From: metares@well.sf.ca.us (Tom Van Flandern)
Subject: Re: gravitational radiation one more time
Organization: Whole Earth 'Lectronic Link
Date: Sun, 24 Jan 1993 06:02:26 GMT


carlip@landau.ucdavis.edu (Steve Carlip) writes:

> I finally got hold of the article by Yu that Tom Van Flandern cited last
> month as proof that there was still debate about gravitational radiation
> in general relativity (Astrophysics and Space Science 194 (1992) 159).
> What a disappointment!  I was hoping for an interesting argument, even
> though I expected it to be wrong; instead, I found --- excuse a little
> rudeness --- a paper that was basically silly.

     For an argument that you think is basically silly, a lot of papers
based on similar premises are making it into the literature.  Since our
last discussion I've learned of "Conservation of vector-valued forms and
the question of the existence of gravitational energy-momentum in general
relativity" by J.G. Vargas and D.G. Torr, Gen.Rel.&Grav. 23, 713-732
(1991).  They conclude that the theory has some real problems, not just
unaesthetic inconveniences from the geometrization of the physics.

     Also "Nonexistence of multiple black holes in asymptotically Euclidean
static vacuum space-time" by G.L. Bunting and A.K.M. Masood-ul-Alam,
Gen.Rel.&Grav. 19, 147-154 (1987), argues for the conclusion in their
title.  This paper also cites mathematical problems with GR, similar to
those Yu, Vargas, and Tor pointed out.

     I have now also seen another recent publication by Damour and Taylor
containing their clearest statement yet that the binary pulsar does not
prove the existence of gravity waves.  The source is: Phys.Rev.D 45, 1840-
1868 (1992), "Strong-field tests of relativistic gravity and binary
pulsars."  I quote: "However, the omega-dot/gamma/P-sub-b-dot test is a
mixed test which combines strong-field and radiative effects in an
indistinct way, so that one cannot logically conclude, when the test is
satisfied, that both the specific strong-field and radiative predictions of
general relativity have been independently confirmed.  In fact, examples of
theoretically well-motivated theories have recently been constructed [ref.
Damour & Farese] which have the same post-Newtonian limit as general
relativity, and can pass the omega-dot/gamma/P-sub-b-dot test without fine-
tuning, while still differing markedly from Einstein's theory because of
the strong self-gravity effects in the pulsar and its companion.  In
extreme cases the three curves defined by omega-dot, gamma, and P-sub-b-dot
can still meet within the observational precision, while the effective
gravitational constant between the pulsar and its companion differs by as
much as 35% from the usual Newtonian value."

     There seems to be a respectable body of peer-reviewed opinion that
there are still mathematical problems with GR, and that its predictions
about gravitational radiation are not cut and dried.  Unless you or someone
can show clear errors in these papers, I think a cautious, open-minded
position is still in order.  -|Tom|-

-- 
Tom Van Flandern / Washington, DC / metares@well.sf.ca.us
Meta Research was founded to foster research into ideas not otherwise
supported because they conflict with mainstream theories in Astronomy.