Tom Roberts" writes:
[Roberts]: In the model of GR, gravity does not propagate at all, but
changes in gravity propagate with speed c.
That is directly in contradiction to experiment and observations. Binary
pulsars are an obvious example, as I demonstrated (without any dissent) in
Reference B below. But even the simplest orbit computation program can show
the same thing. If you use light-time-retarded positions of bodies to
compute orbits, the computed orbits are open spirals, in contradiction to
observations.
But you've obviously never done the experiment yourself, or have used
only propagation delays in the potential field, which are irrelevant for
orbit computation. See Reference (C).
There is no way known to any person on this planet to avoid the
conclusion that gravitational force propagates c without invoking some
kind of physical miracle, such as an effect without a cause or the creation
of new momentum out of nothingness. Mathematical relativists don't seem
bothered by such miracles. Meanwhile, real world physicists know they must
not invoke miracles in their theories because that makes them
non-falsifiable, and therefore unscientific. [See Reference E.]
[Roberts]: The GR model agrees with all these "evidences", and indeed it
accounts MUCH more accurately than the Newtonian model for measurements in
the solar system (including the perihelia of Mercury and other planets,
the Shapiro time delay, the bending of EM radiation by the sun, the
operation of the GPS, the frame dragging measured by the LAGEOS
satellites, etc.).
True but irrelevant because GR is a field theory and describes only the
field. The gravitational potential field causes all the effects on your
list. But it does not cause ordinary orbital motion. Nor do the field
equations describe ordinary orbital motion. To get that, one must take a
gradient of the potential (or its equivalent) to get what you like to call
an "approximation" theory. In simple, classical physics lingo, that process
develops an expression for the 3-space (Euclidean) acceleration of bodies in
coordinate time, which gives the orbital motion, which is then compared
against astronomical observations made in Euclidean 3-space using proper
time clocks.
Try computing an orbit with GR just once in any system with at least two
significant masses, and you will discover that you cannot do it without
adopting near-infinite gravitational force propagation speed between bodies
applying forces to one another. Then the dawn will come, and you will
finally understand what the "speed of gravity" issue is about.
[Roberts]: it is MUCH better to discuss models and their agreement with
experiments than to discuss MODEL-DEPENDENT quantities like "speed of
gravity".
The "speed of gravity" is not a model-dependent concept except at the
level of parts per 100 million, any more than "perihelion motion" is
model-dependent. Its simple meaning is: When a source mass accelerates, the
speed of gravity is the ratio of the distance of a target body to the time
elapsed before the target body responds. And every known experiment measures
that elapsed interval to be zero within experimental error, making the speed
of gravity c and approximately infinite.
Relativists like to redefine the concept to refer to the speed of
changes in the gravitational potential field, which everyone agrees is c.
But that refers to gravitational waves, and avoids the issue of the
propagation speed of gravitational force for determining the ordinary
orbital motion of two masses around a common center of mass. One must either
give up the causal link to a source mass, or agree that the force propagates
from the source mass to the target body faster than c.
Tom Van Flandern does not understand the real issues, and uses egregious
PUNs to promulgate his claims. In particular, what he calls "speed" is not
what anybody else would call "speed". The experiments he cites do NOT
measure speed (usual meaning), and their actual measurements are fully
consistent with GR, in which nothing propagates faster than c.
Quit making up nonsense. The published papers are in references (A),
(B), (C), and (D) below. "Speed" has its unambiguous, classical meaning in
all of them, as the editors, reviewers, and readers have all understood.
Where are your publications on the subject?
[Juan]: For calculations of orbits we have to use the actual positions of
bodies and not the perceived locations.
[Roberts]: True in Newtonian mechanics; irrelevant in GR.
The comparison of theory with observations is not relevant? How absurd!
You are disconnected from reality.
References:
** (A) "Possible new properties of gravity", Astrophys.&SpaceSci.
244:249-261 (1996);
http://metaresearch.org/cosmology/gr...sofgravity.asp
** (B) "The speed of gravity - What the experiments say", Phys.Lett.A
250:1-11 (1998);
http://metaresearch.org/cosmology/speed_of_gravity.asp
** (C) "Reply to comments on 'The speed of gravity'", Phys.Lett.A
262:261-263 (1999).
** (D) "Experimental Repeal of the Speed Limit for Gravitational,
Electrodynamic, and Quantum Field Interactions", T. Van Flandern and J.P.
Vigier, Found.Phys. 32:1031-1068 (2002); preprint under title "The speed of
gravity - Repeal of the speed limit" at
http://metaresearch.org/cosmology/gr...peed_limit.asp
** (E) "Physics has its principles", in Gravitation, Electromagnetism and
Cosmology, K. Rudnicki, ed., C. Roy Keys Inc., Montreal, 87-101 (2001);
http://metaresearch.org/cosmology/Ph...Principles.asp
Tom Van Flandern - Sequim, WA - see our web site on frontier astronomy
research at
http://metaresearch.org