asserting a retarded effect
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Originally Posted by tusenfem
I am not sure, but has it not been shown that there cannot be a retardation in gravitiation? IIRC in that case the whole solar system would be unstable, and we would not be here.
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Quote:
Originally Posted by nutant gene 71
Thanks tusenfem, I think this is correct, that gravity potential cannot have a retardation, or else orbital mechanics would be jeapordized. I believe it was Van Flandern who estimated that gravity U is much faster than light c, per this speed of gravity paper: "Conclusion: The Speed of Gravity is > 2x10^10c," per Van Flandern.
If so, Aspden's paper on Pioneers 10/11 (referenced by Utad3 above) may explain the 'loss of energy' but perhaps not for the reason of gravitational retardation; rather it might be 'for reasons that mimic it only. Aspden says in his paper:
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Thank you tusenfem for having raised the issue on the retardation effect, and for your continued interest in spite of an earlier not so polite comment of mine, and nutant gene 71 for your detailed approach and explanation.
I am no expert in physics and maths, however from my perspective those two fields, as central as they may be to our quest for knowledge, they are not the only available tools to acquire understanding of the same surrounding world in which we live.
As such, comparing to what I have been able to learn [not in physics and maths] the central aspects of Dr. Aspden's theories are correct, that is, in accordance with reality [as I am able to grasp it, and other seekers for sure far better than me]. Taking into consideration the immense aspects of Nature that are needed to take into account when creating a theory intended to describe how Nature works, and also the amount of knowledge in various fields that the individual must previously gather in order to start such an enterprise, it is reasonable to assume that one individual in an always short physical lifetime will not be able to include and develop on every aspect of Nature, or that such individual may even interpret minor aspects in a not entirely correct manner [however, as a carefull study of history can show, the enhancement of the knowledge of particular aspects is usually left onto other individuals continuing the path initiated by such pioneer individual].
All in all, not being myself expert in these fields and therefore not being able to discuss them in a technical manner, please allow to quote, like if here in an humble "Advocatus Dei" position, a passage that I found about what the author, Dr. Aspden, has to say about how gravitational action asserts a retarded effect, being a central tenet of his exposition about the Pioneer 10/11 gravitational anomaly; I leave it open to discussion if possible or if any expert might be willing to explain it or to counter argumenting, I'll do my best to understand the perspectives hereafter presented:
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The Debate
The reference to the ‘speed of gravity’ is itself something that needs definition. If one considers the speed of light, at least one can interrupt the light beam at a distance from the point of measurement and so relate time and distance as needed to make the measurement. Gravity as a force exists given the existence of a source body and we really have no way of turning that force on and off. All we can do is to move the body itself and then the question arises as to whether the gravitational field shares that motion as if rigid (instantaneous action) or adjusts to the motion with a time delay.
Keep in mind that there is a world of difference in physics as between the notional retardation of the action of a force such as gravity and the delay involved in gravitational potential energy redeploying in the field system which envelops the mass involved. The reader, in yielding to theoretical notions, has to decide whether to think in terms of force or in terms of energy, whereas Mother Nature does not ‘think’ but simply ‘acts’ by a process of adjusting the distribution of the energy in the system to optimise action leading to a minimum energy potential state.
If the motion of a planet around the sun were truly a circular motion with the planet’s orbit having a constant radius, then the mutual gravitational energy potential between sun and planet would surely be constant as no energy is being transferred to cater for changes of kinetic energy by the two interacting bodies. If, however, there were to be a cyclical change of that radius, as applies for elliptical orbital motion of the planet, then there would be energy transfer to and from the planet drawing on, or replenishing, that gravitational potential resource. Now, in the context of this situation, what is meant by ‘speed of gravity’? Gravity does not move, so are we referring to the speed of energy that is traversing between planet and the gravitational field system? Then one must ask where that potential energy is seated as it can hardly be that it sits at the Sun’s centre and to apply the proposition that the energy we associate with gravity travels at the speed of light we need to know where it sets out from in its journey in order to reach the planet and resettle as it adds to the kinetic energy of that planet.
