detect? Or 10^100 OOM smaller than this best? Something in between??

 

[reilly]

All this is way above my pay grade. However, it struck me as odd that Einstein, who destroyed the 19th cenury aether, would subsequently ressurect it. So, I looked all this up in Einstein's bio by Abdus Salaam. He says that in Einstein's inaugural address in Leiden, Oct 27, 1920, that the word aether meant the gravitational field: "The aether of the general theory of relativity is a medium without mechanical and kinematic properties, but which codetermines mechanical and electromagnetic events." Without access to the entire paper, I must admit to being clueless as to what that quote means.

But I do know that in his wonderful Relativity, The Special and General Theory Einstein discusses the well-known problems of the aether, and concludes that there ain't none. Much more detail about the history of the demise of the aether is provided by Max Born in his excellent book Einstein's Theory of Relativity.

It makes intuitive sense that the quantum vacuum has physical effects. But, it seems to me, there is a severe computational issue: because the vacuum must be Lorentz invariant, then the vacuum either has zero energy -- in the small and in the large, -- or infinite energy -- a flat radiation spectrum. Maybe, with the addition of, gravitation, the appropriate spatial energy can be made finite -- non-inertial frames and all that. Maybe even chaotic propreties as jonny trig suggests above.

Regards,
Reilly Atkinson

(My apologies if I have written what others have already said. I haven't read all the posts.)

 

[turbo]

All this is way above my pay grade. However, it struck me as odd that Einstein, who destroyed the 19th cenury aether, would subsequently ressurect it. So, I looked all this up in Einstein's bio by Abdus Salaam. He says that in Einstein's inaugural address in Leiden, Oct 27, 1920, that the word aether meant the gravitational field: "The aether of the general theory of relativity is a medium without mechanical and kinematic properties, but which codetermines mechanical and electromagnetic events." Without access to the entire paper, I must admit to being clueless as to what that quote means.

Here you go:

http://www.geocities.com/antonioferrigno/ether.html

 

[turbo]

Nereid, you asked me for a prediction and I gave you five. Then you demand quantification of each.

If you want quantification of the optical effects of vacuum polarization, look at the Pioneer telemetry. Those probes (headed off in different directions) are not slowing down. EM from the probes is traveling along a path that is nearly radial from the outer solar system inward toward the Sun. The vacuum is less polarized (less dense) the farther you get from the Sun and as a result, EM passes through it with less interference (a la the Scharnhorst effect) and is essentially traveling at superluminal speeds WRT the speed of light in the vacuum near Earth orbit. If we believe the speed of light in a vacuum is fixed, we must interpret this shortened return time as if the probes are a little closer than they should be and infer that they are decellerating (Sunward acceleration). I do not believe the speed of light in a vacuum is a constant, because there is no true vacuum in our universe, and the speed of light is dependent on the optical properties of the transmissive media through which it propagates. Any other probe that we send out to the depths of the Solar System will exhibit the same behavior. You can take that as another prediction, if you wish.

I have not bothered working out the equivalent difference in refractive index because the Pioneer anomaly is essentially just two measurements of the density of one field. The principle behind the Pioneer anomaly has universal application to my model of polarized vacuum, but the measurements themselves do not. In my model, the vacuum field is polarized by the presence of matter and is itself self-attractive when so polarized. Given the departures from the simple inverse square relationship exhibited by galaxies (flat rotation curves) and clusters (excess binding energy, excess lensing), I expect quantification of vacuum polarization and gravity to be a very messy process, and one that is beyond my math skills.

If and when the Athena Project shows a differential in the gravitational infall rates of matter and antimatter, the polarizing mechanism will be in place, and the infall differential will be quantified. Then comes the tricky part. We will need the help of the quantum physics crowd to calculate the effect of nearby mass on the orientation in which particle-antiparticle virtual pairs arise. I assume that they will preferentially arise and persist longest in the orientation that requires the least amount of energy. We might need another Feynman to tackle the quantification of vacuum field polarization.

 

[Nereid]

Nereid, you asked me for a prediction and I gave you five. Then you demand quantification of each.

Well, 'ask' rather than 'demand', but you're right, I would like quanitification, at least to the OOM level.

Think about it from the POV of an eager experimenter, or the folk in charge of allocating a science budget among competing proposals, or ...

So much physics to do, so little time and money!

