Tom Roberts wrote on Sat, 12 Apr 2008 16:41:42 +0000:

Only if one accepts at face value your claims that most of classical
physics is wrong.

If you really think that then let me say you misunderstood i said.

Tom Roberts wrote on Fri, 11 Apr 2008 15:36:41 -0500:
The experiments have said NOTHING WHATSOEVER about whether or not the
"geometrical interpretation" [#] of GR is valid. The experiments have
said that the EQUATIONS of GR are valid (for their specific
measurements).

None current experiment verifies:
a1) gravity is due to spacetime curvature b1) interactions are
retarded
because same experiments can be explained using
a2) gravity like a force
b2) instantenous fundamental interactions

Sure. As I said before, experiments cannot distinguish between
interpretations like this.

We are doing some advance here.

[That assumes your second theory is GR in disguise.
If not, it merely shows that the two theories cannot be
distinguished
by these experiments.]

No, you were said that GR arises like an approximation to the more
fundamental theory.

However, recent experiments and theoretical advances are neither
supporting the idea of retarded interactions nor the idea of gravity as
geometry.

But they aren't refuting it, either, which is the relevant point.

Wrong. They are doing it for both *gravitational* and electromagnetic
interactions. Even if you cannot read references (which was you complaint
time ago) you can read the titles:

"Action at a distance as a full-value solution of Maxwell equations"

"Necessity of simultaneous co-existence of instantaneous and retarded
interactions in classical electrodynamics."

"Experimental evidence on non-applicability of the standard retardation
condition to bound magnetic fields"

Etc.

E.g. in my recent work "Newtonian limit difficulties of GR", I analize
both mathematical advancements and experiments invalidating a geometrical
approach to gravity. Several mistakes of Carlip PLA paper are revised in
a specific section.

Both (geometry and retardation) are approximated concepts.

Almost certainly -- it's highly likely that GR itself is an
approximation. But to what?

To a more fundamental theory of gravity based in a Liouville space
extension of dynamics.

E.g. the retarded local tensor potentials h_ab(x,t) are derived up second
order (first order mixed brackets "[}") in the local approximation for
pure states sigma -- delta-6N.

The (geo)metric stucture and even the own concept of spacetime arises
like approximation in a well defined limit.




Thus geoemtric GR is an approximation to a more general description of
classical graviational phenomena.

Except that to date nobody has presented such a "more general
description".

Completely false. Several people has done and published in top journals
including gravitation specific journals. You simply are not aware (as
usual).

For instance, the description given in

Classical Relativistic Many-Body Dynamics. 1999: Springer. Trump, Matthew
A; Schieve, William C.

for gravitation is *not* reducible to GR. In fact, authors rejected both
field and metric theories because of their known flaws.

Today, i sent the outline for a generalization of the theory in that
monograph to a Texas colleague who will discuss it with prof Schieve.

The draft is

"Chubikalo and Smirnov-Rueda dualism: Foundation and generalizations"

and in page 30 explains how one would generalize the 8N potentials on the
cited monograph

V = (m / (SQRT X^2 - c^2T^2)) -- [Tr_E V sigma_E}_8N

General relativity is derived after doing several simplifications from
the more general theory.

My point is that one cannot possibly MEASURE the "gravitational force"
on an orbiting satellite. One can certainly measure geometrical aspects
of its path and INFER a "gravitational force". But that's insufficient
to the task you and Van Flandern have set out for yourselves, because
the geometry of GR can also explain such measurements.

Completely wrong once again.


--
http://canonicalscience.org/en/misce...guidelines.txt

Juan R. González-�lvarez wrote:
[...]

Let me for the moment suspend disbelief and stipulate that everything
you said is true and accepted by the entire physics community, and that
you and your references have described a complete and self-consistent
theory worthy to be the successor to GR as the best theory of gravity.

In that context, please answer this one point:
My point is that one cannot possibly MEASURE the "gravitational force"
on an orbiting satellite.

Completely wrong once again.

So prove it, by describing precisely how one MEASURES the "gravitational
force" on an orbiting satellite. Don't give blank references to
unspecified literature, just give a basic description of the method. A
one-sentence statement of the basic principle of the measurement will
do. And please don't use jargon or undefined notation, but follow the
"colloquium test" -- give a description that is understandable to a
graduate student or postdoc not expert in the field.


Tom Roberts

On Apr 7, 10:39*pm, wrote in
sci.physics.relativity:
TomVan Flandern wrote:

"TomRoberts" writes:
[Roberts]: For those unwilling to wade through the umpteenth time
this has *been discussed, here is the bottom line: ... None of the
experiments Van Flandern cites refute GR ...
* * I am sorry you can't keep your correspondents straight. For the
umpteenth time, I agree with GR as a mathematical theory. Nothing
I've said here is in any way a refutation of GR.