As to the basic orbital component of circular motion, the radius is determined by a balance of centrifugal force and the force of gravity. The balance is an unchanging quantity and if ‘gravity has a speed’ is this something that was only a factor when the solar system was first created or is it somehow something that affects the planet’s motion on an ongoing basis?
The history of this subject tells us that, if we assume the circular component of orbital motion is not affected by the ‘speed of gravity’ but the radial component of motion is so affected, then the radial period of the oscillations will be slightly retarded in relation to the orbital period. This explains why the orbit is subject to a slow progressive advance of its perihelion, something observed and particularly noticeable in the case of planet Mercury.
Indeed, to get the theory to fit what is observed, namely the 43 seconds of arc anomalous advance of perihelion per century, the speed of that radial gravitational retardation effect has to be deemed to involve the speed of light. Gerber in 1898 (Zeitschrift f. Math. u, Phys., 43, 93), in explaining this 43 second of arc advance per century, assumed the gravitational action to have that speed of light limitation.
Readers who regard Einstein as the genius who discovered why the planet Mercury has such an anomalous motion should take note that Gerber’s paper was published 18 years before that of Einstein. Gerber’s formula for the anomaly was exactly that which later appeared in Einstein’s paper. Gerber’s paper was entitled: ‘The Space and Time Propagation of Gravitation’ and, though not published until after Gerber’s decease, a second paper repeating and expanding on Gerber’s analysis appeared in January 1917 in Gerber’s name in the same German scientific periodical: Ann. d. Phys. in which Einstein’s 1916 paper had appeared. It was obvious that there was concern that Gerber’s contribution had been ignored and there was then onward debate as Seelinger drew attention to a mathematical flaw in Gerber’s analysis. Oppenheim responded, stressing that the issue of finite speed was still open, but Seelinger reasserted his position to ensure that his arguments were not eroded by Oppenheim’s views. (See: Ann. d. Phys., 52, 415; 1917: 53, 31 & 163; 1917 and 54, 38; 1917).
That debate revealed the difficulties of picturing how gravitational action asserts a retarded effect, given that one can hardly expect the flow of energy to be along a pencil thin line drawn between Sun and planet and given that point above that one is not even sure where the energy that is fed to the planet is seated before it sets off on that journey. However, one can be certain that somehow the speed of light is a governing factor and that what was needed was the proper interpretation of that observed 43 arc-second value to gain insight into the physical action.
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The Way Forward
To reach a position on common ground with that of physicists familiar with Einstein’s theory I will proceed by making an assumption and I will show how this leads directly to the formulation of Einstein’s law of gravitation. This should be seen as verification of that assumption. Then I will show by separate aether-based theory that the formulation governing light ray deflection arises from the effect of gravity upon the refractive index of the aether. The inference is that, whereas Einstein’s theory explains the perihelion anomaly and light ray deflection by the same modification of the Newton’s law of gravitation, the physics of gravitation requires two separate theoretical foundations for these two phenomena, because there is no analogy between planetary mass and the electromagnetic wave.
I note, however, that before leaving this chapter I will discuss the fascinating topic of whether gravity is an electrodynamic phenomenon, as assumed so far by those who seek a unified field theory, or an electrostatic phenomenon as implied earlier in this work.
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[End of Chapter Footnote]
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All I say is that the speed of gravity, meaning energy in transit owing to change of relative position of Sun and planet does travel at speed c, but, as to the effect Jupiter has on the deflection of the signals we receive from
a quasar, this concerns energy deployment as between Jupiter and the aether through which those signals travel and, whatever the answer, I cannot see how Einstein’s theory could thereby be proved.
in The Law of Gravity (Chapter 5), The Physics of Creation, 2003
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Cheers.
P.S.: I'm aware my written English is still far from perfect 
Last edited by Utad3 : 29-March-2007 at 02:11 PM.
Reason: adding relevant quote from 'End of Chapter Footnote'
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