Why do anything with this quantum vacuum and EM propogation idea, if no one can give you even a hint of what might be expected? Worse, perhaps, nothing to relate any prediction to any other, quantitatively (suppose I get a marginal non-null result in one, what does that tell me about what I could reasonably expect in any of the other four? Nothing).

If you want quantification of the optical effects of vacuum polarization, look at the Pioneer telemetry. Those probes (headed off in different directions) are not slowing down. EM from the probes is traveling along a path that is nearly radial from the outer solar system inward toward the Sun. The vacuum is less polarized (less dense) the farther you get from the Sun and as a result, EM passes through it with less interference (a la the Scharnhorst effect) and is essentially traveling at superluminal speeds WRT the speed of light in the vacuum near Earth orbit. If we believe the speed of light in a vacuum is fixed, we must interpret this shortened return time as if the probes are a little closer than they should be and infer that they are decellerating (Sunward acceleration). I do not believe the speed of light in a vacuum is a constant, because there is no true vacuum in our universe, and the speed of light is dependent on the optical properties of the transmissive media through which it propagates. Any other probe that we send out to the depths of the Solar System will exhibit the same behavior. You can take that as another prediction, if you wish.

Excellent! Now, working backwards (from the size of the observed anomaly), what does that tell you - the ideas author - about the magnitude of the effect? Don't you now have a basis for extrapolating? When you do that extrapolation, what is the expected size of the effect, for all other deep space probes? How do those expectations compare with what's observed (mostly null)? Can we extrapolate from the Pioneer anomaly to predictions about MACHO and OGLE microlensing events (esp caustic crossings)?

I have not bothered working out the equivalent difference in refractive index because the Pioneer anomaly is essentially just two measurements of the density of one field. The principle behind the Pioneer anomaly has universal application to my model of polarized vacuum, but the measurements themselves do not. In my model, the vacuum field is polarized by the presence of matter and is itself self-attractive when so polarized. Given the departures from the simple inverse square relationship exhibited by galaxies (flat rotation curves) and clusters (excess binding energy, excess lensing), I expect quantification of vacuum polarization and gravity to be a very messy process, and one that is beyond my math skills.

If and when the Athena Project shows a differential in the gravitational infall rates of matter and antimatter, the polarizing mechanism will be in place, and the infall differential will be quantified. Then comes the tricky part. We will need the help of the quantum physics crowd to calculate the effect of nearby mass on the orientation in which particle-antiparticle virtual pairs arise. I assume that they will preferentially arise and persist longest in the orientation that requires the least amount of energy. We might need another Feynman to tackle the quantification of vacuum field polarization.

And if ATHENA shows no such difference, to one part in 10^4 (say)? Would that be the end of your idea?

Answering my own question (assuming it were my idea): NO WAY! All that would tell you is the effect is smaller than {insert quantification here}.

 

[turbo]

Excellent! Now, working backwards (from the size of the observed anomaly), what does that tell you - the ideas author - about the magnitude of the effect?

As for magnitude of effect, when the Pioneer probes were at about 70 AU the measured "error" in their positions was about 400,000Km, so the proportion of error (in 10,471,850,900Km) is .0000383. This means that EM is returning at an average speed of 11,360m/s faster than predicted by the standard model's invariant speed of light of 3x10⁸m/s. If we believe that the density of the quantum vacuum falls off in a linear fashion, light travels 22,720m/s faster out at 70 AU from the sun than it does here. We know, however that gravitation on small scales (solar system, for instance) behaves according to the inverse sguare law as a really good approximation, so we should expect that the density of the quantum vacuum (responsible for mass, gravitation, and inertia in my model) follows a similar relationship.

Don't you now have a basis for extrapolating? When you do that extrapolation, what is the expected size of the effect, for all other deep space probes? How do those expectations compare with what's observed (mostly null)? Can we extrapolate from the Pioneer anomaly to predictions about MACHO and OGLE microlensing events (esp caustic crossings)?

Other probes are affected as well. Galileo and Ulysses show effects similar to the Pioneer probes, but the nature of their stabilization can mask the effects and make it hard to quantify.

 

[Nereid]

As for magnitude of effect, when the Pioneer probes were at about 70 AU the measured "error" in their positions was about 400,000Km, so the proportion of error (in 10,471,850,900Km) is .0000383. This means that EM is returning at an average speed of 11,360m/s faster than predicted by the standard model's invariant speed of light of 3x108m/s. If we believe that the density of the quantum vacuum falls off in a linear fashion, light travels 22,720m/s faster out at 70 AU from the sun than it does here. We know, however that gravitation on small scales (solar system, for instance) behaves according to the inverse sguare law as a really good approximation, so we should expect that the density of the quantum vacuum (responsible for mass, gravitation, and inertia in my model) follows a similar relationship.

