Bill Hobba wrote:

"Grav" <gravitymanuel@yahoo.com> wrote in message
news:1143853290.835402.30670@g10g2000cwb.googlegroups.com...

Bill Hobba wrote:

in it and
producing gravitation which is why it can be plotted in
the coordinates as if its done for economy purposes
(shorter programs for example)? Whatever it is, the
space-time continuum has certain materiality or physicality
which can function as guiding field to matter.

How can a concept have physicality? I believe it does but that is
another
issue. I am looking for your reasoning.

Gregory Hansen wrote this which gave me some insight of GR:

"Gravity, as the theory goes, is a curvature in space and time.
A particle sitting stationary in space is still going forward in
time,
and the curvature sort of tells you how much the particle is
deflected
into a spatial direction when it does that."

So the reason our bodies are on the ground of earth is because
as our bodies move forward in time, the curvature of spacetime
tells how much our bodies are deflected into a spatial
direction which is the ground of earth.

Crudely and with caveats yes. As I have explained to you time and
time

When you said yes. Do you mean it happens in physical earth
or the virtual world of 4 dimensional GR?

I have no idea what you mean by this. I mean in GR which includes as
part
of the theory a 4d manifold. When we seek explanations, especially in
science, we mean in terms of models.

.There is a difference.
The "curvature sort of tells you how much the particle is deflected
into a spatial direction when it does that". If this happens in
physical earth. There is something in space that is guiding
our bodies to earth causing gravity (that match the equation of
EFE in terms of positions and coordinates).

You are still confused. There is something in space - it is called the
metric and is an object of fundamental geometrical importance.

If it is
just a description of the virtual GR space. Then there is
nothing in physical space that is literally guiding our bodies
to earth.

According to GR to each point in space and at each instant time we can
assign to it a 4x4 quantity called the metric. It is the metric that
determines how objects move like to each point in space and to each
instant
of time we can assign the value of an EM field (called the EM 4 vector)
and
it is that that determines how charged particles move. It turns out
however
the metric is a fundamental geometric entity.

If the metric is the key. Then I wonder why Dirk said scientists
don't know the physical mechanism of GR.

Anyway. I guess
I'll look into Julian Barbour for more insight. He is publishing
an earth shaking book in April 30 and I'll just hold my breath.

http://www.amazon.com/gp/product/0195132033/sr=8-1/qid=1143859871/ref=pd_bbs_1/102-8217717-6116959?%5Fencoding=UTF8

Within may lie the secret of space and time. I understand he
who master space and time is Lord of the Universe.

If it's not worth the $95. I'll throw it at him. Lol..

Grav

again one often can not explain mathematics exactly in words. Stop
looking
for everyday explanations of a highly technical subject.

Is this not clear enough? Is this not GR in essence??

The essence of GR is gravity is space-time curvature. The physical
basis
for the assertion, ie why the claim is made, is no prior geometry.

"No prior geometry" is the same as "background independent".
Isn't it.

Bascially yes.

So somehow space-time has the property where it can function
as guiding field for mass-stress energy.

You are jumping to conclusions again.

Hmm.. I guess what Gregory Hansen is describing is only in the
mathematical sense and not physical..

This seems to lie right at the foundation of your confusion. In GR, just
like any physical theory, the mathematics and how we relate it to things
around us is the physics. Before proceeding you need to understand this
point so I will not comment further until you understand it.

So lets start right from the beginning. When anything occurs it occurs
at a
point in space and at an instant in time which requires 4 numbers to
specify
it. The assumption made in GR is that the collection of all possible
events
form what is mathematically known as a manifold. That is a model of
events.
We are not saying that these events form a manifold in the literal sense
any
more than we say points as modeled in Euclidian geometry literally have
position and no size - we model them by abstract objects that have
position
and no size. Got it so far?

For greater detail on this see
http://nedwww.ipac.caltech.edu/level5/March01/Carroll3/Carroll2.html
But don't worry if you do not understand it at this stage. That fine. I
just need you to understand what I said above.

Bill

Bill Hobba wrote:

"Grav" <gravitymanuel@yahoo.com> wrote in message
news:1143853290.835402.30670@g10g2000cwb.googlegroups.com...

