On 5/10/2004 2:15 PM, Daniel Weston wrote:
A few days ago I was explaining to my grandson the Newton Bucket Spin
Experiment. I explained the outcome in terms of centrifugal motion.
But the answer cannot be that simple or it would not be referenced so
often. And something about distant stars.

Can anyone explain the complexity of this experiment? What is the big
deal?

There has been a lot of misinformation in this thread -- things related
to "centrifugal force" and "Mach's principle", etc.

In fact, understanding this experiment is quite simple:

[Let me consider the experiment of twisting a rope, hanging
the bucket from the rope, and watching the surface of the
water in the bucket as it spins. The experiment of whirling
the bucket around one's head is quite similar, and the
analysis is basically the same (the details differ).
My theoretical context is Newtonian mechanics.]

As the bucket spins relative to a locally-inertial frame, the walls of
the bucket exert a contact force on the water near the walls, and the
water near the walls exerts a force on the water a bit further away,
etc. all the way to the center of the bucket where these forces cancel
out. In addition, of course, there is also a downward force of gravity
on all portions of the water and bucket. The shape of the water's
surface is completely determined by the dynamic balance of these forces.

The basic confusion here is: why is there a unique inertial frame here?
-- why can't we consider the rotating bucket to be inertial and the
earth to be non-inertial (remember my theoretical context)? The answer
is that we simply OBSERVE that there is a unique inertial frame here,
and the rotating bucket is rotating relative to it. This is a very good
thing, because it permits us to use geometry to model the spatial
relationships among objects.

Newtonian gravitation has no frame dragging -- if one applies
the formulas of Newtonian mechanics to an inertial bucket and
a rotating spherical earth, one finds that the rotation of the
earth is irrelevant to the shape of the surface of the water --
Poisson's equation is independent of time in this case.

Mach attempted to "explain" this by a mystical influence of the "fixed
stars" (it's mystical, because computations of their gravitational
effects fall vastly short of an explanation -- and if one assumes a
uniform density for the distant stars, Poisson's equation is again
independent of time and any rotation of the distant stars is irrelevant).

[There is an enormous literature on this, and I am not
an expert. This is the nickel tour.]

In short, to solve Poisson's equation one must
a) apply it in an inertial frame (it's not valid in a non-inertial
frame)
b) apply boundary conditions at spatial infinity.
These must be put in "by hand"; there is no avoiding it. At base this is
required in order to apply geometry to the problem (and without geometry
we have no way to analyze anything physical...).


If we expand the theoretical context to GR, we find that at every
location there is a unique class of locally-inertial frames. This is
good, because it permits us to model the world using differential
geometry. In GR, "Mach's principle" does not hold, and only a distant
echo of it reamins valid.

To a physicist this is enough: the model works. If one wishes to venture
into metaphysics, one might ask why differental geometry is such a good
model of the actual world, but I have no interest in going there....


Tom Roberts

Tom Roberts wrote in message ...
On 5/10/2004 2:15 PM, Daniel Weston wrote:
A few days ago I was explaining to my grandson the Newton Bucket Spin
Experiment. I explained the outcome in terms of centrifugal motion.
But the answer cannot be that simple or it would not be referenced so
often. And something about distant stars.

Can anyone explain the complexity of this experiment? What is the big
deal?

There has been a lot of misinformation in this thread -- things related
to "centrifugal force" and "Mach's principle", etc.
In fact, understanding this experiment is quite simple:

[Let me consider the experiment of twisting a rope, hanging
the bucket from the rope, and watching the surface of the
water in the bucket as it spins. The experiment of whirling
the bucket around one's head is quite similar, and the
analysis is basically the same (the details differ).
My theoretical context is Newtonian mechanics.]

As the bucket spins relative to a locally-inertial frame, the walls of
the bucket exert a contact force on the water near the walls, and the
water near the walls exerts a force on the water a bit further away,
etc. all the way to the center of the bucket where these forces cancel
out. In addition, of course, there is also a downward force of gravity
on all portions of the water and bucket. The shape of the water's
surface is completely determined by the dynamic balance of these forces.

Of course.

The basic confusion here is: why is there a unique inertial frame here?

Yup...

