Tom Van Flandern wrote on Mon, 21 Apr 2008 11:17:28 -0700:

and "Tom Roberts" writes:

[Prime Mover]: As many published experiments have demonstrated,
gravitational forces cannot possibly propagate at c.

[Roberts]: True, _IF_AND_ONLY_IF_ one assumes that they propagate at
all.

With the standard classical physics definition of "force" = the time
rate of change of (3-space) momentum, it instantly follows that orbiting
bodies are experiencing a force by definition.

In this same thread i asked Tom to write the expression for the force. He
was unable.

I asked and asked and asked and asked and asked. He never was able to
write not even a first PN approximation to the total force.

Since he insist on criticizing gravitational forces, I am obligated to
conclude that Tom likes to criticize topics without studying first. That
seem to imply Tom is not interested in scientific debate but just on
promoting his own view about nature. The often uses a pejorative term
defines his behavior perfectly.

[Roberts]: That is a measurement of the acceleration, not the force.

You are ignoring definitions again. "Force" in this discussion is the
time
rate of change of (3-space) momentum. "Momentum" is mass times velocity.
For constant mass, the time rate of change of momentum is mass times
acceleration, a.k.a. Newton's second law of motion. That is a perfectly
valid way of measuring "force" by its standard definition. Only when you
change the definition, as in geometric GR, is the force concept
suppressed and we would have no means of measuring a true force.

Tom did not even understand difference between F and f.

and Steve Carlip writes:

[Carlip, summarizing Low's paper]: change the source of gravity in R
any way you want. According to GR, nothing at all happens at a point p
outside R until the time for a light signal to reach p from R has
passed. By any sensible definition of "speed" I can imagine, that means
that gravity propagates at the speed of light.

I agree completely with Low's mathematical reasoning that you
summarize
here, and have never claimed anything different from that. I must also
agree that your imagination is limited just as you describe. Indeed,
what you describe is nothing more than a wordy description of the
retarded potential field in GR, similar to the Lienard-Wiechert
potentials.

As was proven in this newsgroup and in sci.physics.research Carlip
confounds the Newtonian potential PHI = PHI(R(t)) with the non-
relativistic limit of the LW potentials PHI = PHI(x,t) and then makes
completely wrong statements about the Newtonian potential and the speed
of gravity issue.

He is also unaware of recent theoretical and experimental advances in the
field.

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

Tom Van Flandern wrote:
[...]
and Steve Carlip writes:

[Tom VF]: no one is disputing that changes in gravitational potential
(the subject of the field equations) propagate at the speed of light, c.
I am always careful to state that "the speed of gravity" measured by the
six available experiments always means the 3-space propagation speed of
gravitational force, and has nothing to do with changes in gravitational
potential.

[Carlip, summarizing Low's paper]: change the source of gravity in R any
way you want. According to GR, nothing at all happens at a point p outside
R until the time for a light signal to reach p from R has passed. By any
sensible definition of "speed" I can imagine, that means that gravity
propagates at the speed of light.

I agree completely with Low's mathematical reasoning that you summarize
here, and have never claimed anything different from that.

If you really agree, then we are arguing over semantics. But lets see...

Let R contain a single mass M moving at a constant velocity. Let's suppose
it has been moving at this velocity for a long time -- much longer than the
light travel time to p. Then both GR and Newtonian gravity agree that a
test mass at p will experience an acceleration toward the "instantaneous"
position of M. In particular, the direction of that acceleration will track
the motion of M.

Now, at time t=0, make the following change in R: stop the motion of M.
You apparently agree that this change will have no affect at p until the
time for a light signal to reach p from R. In particular, if you really believe
this, you now accept that the acceleration of a test mass at p will continue
to "track" the previous motion of M, even though M is no longer moving,
until a time t=d/c, where d is the distance to p.

If you really "agree completely with Low's mathematical reasoning," then
you accept this direct consequence of that reasoning. But we can go
further. Write down the exact solution of the Einstein field equations for
a mass M that initially moves at a constant velocity and then abruptly
stops. (This is not too hard -- you can take the Kinnersley solution, which
I wrote down in my Phys. Lett. A paper, gr-qc/9909087, for a mass with an
arbitrary motion, and put in this special case.) Now just compute the
acceleration at p. (Again, not too hard -- you can use equation (2.2) of
my paper for the Christoffel connection.) You will find exactly the behavior
that I described above, as implied by Low's theorem.

