# Gravitation Discussion Forum

## physicsmyths.org.uk

Comment by William F. Torrance, Jr.
I, personally, am inclined to believe that gravity is only a secondary force, like that of the force of the wind. I believe in the existence of an ether pervading all space, for the reasons explained below. I further believe this ether is dynamic, and descends vertically on to, and in to, the earth, engaged in some dynamic process we have not yet caught on to, but in its vertical descent it causes the effect we call gravity. If this is the case the ether would have escaped detection by the Michelson-Morley team back in 1887 because their equipment (and premises) was orientated for horizontal detection only. They left it up to the rotation of the earth to provide them with all the other possible orientations. However, they missed the vertical possibility. But a steady descending ether still would not have shown up in the type of test they where using.

My reasons for favoring this point of view are the following:

Einstein made a point of letting everybody know that accelerating a body in free space produces the same back pressure as holding a body still against gravity. I fail to see any more mystery in that relationship than in noting that it takes the same amount of steady force to accelerate a body, in still water, up to a fixed speed, say 25mph, as it does to hold a body still in a moving stream of water, moving at 25mph. In the case of acceleration, in an environment where we are plagued with friction, the steady applied force gradually becomes balanced against friction, and we can no longer see the remaining acceleration, which continues as friction. Aside from that lack of visible continued acceleration I see no difference in the mechanics of water, air, and the presumed ether, except that, in the ether the trade off between body (particle) acceleration and frictional acceleration doesn't start to become apparent until the body approaches the speed of light.
You might say that since gravity gets stronger with increasing proximity to bodies it cannot be likened to a stream of water. But a stream of water moves faster when the stream space narrows. Since a flow of ether towards the earth would be approaching a narrower and narrower available transverse cross section of space, it would, also, have to move faster and faster.

I believe the invisibility of the ether has given it a mystery it doesn't deserve. Also, if there is an ether, I would expect it to be at least a little more involved than just a dead sea.

The idea that gravity is not caused by a force between bodies but by a pressure force caused by some kind of background radiation (which is partially shielded by masses) is interesting (I vaguely recall some science fiction where this force could actually be neutralized by shields of a certain material).
Although logically possible (in my opinion), there are certain problems with this model which render it highly unlikely:
in order to reproduce the known law for gravitational interaction, you need not only the 1/r2 dependence (which you would obtain here) but also the proportionality between the masses m1 and m2. This would only be possible if the proposed 'radiation' can penetrate the masses virtually with zero absorption or scattering (extremely optically thin condition), because otherwise the exponential absorption law would produce a significant deviation from the linear behavior.
Some kind of neutrino-like particle might be able to do this, yet as the absorption would have to be so small, the corresponding flux would have to be unrealistically isotropic and homogeneous (if the earth should be kept in its orbit around the sun with the presently known accuracy, the relative anisotropy would have to be many orders of magnitude smaller than a factor 10-5 (the relative spatial angle of the sun as seen from the earth)). This is as good as impossible if this radiation is associated with other physical processes in the universe because the latter is not sufficiently homogeneous.
If on the other hand you assume some kind of metaphysical ether (a property of space itself) in order to achieve the necessary homogeneity, this would, apart from being unsatisfactory as a physical concept, be an untestable theory (the Michelson-Morley experiment does yield a negative result in any case; see the main page under Michelson-Morley Experiment) and you might as well stick with the usual assumption that masses attract each other through some fundamental (probably not further reducible) process.

William F. Torrance, Jr. (2)
Thank you for your reply to my comment on gravity. However, it appears to me that you converted my perspective from a flowing gas basis to a radiation basis. I think these would produce different results. I have since found my basic "boy mechanic" gravitational theory presented on the Internet in a very physics sophisticated way, including the fact that I can't use friction as part of an explanation for the force of gravity. I wonder if you could give his theory a look, and maybe offer a comment. These are the links: Link 1, Link 2.