-- why can't we consider the rotating bucket to be inertial and the
earth to be non-inertial (remember my theoretical context)? The answer
is that we simply OBSERVE that there is a unique inertial frame here,
and the rotating bucket is rotating relative to it. This is a very good
thing, because it permits us to use geometry to model the spatial
relationships among objects.
Newtonian gravitation has no frame dragging -- if one applies
the formulas of Newtonian mechanics to an inertial bucket and
a rotating spherical earth, one finds that the rotation of the
earth is irrelevant to the shape of the surface of the water --
Poisson's equation is independent of time in this case.
Mach attempted to "explain" this by a mystical influence of the "fixed
stars" (it's mystical, because computations of their gravitational
effects fall vastly short of an explanation -- and if one assumes a
uniform density for the distant stars, Poisson's equation is again
independent of time and any rotation of the distant stars is irrelevant).

[There is an enormous literature on this, and I am not
an expert. This is the nickel tour.]

In short, to solve Poisson's equation one must
a) apply it in an inertial frame (it's not valid in a non-inertial
frame)

b) apply boundary conditions at spatial infinity.
These must be put in "by hand"; there is no avoiding it. At base this is
required in order to apply geometry to the problem (and without geometry
we have no way to analyze anything physical...).

Essentially Tom uses Mach's Principle here. The
boundary at spatial infinity is Mach's "distant star's",
in a real universe. There is a dichotomy in TR's arguement
above, Mach's principle was described by TR as "mysitcal"
but Tom's "b" renames that, a "boundary condition".

I think Mach's Principle is a boundary condition,
but IMHO, (agreeing with TR) is mystical.

If we expand the theoretical context to GR, we find that at every
location there is a unique class of locally-inertial frames. This is
good, because it permits us to model the world using differential
geometry. In GR, "Mach's principle" does not hold, and only a distant
echo of it reamins valid.

That sounds so good, I'd agree!

To a physicist this is enough: the model works. If one wishes to venture
into metaphysics, one might ask why differental geometry is such a good
model of the actual world, but I have no interest in going there....
Tom Roberts

Thanks Tom

Since Maxwell's Equations (ME) are practically incestuous
with relativity, it's predicted by ME that the propagation of
a light wave obeys the orthogonal relation, E x B = c and
E.B=0, (all vectors). In a so-called inertial FoR, those hold
and no deflection of light-waves occurs.

However in accelerating FoR's (non-inertial) light-waves
are observed to deflect, as the sun bends light paths.
Hence the ME relations ExB=c and E.B=0 do NOT hold
true, in accelerated FoR's.
That lead to the requirement of nonorthogonal geometry
in g-fields and non-inertial FoR's in general, to account for
ExB =/= c and E.B =/=0, that is required by deflection.

As we all know, we need three points to find if a line is
curving, same for the deflection of light on Newton's pail.
The light-wave path that curves relative to the pails's FoR
can have ANY source, ie. distant stars or a local source.
All light-waves bend the same way when subject to
measurement by an accelerating FoR in GR.

Regards
Ken S. Tucker

"Tom Roberts" wrote in message
...
On 5/10/2004 2:15 PM, Daniel Weston wrote:
A few days ago I was explaining to my grandson the Newton Bucket Spin
Experiment. I explained the outcome in terms of centrifugal motion.
But the answer cannot be that simple or it would not be referenced so
often. And something about distant stars.

Can anyone explain the complexity of this experiment? What is the big
deal?

There has been a lot of misinformation in this thread -- things related
to "centrifugal force" and "Mach's principle", etc.

In fact, understanding this experiment is quite simple:

[Let me consider the experiment of twisting a rope, hanging
the bucket from the rope, and watching the surface of the
water in the bucket as it spins. The experiment of whirling
the bucket around one's head is quite similar, and the
analysis is basically the same (the details differ).
My theoretical context is Newtonian mechanics.]

As the bucket spins relative to a locally-inertial frame, the walls of
the bucket exert a contact force on the water near the walls, and the
water near the walls exerts a force on the water a bit further away,
etc. all the way to the center of the bucket where these forces cancel
out. In addition, of course, there is also a downward force of gravity
on all portions of the water and bucket. The shape of the water's
surface is completely determined by the dynamic balance of these forces.

Much better explanation than I gave. I forgot to mention I was considering
a bucket hanging from a rope in a gravitational field pulling down on the
bucket. I also neglected the physical explanation of what is happening -
apart from a vague reference to centrifugal forces. Thanks for that Tom.