Are you now ready to accept this? If so, I'll believe that you accept the
mathematics of GR. If not, then you don't, period. This is not a question
of an "interpretation" -- it is a direct, unambiguous mathematical
prediction. If you don't accept it, fine. But then stop hiding your beliefs
and pretending that you really accept GR, and are just arguing about an
interpretation of the math.

[...]
Now, consider the 2-body problem with one source mass and one (nearly)
massless target body. By construction, the source mass represents Low's R,
a collection of smaller masses that are the source of a gravitational
potential field. We all agree that changes in the potential field propagate
or update at speed c. So there is no issue there. Now let's look at the
gravitational force generated outside R, assuming R is a single, fixed
mass - the simplest case. Even with nothing changing at the field source, we
still have a problem about the force applied to the target body.

The one and only mathematical question of importance here to the speed
of gravity issue is this: For a target body with a transverse motion
relative to the source mass, should we use the retarded gradient or the
instantaneous gradient to get the force?

There is no such thing as a "retarded gradient." The gradient of a function
is the vector of its spatial derivatives. Time doesn't come into it.

It is also an elementary mathematical fact, of course, that if a function at
x at time t is determined by the behavior of some source at an earlier
time t', then the gradient of the function of x at time t is also determined
by the behavior of some source at time t'.

If this force, or "gravitational influences" (your term), propagates
from source mass to target body at speed c, then we must use the retarded
gradient, which leads to wrong answers (outward spiraling orbits).

You are managing to thoroughly confuse yourself about some fairly
elementary mathematics. Apparently you find the use of potentials
-- which are just auxiliary functions used to simplify computations --
confusing. You can, in fact, do all of the calculations without ever using
a potential. For electromagnetism, for instance, you can directly solve
Maxwell's equtions for the electric and magnetic fields, without ever
using potentials; you again find that the fields are completely determined
by the retarded behavior of the sources (in this case, the current and
its first derivative). For GR, things are harded, since the equations are
nonlinear, but you can again derive wave equations for the full curvature
tensor.

Steve Carlip

On Apr 22, 8:10*pm, wrote:
Tom Van Flandern wrote:
[...]

and Steve Carlip writes:
[Tom VF]: no one is disputing that changes in gravitational potential
(the subject of the field equations) propagate at the speed of light, c.
I am always careful to state that "the speed of gravity" measured by the
six available experiments always means the 3-space propagation speed of
gravitational force, and has nothing to do with changes in gravitational
potential.
[Carlip, summarizing Low's paper]: change the source of gravity in R any
way you want. According to GR, nothing at all happens at a point p outside
R until the time for a light signal to reach p from R has passed. By any
sensible definition of "speed" I can imagine, that means that gravity
propagates at the speed of light.
I agree completely with Low's mathematical reasoning that you summarize
here, and have never claimed anything different from that.

If you really agree, then we are arguing over semantics. *But lets see....

Let R contain a single mass M moving at a constant velocity. *Let's suppose
it has been moving at this velocity for a long time -- much longer than the
light travel time to p. *Then both GR and Newtonian gravity agree that a
test mass at p will experience an acceleration toward the "instantaneous"
position of M. *In particular, the direction of that acceleration will track
the motion of M.

Now, at time t=0, make the following change in R: stop the motion of M.
You apparently agree that this change will have no affect at p until the
time for a light signal to reach p from R. *In particular, if you really believe
this, you now accept that the acceleration of a test mass at p will continue
to "track" the previous motion of M, even though M is no longer moving,
until a time t=d/c, where d is the distance to p.


I don't think he agrees, but anyway, I am coinfused with what he
agrees and what he doesn't.

I do not agree. The change will have an instantaneous effect at p.

What does light have to do with gravitational effects anyway? Can you
show the connection first?

Write down the equations.


If you really "agree completely with Low's mathematical reasoning," then
you accept this direct consequence of that reasoning. *But we can go
further. *Write down the exact solution of the Einstein field equations for
a mass M that initially moves at a constant velocity and then abruptly
stops. *(This is not too hard -- you can take the Kinnersley solution, which
I wrote down in my Phys. Lett. A paper, *gr-qc/9909087, for a mass with an
arbitrary motion, and put in this special case.) *Now just compute the
acceleration at p. *(Again, not too hard -- you can use equation (2.2) of
my paper for the Christoffel connection.) *You will find exactly the behavior
that I described above, as implied by Low's theorem.