I had a look at the theory, and I am afraid to say that it merely takes the inconsistent assumption of Relativity that Space and Time are physical objects in their own right a step further. I just wonder what the advantage should be of replacing the mysterious force between masses called gravity by an equally mysterious force between objects and some proposed medium that one can't even see directly. It is not at all so, as claimed in one of the links, that we are in this respect in the same position as the old Greeks and their philosophy about the physical reality of air. The latter has a well defined system of rest and a direct mechanical effect corresponding to the relative speed of objects. Space on the other hand can not have a system of rest as it can not be associated with any physical medium but is merely the void between objects (the assumption of corresponding ether drift experiments that the medium would rest relative to the sun (hence causing an ether drift of 30 km/sec) is very naive and indeed logically flawed). There are in fact further fundamental inconsistencies with the theory: it proposes that the gravitational attraction between objects is caused by the inflow of space into masses and the objects being dragged with them, yet how can the masses both move relative to each other and space with the same speed? Also, how does it explain the case of a mass orbiting another mass, i.e. not falling into the latter at all? Furthermore, the effect should produce a large redshift of solar spectral lines, which is not observed.
The Relativity experiments that the theory mainly quotes as supporting evidence could indeed be interpreted in more conventional ways: the redshift of solar spectral lines could be caused by the electric microfield due to the plasma in the solar atmosphere (I have suggested the same mechanism already for the redshift of galaxies; see the page Plasma Theory of Hubble Redshift of Galaxies) on my site plasmaphysics.org.uk; the apparent ether drift due to the earth's rotation (Brillet and Hall experiment) could be caused by the earth's magnetic field (I have suggested this already as an explanation for the apparent slowdown of clocks in moving aircraft; see the reply to David Cooper in the Relativity discussion forum); the bending of light near the sun could be due to the electric field in the solar atmosphere etc.. All the corresponding experiments involve either directly or indirectly light (i.e. electromagnetic waves) or charged particles (as atoms consist of them) and it is therefore more than likely that it is electromagnetic phenomena which cause the alleged relativistic effects. Additionally, for some experiments one might also have to take into account that the Speed of Light is in fact inconsistently defined in present physics (this may have led for instance to the incorrect conclusion of an anomalous acceleration (slowdown) of the Pioneer 10 and 11 spacecraft as its distance was underestimated (see my page regarding the Speed of Light and Anomalous Acceleration)).

Comment by Amrit Sorli
Gravitational force is immediate, it acts directly via density of physical space. Other three basic forces (electromagnetic, weak and strong nuclear force) are indirect, carried by some particle or wave that is moving through physical space. "Indirect forces" need some time to act, for example: duration of the movement of light wave from the Sun to the Earth is around 8 minutes. For gravitational force to be transmitted between Sun and Earth no time is needed. Gravitational force is immediate.
Above interpretation of gravitation also explains hypothetical gravitational fields that should propagate faster than light: "Modern physics has introduced the concept of "fields", such as charge around a particle or gravitation around a mass. When the particle or mass moves, its entire field moves with it. However, this cannot happen acausally. For example, the mass may cause adjacent parts of its field to move, which in turn move more distant parts, and so on. This is what happens in any rigid body when one part of it is pushed: a pressure wave propagates through it, conveying the push to all parts of the rigid body.
Gravitational force is immediate. It does not propagate through the physical space, it is always there. This property of gravitational field brings new light about experiment of Einstein, Podolsky and Rosen (EPR). This experiment shows that two quantum A and quantum B which have been together and than send in the space in opposite directions "know" for each other in an instant moment. When the spin of particle A is unilaterally changed, an astounding experimental result is that the other (B) particle's spin "immediately" flips of its own accord. Furthermore, the means by which the information of the first spin flip is transferred to the second particle (so that it too can flip) is information which is required to travel faster than the speed of light.

I would agree that, contrary to common opinion, the gravitational force acts instantaneously, but so do all static forces (see my page regarding Retarded Forces which proves that a retardation of the interaction yields different forces in different reference frames moving relatively to each other, which is not possible as it contradicts the definition of a force). You have to think of the static force field as being fixed to the particle and moving with it instantaneously. This does of course not mean that two objects are rigidly connected to each other through their fields. They can still move freely and because of their inertia it takes therefore some time before the movement of one particle causes a visible reaction for the other particle (in this sense, no physical body can be truly rigid simply because it is composed of many particles with space between them, but any movement is nevertheless propagated instantaneously even if only by an infinitesimal amount). Because of this, there is in fact no causality problem with an instantaneous propagation of gravitational (or other static) fields as the latter are not directly observable but only the response of objects to it (logically, causality would anyway be only violated if the effect precedes the cause, which is not even the case for instantaneous reactions; the non-local interaction allegedly demonstrated in the EPR experiments would therefore not be a logical problem as such, but the interpretation of these experiments is rather questionable anyway and may after all indicate a causal connection to a common cause rather than a causal connection between each other (see my Reply to Julian S. on my the Quantum Physics Discussion Page and also my entry on Hidden Variables on the Home page).