The basic confusion here is: why is there a unique inertial frame here?
-- why can't we consider the rotating bucket to be inertial and the
earth to be non-inertial (remember my theoretical context)? The answer
is that we simply OBSERVE that there is a unique inertial frame here,
and the rotating bucket is rotating relative to it. This is a very good
thing, because it permits us to use geometry to model the spatial
relationships among objects.

Newtonian gravitation has no frame dragging -- if one applies
the formulas of Newtonian mechanics to an inertial bucket and
a rotating spherical earth, one finds that the rotation of the
earth is irrelevant to the shape of the surface of the water --
Poisson's equation is independent of time in this case.

Mach attempted to "explain" this by a mystical influence of the "fixed
stars" (it's mystical, because computations of their gravitational
effects fall vastly short of an explanation -- and if one assumes a
uniform density for the distant stars, Poisson's equation is again
independent of time and any rotation of the distant stars is irrelevant).

I have always believed Machs principle was mystical - I have never liked it.
And despite what people claim I have never found explanations that try to
incorporate it into GR that convincing. For example
http://chaos.fullerton.edu/~jimw/general/inertia/ argues that it is
explained by GR citing works by Dennis Sciama and others - but its trail
inevitably leads to a Wheeler-Feynman absorber type theory which seems way
overkill for what I do no think is necessary to explain anyway. Your
explanation looks just fine.


[There is an enormous literature on this, and I am not
an expert. This is the nickel tour.]

In short, to solve Poisson's equation one must
a) apply it in an inertial frame (it's not valid in a non-inertial
frame)
b) apply boundary conditions at spatial infinity.
These must be put in "by hand"; there is no avoiding it. At base this is
required in order to apply geometry to the problem (and without geometry
we have no way to analyze anything physical...).


If we expand the theoretical context to GR, we find that at every
location there is a unique class of locally-inertial frames. This is
good, because it permits us to model the world using differential
geometry. In GR, "Mach's principle" does not hold, and only a distant
echo of it reamins valid.

To a physicist this is enough: the model works. If one wishes to venture
into metaphysics, one might ask why differental geometry is such a good
model of the actual world, but I have no interest in going there....

Thanks again for the excellent explanation
Bill

"Ken S. Tucker" wrote in message
om...
Tom Roberts wrote in message
...
On 5/10/2004 2:15 PM, Daniel Weston wrote:
A few days ago I was explaining to my grandson the Newton Bucket Spin
Experiment. I explained the outcome in terms of centrifugal motion.
But the answer cannot be that simple or it would not be referenced so
often. And something about distant stars.

Can anyone explain the complexity of this experiment? What is the big
deal?

There has been a lot of misinformation in this thread -- things related
to "centrifugal force" and "Mach's principle", etc.
In fact, understanding this experiment is quite simple:

[Let me consider the experiment of twisting a rope, hanging
the bucket from the rope, and watching the surface of the
water in the bucket as it spins. The experiment of whirling
the bucket around one's head is quite similar, and the
analysis is basically the same (the details differ).
My theoretical context is Newtonian mechanics.]

As the bucket spins relative to a locally-inertial frame, the walls of
the bucket exert a contact force on the water near the walls, and the
water near the walls exerts a force on the water a bit further away,
etc. all the way to the center of the bucket where these forces cancel
out. In addition, of course, there is also a downward force of gravity
on all portions of the water and bucket. The shape of the water's
surface is completely determined by the dynamic balance of these forces.

Of course.

The basic confusion here is: why is there a unique inertial frame here?

Yup...

-- why can't we consider the rotating bucket to be inertial and the
earth to be non-inertial (remember my theoretical context)? The answer
is that we simply OBSERVE that there is a unique inertial frame here,
and the rotating bucket is rotating relative to it. This is a very good
thing, because it permits us to use geometry to model the spatial
relationships among objects.
Newtonian gravitation has no frame dragging -- if one applies
the formulas of Newtonian mechanics to an inertial bucket and
a rotating spherical earth, one finds that the rotation of the
earth is irrelevant to the shape of the surface of the water --
Poisson's equation is independent of time in this case.
Mach attempted to "explain" this by a mystical influence of the "fixed
stars" (it's mystical, because computations of their gravitational
effects fall vastly short of an explanation -- and if one assumes a
uniform density for the distant stars, Poisson's equation is again
independent of time and any rotation of the distant stars is irrelevant).

