There are evidences showing that in Solar system,
the speed of gravity is many orders of magnitude higher
than the speed of light. But, what must we understand
by speed of gravity?. Aetherists often claim that gravity
are longitudinal waves, whereas light are transverse
waves through the aether. We know that in any medium
longitudinal waves travel faster than transverse waves.
We can find that longitudinal speed, c_L, and transverse
c_S, in a medium, with Young's modules E, Poison's ratio
v and mass density d_0, are

c_L^2 = (E/d_0(1+v))(1-v)/(1-2v)
c_S^2 = (E/d_0(1+v))(1/2)

We also know there exists a relation between those
elastic constants, as

E=2G(1+v)=3K(1-2v),

where G is shear modulus and K is bulk modulus.
So, we have

c_L^2 = (2G/d_0)(1-v)/(1-2v)
c_S^2 = G/d_0

Therefore, for a Poison's ratio of v=1/2, it would result an
infinite longitudinal speed. In general we have

c_L^2 + c_S^2 = (G/d_0)(2(1-v)/(1-2v) + 1)

This quadratic relation suggests (G/d_0)(2(1-v)/(1-2v) + 1) is
a universal constant for vacuum. This suggests

(G/d_0)(2(1-v)/(1-2v) + 1) = (R/t_p)^2,
where R is a scale parameter and t_p is Planck time.
or
(G/d_0)(2(1-v)/(1-2v) + 1) = c^2 (R/l_p)^2,
where l_p is Planck length.

c_L^2 + c_S^2 = c^2 (R/l_p)^2,

So, for a speed of light being c_S=c, it would yield

c_L^2 + c^2 = c^2 (R/l_p)^2,

c_L = c sqrt((R/l_p)^2 - 1), which is roughly

c_L = c R/l_p,

if R is meaningfully larger than l_p.

If we define R = R_h (Hubble radius), then the speed
of gravity, there where the local speed of light is c,
would be

c_L = c R_h/l_p,

it is saying it would be a very superluminal speed
(i.e. infinite for practical purposes).

On Mar 6, 3:41*pm, Albertito wrote:
There are evidences showing that in Solar system,
the speed of gravity is many orders of magnitude higher
than the speed of light.

There is evidence of that when you push a car.
It pushes back instantly. But that doesn't
mean gravity moves faster than c.

The finite speed of light is in evidence
as the car begins to move forward and the
remainder of the universe shifts position just a bit
to make room for the car's field from
a new position. That realignment propagates
at less than c.


But, what must we understand
by speed of gravity?.

See above:

I can't find a source or destination in
your equations. I can with Koroupolis
and the light paths are identified.

http://arxiv.org/abs/physics/0107015

[...]

On Mar 6, 11:41 am, Albertito wrote:
There are evidences showing that in Solar system,
the speed of gravity is many orders of magnitude higher
than the speed of light.

No, there is not. Just because you say so doesn't mean it is true.

But, what must we understand
by speed of gravity?. Aetherists often claim that gravity
are longitudinal waves, whereas light are transverse
waves through the aether.

Why even mention this? Ether has been ruled out as a viable concept
EVERY SINGLE TIME for the last hundred and thirty years. Nobody but
cranks in the fringe take ether seriously anymore.

We know that in any medium
longitudinal waves travel faster than transverse waves.

Only if the medium is anisotropic. Where are the calculations in which
you actually derive the things you write?

We can find that longitudinal speed, c_L, and transverse
c_S, in a medium, with Young's modules E, Poison's ratio
v and mass density d_0, are

c_L^2 = (E/d_0(1+v))(1-v)/(1-2v)
c_S^2 = (E/d_0(1+v))(1/2)

Stating the answer without derivation isn't acceptable anywhere, why
do you think we will accept what you write down without
rationalization?

