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Jim:

Once again you don't get it.

You say:

Gravitational ripples in spacetime due to changes in the distribution of mass are tidal changes. Two bodies in a stable binary star system are each moving uniformly along their geodesics, and their orbits will produce tidal ripples, but that in itself shouldn’t cause the orbital system to decay. If there is a decaying orbit there is some factor that is slowing the relative kinetic energy (producing a lower orbit), while increasing their relative kinetic energy in the lower orbit. Parenthetically, I’d be very interested in your interpretation of what could be producing the orbital decay. Pulsars are highly magnetic - could the interaction of their magnetic fields be producing a radiation of magnetic energy, and hence, a decay of their orbits? That seems to me to be the most likely explanation. And it would give substance to the prediction of the General Theory without introducing an exotic form of (gravitational) radiation.

First, in the near field (close to the orbiting bodies*), you are correct to talk about tidal effects. The difference is that since General Relativity does not allow gravitational effects to travel at infinite velocity (unlike Newton), there are waves that are set up and propagate away from the system at the speed of light. It is these wave that are referred to as Gravitational Waves, not the near field tidal effects. (You also appear to have totally ignored, or not recognized, my discussion on the difference in how such effects diminish with distance, such that the waves will always dominate at sufficiently large distances.)

(I'll ignore your perpetual confusion concerning orbital mechanics and the energies involved.)

Second, you are correct that if there is a decaying orbit there must be something that is causing or facilitating the reduction of total energy of the system: Energy is "going away" (somewhere). Since all of science has found that energy can neither be created nor destroyed, but can only change form, one will certainly expect that the orbital energy has been transformed into some other form and is, in some way, leaving the system. (Unless we find that the system is heating up, in which case it will eventually leave through electromagnetic radiation in the infrared, etc.)

You are correct that pulsars are "highly magnetic". However, to suggest that the energy is leaving in some form of "magnetic energy" (don't you mean electromagnetic energy?) would "give substance to the prediction of the General Theory without introducing an exotic form of (gravitational) radiation" is to show a complete misunderstanding of the "substance" of the "prediction(s)" of the "General Theory (of Relativity)".

First off, the prediction of gravitational waves, from the General Theory of Relativity, is derived from first principles within said theory, without any electromagnetic fields being involved. Hence, if the observations could be completely explained via electromagnetic effects, this could actually be viewed as a refutation of the General Theory of Relativity!

Secondly, you act almost as if someone concocted these gravitational waves in order to try and explain the decay of such orbits. Yet it's quite the opposite! The prediction of gravitational waves came directly from General Relativity, before any evidence for such had been observed. In fact, it was a prediction that was so far beyond anything one would expect, from our experience with Newtonian mechanics and observational astronomical mechanics, that it was quite controversial. (What?! You mean that "stable" orbits are only an approximation?!)

Jim, face it, this "exotic form of (gravitational) radiation" is inextricably tied to the field equations of General Relativity, and, just as with any dynamics within any form of spacetime that has an indefinite metric (like that of Special Relativity), these waves have a finite speed of propagation (which is really one of the reasons they are "waves", and not just "undulations"). This is why I have asserted that you cannot hold that you don't dispute the field equations of General Relativity, while only disputing interpretations that use "force"-like concepts (and, by extension, and your own assumptions, "energy"-like concepts), if you assert that the predicted nature of gravitational waves are not as predicted by General Relativity. You can't have it both ways!

So, you have but two choices (a "two-choice dilemma", if you will), if you wish to retain any semblance of integrity. You may accept that the General Theory of Relativity predicts Gravitational waves, with their predicted characteristics of causing orbits to decay (thus maintaining that you believe in the field equations of General Relativity, while disputing interpretational issues). Or, you must admit that there is more to your dispute with the General Theory of Relativity than the interpretational disputes you have admitted to thus far.

That's the choices you are left with. That's your dilemma.

Fare well.

David

* "Close" in this case meaning less than about one wavelength of the associated gravitational wave, or any other hypothetical wave that travels at about the speed of light and has a period like that of the objects' motion (their orbital period, in this case).