[There is an enormous literature on this, and I am not
an expert. This is the nickel tour.]

In short, to solve Poisson's equation one must
a) apply it in an inertial frame (it's not valid in a non-inertial
frame)

b) apply boundary conditions at spatial infinity.
These must be put in "by hand"; there is no avoiding it. At base this is
required in order to apply geometry to the problem (and without geometry
we have no way to analyze anything physical...).

Essentially Tom uses Mach's Principle here. The
boundary at spatial infinity is Mach's "distant star's",
in a real universe.

Tom is trying to explain the problems with Mach's principle - he is not
invoking it.

There is a dichotomy in TR's arguement
above, Mach's principle was described by TR as "mysitcal"
but Tom's "b" renames that, a "boundary condition"

I think Mach's Principle is a boundary condition,
but IMHO, (agreeing with TR) is mystical.

Ken if you want to know the modern version of Mach's principle see
http://chaos.fullerton.edu/~jimw/general/inertia/. You will see it leads to
ideas that are rather strange indeed.

Thanks
Bill


If we expand the theoretical context to GR, we find that at every
location there is a unique class of locally-inertial frames. This is
good, because it permits us to model the world using differential
geometry. In GR, "Mach's principle" does not hold, and only a distant
echo of it reamins valid.

That sounds so good, I'd agree!

To a physicist this is enough: the model works. If one wishes to venture
into metaphysics, one might ask why differental geometry is such a good
model of the actual world, but I have no interest in going there....
Tom Roberts

Thanks Tom

Since Maxwell's Equations (ME) are practically incestuous
with relativity, it's predicted by ME that the propagation of
a light wave obeys the orthogonal relation, E x B = c and
E.B=0, (all vectors). In a so-called inertial FoR, those hold
and no deflection of light-waves occurs.

However in accelerating FoR's (non-inertial) light-waves
are observed to deflect, as the sun bends light paths.
Hence the ME relations ExB=c and E.B=0 do NOT hold
true, in accelerated FoR's.
That lead to the requirement of nonorthogonal geometry
in g-fields and non-inertial FoR's in general, to account for
ExB =/= c and E.B =/=0, that is required by deflection.

As we all know, we need three points to find if a line is
curving, same for the deflection of light on Newton's pail.
The light-wave path that curves relative to the pails's FoR
can have ANY source, ie. distant stars or a local source.
All light-waves bend the same way when subject to
measurement by an accelerating FoR in GR.

Regards
Ken S. Tucker

"Tom Roberts" escribió en el mensaje
...
On 5/10/2004 2:15 PM, Daniel Weston wrote:
A few days ago I was explaining to my grandson the Newton Bucket Spin
Experiment. I explained the outcome in terms of centrifugal motion.
But the answer cannot be that simple or it would not be referenced so
often. And something about distant stars.

Can anyone explain the complexity of this experiment? What is the big
deal?

There has been a lot of misinformation in this thread -- things related
to "centrifugal force" and "Mach's principle", etc.

In fact, understanding this experiment is quite simple:

[Let me consider the experiment of twisting a rope, hanging
the bucket from the rope, and watching the surface of the
water in the bucket as it spins. The experiment of whirling
the bucket around one's head is quite similar, and the
analysis is basically the same (the details differ).
My theoretical context is Newtonian mechanics.]

As the bucket spins relative to a locally-inertial frame, the walls of
the bucket exert a contact force on the water near the walls, and the
water near the walls exerts a force on the water a bit further away,
etc. all the way to the center of the bucket where these forces cancel
out. In addition, of course, there is also a downward force of gravity
on all portions of the water and bucket. The shape of the water's
surface is completely determined by the dynamic balance of these forces.

The basic confusion here is: why is there a unique inertial frame here?
-- why can't we consider the rotating bucket to be inertial and the
earth to be non-inertial (remember my theoretical context)? The answer
is that we simply OBSERVE that there is a unique inertial frame here,
and the rotating bucket is rotating relative to it. This is a very good
thing, because it permits us to use geometry to model the spatial
relationships among objects.