There is a rigorous proof, using the full Einstein field equations (and not
just a low-order approximation that can hide the underlying structure),
that gravitational influence propagates at the speed of light:

Robert J Low, "Speed Limits in General Relativity," Class. Quant. Grav. 16
(1999) 543, http://arxiv.org/abs/gr-qc/9812067. *If you really "agree[d] with
GR as a mathematical theory," the argument would be over.

Steve Carlip

But, Carlip Carlip, in a gravitational field the speed of light is
VARIABLE, as Divine Albert said in 1920 and as you have been teaching
in Einstein zombie world for quite a long time:

http://groups.google.com/group/sci.p...bd437bc899633?
Steve Carlip, Aug 1 1997: "In special relativity, the speed of light
is constant when measured in any *inertial* frame. In general
relativity, the appropriate generalization is that the speed of light
is constant in any freely falling reference frame (in a region small
enough that tidal effects can be neglected). In this passage, Einstein
is not talking about a freely falling frame, but rather about a frame
at rest relative to a source of gravity. In such a frame, the speed of
light can differ from c, basically because of the effect of gravity
(spacetime curvature) on clocks and rulers." Steve Carlip


http://math.ucr.edu/home/baez/physic...of_light..html
Steve Carlip: "Einstein went on to discover a more general theory of
relativity which explained gravity in terms of curved spacetime, and
he talked about the speed of light changing in this new theory. In the
1920 book "Relativity: the special and general theory" he wrote:
". . . according to the general theory of relativity, the law of the
constancy of the velocity of light in vacuo, which constitutes one of
the two fundamental assumptions in the special theory of relativity
[. . .] cannot claim any unlimited validity. A curvature of rays of
light can only take place when the velocity of propagation of light
varies with position." Since Einstein talks of velocity (a vector
quantity: speed with direction) rather than speed alone, it is not
clear that he meant the speed will change, but the reference to
special relativity suggests that he did mean so. THIS INTERPRETATION
IS PERFECTLY VALID AND MAKES GOOD PHYSICAL SENSE...."

Now Carlip Carlip, even if that "gravitational influence propagates at
the speed of light" had been rigorously proved, Einstein zombie world
wants to know (or may ask some day): If the propagation of the
selfsame gravitational influence is accompanied by propagation of
light, the speed of this light will decrease perhaps, at least so you
and Divine Albert suggest (after all, you measure both speeds in "a
frame at rest relative to a source of gravity", that is, the initial
source of gravity, before the beginning of the propagation). Will the
speed of the gravitational influence decrease as well? Do you know how
to camouflage the problem?

Pentcho Valev

On Apr 11, 10:36*pm, Tom Roberts wrote in
sci.physics.relativity:
[I'm picking just the main points.]

Tom Van Flandern wrote:
"Tom Roberts" writes:
... None of the
experiments Van Flandern cites refute GR ...

I agree with GR as a mathematical theory. Nothing I've
said here is in any way a refutation of GR.

As Carlip said, if you really understood what you just said, this
argument would be over.

Experiments can test theories.

Can experiments test single statements Roberts Roberts? This question
sounds silly and yet it is important because some Divine Juggler may
place two contradictory statements - e.g. that the speed of light is
both constant and variable - in his Divine Theory and then experiments
may always confirm Divine Juggler's Divine Theory. Just answer this
Roberts Roberts: Is the gravitational redshift factor 1+V/c^2
experimentally confirmed by Pound and Rebka consistent with the
statement that the speed of light in a gravitational field is variable
and obeys Einstein's 1911 equation c'=c(1+V/c^2), or is it consistent
with the statement that the speed of light is a gravitational field is
constant and obeys the equation c'=c?

But first learn what your Masters teach Roberts Roberts:

http://www.physlink.com/Education/AskExperts/ae13.cfm
"So, it is absolutely true that the speed of light is _not_ constant
in a gravitational field [which, by the equivalence principle, applies
as well to accelerating (non-inertial) frames of reference]. If this
were not so, there would be no bending of light by the gravitational
field of stars....Indeed, this is exactly how Einstein did the
calculation in: 'On the Influence of Gravitation on the Propagation of
Light,' Annalen der Physik, 35, 1911. which predated the full formal
development of general relativity by about four years. This paper is
widely available in English. You can find a copy beginning on page 99
of the Dover book 'The Principle of Relativity.' You will find in
section 3 of that paper, Einstein's derivation of the (variable) speed
of light in a gravitational potential, eqn (3). The result is,
c' = c0 ( 1 + V / c^2 )
where V is the gravitational potential relative to the point where the
speed of light c0 is measured."

