Vern wrote:
Tom Roberts wrote (to TVF)
You keep displaying your rather complete ignorance of GR. Perhaps
you should actually study the theory before attempting to discuss
it.

This whole debate hinges on whether motion in GR is due to geometry
or whether the equations could also represent the description of a
field.

There is such a big PUN in there (on "field") it makes whatever you're
trying to say either tautological or inconsistent.


It was, at first, called a field theory. The geometric
interpretation came later.

Hmmm. Why is it then that Einstein studied Riemannian GEOMETRY in order
to formulate GR? As do all students of GR (except, apparently, TVF).
Indeed, Riemannian GEOMETRY is one of the foundations on which GR is
built. GR was explicitly geometrical from the beginning. The puzzle is
that it is SEMI-Riemannian geometry, and it took a while for the
implications of that to be appreciated.

And like all other fundamental theories we know today,
the Lagrangian density of GR is the curvature scalar
of the appropriate manifold. Curvature is inherently
and quintessentially geometrical.

Just because Tom Van Flandern has a fantasy does not mean you should buy
into it. shrug

There are (at least) two parts to his fantasy:
A) that gravity has been "proven" to travel with speed
c, because the combination of the equations of NG
and an "interaction speed" of c is inconsistent with
observations. The fantasy of this is that there is
no such theory, and GR itself is not at all like that.
Not even close. Indeed the predictions of GR are in
agreement with those experiments, so they are unable
to establish that the "speed of gravity" is c.
B) that somehow his so-called "field interpretation of
GR" can change many of the basic results about GR,
such as being not geometrical, and having a "physical"
"gravitational force" that propagates with local
speed c. The fantasy of this is that interpretations
cannot change the equations of the theory, or properties
of their solutions. Another aspect is that the analog to
"gravitational force" in GR is inherently COORDINATE
DEPENDENT -- since coordinates are imaginary inventions
of humans, no real physical quantity can possibly be
dependent on them. HINT: that's why tensors are so
important to physics in general, and to GR in
particular. In a very real sense, GR taught this to us.


Tom (Roberts) has indicated either that the field version is the same
thing as the geometric version, or that there is no field version,
there is just a geometric version. This issue needs to settled
definitely, as Tom (VanFlandern) is basing his arguments on the field
version and Tom (Roberts) is basing his arguments on the geometric
version.

Not really -- there's no real "issue" here, for people interested in
Science. Tom Van Flandern is "basing" his arguments on his personal
FANTASY, and on some supposed special knowledge he has of "reality" that
tells him how things "actually" work (see my previous post for examples
of such claims of his). Note also that GR most definitely _IS_ a field
theory: the most important field of the theory is the metric, which
describes and determines the geometry (that's how we use those words).

[Yes, there is a remarkable correspondence to a theory of
spin-2 gravitons, as discussed by Feynman and others.
But that is a DIFFERENT theory from GR.]

Just because Tom Van Flandern has a fantasy does not mean you should buy
into it. shrug


Tom Roberts

Pentcho Valev writes:

[Valev]: explain: What is the nature of Halton Arp's "intrinsic redshift"?

Ordinary gravitational redshift. -|Tom|-


Tom Van Flandern - Sequim, WA - see our web site on frontier astronomy
research at http://metaresearch.org

Vern writes:

This whole debate hinges on whether motion in GR is due to geometry or
whether the equations could also represent the description of a field. It
was, at first, called a field theory. The geometric interpretation came
later. Tom (Roberts) has indicated either that the field version is the
same thing as the geometric version, or that there is no field version,
there is just a geometric version. This issue needs to settled definitely,
as Tom (Van Flandern) is basing his arguments on the field version and Tom
(Roberts) is basing his arguments on the geometric version. Could a
referee be used to pose this question to, to settle the debate?

The "debate" consists of observations, experiments, reasoning, and
citations I've used, against unbacked opinions Tom Roberts has used. I'm not
sure what more you might want to see to make up your mind.