Newtonian gravitation has no frame dragging -- if one applies
the formulas of Newtonian mechanics to an inertial bucket and
a rotating spherical earth, one finds that the rotation of the
earth is irrelevant to the shape of the surface of the water --
Poisson's equation is independent of time in this case.

Mach attempted to "explain" this by a mystical influence of the "fixed
stars" (it's mystical, because computations of their gravitational
effects fall vastly short of an explanation -- and if one assumes a
uniform density for the distant stars, Poisson's equation is again
independent of time and any rotation of the distant stars is irrelevant).

De Sciama used a "toy model" which, with GR equations, tried to explain this
"mystical" influence. He later developed a more detailed theory, though it
was never completed successfully.

Apart from that, it is not clear and there is no consensus about what the
Mach's principle is as originally formulated, and the interpretation
regarding the "fixed stars" is one of many, but obviously the most famous.

[There is an enormous literature on this, and I am not
an expert. This is the nickel tour.]

In short, to solve Poisson's equation one must
a) apply it in an inertial frame (it's not valid in a non-inertial
frame)
b) apply boundary conditions at spatial infinity.
These must be put in "by hand"; there is no avoiding it. At base this is
required in order to apply geometry to the problem (and without geometry
we have no way to analyze anything physical...).


If we expand the theoretical context to GR, we find that at every
location there is a unique class of locally-inertial frames. This is
good, because it permits us to model the world using differential
geometry. In GR, "Mach's principle" does not hold, and only a distant
echo of it reamins valid.

Even there is controversy about the Lense-Thirring effect being a completely
Anti-Machian effect.

To a physicist this is enough: the model works. If one wishes to venture
into metaphysics, one might ask why differental geometry is such a good
model of the actual world, but I have no interest in going there....

The existence of inertia is not metaphysical, and recent models have been
tried (Rueda, Puthoff, Haisch, etc).

Tom Roberts

"Bill Hobba" wrote in message ...
"Ken S. Tucker" wrote in message
. com...
Tom Roberts wrote in message ...

[There is an enormous literature on this, and I am not
an expert. This is the nickel tour.]
In short, to solve Poisson's equation one must

a) apply it in an inertial frame (it's not valid in a non-inertial
frame)

b) apply boundary conditions at spatial infinity.

These must be put in "by hand"; there is no avoiding it. At base this is
required in order to apply geometry to the problem (and without geometry
we have no way to analyze anything physical...).

Essentially Tom uses Mach's Principle here. The
boundary at spatial infinity is Mach's "distant star's",
in a real universe.

Tom is trying to explain the problems with Mach's principle - he is not
invoking it.

Agreed, Tom can use Mach's principle without invoking it,
please don't twist my words, I didn't twist Tom's.

There is a dichotomy in TR's arguement
above, Mach's principle was described by TR as "mysitcal"
but Tom's "b" renames that, a "boundary condition"
I think Mach's Principle is a boundary condition,
but IMHO, (agreeing with TR) is mystical.

Ken if you want to know the modern version of Mach's principle see
http://chaos.fullerton.edu/~jimw/general/inertia/. You will see it leads to
ideas that are rather strange indeed.

Thanks Bill, I checked it out, and bookmarked for
further study.

Thanks
Bill

Ken S. Tucker

I would like to focus my question a bit by making the following
argument. I am not saying that I am correct, rather where is my serious
error.

Whenever someone says that an object is spinning, someone will
challenge, A) "In what FoR?", or B) "How do you know it is spinning
since there is no absolute space.?" My answer is that if a disk is
spinning, it is spinning INHERENTLY. I.e. it is spinning in its own
FoR, and spinning in its own space.

Let us return to our disk in inter-galactic space. Someone says that
its overall temperature has risen 100 degrees F. Someone challenges it
with, "relative to what?" Answer: Relative to a thermometer, or more
precisely, relative to the disk's internal temperature sensors.
The internal sensors are getting their information from the change in
atomic behaviour.

Let us assume further that this disk is a mile deep and 50 miles wide
with rockets on the edges that can be fired to make it spin. And
further that it has many stress and strain embedded sensors. It is in
deep space and the stress and strain indicators show a baseline value.
The rockets are fired and the indicators are showing more stress, and
then more stress etc. as the sensors measure the changing atom
configurations within it.
This shows that SPINNING IS INHERENT. It is not dependant upon an
external FoR, nor any kind of space external to its own. The disk
eventually flies apart. On objective occurance.