http://www.blazelabs.com/f-g-gcont.asp "The first confirmation of a
long range variation in the speed of light travelling in space came in
1964. Irwin Shapiro, it seems, was the first to make use of a
previously forgotten facet of general relativity theory -- that the
speed of light is reduced when it passes through a gravitational
field....Faced with this evidence, Einstein stated:"In the second
place our result shows that, according to the general theory of
relativity, the law of the constancy of the velocity of light in
vacuo, which constitutes one of the two fundamental assumptions in the
special theory of relativity and to which we have already frequently
referred, cannot claim any unlimited validity. A curvature of rays of
light can only take place when the velocity of propagation of light
varies with position."......Today we find that since the Special
Theory of Relativity unfortunately became part of the so called
mainstream science, it is considered a sacrilege to even suggest that
the speed of light be anything other than a constant. This is somewhat
surprising since even Einstein himself suggested in a paper "On the
Influence of Gravitation on the Propagation of Light," Annalen der
Physik, 35, 1911, that the speed of light might vary with the
gravitational potential. Indeed, the variation of the speed of light
in a vacuum or space is explicitly shown in Einstein's calculation for
the angle at which light should bend upon the influence of gravity.
One can find his calculation in his paper. The result is c'=c(1+V/c^2)
where V is the gravitational potential relative to the point where the
measurement is taken. 1+V/c^2 is also known as the GRAVITATIONAL
REDSHIFT FACTOR."

Pentcho Valev

On Apr 12, 10:18 pm, Tom Roberts wrote:
Juan R. González-Álvarez wrote:
[...]

Let me for the moment suspend disbelief and stipulate that everything
you said is true and accepted by the entire physics community, and that
you and your references have described a complete and self-consistent
theory worthy to be the successor to GR as the best theory of gravity.

In that context, please answer this one point:

My point is that one cannot possibly MEASURE the "gravitational force"
on an orbiting satellite.

Completely wrong once again.

So prove it, by describing precisely how one MEASURES the "gravitational
force" on an orbiting satellite. Don't give blank references to
unspecified literature, just give a basic description of the method. A
one-sentence statement of the basic principle of the measurement will
do. And please don't use jargon or undefined notation, but follow the
"colloquium test" -- give a description that is understandable to a
graduate student or postdoc not expert in the field.

Tom Roberts

The idea of instanteous transmission is logically
flawed to be ABSOLUTELY ridiculous.
It enables scenarios like, the Sun appears in
front of me, but it could *truly* be behind me,
so the Sun could be anywhere else instead of
where it appears to be.
I suppose next TV Flandern will introduce a
probabilistic location for the "true" location
of the Sun. That will simplify the art of
Celestrial Mechanics to flipping coins.

On Apr.8, in this thread, I posted clear simple
diagrams, based on Equivalence Principle on how
GR permits using the imaged location of the Sun
to calculate orbits.
That accounts for the fact that if the Earth
were to stop and reverse revolutional direction
the aberrated image of the Sun would shift in
direction too, to it's opposite (asymmetrical)
from the Newtonian position, going from +20" to
-20".
I went on to use the geodesic equation of motion
to show how that is accounted for.
Regards
Ken S. Tucker

Tom Roberts wrote on Sun, 13 Apr 2008 05:18:54 +0000:

In that context, please answer this one point:
My point is that one cannot possibly MEASURE the "gravitational force"
on an orbiting satellite.

It is really ironic now i am revising a published work by a colleague
where he proposes an experiment to differentiate between GR and
alternative theory of gravity by measuring one specific effect on the
gravitational force on orbiting bodies!

So prove it, by describing precisely how one MEASURES the "gravitational
force" on an orbiting satellite.

Recently I waste time in spr trying to explain to a guy measurements of
velocities for Dirac electrons, when he did not even understood that was
being measured.

I do not usually repeat the same mistakes.

To avoid wasting time now, it would be good to define first the
expression for the gravitational force that astronomers working in
celestial mechanics measure for an orbiting body.

You claimed that one cannot possibly measure the gravitational force.
Before discussing your claim, it may be a good thing if you write first
the expression for the gravitational force for an orbiting body (e.g.
Mercury planet).

By simplicity use, for instance, Schwarzild coordinates.


--
http://canonicalscience.org/en/misce...guidelines.txt

Juan R. González-�lvarez wrote:
It is really ironic now i am revising a published work by a colleague
where he proposes an experiment to differentiate between GR and
alternative theory of gravity by measuring one specific effect on the
gravitational force on orbiting bodies!