[remaining snipped]

On Mar 6, 3:41*pm, Albertito wrote:
There are evidences showing that in Solar system,
the speed of gravity is many orders of magnitude higher
than the speed of light. But, what must we understand
by speed of gravity?. Aetherists often claim that gravity
are longitudinal waves, whereas light are transverse
waves through the aether. We know that in any medium
longitudinal waves travel faster than transverse waves.
We can find that longitudinal speed, c_L, and transverse
c_S, in a medium, with Young's modules E, Poison's ratio
v and mass density d_0, are

* * * * * * c_L^2 = (E/d_0(1+v))(1-v)/(1-2v)
* * * * * * c_S^2 = (E/d_0(1+v))(1/2)

We also know there exists a relation between those
elastic constants, as

* * * * * * E=2G(1+v)=3K(1-2v),

where G is shear modulus and K is *bulk modulus.
So, we have

* * * * * *c_L^2 = (2G/d_0)(1-v)/(1-2v)
* * * * * *c_S^2 = G/d_0

Therefore, for a Poison's ratio of v=1/2, it would result an
infinite longitudinal speed. In general we have

* * * * * *c_L^2 *+ c_S^2 = (G/d_0)(2(1-v)/(1-2v) + 1)

This quadratic relation suggests *(G/d_0)(2(1-v)/(1-2v) + 1) is
a universal constant for vacuum. This suggests

* * * * * * (G/d_0)(2(1-v)/(1-2v) + 1) = (R/t_p)^2,
* * * * * * where R is a scale parameter and t_p is Planck time.
* * * * * * or
* * * * * *(G/d_0)(2(1-v)/(1-2v) + 1) = c^2 (R/l_p)^2,
* * * * * *where l_p is Planck length.

* * * * * * c_L^2 *+ c_S^2 = c^2 (R/l_p)^2,

So, for a speed of light *being c_S=c, it would yield

* * * * * * c_L^2 *+ c^2 = c^2 (R/l_p)^2,

* * * * * * c_L = c sqrt((R/l_p)^2 - 1), which is roughly

* * * * * * c_L = c R/l_p,

* * * * * * if R is meaningfully larger than l_p.

If we define R = R_h (Hubble radius), then the speed
of gravity, there where the local speed of light is c,
would be

* * * * * * *c_L = c R_h/l_p,

it is saying it would be a very superluminal speed
(i.e. infinite for practical purposes).

xxein: 'Knowing' doesn't appear reliable because it had already been
just a product of 'ifs' and 'suggestions'. Somewhere along the way a
chameleon math told the physic how it operated. Think of how stupid
that is. You can mathematically describe the physic in countless
ways, but you can't change the physic, itself. If each notion
associated with any line of math were taken as truth, the physic loses
its integrity. We know that can't happen and yet we continually will
it.

On 6 mar, 21:20, "Sue..." wrote:
On Mar 6, 3:41 pm, Albertito wrote:

There are evidences showing that in Solar system,
the speed of gravity is many orders of magnitude higher
than the speed of light.

There is evidence of that when you push a car.
It pushes back instantly. But that doesn't
mean gravity moves faster than c.

The finite speed of light is in evidence
as the car begins to move forward and the
remainder of the universe shifts position just a bit
to make room for the car's field from
a new position. That realignment propagates
at less than c.

But, what must we understand
by speed of gravity?.

See above:

I can't find a source or destination in
your equations. I can with Koroupolis
and the light paths are identified.

http://arxiv.org/abs/physics/0107015

[...]

Can't you find a source or destination in my equations?
It is easy to find. If you can find the source and destination
for electromagnetic waves, then you can for gravitational
waves, too, because the source is the same and so is
the destination. The difference is that there is a pair of
events, S_e and S_g. The electromagnetic event S_e
is delayed and the gravitational event is advanced, they
are not simultaneous events at the receiver. If you are
able to detect a gravitational wave at time t_0, then you
should be able to detect the associated electromagnetic
wave at time t_1 t_0. If the difference (t_1 - t_0) is very
large, say of some centuries, you will be in serious troubles
to find the source. This is the issue that might be happening
with distant astronomical objects: a great observed shift
between gravitational an electromagnetic events.

On 6 mar, 23:02, Eric Gisse wrote:
On Mar 6, 11:41 am, Albertito wrote:

There are evidences showing that in Solar system,
the speed of gravity is many orders of magnitude higher
than the speed of light.

No, there is not. Just because you say so doesn't mean it is true.

But, what must we understand
by speed of gravity?. Aetherists often claim that gravity
are longitudinal waves, whereas light are transverse
waves through the aether.

