Newton's Bucket Spin Experiment.
Daniel Weston
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?
César Sirvent
"Daniel Weston" <dani...@webtv.net> escribió en el mensaje
news:19580-409...@storefull-3136.bay.webtv.net...
It has to deal with the Mach's principle. I will not give a definition as
there are almost a dozen of different versions or interpretations, but you
can try this laypeople article by Paul Davies:
http://www.padrak.com/ine/INERTIA.html
The issue of some General Relativity (GR) effects being or not being
Machian -- for example, the Lense-Thirring effect -- is an open issue which
has been controversial even in recent times.
Cesar
Bill Hobba
"Daniel Weston" <dani...@webtv.net> wrote in message
news:19580-409...@storefull-3136.bay.webtv.net...
There is no big deal. If you consider the bucket rotating in an inertial
frame then you get the standard curved water shape as a result of
centrifugal forces. But the question is how does the water know how to
curve? - the answer is - because it is rotating relative to an inertial
frame. But wait a minute - an inertial frame is simply a conceptual
conventional standard of rest with a conceptual coordinate system - how can
acceleration wrt to something conceptual cause the water to curve? The
answer of course is that it is no more a problem than the forces that appear
when you accelerate wrt to an internal frame (it fact it is a result of
those). To get around these 'problems' Mach proposed it was rotation
relative to the distant stars. It has long been known that a frame at rest
relative to the distant stars was inertial. This provided the 'thing' it
accelerated relative to when an inertial frame was otherwise just something
conceptual. Me - I think it is a load of codswallop - but each to their
own. The answer is obvious - Newton's first law is in fact saying the
conceptually there always exits a frame where particles move with constant
velocity unless acted on by a force - whenever we see non inertial forces
appear it is obvious you must be accelerating wrt to some frame - even if it
is just conceptual. The is not to say Mach's principle is wrong - it may be
correct - I just think it is not required.
Thanks
Bill
Daniel Weston
The one I had I mind was the experiment of the bucket connected to a
rope, and this twisted rope when released provides torque to the bucket
causing it to spin on its axis.
Question: Is different analysis required between the overhead bucked
rotation, and the spin on a rope experiment?
dlzc1 D:cox T:net@nospam.com N:dlzc D:aol T:com (dlzc)
"Bill Hobba" <bho...@hotmail.com> wrote in message
news:oXSnc.31322$TT....@news-server.bigpond.net.au...
...
It would be a little hard to spin the Universe to find out, wouldn't it?
How would you feel if Gravity probe B showed frame dragging? Wouldn't this
apply to the "bucket test"?
(In case you hadn't figured it out, I pretty much like Mach's
interpretation.)
David A. Smith
Bill Hobba
"N:dlzc D:aol T:com (dlzc)" <N: dlzc1 D:cox T:n...@nospam.com> wrote in
message news:DKUnc.104035$Jy3.51618@fed1read03...
That the problem with Machs principle - how to test it. Although it has
been mentioned that Wheeler formulates it as mass causes space-time
curvature which is probably true and definitely testable.
>
> How would you feel if Gravity probe B showed frame dragging? Wouldn't
this
> apply to the "bucket test"?
I think it is a prediction of GR. GR also has inertial reference frames -
local ones. Indeed that is one of the ideas behind curvature - it is
locally inertial. So the question is why does the universe behave that way?
Answer - I don't really know - it does that's all. The real cause of
inertia is the symmetry properties of an inertial frame which basically is
why is an infintesimal sized frame in free fall homogeneous in space and
time and isotopic in space? Indeed even for macroscopic frames these
conditions are often satisfied to a high degree of accuracy. Well for one
thing science would be a pretty pointless endeavor if they did not exist a
least conceptually - after all it would be pretty hard to repeat excrement's
otherwise. And once you have such a frame the principles of QM imply the
law of inertia.
>
> (In case you hadn't figured it out, I pretty much like Mach's
> interpretation.)
Nothing wrong with that - any resonable view in accord iwth exprimnet is
fine with me. You might like to check out
http://chaos.fullerton.edu/~jimw/general/inertia/.