Especially "ironic" is the fact that you cannot meet my challenge to
describe how to measure it. Actually, the irony is that you do not
understand WHY this challenge cannot be met, and yet you think you are
an "expert".


Tom Roberts wrote:
So prove [your claim that I am "completely wrong"], by describing precisely how one MEASURES the "gravitational
force" on an orbiting satellite.

[...complete failure to do so]

If you were actually familiar with this subject and able to meet my
challenge, it would be MUCH EASIER to simply describe how to measure
"gravitational force" on an orbiting satellite, than doing all the
evasion and obfuscation you write to avoid facing the fact that you
cannot meet my challenge.


To avoid wasting time now, it would be good to define first the
expression for the gravitational force that astronomers working in
celestial mechanics measure for an orbiting body.

More evasion -- YOU are the one "wasting time". My challenge is clear
and concise. Why is it that you cannot meet the challenge? Even though
you claim to be an expert (and are "revising" a colleague's work). (of
course _I_ know why you cannot do it, I'm trying to get YOU to
understand why this challenge cannot be met)


You claimed that one cannot possibly measure the gravitational force.
Before discussing your claim, it may be a good thing if you write first
the expression for the gravitational force for an orbiting body (e.g.
Mercury planet).

Still more evasion -- Don't evade the challenge, use whatever expression
you wish. Use whatever definition of "gravitational force" you wish. But
be sure to meet the challenge: describe how to MEASURE the
"gravitational FORCE" on an orbiting satellite, not any indirect or
model-dependent implications of it (such as orbit parameters, which are
geometrical, not any sort of force).

From the nature of this challenge I would expect the answer
to be an English description of an experimental technique,
and not need any equations at all. But however you phrase
your response is up to you.

EXAMPLE: when one whirls a stone on a string around
one's head, it is easy to measure the centripetal force on
the stone -- it is tension and one can simply put a spring
scale between stone and string. But it simply is not possible
to measure the "centrifugal force" -- there is no place to
put the scale. HINT: there is a deep relationship between
this inability and the inability to measure "gravitational
force". HINT2: both "centrifugal force" and "gravitational
force" are coordinate dependent (this is true in both GR and
Newtonian mechanics).


Tom Roberts

Juan R. González-�lvarez wrote:
Necessity of simultaneous co-existence of instantaneous and retarded
interactions in classical electrodynamics. 1999: Int. J. of Mod. Phys. A
14(24), 3789. Chubykalo, Andrew E; Vlaev, Stoyan J.

I have now read this paper. Apparently you have not (at least not with a
critical eye that does not accept claims that are not established
mathematically). I suggest you do so before making additional false
claims about its implications.


In all papers, the conclusions are that electromagnetic interactions are
not retarded by c.

This is just plain wrong -- the above-referenced paper does not say this
at all.


it is proven that speed of
electromagnetism cannot be "c".

This, too, is not established in the above-referenced paper.


Mistakes of relativist literature are noticed and corrected.

This, too, is not established in the above-referenced paper.



Yes, that paper has "instantaneous interactions" in its title, but it
does not establish them at all. This is quite easy to see: if there were
"instantaneous interactions", then to compute the field at (x,y,z,t)
they would need to evaluate the Lienard-Wiechert potentials [their eq.
2] at time t, rather than at the retarded time t0. Nowhere in the paper
is this done. Nowhere does the paper present any alternate formulation,
only L-W potentials are used, with ALL SOURCE QUANTITIES EVALUATED AT
THE RETARDED TIME t0. So there is no "instantaneous interaction"
anywhere in the paper, except the title.

AT MOST what they have established is that the conventional notation is
inadequate to express the subtleties of differentiating a retarded-time
function of the source trajectory with respect to the implicitly-defined
retarded time, and relating it to the coordinate time of the point at
which the fields are to be evaluated. But given the comment by J.D.
Jackson (yes, THAT Jackson, author of _Classical_Electrodynamics_), I'm
not convinced they even did that.

It is not terribly surprising that the notation is strained
-- in other fields of physics it is well established that
the usual partial and total derivatives are inadequate [#].
Hydrodynamics comes to mind, where there the operator
d/dt+v.Del is neither "partial" nor "total" (it is a co-
moving derivative). Thermodynamics, too, needs careful
notation for its "partial" derivatives.

[#] Not to mention various geometrical derivatives such as
covariant and Lie derivatives.

In any case, this is just a tempest in a teapot: only a theoretical
physicist or a mathematician would ever differentiate their [eq. 2] with
respect to the retarded time t0 and relate it to the coordinate time t,
and then do it again to verify Maxwell's equations -- nobody else would
have the fortitude to wade through the many pages of algebra involved
(of which this paper is merely a summary). This paper is probably a
useful and important lesson for such people.