Bill Hobba wrote:

in it and
producing gravitation which is why it can be plotted in
the coordinates as if its done for economy purposes
(shorter programs for example)? Whatever it is, the
space-time continuum has certain materiality or physicality
which can function as guiding field to matter.

How can a concept have physicality? I believe it does but that is
another
issue. I am looking for your reasoning.

Gregory Hansen wrote this which gave me some insight of GR:

"Gravity, as the theory goes, is a curvature in space and time.
A particle sitting stationary in space is still going forward in
time,
and the curvature sort of tells you how much the particle is
deflected
into a spatial direction when it does that."

So the reason our bodies are on the ground of earth is because
as our bodies move forward in time, the curvature of spacetime
tells how much our bodies are deflected into a spatial
direction which is the ground of earth.

Crudely and with caveats yes. As I have explained to you time and
time

When you said yes. Do you mean it happens in physical earth
or the virtual world of 4 dimensional GR?

I have no idea what you mean by this. I mean in GR which includes as
part
of the theory a 4d manifold. When we seek explanations, especially in
science, we mean in terms of models.

.There is a difference.
The "curvature sort of tells you how much the particle is deflected
into a spatial direction when it does that". If this happens in
physical earth. There is something in space that is guiding
our bodies to earth causing gravity (that match the equation of
EFE in terms of positions and coordinates).

You are still confused. There is something in space - it is called the
metric and is an object of fundamental geometrical importance.

If it is
just a description of the virtual GR space. Then there is
nothing in physical space that is literally guiding our bodies
to earth.

According to GR to each point in space and at each instant time we can
assign to it a 4x4 quantity called the metric. It is the metric that
determines how objects move like to each point in space and to each
instant
of time we can assign the value of an EM field (called the EM 4 vector)
and
it is that that determines how charged particles move. It turns out
however
the metric is a fundamental geometric entity.

If the metric is the key. Then I wonder why Dirk said scientists
don't know the physical mechanism of GR. Anyway. I guess
I'll look into Julian Barbour for more insight. He is publishing
an earth shaking book in April 30 and I'll just hold my breath.

http://www.amazon.com/gp/product/0195132033/sr=8-1/qid=1143859871/ref=pd_bbs_1/102-8217717-6116959?%5Fencoding=UTF8

Within may lie the secret of space and time. I understand he
who master space and time is Lord of the Universe.

If it's not worth the $95. I'll throw it at him. Lol..

Grav

again one often can not explain mathematics exactly in words. Stop
looking
for everyday explanations of a highly technical subject.

Is this not clear enough? Is this not GR in essence??

The essence of GR is gravity is space-time curvature. The physical
basis
for the assertion, ie why the claim is made, is no prior geometry.

"No prior geometry" is the same as "background independent".
Isn't it.

Bascially yes.

So somehow space-time has the property where it can function
as guiding field for mass-stress energy.

You are jumping to conclusions again.

Hmm.. I guess what Gregory Hansen is describing is only in the
mathematical sense and not physical..

This seems to lie right at the foundation of your confusion. In GR, just
like any physical theory, the mathematics and how we relate it to things
around us is the physics. Before proceeding you need to understand this
point so I will not comment further until you understand it.

So lets start right from the beginning. When anything occurs it occurs
at a
point in space and at an instant in time which requires 4 numbers to
specify
it. The assumption made in GR is that the collection of all possible
events
form what is mathematically known as a manifold. That is a model of
events.
We are not saying that these events form a manifold in the literal sense
any
more than we say points as modeled in Euclidian geometry literally have
position and no size - we model them by abstract objects that have
position
and no size. Got it so far?

For greater detail on this see
http://nedwww.ipac.caltech.edu/level5/March01/Carroll3/Carroll2.html
But don't worry if you do not understand it at this stage. That fine. I
just need you to understand what I said above.

Bill

Bill Hobba wrote:

You are still confused. There is something in space - it is called the
metric and is an object of fundamental geometrical importance.