Thanks
Bill
Daniel Weston
absolute. Take 14 buckets on a rope and wind them up in such a manner
that when they are released, 7 spin clockwise, and 7 counter clockwise.
All 14 cannot be spinning only relatively. The same idea is at work in
our solar system with clockwise and counter clockwise spinning of the
planets.
On a different approach, let there be a sphere in deep inter galactic
space. And in the center of the sphere let there be a round table 10 ft
in diameter. It is noticed that there is relative spin between the
sphere and the table. Which is spinning though? Then place a marble 1
ft from the center of the table and note what happens. If the marble
moves away from the center spiraling out toward the edge, then we know
that it is the table that is spinning. If the marble does not move,
then we know that the sphere is spinning.
This looks like spin which can be called absolute.
dlzc1 D:cox T:net@nospam.com N:dlzc D:aol T:com (dlzc)
"Bill Hobba" <bho...@hotmail.com> wrote in message
news:kcYnc.31741$TT....@news-server.bigpond.net.au...
>
> "N:dlzc D:aol T:com (dlzc)" <N: dlzc1 D:cox T:n...@nospam.com> wrote in
> message news:DKUnc.104035$Jy3.51618@fed1read03...
...
Well, just a point, GR invokes geometries. Geometries that are the product
of mass/energy. So saying that "frame dragging" is a prediction of GR is
saying that not-quite-local matter might affect local inertia... no?
> > (In case you hadn't figured it out, I pretty much like Mach's
> > interpretation.)
>
> Nothing wrong with that - any resonable view in accord iwth exprimnet is
> fine with me. You might like to check out
> http://chaos.fullerton.edu/~jimw/general/inertia/.
I read it and navigated to the Overview page, and marked it as a favorite.
Thanks!
I've got my crank's version of the cause for inertia, but in response to a
newbie post is not the time or place.
David A. Smith
dlzc1 D:cox T:net@nospam.com N:dlzc D:aol T:com (dlzc)
"Daniel Weston" <dani...@webtv.net> wrote in message
news:26291-40A...@storefull-3137.bay.webtv.net...
> Not all spin is relative. Some spin is not relative and is therefor
> absolute. Take 14 buckets on a rope and wind them up in such a manner
> that when they are released, 7 spin clockwise, and 7 counter clockwise.
> All 14 cannot be spinning only relatively. The same idea is at work in
> our solar system with clockwise and counter clockwise spinning of the
> planets.
All 14 could be set to spin on different axes. Their rotation would EACH
still be relative.
> On a different approach, let there be a sphere in deep inter galactic
> space. And in the center of the sphere let there be a round table 10 ft
> in diameter. It is noticed that there is relative spin between the
> sphere and the table. Which is spinning though? Then place a marble 1
> ft from the center of the table and note what happens. If the marble
> moves away from the center spiraling out toward the edge, then we know
> that it is the table that is spinning. If the marble does not move,
> then we know that the sphere is spinning.
> This looks like spin which can be called absolute.
Still only relative. And still a glorified version of an accelerating
frame.
David A. Smith
Evan Kress
"Daniel Weston" <dani...@webtv.net> wrote in message
news:26291-40A...@storefull-3137.bay.webtv.net...
That's not the point of the discussion. Of course we see which reference
frame is subject to centrifugal and coriolis "forces", but Newton made the
point of asking why there is such a distinction in the first place. In
other words, how does the spinning reference frame "know" that it's spinning
with respect to the universe?
Evan
Bill Hobba
To be truthful it is not something I have really investigated. I must
devote a bit of time to looking into the details now the gravity probe is up
there.
Thanks
Bill
Bill Hobba
"Evan Kress" <flobb...@yahoo.com> wrote in message
news:c7ptdl$f03$1...@daisy.noc.ucla.edu...
That is the exact question. The importance you assign to it however is up
for grabs. Personally I think the existence of conceptual inertial frames
is all that is required. The link I gave David examines the issue in detail
and its relation to GR.
Thanks
Bill
Mike
No everage man can understand the ramifications of that simple
experiment, more so a grandson, probably a kid who is not yet
aquainted with linear equations of a single unknown. You are correct
it is not that simple but why are you torturing the child?