Your oversimplifications of field equations for the purpose of
obtaining the solutions you have in mind a priori do not concern
anyone. If you want to solve a REAL WORLD problem forget about test
mass and point mass and solve the two-body problem. But you can't.

Are you now ready to accept this? *If so, I'll believe that you accept the
mathematics of GR. *If not, then you don't, period. *This is not a question
of an "interpretation" -- it is a direct, unambiguous mathematical
prediction. *If you don't accept it, fine. *But then stop hiding your beliefs
and pretending that you really accept GR, and are just arguing about an
interpretation of the math.

[...]

Now, consider the 2-body problem with one source mass and one (nearly)
massless target body. By construction, the source mass represents Low's R, *
a collection of smaller masses that are the source of a gravitational
potential field. We all agree that changes in the potential field propagate
or update at speed c. So there is no issue there. Now let's look at the
gravitational force generated outside R, assuming R is a single, fixed
mass - the simplest case. Even with nothing changing at the field source, we
still have a problem about the force applied to the target body.
* * The one and only mathematical question of importance here to the speed
of gravity issue is this: For a target body with a transverse motion
relative to the source mass, should we use the retarded gradient or the
instantaneous gradient to get the force?

There is no such thing as a "retarded gradient." *The gradient of a function
is the vector of its spatial derivatives. *Time doesn't come into it.


Yes, I agree, there are only retarded people.


It is also an elementary mathematical fact, of course, that if a function at
x at time t is determined by the behavior of some source at an earlier
time t', then the gradient of the function of x at time t is also determined
by the behavior of some source at time t'.

* * If this force, or "gravitational influences" (your term), propagates
from source mass to target body at speed c, then we must use the retarded
gradient, which leads to wrong answers (outward spiraling orbits).

You are managing to thoroughly confuse yourself about some fairly
elementary mathematics. *Apparently you find the use of potentials
-- which are just auxiliary functions used to simplify computations --
confusing. *You can, in fact, do all of the calculations without ever using
a potential. *For electromagnetism, for instance, you can directly solve
Maxwell's equtions for the electric and magnetic fields, without ever
using potentials; you again find that the fields are completely determined
by the retarded behavior of the sources (in this case, the current and
its first derivative). *For GR, things are harded, since the equations are
nonlinear, but you can again derive wave equations for the full curvature
tensor.

Steve Carlip

Mike

On Apr 23, 12:52*am, Mike wrote:

[snip]

I do not agree. The change will have an instantaneous effect at p.

The literature disagrees.

http://arxiv.org/abs/gr-qc/9812067v1


What does light have to do with gravitational effects anyway? Can you
show the connection first?

Light and gravitational perturbations travel along the same - null -
geodesic. The connection, as it were, is in any general relativity
textbook that discusses perturbation theory. If you don't want to
discuss perturbation theory, read Low's paper.


Write down the equations.

If you really "agree completely with Low's mathematical reasoning," then
you accept this direct consequence of that reasoning. *But we can go
further. *Write down the exact solution of the Einstein field equations for
a mass M that initially moves at a constant velocity and then abruptly
stops. *(This is not too hard -- you can take the Kinnersley solution, which
I wrote down in my Phys. Lett. A paper, *gr-qc/9909087, for a mass with an
arbitrary motion, and put in this special case.) *Now just compute the
acceleration at p. *(Again, not too hard -- you can use equation (2.2) of
my paper for the Christoffel connection.) *You will find exactly the behavior
that I described above, as implied by Low's theorem.

Your oversimplifications of field equations for the purpose of
obtaining the solutions you have in mind a priori do not concern
anyone. If you want to solve a REAL WORLD problem forget about test
mass and point mass and solve the two-body problem. But you can't.

What's so special about the two body problem in your mind?

[snip]

carlip-nospam wrote on Wed, 23 Apr 2008 00:10:12 +0000:

sniped the same misunderstandings.

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

Hi Juan

On Apr 23, 4:35 am, "Juan R." González-Álvarez
wrote:
carlip-nospam wrote on Wed, 23 Apr 2008 00:10:12 +0000:

sniped the same misunderstandings.