Why even mention this? Ether has been ruled out as a viable concept
EVERY SINGLE TIME for the last hundred and thirty years. Nobody but
cranks in the fringe take ether seriously anymore.


What is spacetime but a kind of ether?

We know that in any medium
longitudinal waves travel faster than transverse waves.

Only if the medium is anisotropic. Where are the calculations in which
you actually derive the things you write?

Wrong. Anisotropy is not a requirement for the speed of longitudinal
waves were higher than the speed of transverse ones. In isotropic
and homogenous medium that difference in speed holds too.

We can find that longitudinal speed, c_L, and transverse
c_S, in a medium, with Young's modules E, Poison's ratio
v and mass density d_0, are

c_L^2 = (E/d_0(1+v))(1-v)/(1-2v)
c_S^2 = (E/d_0(1+v))(1/2)

Stating the answer without derivation isn't acceptable anywhere, why
do you think we will accept what you write down without
rationalization?

I do not expect you will accept anything coming from me :-)
I know I've introduced some conjetures on my equations, without
rationalization. For example, to define the scale parameter
R = R_h (Hubble radius) is hand-waving. Actually that scale
parameter could be tuned to be exactly a Schwarzschild radius,

R = 2 GM/c^2

and the quadratic form c_L^2 + c_S^2 = c^2 (R/l_p)^2, would read

c_L^2 + c_S^2 = (2 GM/c l_p)^2,

Knowing that l_p = sqrt(h_bar G/c^3), it would get

c_L^2 + c_S^2 = 4 c G M^2/h_bar

But, a Planck mass is defined as m_p = sqr(h_bar c/G), so

c_L^2 + c_S^2 = 4 c^2 (M / m_p)^2

And, in a place where c_S = c, it would yield

c_L^2 + c^2 = 4 c^2 (M / m_p)^2,
c_L^2 = c^2 ( 4(M / m_p)^2 - 1),
c_L = c sqrt ( 4(M / m_p)^2 - 1).

If that value c_S = c is measured locally here on the Earth,
and M is the mass of the Sun, you can easily compute the
speed of gravity the Sun induces here on Earth. For practical
purposes, we can approximate that c_L to read

c_L = 2c (M / m_p).

On Mar 7, 5:13*am, Albertito wrote:
On 6 mar, 21:20, "Sue..." wrote:





On Mar 6, 3:41 pm, Albertito wrote:

There are evidences showing that in Solar system,
the speed of gravity is many orders of magnitude higher
than the speed of light.

There is evidence of that when you push a car.
It pushes back instantly. But that doesn't
mean gravity moves faster than c.

The finite speed of light is in evidence
as the car begins to move forward and the
remainder of the universe shifts position just a bit
to make room for the car's field from
a new position. That realignment propagates
at less than c.

But, what must we understand
by speed of gravity?.

See above:

I can't find a source or destination in
your equations. I can with Koroupolis
and the light paths are identified.

http://arxiv.org/abs/physics/0107015

[...]

Can't you find a source or destination in my equations?
It is easy to find. If you can find the source and destination
for electromagnetic waves, then you can for gravitational
waves, too, because the source is the same and so is
the destination. The difference is that there is a pair of
events, S_e and S_g.

OK... at a glance, I'll give ya that.

The electromagnetic event S_e
is delayed and the gravitational event is advanced, [...]

What is your basis for that?

Hopefully not a null solution of Maxwell's equations:
http://farside.ph.utexas.edu/teachin...es/node51.html

Before you spend too much time trying to make that curve
fit, read my initial response about the reaction force.
The pushed car is *instantly* indistinguishable from
a brick wall. There is no Young's modulus that will
pull that out of Hubble-scale distances.

Hint:
Matter curves space-time.
http://en.wikipedia.org/wiki/Stress-...ral_relativity

Sue...

On Mar 6, 9:41 pm, Albertito wrote:
There are evidences showing that in Solar system,
the speed of gravity is many orders of magnitude higher
than the speed of light. But, what must we understand
by speed of gravity?. Aetherists often claim that gravity
are longitudinal waves, whereas light are transverse
waves through the aether.