It is not clear what the bucket experiment is all about. This was an
attempt of Newton to rebutt Leibniz assertions that absolute space is
not a well-founded phenomenon. Kant spent his life in an effort to
support such a priori synthetic constructions in Newton's philosophy.
The bucket experiment carries ontological claims, i.e. the existence
of absolute space, from the 'interpretation' of such experiment. This
cannot be possible. IMO, the bucket experiment is devoid of any
meaningful conclusions.
Mike
Daniel Weston
contributors. My question now is; Is it possible to reasonable
conclude that an object is spinning without reference to any frame of
reference, or reference to absolute or non-absolute space? Is this a
legitimate simplification of what appears to be a somewhat intractable
problem?
Consider the following: In deep inter-galactic space, there is a
massive disk that appears to be rotating to a passing rocket. The disk
then breaks up with its pieces flying off roughly equally in all
directions along the apparent plane of rotation. The pilot of the
rocket concludes that the disk was in fact spinning, and broke up as
described, do to the internal stresses that eventually manifested
themselves by the disk breaking up. The disk would break up do to
internal stresses whether space was absolute or not. The disk would
break up do to internal stresses with or without the mental invention of
its frame of reference; or if you wish the disc was in its _own_ For.
INFERENCE; Rotating disks that break up as described, or planets that
bulge at the apparent equator, are inherently spinning and not
_relatively_ spinning. I.e. spinning is absolute. Note, we can conlude
that spinning is inherent without referance to whether space is absolute
or not.
Tom Roberts
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 tjro...@lucent.com
Ken S. Tucker
>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...
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 tjro...@lucent.com
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
Harry
It was indeed Newton's conclusion that rotation can be called
absolute, I think he meant relative to something in space that causes
inertia (I don't remember how he formulated it). It was in reply to
Descartes who claimed that everything was relative (that is, between
masses). Mach tried to provide an alternative by suggesting that it
was movement relative to the stars that does this.
A smart young boy will have less difficulty to understand these
concepts then with some of the replies that sound like suggestions
that our imagination makes the inertia that bends the water surface!
Harald
Bill Hobba
"Harry" <harald.v...@epfl.ch> wrote in message
news:3bff5641.04051...@posting.google.com...
Interesting take Harry. If your referring to my replies that is not what I
was suggesting. I was suggesting it was the principles of QM and symmetry
that creates inertia not necessarily the action of the distant stars. If
you investigate the line of reasoning that it is the distant masses then you
are inevitably lead to a Wheeler-Feynman absorber type model (see
http://chaos.fullerton.edu/~jimw/general/inertia/). Now this may quite well
be true but not everyone warms to the idea. The alternative explanation I
put forward (and I am not the only one) is QM and the symmetry properties of
an inertial frame causes free particles to move at constant velocity. This
just leaves why particles resist being changed from constant velocity ie why
do they push back ie why does action equal reaction ie why is momentum
conserved. The answer is the same - symmetry properties and QM. The
details can be found here:
http://arxiv.org/ftp/physics/papers/0207/0207047.pdf.
Now Harry are you seriously going to tell me that symmetry combined with the
laws of QM is unreasonable compared to the idea of gravitational influences
traveling forward and backward in time? Pull the other one Harry it plays
jingle bells. BTW I am not saying such a view is wrong but it is not
a-priori correct either.
Thanks
Bill
Bill Hobba
"Tom Roberts" <tjro...@Lucent.com> wrote in message
news:40A0E780...@Lucent.com...
> > 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
Bill Hobba
"Ken S. Tucker" <dyna...@vianet.on.ca> wrote in message
news:2202379a.04051...@posting.google.com...
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
Bill Hobba
Please see Tom Roberts response. My explanation is crap compared to his.
Thanks
Bill
Bill Hobba
> I have carefully read all the above posts, for which I thank all the
> contributors. My question now is; Is it possible to reasonable
> conclude that an object is spinning without reference to any frame of
> reference, or reference to absolute or non-absolute space? Is this a
> legitimate simplification of what appears to be a somewhat intractable
> problem?