On the other hand, light (i.e. electromagnetic waves) does of course not propagate instantaneously as it is not a static force field fixed to a particle but one that detaches from one atomic system and attaches to another atomic system (see also my page about the Speed of Light).

Comment by Mark Mattice
Your discussion on Gravity so far has been limited to disproving any and all possible explanations on why gravity works. We are left with the same problem Newton asked, why does mass attract mass? So far you have dismissed the ideas of space-time curvature and space flow. I also assume the ideas of atomic expansion and rotational angular velocities are equally unsatisfactory, as they are to me. So, what are we left with? Does mass attract mass simply because it is a law of nature, much as your concept of velocity of light not being independent movement through space, but only related to distance and travel-time, or are there other reasonable hypotheses which could explain the mass/mass attraction?

I have one hypothesis which you may be able to dismiss easily, if so I'm hoping for a few other ideas that may explain why gravity exits. My hypothesis is that gravity is actually a residual nuclear force. For example we know that protons attract protons at the atomic scale, this so called strong nuclear force is so strong that it overcomes the coulomb electrical force of like charges repelling. The strong nuclear force is now being called the residual nuclear force as it is a residual effect of the strong interaction between quarks confined within proton and neutrons. If quark interaction can produce a residual nuclear force of nucleons attracting nucleons, then perhaps there is another residual aspect to nuclear forces such that massive numbers of nucleons can attract nucleons on a much more massive scale. The strong nuclear force is said to diminish to zero exponentially as nucleons are separated by a distance of only a few atomic nuclei diameters. If true would discount my hypothesis entirely. What I'm suggesting is perhaps the strong nuclear force doesn't actually decay to zero but to a very small number close to zero. A value too small to be measured at the atomic scale with current technology. This small non-zero residual force between nucleons becomes measurable when large number of nucleons are grouped together at the scale of planets, suns and galaxies. Of course this residual nuclear force of nucleons would be additive so that the larger the number (greater the mass) the larger the force; and proportional to the distance between nucleons or groups of nucleons by (1/r2). Perhaps Newtons law of gravity could actually be derived from such a non-zero residual nuclear force. Or alternatively: show that the gravitational force between nucleons exists but is impossible to measure, at the atomic scale.

I've never seen this idea in print before, and as such may have been discarded long ago for one reason or another. I would appreciate your thoughts on this and also any additional hypothesis on how mass can attract mass.

If one accepts gravity as a fundamental force, then (by the very definition of the word 'fundamental') there is not only no explanation required, but in fact it makes no sense to look for an explanation. So fundamental forces indeed have to be accepted as laws of nature. Of course, one can obviously question that gravity is a fundamental force, but as far as I am aware there is no evidence at all for this. In fact, gravity is probably more fundamental than the other known forces considering the equality of the gravitational with the inertial mass (all other forces are merely associated with masses and their strength does not depend on the mass itself but rather on other properties like charge etc.).
Having said this, I can understand that you question the nature of the strong interaction force, as I think that the assumption of the force decreasing exponentially with distance is conceptually flawed. The exponential decrease rests on the assumption that the strong force is mediated by certain particles (Pions) that have a finite lifetime, but this 'mediation model' is actually circular reasoning as you then would need a further force in order to explain how the mediating particles interact with the nucleons. True fundamental static forces between point masses should in any case decrease with distance like 1/r2, as this simply reflects the geometrical property of space (a surface has 2 dimensions). If there are two 'charges' of the force (like for the electrostatic force), then the distance dependence can be different (for large distance the force of an electric dipole decreases like 1/r3 and for a quadrupole like 1/r4 etc.), but this is then merely a composite behaviour of more than one particle and does not reflect the 'naked' force as such. So the problem is that either you have only one kind of 'charge' for the particular force (in which case the mere 1/r2 decrease would result in a catastrophically strong force many orders magnitude stronger than the gravitational force). If you have different 'charges' on the other hand, then, as indicated, you can get forces decreasing faster than 1/r2 and you might be able to match the magnitude of the gravitational force at a certain distance, but then obviously this would not be consistent with the observed 1/r2 dependence of the gravitational force i.e. for other distances you would not match the latter anymore. So in this sense I would see fundamental problems with your idea. But as I said, I don't really think that an explanation for gravity is needed as there is no evidence of it not being a fundamental force.

