On Apr 10, 2011, at 8:26 PM, c_k_raju@vsnl.net wrote:

What happens if you add Wheeler-Feynman advanced effects? - another line of inquiry.

*An interesting line of enquiry. The key difficulty is how to solve the resulting equations. I have been trying to solve such equations in the case of electrodynamics ("Simulating a tilt in the arrow of time", 1995 unpublished conference paper), and I did suggest a technique some years ago, but did not follow it up, though I intend to do so shortly. Hence, the retardation is explicit in the title. *
CK

On Apr 10, 2011, at 8:20 PM, c_k_raju@vsnl.net wrote:

*Dear Jack,*

Thanks for your questions.
Are you sure that Einstein's GR in the post-Newtonian approximation

does not already contain the new terms you use?

*No, I am not sure since I did not do the calculations myself, but the published claim is that the GR frame drag cannot account for the flyby anomaly.*

There would be further difficulties. If oblateness is important, one cannot use the Kerr solution. One could patch an external Kerr-like solution to an oblate object using my method ("Junction Conditions in General Relativity", J. Phys. A: 15 (1982) 1785-97, or its generalisation arXiv:0804.1991), but it seems complicated. *There is no clear-cut statistical way of going from a system of particles to a density in GRT, as there is in classical thermodynamics. Though the galaxy seems a collection of discrete stars a typical relativist would model it using a "fluid". However, the observed mass distribution can be related to the theoretically assumed one only "intuitively". Moreover, as far as I know, no one has actually managed to account for galactic rotation curves in this way.*

Accordingly, I have not yet taken a position on whether or not GRT can account for the effects that are a clear consequence of RGT.

Clearly, RGT is so much *easier* for many-body problems.

Since Lorentz covariance is absolutely essential to [present-day] physics, it seems to me more important to first settle *experimentally* the question of (a) RGT vs Newtonian gravitation, before tackling the question of (b) RGT vs GRT.
CKR