As to whether where is a field version or not, does Nobel Laureate
Richard Feynman count as a knowledgeable physicist? In Feynman Lectures on
Gravitation, R.P. Feynman, Addison-Wesley, New York (1995), Section 8.4, p.
113, he says: "It is one of the peculiar aspects of the theory of
gravitation, that it has both a field interpretation and a geometrical
interpretation. ... the fact is that a spin-two field has this geometrical
interpretation: this is not something readily explainable -- it is just
marvelous. The geometrical interpretation is not really necessary or
essential to physics."

As to whether the geometric interpretation is the same as the field
interpretation or not, yhe two are essentially the same mathematically, but
not the same in the underlying physics. My paper with J.P. Vigier argued
that the geometric interpretation is now falsified on physical grounds
because it provides no cause to initiate new 3-space motion and no source
for the new momentum. This passed three referees at the journal, not to
mention hundreds of readers who have written about various aspects of the
article in the six years since it appeared.

The point is important. If a small body is at rest in a gravitational
field, "curvature" of anything cannot make it begin to move. It will just
stick there on the side of a potential hill forever, until a force acts. The
"rubber sheet" analogy only works in our imaginations because we imagine
gravity under the rubber sheet making the small body start to roll. But if
there is no gravitational force, just curvature, then the small body cannot
start to move because there is no preferred direction for it to move in, and
no momentum being added to it. The geometric interpretation fails precisely
because it has no forces in it. -|Tom|-


Tom Van Flandern - Sequim, WA - see our web site on frontier astronomy
research at http://metaresearch.org

On Sep 26, 9:24*am, "Tom Van Flandern" wrote:
Pentcho Valev writes:
[Valev]: explain: What is the nature of Halton Arp's "intrinsic redshift"?

* * Ordinary gravitational redshift. -|Tom|-

Tom Van Flandern - Sequim, WA - see our web site on frontier astronomy
research at http://metaresearch.org

OK that is a reasonable explanation. Then we remember how the
frequency varies with the gravitational potential V (experimentally
confirmed by Pound and Rebka):

f'=f(1+V/c^2)

We also remember the formula:

frequency = (speed of light)/(wavelength)

and we ask: Does the speed of light vary with the frequency, in
accordance with Einstein's 1911 equation c'=c(1+V/c^2), or is it the
wavelength that varies with the frequency (as half of today's
Einsteinians claim)? If Einstein's 1911 equation is correct, then
perhaps light leaves the gravitational field of the emitting body,
continues its journey and in the end reaches the observer having a
reduced speed all along?

Pentcho Valev

Tom Roberts writes:

[Roberts]: in the domain where NG is valid (e.g. here on earth, most of
the solar system), the predictions of GR and NG are experimentally
indistinguishable.

[TomVF]: So you agree that in most of the solar system, GR is
experimentally indistinguishable from NG, a theory with infinite force
propagation speeds that gives strongly spiral orbits if the force
propagation speed is reduced as low as c?

[Roberts]: Why do you keep bringing up a FANTASY theory? There _IS_ no
such theory as "NG with force propagation speed reduced as low as c".

As even you know, the propagation speed of gravitational force in
Newtonian gravity (NG) is infinite. And as every student of celestial
mechanics knows, when the propagation speed is reduced in NG (with no other
changes), orbits become open spirals instead of closed ellipses.

There is no shame in the fact that you are totally unfamiliar with
celestial mechanics. No one knows everything. But there is shame in your
making false statements that pretend you know something about celestial
mechanics when in reality you do not. And you make yourself look pompous and
uneducable to everyone reading this who does know a little celestial
mechanics.

The original point is that it is impossible to have a system in which
gravity is the only operating force, yet have that force propagate at less
than infinite speed and still have closed orbits. Therefore, when
relativists say that GR reduces to NG in the weak-field, low-velocity limit,
there are only two possibilities: (1) the claim is false; or (2) GR becomes
a theory with infinite force propagation speed in the weak-field,
low-velocity limit.