I therefore conclude that spinning is absolute, it is inherent, and
proof of spinning can be done without an external space of For.

Where have I erred?

"Bill Hobba" escribió en el mensaje
...

"Tom Roberts" wrote in message
...
On 5/10/2004 2:15 PM, Daniel Weston wrote:
A few days ago I was explaining to my grandson the Newton Bucket Spin
Experiment. I explained the outcome in terms of centrifugal motion.
But the answer cannot be that simple or it would not be referenced so
often. And something about distant stars.

Can anyone explain the complexity of this experiment? What is the big
deal?

There has been a lot of misinformation in this thread -- things related
to "centrifugal force" and "Mach's principle", etc.

In fact, understanding this experiment is quite simple:

[Let me consider the experiment of twisting a rope, hanging
the bucket from the rope, and watching the surface of the
water in the bucket as it spins. The experiment of whirling
the bucket around one's head is quite similar, and the
analysis is basically the same (the details differ).
My theoretical context is Newtonian mechanics.]

As the bucket spins relative to a locally-inertial frame, the walls of
the bucket exert a contact force on the water near the walls, and the
water near the walls exerts a force on the water a bit further away,
etc. all the way to the center of the bucket where these forces cancel
out. In addition, of course, there is also a downward force of gravity
on all portions of the water and bucket. The shape of the water's
surface is completely determined by the dynamic balance of these forces.

Much better explanation than I gave. I forgot to mention I was
considering
a bucket hanging from a rope in a gravitational field pulling down on the
bucket. I also neglected the physical explanation of what is happening -
apart from a vague reference to centrifugal forces. Thanks for that Tom.


The basic confusion here is: why is there a unique inertial frame here?
-- why can't we consider the rotating bucket to be inertial and the
earth to be non-inertial (remember my theoretical context)? The answer
is that we simply OBSERVE that there is a unique inertial frame here,
and the rotating bucket is rotating relative to it. This is a very good
thing, because it permits us to use geometry to model the spatial
relationships among objects.

Newtonian gravitation has no frame dragging -- if one applies
the formulas of Newtonian mechanics to an inertial bucket and
a rotating spherical earth, one finds that the rotation of the
earth is irrelevant to the shape of the surface of the water --
Poisson's equation is independent of time in this case.

Mach attempted to "explain" this by a mystical influence of the "fixed
stars" (it's mystical, because computations of their gravitational
effects fall vastly short of an explanation -- and if one assumes a
uniform density for the distant stars, Poisson's equation is again
independent of time and any rotation of the distant stars is
irrelevant).

I have always believed Machs principle was mystical - I have never liked
it.
And despite what people claim I have never found explanations that try to
incorporate it into GR that convincing. For example
http://chaos.fullerton.edu/~jimw/general/inertia/ argues that it is
explained by GR citing works by Dennis Sciama and others - but its trail
inevitably leads to a Wheeler-Feynman absorber type theory which seems way
overkill for what I do no think is necessary to explain anyway. Your
explanation looks just fine.

Yes, yes, but still no trace of the Higgs boson.

[There is an enormous literature on this, and I am not
an expert. This is the nickel tour.]

In short, to solve Poisson's equation one must
a) apply it in an inertial frame (it's not valid in a non-inertial
frame)
b) apply boundary conditions at spatial infinity.
These must be put in "by hand"; there is no avoiding it. At base this is
required in order to apply geometry to the problem (and without geometry
we have no way to analyze anything physical...).


If we expand the theoretical context to GR, we find that at every
location there is a unique class of locally-inertial frames. This is
good, because it permits us to model the world using differential
geometry. In GR, "Mach's principle" does not hold, and only a distant
echo of it reamins valid.

To a physicist this is enough: the model works. If one wishes to venture
into metaphysics, one might ask why differental geometry is such a good
model of the actual world, but I have no interest in going there....

Thanks again for the excellent explanation
Bill

"Daniel Weston" wrote in message
...
I would like to focus my question a bit by making the following
argument. I am not saying that I am correct, rather where is my serious
error.