Mark Mattice (2)
If I understand you correctly your fundamental objection with the strong nuclear force decreasing into a residual force called gravity is that the strong nuclear force decreases at a exponential rate (approximately 1/r7) when nucleons are separated by about 1 atomic nuclei in distance. The force of gravity however decreases by 1/r2 as objects are separated. That of course is one of the classic observations. What I'm suggesting is that within or near the atomic radius of an atom the strong nuclear force decreases by (1/r7), and after nucleons exceed separation distances of about one atomic nuclei the force becomes greatly reduced and decrease by 1/r2 reflecting the geometrical property of space. Why the change in dependence on the separation distance, I don't know, but could be answered by your assertion that it is a law of nature.
As I understand the strong interaction between quarks the strong interaction actually increases as the distance between quarks are separated, with the force bringing quarks closer together after being "stretched" too far apart. But, quarks never expand past the radius of a nucleon. A completely different dependence on separation distance as the residual nuclear force. And yet the strong interaction between quarks are responsible for the strong nuclear force between nucleons. The strong interaction is considered much stronger than the residual nuclear force, and occurs over a much smaller distance. Why not extend that idea to a force outside the distance of a atomic nuclei; call it the residual of the residual nuclear force, or the second residual of strong interaction, or just call it gravity for short.

First of all, you seem to forget about the electrons, which have a mass as well. Of each few kg of normal matter, one gram or so (i.e. a significant amount) is due to the electrons, and you hardly could invoke the strong force for these.

But more importantly, as I mentioned above already, any 'bare' (i.e. non-composed) force should decrease like 1/r2 simply for geometrical reasons (in the same way as the apparent surface of an object gets smaller with distance according to 1/r2). Forces decreasing faster than that must be composed of particles with opposite 'charges' (in equal numbers) which thus tend to neutralize each other for larger distances (these composite aggregates are called 'multipoles' (e.g. dipoles, quadrupoles etc.)). So if you have already a decrease like 1/r7 at a certain distance, this shows that the overall 'charge' (the monopole field) is zero. It is thus not possible that the behaviour becomes 1/r2 again for even larger distances as this would mean that just by going further away you could 'charge' the aggregate. You might as well assume that an object gets apparently larger with distance. The point is that this contradicts the laws of geometry (so it is not a matter of 'laws of nature').
Again, any force not decreasing like 1/r2 can in principle not be a 'bare' fundamental force but must be a composed force. Consider for instance Hooke's law where the elastic force of a spring increases with extension. This elastic force is quite obviously not a fundamental force but merely a macroscopic force due to the collective behaviour of charges (see my page regarding Hooke's Law in this context). So in this sense, one has to conclude that not only the 'residual strong force' but also the 'strong force' itself is not a fundamental force but a composed force.

So it might be worth thinking about how to explain the strong force, but not how to explain the gravitational force (as the latter exhibits already the characteristics of a fundamental force, i.e. the 1/r2 dependence) .

Question by Mark Kuch
I would be interested in why you think the theories about gravitational waves are flawed. My level of understanding is theoretical and a hobby. I am not a scientist, but have a great sense of curiosity. There are recent claims pertaining to producing very small antigravity effects in the lab. It would only seem appropriate for me to understand as much as I can about gravity prior to delving into antigravity effects. My research thus far pertaining to gravity began fairly recently and hence one of the reasons I encountered your website.
As personal theories go, I am investigating where my logic might be flawed. I will adjust my theory should I find any inconsistency with facts I may have overlooked or failed to consider. Since, you state you think the theories from the postings you referenced are incorrect, I am very interested in identifying the areas you do not agree with and where you see flaws.