Hmm. Perhaps I haven't really understood this (wouldn't be the first time ).

At ~70au, we have ~40 ppm, in the 'speed of light'.

In your idea, the 'speed of light' is related to the (local) vacuum density, which in turn is proportional to the (local) gravitational field (strength).

Whatever the strength of the gravitational field at 70au, we can test the effect by scaling other, well-understood, gravitational field environments wrt this '70 au' benchmark.

Specifically, we can probe the relationship here on the surface of the Earth, all kinds of locations with lower strengths (throughout the solar system), and (maybe) a few with higher strengths (e.g. Galileo, as it plunged into Jupiter; SOHO comets, as they come close to the Sun; light, coming from the surface of a white dwarf; radio waves, in the vicinity of binary pulsars; ...).

If one does this kind of analysis - even at an OOM level - what does one find, wrt this 'EM propogation through a (machain-modulated?) vaccuum'?

 

[turbo]

Hmm. Perhaps I haven't really understood this (wouldn't be the first time ).

At ~70au, we have ~40 ppm, in the 'speed of light'.

At about 70 AU, the measured distance to the probes (assuming EM propagates at an invariant 3x10⁸m/s) was 400,000km. This is an error of about 40ppm in the average propagation rate of the EM along its entire path.

In your idea, the 'speed of light' is related to the (local) vacuum density, which in turn is proportional to the (local) gravitational field (strength).

Yes, EM propagates more slowly through denser media. EM waves are also bent when they encounter density gradients in their propagaating media that are not perpendicular to their wave-fronts. Both of these concepts are key to classical optics. As an optician, I require that in my model, EM waves have a medium through which to propagate - no massless photons hurtling along curved geodesics.

Whatever the strength of the gravitational field at 70au, we can test the effect by scaling other, well-understood, gravitational field environments wrt this '70 au' benchmark.

Specifically, we can probe the relationship here on the surface of the Earth, all kinds of locations with lower strengths (throughout the solar system), and (maybe) a few with higher strengths (e.g. Galileo, as it plunged into Jupiter; SOHO comets, as they come close to the Sun; light, coming from the surface of a white dwarf; radio waves, in the vicinity of binary pulsars; ...).

If one does this kind of analysis - even at an OOM level - what does one find, wrt this 'EM propogation through a (machain-modulated?) vaccuum'?

Galileo, NEAR, and Cassini data also show signs of the effect according to:

http://www.planetary.org/news/2005/pioneer_anomaly1_0510.html

It will be interesting to see what can be uncovered from the earlier Pioneer data, too, assuming it can be successfully transferred to more usable media for analysis. Charting the shortened EM return time in that data could be a direct measure of the refractive index of the quantum vacuum surrounding our Solar system.

 

[selfAdjoint]

Yes, EM propagates more slowly through denser media. EM waves are also bent when they encounter density gradients in their propagaating media that are not perpendicular to their wave-fronts. Both of these concepts are key to classical optics. As an optician, I require that in my model, EM waves have a medium through which to propagate - no massless photons hurtling along curved geodesics.

Isn't this a private theory? Shouldn't it be treated like any private theory on PF?

 

[Jonny_trigonometry]

to my knowledge, that is the accepted theory. GR predicts it right? GR deals with energy density of space, therefore this "private theory" is just a different take on GR, they both use the same relation of energy density. I haven't studied GR formally though, so I'm probably wrong.

I would like to see a theory that predicts the speed of light to be constant in a referance frame that sees no change of gravitational energy per unit volume, but when there is a big enough change (i.e. over a very large distance like the distance between the sun and the pioneer space probe) the speed of light is not constant throughout that given frame. The lower the gravitational energy per unit volume, the faster the speed of light as compared to a region of much higher gravitational energy per unit volume. If you suppose that during the big bang, there existed the highest gravitational energy density, then every frame further from the center of the big bang allows light to travel faster than how fast it can travel in the center. This would explain why there is a sphere of galaxies surrounding the central void of the universe, it's because our frame is moving faster away from the center than the light is moving away from the center. Light "accelerates" from higher gravitational potentials to lower ones.