I'm not sure I follow. Gravity are [sic] longitudinal waves??
Gravity is a force.. are you talking about gravitational waves?

Or are you saying that graviational forces are somehow carried out by
absorption and emission of some waves? That seems unlikely
considering gravitational lensing and other effects.


We know that in any medium
longitudinal waves travel faster than transverse waves.

Not "in any medium", but in a medium defined with elasticity/solid
stress parameters E,G,v and K you use below. Right?



We can find that longitudinal speed, c_L, and transverse
c_S, in a medium, with Young's modules E, Poison's ratio
v and mass density d_0, are

c_L^2 = (E/d_0(1+v))(1-v)/(1-2v)
c_S^2 = (E/d_0(1+v))(1/2)

We also know there exists a relation between those
elastic constants, as

E=2G(1+v)=3K(1-2v),

where G is shear modulus and K is bulk modulus.
So, we have

c_L^2 = (2G/d_0)(1-v)/(1-2v)
c_S^2 = G/d_0

Therefore, for a Poison's ratio of v=1/2, it would result an
infinite longitudinal speed. In general we have

c_L^2 + c_S^2 = (G/d_0)(2(1-v)/(1-2v) + 1)

This quadratic relation suggests (G/d_0)(2(1-v)/(1-2v) + 1) is
a universal constant for vacuum. This suggests

(G/d_0)(2(1-v)/(1-2v) + 1) = (R/t_p)^2,
where R is a scale parameter and t_p is Planck time.
or
(G/d_0)(2(1-v)/(1-2v) + 1) = c^2 (R/l_p)^2,
where l_p is Planck length.

c_L^2 + c_S^2 = c^2 (R/l_p)^2,

So, for a speed of light being c_S=c, it would yield

c_L^2 + c^2 = c^2 (R/l_p)^2,

c_L = c sqrt((R/l_p)^2 - 1), which is roughly

c_L = c R/l_p,

if R is meaningfully larger than l_p.

If we define R = R_h (Hubble radius), then the speed
of gravity, there where the local speed of light is c,
would be

c_L = c R_h/l_p,

it is saying it would be a very superluminal speed
(i.e. infinite for practical purposes).

On Mar 7, 2:16 am, Albertito wrote:
On 6 mar, 23:02, Eric Gisse wrote:



On Mar 6, 11:41 am, Albertito wrote:

There are evidences showing that in Solar system,
the speed of gravity is many orders of magnitude higher
than the speed of light.

No, there is not. Just because you say so doesn't mean it is true.

But, what must we understand
by speed of gravity?. Aetherists often claim that gravity
are longitudinal waves, whereas light are transverse
waves through the aether.

Why even mention this? Ether has been ruled out as a viable concept
EVERY SINGLE TIME for the last hundred and thirty years. Nobody but
cranks in the fringe take ether seriously anymore.

What is spacetime but a kind of ether?

Spacetime in no way resembles ether. Learn what both the concepts
represent.


We know that in any medium
longitudinal waves travel faster than transverse waves.

Only if the medium is anisotropic. Where are the calculations in which
you actually derive the things you write?

Wrong. Anisotropy is not a requirement for the speed of longitudinal
waves were higher than the speed of transverse ones. In isotropic
and homogenous medium that difference in speed holds too.

Show me the derivation.

[snip spew]

You are not listening. You write down a bunch of equations but you
don't justify or derive any of them.

Albertito wrote:
There are evidences showing that in Solar system,
the speed of gravity is many orders of magnitude higher
than the speed of light.

Sure. But this is MODEL DEPENDENT. In the model of Newtonian
gravitation, gravity propagates INSTANTLY (i.e. with infinite speed). In
the model of GR, gravity does not propagate at all, but changes in
gravity propagate with speed c. 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
perihelions 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.).

Bottom line: it is MUCH better to discuss models and their agreement
with experiments than to discuss MODEl-DEPENDENT quantities like "speed
of gravity". That is, discuss science (experiments) rather than
engineering (measurements), and avoid unacknowledged puns (such as
model-dependent meanings of words that are treated as if they had a
single meaning) like "speed of gravity".


[... further nonsense based on unrealistic models ("aetherists")...]


Tom Roberts