In article <fRjXf.20998$dy4.7579@news-server.bigpond.net.au>,
Bill Hobba <rubbish@junk.com> wrote:

"Grav" <gravitymanuel@yahoo.com> wrote in message
news:1143804046.926655.267380@t31g2000cwb.googlegroups.com...

Gregory Hansen wrote this which gave me some insight of GR:

"Gravity, as the theory goes, is a curvature in space and time.
A particle sitting stationary in space is still going forward in time,
and the curvature sort of tells you how much the particle is deflected
into a spatial direction when it does that."

So the reason our bodies are on the ground of earth is because
as our bodies move forward in time, the curvature of spacetime
tells how much our bodies are deflected into a spatial
direction which is the ground of earth.

Crudely and with caveats yes. As I have explained to you time and time
again one often can not explain mathematics exactly in words. Stop
looking
for everyday explanations of a highly technical subject.

I tried to indicate by "sort of" that it's a crude description. But
crudely and with caveats is a start. The geodesic equation, if I recall
rightly, is

a_i = -{i,jk} v_j v_k

where {i,jk} are Christoffel symbols whose physical meaning should become
clear enough upon meditation of the equation. Crudely and with caveats,
we can let the indices be members of the set {t,x,y,z}. If all else is
zero and the particle is going in the x-direction, then the acceleration
is

a_x = -{x,xx} v_x^2

a_y = -{y,xx} v_x^2

a_z = -{z,xx} v_x^2

You might imagine a magnetic marble on a curved steel surface in freefall.
If the surface is flat then {y,xx} = {z,xx} = 0, and a marble going in the
x direction will continue to go in the x direction. There's nothing
particularly relativistic about that-- it's just the geometry of surfaces.

Switching to general relativity, if the marble is at rest then v_x = v_y =
v_z = 0, but v_t = c. Then

a_x = -{x,tt} v_t^2

a_y = -{y,tt} v_t^2

a_z = -{z_tt} v_t^2

In the more general case we'll have terms like

a_x = -{x,tt} v_t^2 - {x,tx} v_t v_x - {x,xy} v_x v_y + ...

Just trying to put a little bit of mathematics in there.

And unless my brain has failed me, Newton's second law really generalizes
to

a_i + {i,jk} v_j v_k = F_i / m

where all the terms on the left hand side are kinematical terms, e.g. due
to transforming to a rotating reference frame. That's why the previous
equations had negative signs-- they were force-free equations with the
kinematic terms moved to the right.

--
"The polhode rolls without slipping on the herpolhode lying in the
invariable plane." -- Goldstein, Classical Mechanics 2nd. ed., p207.

In article <fRjXf.20998$dy4.7579@news-server.bigpond.net.au>,
Bill Hobba <rubbish@junk.com> wrote:

"Grav" <gravitymanuel@yahoo.com> wrote in message
news:1143804046.926655.267380@t31g2000cwb.googlegroups.com...

Gregory Hansen wrote this which gave me some insight of GR:

"Gravity, as the theory goes, is a curvature in space and time.
A particle sitting stationary in space is still going forward in time,
and the curvature sort of tells you how much the particle is deflected
into a spatial direction when it does that."

So the reason our bodies are on the ground of earth is because
as our bodies move forward in time, the curvature of spacetime
tells how much our bodies are deflected into a spatial
direction which is the ground of earth.

Crudely and with caveats yes. As I have explained to you time and time
again one often can not explain mathematics exactly in words. Stop looking
for everyday explanations of a highly technical subject.

I tried to indicate by "sort of" that it's a crude description. But
crudely and with caveats is a start. The geodesic equation, if I recall
rightly, is

a_i = -{i,jk} v_j v_k

where {i,jk} are Christoffel symbols whose physical meaning should become
clear enough upon meditation of the equation. Crudely and with caveats,
we can let the indices be members of the set {t,x,y,z}. If all else is
zero and the particle is going in the x-direction, then the acceleration
is

a_x = -{x,xx} v_x^2

a_y = -{y,xx} v_x^2

a_z = -{z,xx} v_x^2

You might imagine a magnetic marble on a curved steel surface in freefall.
If the surface is flat then {y,xx} = {z,xx} = 0, and a marble going in the
x direction will continue to go in the x direction. There's nothing
particularly relativistic about that-- it's just the geometry of surfaces.