Kindly recall the definition of "force" in 3-space so we don't just play
word games.

[Roberts]: In GR, nothing that carries energy, momentum, or information
can travel faster than c. This is a rigorous result based on the structure
of the ACTUAL THEORY.

That *belief* of yours is definitely NOT a rigorous result based on the
structure of the actual theory, and you cannot defend such a claim that it
is.

I have shown repeatedly in my papers that there are two versions of the
relativity of motion with the same mathematics: special relativity (SR) and
Lorentzian relativity (LR). GR was supposed to based on SR, but in reality
is based on LR. The difference is that, in SR, the Lorentz transformations
apply both ways between any two inertial frames, whereas in LR they apply
only one way, from the local gravitational potential field frame to the
frame with a relative motion. GR uses the Lorentz transformations only one
way, so it is based on LR rather than SR. SR has the speed limit you
describe, whereas LR does not. And that is where the "rigor" in your claim
fails.

Even if what I just said contained some not-yet-identified error, it is
still a fact that LR explains all the same experiments as SR and has never
been falsified. So there is no longer reason to believe that the speed of
light is any more of a universal speed limit than the sound barrier proved
to be.

[Roberts]: As I keep saying, GR itself has no "propagation speed" for
gravity.

You are playing word games. Our discussion is about physics, not math;
so our context is 3-space, the physical reality in which astronomers make
observations. In 3-space, the definition of "force" is the time rate of
change of momentum, where momentum is the product of mass and the velocity
vector. The "velocity vector" producing the momentum change is the
propagation speed and direction of the force that causes an orbiting target
body to orbit, continually changing its momentum.

Let's stick to reality, not some mathematical fantasy "4-space" world.
All kinds of weird things can be claimed of 4-space, but many of them have
no counterparts in the real, observable, testable 3-space world.

[Roberts]: But if you really want to consider that speed, you can look at
the linearized APPROXIMATION to GR. In this approximation, the equations
of motion are solvable with a Green's function that clearly involves the
source at a retarded time. As in electrodynamics, this is easily
interpreted as "gravity propagating with speed c".

More word games. No one disputes that changes in the gravitational
potential field propagate at speed c. This has nothing to do with ordinary
gravitational force that causes elliptical orbits. It relates only to
light-bending, perihelion advance, and other small (c^-2) GR effects that
arise from the potential field (or whatever you want to call it in 4-space).

[Roberts]: for any situation in which that extrapolated position is
indistinguishable from the instantaneous position of the source, the two
theories (NG and this approximation to GR) give indistinguishable results.

I see. If you don't want to answer, just change the question. However, I
was talking about simple orbital motion of a very small target body around a
fixed source mass. The instantaneous and retarded source positions of the
source mass are well-distinguished for target bodies with ordinary solar
system speeds. Yet the only way to predict the correct orbits is with zero
retardation of gravitational force in both theories. So your dilemma
remains, even if you are in denial about it.

[Roberts]: the reason you are so confused is quite simple: you use your
FANTASY theory (i.e. NG with finite speed of propagation), rather than the
actual equations of GR, or the actual equations of this approximation.

Everyone but you seems to know about NG with force propagation speed
reduced. Why is that?

[TomVF]: Why has no one anywhere in physics attempted to do an experiment
to learn if the force between *accelerating* charges propagates at speed
c or faster?

[Roberts]: There have been literally ZILLIONS of experiments that show
that the speed of radio waves is c. They are detected by the
electromagnetic forces on the charge carriers of the receiving antenna,
generated by the accelerating charge carriers in the transmitting antenna.

If you have no answer, you just change the question. And play word games
while doing so.

There are no Coulomb forces in radio waves. All electromagnetic waves
travel at speed c. Coulomb forces (a type of electro-*dynamic* force)
propagate c.

[TomVF]: It's a pretty important matter, and many physics texts read as
if the experiment was done and the result is known.