Can light be accelerated? Experimental evidence shows that gravity bends light (if the light path goes close enough to a strong gravitational source), in other words, light can be accelerated. However, in the process, since its speed is constant, this tells us that the light itself is not speeding up, but the space around it is more “dense” with energy, and so space-time is contracted within a strong gravity field more than it is in a weaker gravity field. so it's really not the light accelerating, it's space-time that is getting bigger than the space time in the higher potential.

In our frame and grav energy density, a cubic meter is a cubic meter, but when measured in a much higher grav potential (from our frame), it's a fraction of a cubic meter as measured in our frame, but if you were in that same higher grav potential, you would measure it to be a cubic meter because there is no difference in grav energy density where you are measuring, just as when you measure a cubic meter in the original frame you started at.

 

[turbo]

Isn't this a private theory? Shouldn't it be treated like any private theory on PF?

Treating the optical effects of the fabric of space in light of classical optics may seem like a private theory to you. It is not. The concept of an all-pervasive ether was embraced by lots of early physicists, and was initially rejected in the 20th Century, only to be later re-embraced by Einstein and Dirac. You may have missed the earlier references to the necessity of an "ether" or fixed frame of reference in the links I posted by both men - I encourage you to read those and consider the ideas. The thought of velocity, acceleration, spin, etc being "real" without reference to a "real" reference frame is a problem that they had to address. The reference frame HAS to be real. An ether (frame of reference) must exist, or these qualities (all relative to SOMETHING) cannot exist. Mach expressed this as if they were the physical motions of a body relative to all the other bodies in the Universe. Einstein categorically rejected this action-at-a-distance interpretation, and insisted on a local, dynamical ether.

Andrei Sakharov also came to appreciate this concept, and was perhaps one of the earliest to express the opinion that the interaction of matter with the all-pervasive quantum vacuum was the source of all mass, inertia, and gravitation. This was hinted at in Einstein's later work, but never came to full fruit. Understanding the optical qualities of the vacuum may allow us to quantify gravitation on galactic and cluster scales, where GR breaks down and requires the ad-hoc insertion of dark matter and dark energy so the Standard Model can remain predictive.

You may choose to disagree with the my interpretation of how these optical effects occur, but surely the "massles photons following geodesics in curved space-time" concept needs some bones under it, especially in light of Einstein's comments in the 1920s and 1930s about the necessity for an ether and that matter is only a player on the stage of space and emerges from it.

"Empty" space is not empty, and it is not a non-entity. The universe is likely VERY simple at its basis, and its complexity arises from interaction, with basic rules that are the same EVERYWHERE and EVERYWHEN, else the U would not be even the sightest bit homogeneous and isotropic (even excluding local clumpiness). The Standard Model gets more and more complex as it matures, with more and more entities tacked onto it to protect the integrity of "accepted" results. I wish everyone could attend at least one or two of Rocky Kolb's lectures and pay a bit of attention to see if their complacency with regard to this trend is shaken at least a bit.

These ideas (the quantum vacuum is polarized/densified by the presence of matter, the vacuum field is responsible for the optical effects of "gravitational lensing", and interaction with it endows matter with mass, inertia, and gravitational attraction) will eventually be proven. Probably not until countless millions of dollars have been spent chasing the graviton, the Higgs boson, the supersymmetrical particles, etc, but it will happen.

I came to this field late in my life, and only after modeling astronomical lensing effects in terms of classical optics did I realize that we need a model for how "empty" space can act as a refractive medium. As I researched papers and chased citations, it became obvious to me that it is common practice in physics to treat "empty" space as if were nothing, and as if it could have no possible effect on gravitational attraction and EM propagation.

This seems to be a HUGE disconnect between GR and quantum theory (which is pretty much nailed down) that claims that the observed expansive force of the quantum vacuum is 120 OOM too large to be our cosmological constant and that the observed gravitational equivalence of that energy is 120 OOM too small to account for the fact that our universe has not been smashed to the diameter of a few thousand Km. If both of these are true, both must be dynamically balanced features of the SAME field, since small imbalances in either field would have either exploded or squashed many parts of our universe, giving rise to lots of non-isotropic and non-homogeneous behavior.

Nereid thought (as Space Tiger expressed early on) that this thread was more appropriate for the Quantum Physics forum and it was moved here. If you wish to have it closed, fine. Have at it.

 

[Jonny_trigonometry]

I agree with you Turbo-1, could this pry into QM with a hidden variable type theory?