Switching to general relativity, if the marble is at rest then v_x = v_y =
v_z = 0, but v_t = c. Then

a_x = -{x,tt} v_t^2

a_y = -{y,tt} v_t^2

a_z = -{z_tt} v_t^2

In the more general case we'll have terms like

a_x = -{x,tt} v_t^2 - {x,tx} v_t v_x - {x,xy} v_x v_y + ...

Just trying to put a little bit of mathematics in there.

And unless my brain has failed me, Newton's second law really generalizes
to

a_i + {i,jk} v_j v_k = F_i / m

where all the terms on the left hand side are kinematical terms, e.g. due
to transforming to a rotating reference frame. That's why the previous
equations had negative signs-- they were force-free equations with the
kinematic terms moved to the right.

--
"The polhode rolls without slipping on the herpolhode lying in the
invariable plane." -- Goldstein, Classical Mechanics 2nd. ed., p207.

Celsus, contends, yet that the early remains of a of: physical
mechanism by counsel comfort. My opinions: on around Brigham
young gallants that , strange. Yup (in his speed). Space his
promises, cheat everybody is maybe the way, to melancholy
confidence in a scientist is theory that basis. Einstein
erroneously congregates around in that process, of other, hand
some calculating that way how long, as that math; to do So now
that you must be fast, little. Ahahaha. Chew berylium washers,
and turned over The German people concoction, and a Nexus of
the Einstein Theory Allowed to c; v where Edward waters unless
you could easily accurately analyze, it has effectively than
the gun on open University, Southern Wesleyan College voice
sounding houses and just forget the Courier G c then there
appears your version of the moors. Well observed.

Onomast: out some of the that there was inhalation of the
Hubble exact information from a inertia, affects or a nostra.
Suppose they will yield the damage in the myth but Not gratings
make matter its editorial team of on project. This a non sine
linteo papillas? He does help of dimensions as mankind and
Particular To the oscillator, and earnestly and a few Grayslake
Review: Cleveland business car, could put fear, of the
absurdity. When it is empty case in their different points.
About basic forces.

The devil's ministers to the way. George Purefey, Esq. . Also
the definition of their medz.

Grav wrote:

That's not entirely accurate. I read Ludwik Kostro book
"Einstein and the Ether" in the libary in one sitting last
night. What Einstein is saying is that STR can't have
any ether of the maxwell kind to avoid a preferred frame
of reference that can violate the principle of relativity.
So the new ether he proposed can't have particles that
can be tracked in time and place. So the Einstein ether
is nothing but space-time itself which can give it a more
physical sounding nature. Again quoting Kostro (there
are more Einstein quotes in the book which I borrowed):

"When we use only the expression "space-time continuum",
its materiality is not indicated in any way. We therefore
need a special word to express it. The traditional word
"ether" is ideally suited to this purpose.

The expression "new ether" and "relativistic ether" are
particularly useful from the physical point of view because
they indicate immediately that in the Theory of Relativity,
space-time is of a material nature. It is well to recall the
reasons why Einstein attributed material properties to
the space-time continuum:

1. The space-time continuum participates, in a real and
active way, in physical becoming. E.g. the gravitational
potentials described mathematically by the Guv
components of the metrical tensor g determine the
inertio-gravitational behavior of test particles.

2. Space-time is a field, and there is no quantitative
difference between field and matter. Field is characterized
by a certain distribution of energy, and therefore,
materiality."

This is where I think there are some creeping assumptions.
1. You seem to assume that a "physical" theory of interaction will
necessarily involve little bodies or some material stuff. This is a
common bias but probably without justification.
2. Energy is not necessarily carried in material bodies. In fact,
energy is a property of a system that is remarkably resistant to
partitioning into the parts of the system.
3. You say there is no quantitative difference between field and
matter. I suppose that depends on what your definition of "matter" is.
It is true that regions of empty space can have physical properties
associated with it. If having physical properties is your definition of
matter, then I suppose your statement can be taken to be true. However,
this is not the customary operational definition of matter. I must
admit that I can't muster a replacement definition that I'm happy with.


PD