[Roberts]: Yes. It is.

I was talking about reproducing the Sherwin-Rawcliffe experiment showing
that the Coulomb force between charges propagates faster than c. You didn't
like answering that challenge, so you switched to radio waves and answered a
totally different question.

Is this "change the question" tactic working for you? I doubt it is
fooling any of our readers.

[Roberts]: There is no "interaction speed" anywhere in either the
equations of GR, in their derivation, or in their solution(s). This is so
because there is no "interaction" -- gravity is geometry in GR, and the
source mass/energy and the geometry evolve in a coordinated manner (as
described by Einstein's field equation). Any test particle responds to its
local geometry, not to any sort of "interaction" with the source
mass/energy.

The geometric interpretation of GR is now off the table precisely
because it invokes just such magical, causeless effects as you describe. In
3-space, curvature alone cannot initiate motion in the absence of a force.
And the force must be causally connected to the source mass.

[Roberts]: You keep displaying your rather complete ignorance of GR.
Perhaps you should actually study the theory before attempting to discuss
it.

Hmmm. This thread is displaying lots of ignorance. I back up my
statements with observations, experiments, logical arguments, and/or
citations. You simple bluster on and hurl insults. Is *that* working for
you?

[Roberts]: at each and every point in the manifold the value of the metric
depends ONLY on the values of the metric and the energy-momentum tensor in
an infinitesimal neighborhood of the point in question within its past
lightcone. This is what differential equations are, and "causality" in GR
limits the dependence to the past lightcone.

You are thinking only of the math. In physics, something must contact
something else to produce any action. If the action source or cause is as
you describe, but the action target is moving, that necessarily affects the
resultant direction of the action.

If you deny this basic physics, you are the one in fantasyland. If you
accept it, then it follows that the resultant direction of the action is
affected by the retarded direction of the source, which is why angular
momentum cannot be conserved if the retarded direction is confined to the
lightcone.

[Roberts]: Do not babble on about "interpretations" of GR. That is just
more of your fantasy.

Well, I cited Einstein, Dirac, and Feynman as sharing my "fantasy". Who
do you have in your corner?

[Roberts]: And I point out that here you make reference to "basic physics"
when you really mean "God" or "TVF's personal channel to God", or "TVF's
personal channel to 'reality'", or some such. Those of us doing science
can only understand reality through formulating and testing physical
theories.

I advocate "no effects without a preceding cause" and "no creation (of
new momentum) from nothing". You advocate that both should be allowed. My
principles require no miracles. Yours are both miracles.

So which of us must have a "personal channel to God"? Congratulations.
:-)

[Roberts]: You have a direct channel to "reality"????

Uh . yes. It is called observation, experiment, and reasoning.

[Roberts]: The rest of us are limited to interpreting reality via
THEORIES.

We all do. But some of us constrain our theories to those that are
physically possible (i.e., require no miracles), and some of us do not. That
is what led Michael Kroyter to quip: "Physics is about everything one can
see, hear or think about in the whole world. Mathematics is about
everything!"

[Roberts]: the analog to "gravitational force" in GR is inherently
COORDINATE DEPENDENT -- since coordinates are imaginary inventions of
humans, no real physical quantity can possibly be dependent on them. HINT:
that's why tensors are so important to physics in general, and to GR in
particular. In a very real sense, GR taught this to us.

This belief in "covariance" (coordinate independence) is charming but
unscientific. Newtonian gravitation is coordinate-dependent, yet this poses
no problems for doing orbital mechanics or comparing theory with
observations. There is no law of physics saying that reality must be
covariant, and the argument that "no physical quantity can possibly be
dependent on them" is specious. We use convenient coordinate systems all the
time for making measurements. What you should have said is that the
comparison of theory with observations should not be dependent on the choice
of coordinates. But it isn't anywhere in physics, even long before GR and
the idea of covariance were conceived.