In the real world, experimental physicists and engineers use computer
programs to solve problems in electrodynamics. Those programs take an
ALGORITHMIC approach to solving the L-W potentials of [eq. 2], and they
do PRECISELY what it says. That is, they first establish a mesh in
{x,y,z,t} (or equivalent coordinates); to evaluate the potential at each
point in the mesh they solve the retardation equation [eq. 8]
numerically, and then evaluate [eq. 2] at the retarded time.
Differentiating the potential on the mesh at any point involves only
nearest neighbors, so there is no doubt that there is no "instantaneous
action-at-a-distance" involved. Yes, some programs make other
approximations, and use algorithms that avoid the differentiation on the
mesh, but all are equivalent to what I described, except for purely
numerical issues. Once the fields on the mesh are available, it is again
a simple differentiation (involving only nearest neighbors) to verify
that Maxwell's equations are satisfied -- this is routinely done when
testing these programs, and again it is clear that no "instantaneous
action-at-a-distance" is involved. Zillions of successful products and
equipment have been designed using such programs -- so this approach is
validated IN THE REAL WORLD.


I wanted to title this note "Outrageous Claims are Flat-Out WRONG", but
scholarly restraint prevented it. Unfortunately, Chubykalo and Vlaev
felt no such restraint: they DID make an outrageous claim, and it IS
flat-out wrong.



When i first meet that paper i said myself "That may be wrong". Then i
tried hard to find the mistake and i did not.

Try again: Look for a place where they evaluate [eq. 2] at time t rather
than the retarded time t0. THAT is what an "instantaneous interaction"
would involve, not their subtleties about differentiating with respect
to implicitly-defined variables (which may well be valid). The fact that
non-retarded derivatives with respect to {x,y,z,t} appear is due to the
way fields are LOCALLY related to potentials, and due to the fact that
Maxwell's equations are purely LOCAL. This is not any sort of
"instantaneous interaction", because the source trajectory is ALWAYS
evaluated at the retarded time.


Tom Roberts

Tom Roberts wrote on Mon, 14 Apr 2008 14:30:05 +0000:

You claimed that one cannot possibly measure the gravitational force.
Before discussing your claim, it may be a good thing if you write first
the expression for the gravitational force for an orbiting body (e.g.
Mercury planet).

Still more evasion -- Don't evade the challenge, use whatever expression
you wish. Use whatever definition of "gravitational force" you wish. But
be sure to meet the challenge: describe how to MEASURE the
"gravitational FORCE" on an orbiting satellite, not any indirect or
model-dependent implications of it (such as orbit parameters, which are
geometrical, not any sort of force).

Excuses excuses excuses...

I am still waiting from you to write the force, just that you say cannot
be measured Tom.

Or maybe as usual you are writting about stuff you never studied Tom.
from guidelines:

{DO NOT ARGUE AGAINST PROUD NON-SPECIALISTS
Some people strongly argue over a topic they did not even take the
time to study. Some of this people even reject to read the
references you provide to support your point!

When you correct some of their mistakes, they often reply by making
more mistakes. Avoid this trap also! It fills the network with
useless noise in some exponential way.
}

no place to put the scale. HINT: there is a deep relationship
between
this inability and the inability to measure "gravitational force".
HINT2: both "centrifugal force" and "gravitational force" are
coordinate dependent (this is true in both GR and Newtonian
mechanics).

I waited just that kind of mistaken argument from you Tom and that is
because ironically i cited certain paper i am now studying.

That paper shows how the equation for the orbit (in terms of
gravitational force, which is computed) in the alternative theory is
*independent* of the system of coordinates (whereas you are at least
correct here) the corresponding equation for GR is coordinate dependant.

Game over.

--
http://canonicalscience.org/en/misce...guidelines.txt

"Juan R." González-�lvarez wrote on Mon, 14 Apr 2008 19:50:57 +0200:


That paper shows how the equation for the orbit (in terms of
gravitational force, which is computed) in the alternative theory is
*independent* of the system of coordinates (whereas you are at least
correct here) the corresponding equation for GR is coordinate dependant.

May be

That paper shows how the equation for the orbit (in terms of
gravitational force, which is computed) in the alternative theory is
*independent* of the system of coordinates chosen, whereas (you are at
least correct here) the corresponding equation for GR is coordinate
dependant. This is the reason which one can speak about *gravitational
force* on that alternative approach.


--
http://canonicalscience.org/en/misce...guidelines.txt