First of all, gravitational waves should not be mixed up with the gravitational force (and a hypothetical anti-gravity force). They are formally predicted as a consequence of gravity on the basis of Einstein's field equations, but they are merely associated with the motion of masses and do not affect the gravitational force. Basically, according to General Relativity, they represent propagating fluctuations in the space-time metric which are associated with certain kinds of oscillating mass distributions, somewhat analogous to oscillating charges producing electromagnetic waves. It is argued that these oscillations could then be detected in terms of tiny oscillations of the size of objects here on earth.
The flaw with this theory (in my view anyway) is that Einstein's field equations rest on the concept of a 'curved space' which can be shown to be conceptually flawed (see the 'General Relativity' paragraph on the Relativity page), so gravitational waves are actually theoretically without any foundation. In this sense it must not come as a surprise that they have not been positively detected yet. This does not strictly rule them out of course if another (consistent) theory can be found, but the whole idea seems somewhat implausible in views of an essential difference between gravitational and electric forces: the latter can act statically only over short distances due to the shielding by opposite charges, whereas the gravitational force has an infinite range. In contrast to electromagnetic radiation, there is no reason what difference the presence of gravitational waves would make for the workings of the universe.
(note that I re-edited the 'Gravitational Waves' entry on the home page to clarify these points).

Comment by Dugan King
I saw nothing close to logical in all of those attempts to explain gravity. Gravity does not in any way appear to be a fundamental force but just one of many subsequent effects arising from an ethereal vortex. There is really no such thing as an indivisible particle. We can invent neutrinos, gravitons, gyrons, muons, gluons, duons, puons and so on ad infinitum. The theory of atomism, or the idea that a fundamental particle exists in nature, is seriously flawed. I reject it. There is only the fundamental substance of the Ether which is infinitely divisible. No matter how many times you divide it, it's still Ether. The galaxies, stars and planets of the universe are adrift in an infinite ethereal sea. When at rest, the Ether mimics emptiness. That's because our human sense organs cannot detect the Ether at rest. Our sense organs are like motion detectors. We can only detect the Ether in motion. Ethereal motion is hydrodynamic. It only exists as currents, waves and vortices. The flow of the ether is the fundamental force which creates ethereal illusions such as heat, light, electromagnetism, matter and gravity. Ethereal vortices exist within every level of the infinite microcosm and macrocosm. On our plane of existence, they range from the galactic vortex to the electron vortex. Our Earth is likewise a vortex and we will never unlock its secrets until we fully understand the causes of vortex motion. It requires a talent for deductive reasoning. I believe I have found the principal of unification which includes a plain and simple explanation for gravity, but I will not disclose it here and now. It will be revealed under copyright in an essay I'm preparing on the "Origin of Force." I just happened to be surfing the internet and thought I would drop in with a comment.

As already mentioned in my reply to Mark Mattice above, a fundamental force does not only not require an explanation but is in fact not supposed to have one. If you are saying that gravity is not a fundamental force, then it should be explained in terms of known fundamental forces. Proposing some hypothetical ether which in some unspecified way interacts with matter can not count as an explanation, as it would be at least as mysterious as a fundamental force of gravitation. You would have merely shifted the problem from an unexplained gravitational force to the unexplained force with which the object and the ether interact. If you consider for instance the usual drag force of objects moving in a medium, then this can be explained in terms of the collisions of the atoms of the medium with the atoms of the object i.e. in terms of the Coulomb force and the conservation laws of momentum and energy. The problem with the ether vortex theory (or push-gravity models in general) is that, unlike the usual drag force, you can't base this on any known fundamental interaction force. And if you postulate a new fundamental force just for this purpose, then you might just as well stay with the gravitational force in the first place.
Apart from these conceptual points, push-gravity theories in general and the vortex theory in particular yield actually a number of inconsistencies with reality. Regarding the former, see for instance my reply to William F. Torrance, Jr. above (top of the page). Regarding the latter, I found (in the absence of details of your own theory) an article Principles of the Theory of Vortex Gravitation which quotes the density of the proposed aether as about 10-11 kg/m3. Now this is about identical to the density of the earth's atmosphere at a height of 200 km and the drag associated with this density is enough to let any satellite fall back to earth from this height within a matter of days (see the graphic of the orbital decay of the Solar Maximum Mission satellite) So with this kind of matter density, all satellites (even those at high altitude like the GPS- and geostationary satellites) would have long fallen out of the sky, and interplanetary space probes would drastically come off course. I haven't checked the theory in the quoted reference in more detail, but I reckon that there would be numerous other inconsistencies associated with it as well.