It is really the first postulate of SR that led to the belief that
reality was covariant because the second postulate, the invariance of the
speed of light with coordinate frame, required it. But with SR now falsified
in favor of LR, what we have learned is that reality is not covariant in the
SR/GR sense. The idea that it is was a bad one, and has led to much of the
conflict between GR and QM, which is now resolved by dropping covariance and
the notion of a universal speed limit.

[Roberts]: At present, the best theory of gravitation we have is General
Relativity. You should learn about it. It does NOT have the structure you
keep claiming.

You would probably enjoy learning about the physics behind GR, as most
people do when first exposed to it via works such as the 20-author "Pushing
Gravity" treatise. But sadly, you seem to have no interest in learning about
the interface between your beloved mathematical GR model and the real world.

[Roberts]: There's no point in continuing. I am interested in science, not
the personal religion you keep trying to discuss. You phrase your religion
using the words of physics, but you do not understand the nature of
physics. Or science. Or modern theories of physics, such as GR. Like all
too many other crackpots around here, you do not bother to understand the
subject you have devoted a major part of your life to. That's rather
sad....

Hold up a mirror. I ask again, where are your publications, what are
your qualifications to make your claims, and what can you mention in support
of anything you have said? But you just ignore my main points and challenges
here and in my previous messages, which leaves you invincibly ignorant.

Sad indeed. -|Tom|-


Tom Van Flandern - Sequim, WA - see our web site on frontier astronomy
research at http://metaresearch.org

Tom Van Flandern wrote in message


[snip]

Hold up a mirror.

Yes:
http://www.metaresearch.org/solar%20...iles/proof.asp

I ask again, where are your publications, what are
your qualifications to make your claims, and what can you mention in support
of anything you have said? But you just ignore my main points and challenges
here and in my previous messages, which leaves you invincibly ignorant.

Creep movie: http://www.youtube.com/watch?v=Qo0mSKd9HeM

Dirk Vdm

On Mon, 22 Sep 2008 (PDT), Vern wrote:
This whole debate hinges on whether motion in GR is due to geometry
or whether the equations could also represent the description of a
field.

No, this "debate" (not quite an accurate term, but mind) does not
hinge on the well-known fact that the field equations of general
relativity have a field interpretation in flat spacetime. The reason
nothing "hinges" on this fact is simply that the distinction has no
empirical consequences. When there are empirical differences between
to sets of ideas, they are said to represent two different theories,
whereas when there are no empirical differences, they are said to be
two interpretations of the same theory. Tom van Flandern is a
charlatan, because he tries to fool people by first saying he is
talking about another interpretation of some empirically successful
theory (such as special or general relativity), thereby claiming that
his ideas pass all the empirical tests of that successful theory, and
then he immediately turns around and claims different empirical
predictions for his interpretation, disagreeing with the predictions
of the successful theory. In this he is simply lying. The Lorentzian
interpretation of special relativity is empirically indistinguishable
from special relativity (in terms of limiting speeds, etc), and the
field interpretation of general relativity is empirically
indistinguishable from the geometric interpretation. (Some people
would argue that the geometrical interpretation has the potential to
accommodate certain global phenomenological topologies that would be
difficult to map to the field interpretation in flat spacetime, but
this is debatable, and in any case has no bearing on Tom van
flandern's idiocies.)

On Sep 26, 12:11 am, "Tom Van Flandern"
wrote:
snip

Read Sam Hay's post and go away. For good.

Dono wrote in message

On Sep 26, 12:11 am, "Tom Van Flandern"
wrote:
snip

Read Sam Hay's post and go away. For good.

Give him a break.
The guy has to make a living somehow, right?

Dirk Vdm

On Sep 26, 7:23 am, "Dirk Van de moortel"
wrote:
Dono wrote in message



On Sep 26, 12:11 am, "Tom Van Flandern"
wrote:
snip

Read Sam Hay's post and go away. For good.

Give him a break.
The guy has to make a living somehow, right?

Dirk Vdm



by lying?
he's been doing it for years, time to retire :-)