Whenever someone says that an object is spinning, someone will
challenge, A) "In what FoR?", or B) "How do you know it is spinning
since there is no absolute space.?" My answer is that if a disk is
spinning, it is spinning INHERENTLY. I.e. it is spinning in its own
FoR, and spinning in its own space.

There only exists spinning relative to frames of reference.


Let us return to our disk in inter-galactic space. Someone says that
its overall temperature has risen 100 degrees F.
Someone challenges it
with, "relative to what?" Answer: Relative to a thermometer, or more
precisely, relative to the disk's internal temperature sensors.

But temperatire is not a coorinarte dependant phnomena like the proper time
or length are not coordinate dependant phenomena.

The internal sensors are getting their information from the change in
atomic behaviour.

So?


Let us assume further that this disk is a mile deep and 50 miles wide
with rockets on the edges that can be fired to make it spin.


Again spin relative to what?

And
further that it has many stress and strain embedded sensors. It is in
deep space and the stress and strain indicators show a baseline value.
The rockets are fired and the indicators are showing more stress, and
then more stress etc. as the sensors measure the changing atom
configurations within it.
This shows that SPINNING IS INHERENT.

All it shows is that like the use of accelerometers you can detect non
inertial coordinate systems.

It is not dependant upon an
external FoR, nor any kind of space external to its own. The disk
eventually flies apart. On objective occurrence.

Sure, but all you have shown is that your able to detect non inertial frames
just like accellerometers do. That has never been questioned. What
machiens question is the cause of those forces - they say that the disk may
not be spinning - the universe around the disk may be rotating and that is
what causes the forces you measure.


I therefore conclude that spinning is absolute, it is inherent, and
proof of spinning can be done without an external space of For.

Where have I erred?

No where. All you have done is measured non inertial forces. No one
claimed you could not do that. What some claim is that such forces are not
necessarily caused by the object spinning but by the universe around it
rotating.

Thanks
Bill

(Daniel Weston) wrote in message ...
I would like to focus my question a bit by making the following
argument. I am not saying that I am correct, rather where is my serious
error.

Whenever someone says that an object is spinning, someone will
challenge, A) "In what FoR?", or B) "How do you know it is spinning
since there is no absolute space.?" My answer is that if a disk is
spinning, it is spinning INHERENTLY. I.e. it is spinning in its own
FoR, and spinning in its own space.

Let us return to our disk in inter-galactic space. Someone says that
its overall temperature has risen 100 degrees F. Someone challenges it
with, "relative to what?" Answer: Relative to a thermometer, or more
precisely, relative to the disk's internal temperature sensors.
The internal sensors are getting their information from the change in
atomic behaviour.

Let us assume further that this disk is a mile deep and 50 miles wide
with rockets on the edges that can be fired to make it spin. And
further that it has many stress and strain embedded sensors. It is in
deep space and the stress and strain indicators show a baseline value.
The rockets are fired and the indicators are showing more stress, and
then more stress etc. as the sensors measure the changing atom
configurations within it.
This shows that SPINNING IS INHERENT. It is not dependant upon an
external FoR, nor any kind of space external to its own. The disk
eventually flies apart. On objective occurance.

I therefore conclude that spinning is absolute, it is inherent, and
proof of spinning can be done without an external space of For.

Where have I erred?

((erred is a bit strong, but....))
Because the centrifugal force can be replaced by
gravitational force. Let me simplify using a baton
(use a barbell if you're feeling masculine).

In Fig1 a rigid rod is rotating about the center

A--------+----------B
^
center Fig1.

Observers at either A or B sense a centrifugal force.

In Fig2 that same rigid rod is not rotating, instead
two gravitating masses "O" are situated like,

O A--------+----------B O
^
center Fig2.

The observers at A or B sense a gravitational force,
from the "O"'s and that force is indistguishable from
the centrifugal force that observers in Fig1 sense.
That's an example of the Principle of Equivalence,
and shows that "spinning" is not absolute, relative to
A or B.

That doesn't mean inertial forces in Fig1 and gravitational
forces in Fig2 are the same, metrically they are quite
different. For example, observers at A and B in Fig1
will observe a varying aberation of the position of Mach's
"distant stars", but A and B in Fig2 will not. Also A and B
in Fig1 will observe a reversal of the aberation if the direction
of rotation is reversed.
If you want I can detail these metrics.
Regards
Ken S. Tucker