Dugan King (2)
The notion of action at a distance is totally absurd. There has to be a common mechanical connection between two objects if one is to react to the other. We must otherwise write it off as voodoo or magic. Our human sense organs were not designed to detect everything that exists, but we can deduce the reality of the Ether by observing its secondary effects. We can't see or touch or smell the air we breath, but we know it is there. Take it away and we suffocate. If we could take away the Ether that surrounds us, we would completely vanish. You quoted a possible quantity for the density of Ether. I would suggest that the Ether at rest has no measurable density. Density is similar to gravity in that it can only be measured as a pressure differential. When the Ether is at rest, there can be no pressure differentials to give us those subsequent illusions of mass, density, solidity, resistance, weight or gravity. These secondary effects only occur when the Ether is set in hydrodynamic motion. I posit that the Ether exists as the fundamental substance, infinite in space and eternal in time! You stated your premise that if a force or substance is fundamental it shouldn't have to be explained. Well, the Ether can be regarded as that very same unexplainable starting point from which all universal phenomena arise. Even nothingness is a secondary illusion derived from the Ether.

Obviously, one can not necessarily conclude that something isn't there just because we don't see it, but you seem to suggest that even a non-substance (empty space) has substance. This is clearly a logical contradiction in terms. On the other hand, it is not enough just to deduce the existence of something due its alleged secondary effects (for which there are anyway already straightforward explanations). If you want to prove the existence of some substance, then (as in case of the air) you must be able to take it away from a given volume of space and observe the resultant consequences. If you say that this is a priori not possible for the ether, then its existence can never be positively proven i.e. the whole concept is conceptually flawed (you might as well give God as the unexplainable starting point of all universal phenomena; it may be acceptable as a philosophical concept but not as a scientific one).
Anyway, as already mentioned above, postulating a substance which communicates the gravitational force (or any other force for that matter) does not change the situation of having an unexplained force, as then you would have to explain by means of which force the substance interacts with bodies. So now you are stuck not only with an unexplained force but also with a hypothetical substance which can not be proven. So in this situation, it makes clearly more sense to assume that the gravitational force is a fundamental force due to the presence of masses as such (especially given the fact that its strength varies with distance according to the geometrical 1/r2 law (see my discussion with Mark Mattice above)).
It should be also clear from this argumentation that an action-at-a-distance force is in fact the only conceptually consistent form of a fundamental force (so Quantum Field Theory for instance is conceptually flawed for exactly the same reason).

Comment by Richard Rose
The reason why modern physics is completely irrational stems from the theory of gravity and its acceptance. The theory of gravity should have been dismissed when the concept of energy and the conservation of energy and matter was established. Newton made two mistakes in his theory of gravity.
The first was that an object will procede in a straight line unless a force acts on it. Nothing goes in a straight line. What the premise should be is that an object will maintain its energy unless energy is added to it or lost by it.
The second is that there is an acceleration of gravity and to understand this one must examine the interaction of energy and an object. An object will absorb energy or lose energy to equalize with the energy field around it. This is why in orbits where an object is in equilibrium you lose energy (slow down) to gain more energy (increase speed) and add energy to slow down. The energy of the solar system is centered at the sun and decreases by distance. The planets are in equilibrium with the energy field from the sun and so their energy (v2) divided by the distance from the sun d is a constant E for the energy of the solar system. Newton changed this energy unit (v2) divided by distance to an acceleration d/t2. This is like saying that a six inch bolt torqued to 10 foot pounds must weigh 20 pounds.
If you wish to see more of this alternate theory go to my webpage and push button three.

What one has to realize is that in fact the concepts of energy and energy conservation have been developed and only make strict sense in the context of classical mechanics (i.e. for conservative force fields) where they are useful but ultimately redundant concepts (one can for instance calculate planetary orbits without even mentioning the word 'energy' if one strictly integrates the corresponding equations of motion). There is thus no rational reason why the concept of 'energy' (as well as that of 'momentum') should have any general relevance in nature beyond this, and such an assumption leads indeed to theoretical as well as experimental inconsistencies (see my page regarding Energy and Momentum Conservation for more). So as far as fundamental concepts are concerned, it is not the gravitational force which should be questioned here but that of 'energy'.

Question by Bruce Rennie
Have you had a look at any of Prof. Andre Assis' papers on the subject. He submits a proposal that gravity is a "fourth order" effect of the interaction on electrons with protons in a nucleus. In effect a residual electric dipole effect. When I first came across his paper on the subject, it reminded me of the questions I was thinking about in my undergraduate days in the University Of Queensland Electrical Engineering department in the late '70s when studying electrostatics.
Do you know of any researchers who might be looking into this area?