Using a deeper analysis, employing a Unified
Field Theory class solution briefed here,

http://physics.trak4.com/GR_Charge_Couple.pdf

we are able to merge the effects of electricity
and gravitation via GR in an inseparable way, as
magnetism was unified with electricity via SR.

That further verifies my previous analysis
above (using diagram's) that variations of
material structures propagate that change
visually and gravitationally at the speed
of light "c".

--http://canonicalscience.org/en/miscellaneouszone/guidelines.txt
Do you still use those guidelines?
(Doesn't seem so, Dr. Carlip was quite polite).
Anyway
Regards
Ken S. Tucker

On Apr 23, 5:53*am, Eric Gisse wrote:
On Apr 23, 12:52*am, Mike wrote:

[snip]

I do not agree. The change will have an instantaneous effect at p.

The literature disagrees.

http://arxiv.org/abs/gr-qc/9812067v1

This paper is full of misunderstanding and I do not expect you to have
read it and understand it cause you never graduated hiugh school.





What does light have to do with gravitational effects anyway? Can you
show the connection first?

Light and gravitational perturbations travel along the same - null -
geodesic. The connection, as it were, is in any general relativity
textbook that discusses perturbation theory. If you don't want to
discuss perturbation theory, read Low's paper.







Write down the equations.

If you really "agree completely with Low's mathematical reasoning," then
you accept this direct consequence of that reasoning. *But we can go
further. *Write down the exact solution of the Einstein field equations for
a mass M that initially moves at a constant velocity and then abruptly
stops. *(This is not too hard -- you can take the Kinnersley solution, which
I wrote down in my Phys. Lett. A paper, *gr-qc/9909087, for a mass with an
arbitrary motion, and put in this special case.) *Now just compute the
acceleration at p. *(Again, not too hard -- you can use equation (2.2) of
my paper for the Christoffel connection.) *You will find exactly the behavior
that I described above, as implied by Low's theorem.

Your oversimplifications of field equations for the purpose of
obtaining the solutions you have in mind a priori do not concern
anyone. If you want to solve a REAL WORLD problem forget about test
mass and point mass and solve the two-body problem. But you can't.

What's so special about the two body problem in your mind?

It's the problem you couldn't solve. Do you remmeber that imbecile?
It's less than a year and a half ago you did not know how to solve a
free-fall equation:

http://groups.google.gr/group/sci.ph...24a9cdf16c4daf

Also, you do not know there are spin-1, spin-2 and spin-3/2 gravitons:

http://groups.google.com/group/sci.p...4313544b176925

So I wonder what makes you think you can answer any post in these
groups you imbecile

Mike




[snip]- Hide quoted text -

- Show quoted text -

Mike wrote in message

On Apr 23, 5:53 am, Eric Gisse wrote:
On Apr 23, 12:52 am, Mike wrote:

[snip]

I do not agree. The change will have an instantaneous effect at p.

The literature disagrees.

http://arxiv.org/abs/gr-qc/9812067v1

This paper is full of misunderstanding and I do not expect you to have
read it and understand it cause you never graduated hiugh school.

http://users.telenet.be/vdmoortel/di...hysics101.html

Dirk Vdm

Ken S. Tucker wrote in message

Hi Juan

On Apr 23, 4:35 am, "Juan R." González-Álvarez
wrote:
carlip-nospam wrote on Wed, 23 Apr 2008 00:10:12 +0000:

sniped the same misunderstandings.

[snip]

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

Do you still use those guidelines?

Yes:
http://users.telenet.be/vdmoortel/di...uidelines.html
http://users.telenet.be/vdmoortel/di...uidelines.html

Dirk Vdm

On Apr 23, 9:07*am, "Dirk Van de moortel" dirkvandemoor...@ThankS-NO-
SperM.hotmail.com wrote:
Mike wrote in message

*

On Apr 23, 5:53 am, Eric Gisse wrote:
On Apr 23, 12:52 am, Mike wrote:

[snip]

I do not agree. The change will have an instantaneous effect at p.

The literature disagrees.

http://arxiv.org/abs/gr-qc/9812067v1

This paper is full of misunderstanding and I do not expect you to have
read it and understand it cause you never graduated hiugh school.

* *http://users.telenet.be/vdmoortel/di...hysics101.html

Perfectly correct. Put on your glasses old fart and go look for the
centripetal force reaction in the inertial frame you imbecile. You
still haven't learned Newton's third law.

Mike




Dirk Vdm