>
> Consider the following: In deep inter-galactic space, there is a
> massive disk that appears to be rotating to a passing rocket.
Rotating relative to what - the rocket, a conceptual inertial frame or the
fixed distant stars?
> The disk
> then breaks up with its pieces flying off roughly equally in all
> directions along the apparent plane of rotation. The pilot of the
> rocket concludes that the disk was in fact spinning,
Wait a minute - you have already said it was rotating - are you saying that
the pilot of the rocket did not know it was rotating and that they simply
observed it break up?
> and broke up as
> described, do to the internal stresses that eventually manifested
> themselves by the disk breaking up. The disk would break up do to
> internal stresses whether space was absolute or not.
Stresses caused by what - its rotation? Suppose you are in a space station
(rotating relative to the fixed distant stars which are usually taken to
represent an inertial frame) constructed so it has a 'circle' in the middle
so that objects put in the circle do not have the forces of rotation
transmitted to them. Then from the station a disk placed there will be seen
to rotate but it will not have any rotation relative to the distant stars
hence will not have any stresses. Thus it is not rotation relative to some
frame that causes stresses it is rotation relative to an inertial frame.
> The disk would
> break up do to internal stresses with or without the mental invention of
> its frame of reference; or if you wish the disc was in its _own_ For.
> INFERENCE; Rotating disks that break up as described, or planets that
> bulge at the apparent equator, are inherently spinning and not
> _relatively_ spinning. I.e. spinning is absolute. Note, we can conlude
> that spinning is inherent without referance to whether space is absolute
> or not.
As explained above it depends on the frame of reference it is rotating wrt.
Thanks
Bill
Hayek
You will like it even more once you realize that a
clock is an inertiameter. The Earth does not only
drags the frames, it creates its own inertia. Every
inertiameter, formerly called clock, shows that on
Earth inertia is a little bit higher, one in a
billion. We just need to look at the inertiameters
that are carried on board of the gps-satellites :
these run fast, because there is a billionth part
less inertia at their altitude. Mach's principle is
confirmed by every clock, but we morons looked right
past it, all the time, or should I say, with all our
inertia ? :-)
Uwe Hayek.
--
To be controlled in our economic pursuits,
is to be controlled in everything -- F.A.Hayek.
Harry
Thanks for the elaboration Bill - that sounds a lot better indeed! Although
much too technical for a young boy of course.
Harald
Bill Hobba
That is a problem I have actually been thinking about lately. The truth is
a lot of these things are not simple - yet they are the type of things
intelligent curious young (and not so young) people ask. Exactly how they
can be explained without the math I have no idea. Because of that I do not
think you should even try. What I believe is, as difficult as it sounds, we
must move calculus down to lower grades - out to those who are actually
asking such questions. All that I can suggest is that we need to tell
people - yes these are legit questions and they do have an answer but you
need a bit more math to understand it. Are you interested in finding out?
Have a look at http://www.thefutureschannel.com/escalante_math_program.htm.
Thanks
Bill
César Sirvent
"Tom Roberts" <tjro...@Lucent.com> escribió en el mensaje
news:40A0E780...@Lucent.com...
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 tjro...@lucent.com
>
Ken S. Tucker
>"Ken S. Tucker" <dyna...@vianet.on.ca> wrote in message
>news:2202379a.04051...@posting.google.com...
>> Tom Roberts <tjro...@Lucent.com> wrote in message news:<40A0E780...@Lucent.com>...
>> > [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
Daniel Weston
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?
César Sirvent
"Bill Hobba" <bho...@hotmail.com> escribió en el mensaje
news:u5doc.33380$TT....@news-server.bigpond.net.au...
Yes, yes, but still no trace of the Higgs boson.
Bill Hobba
> 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
Ken S. Tucker
((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
Tom Roberts
> Tom Roberts <tjro...@Lucent.com> wrote in message news:<40A0E780...@Lucent.com>...
>>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.
No. Mach's principle is rather vague, mostly because he made about a
dozen different statements that are similar, but are all lumped together
as "Mach's principle". But its essence is that all the matter in the
universe is inherently involved, AND NOTHING ELSE. My point above is
that boundary conditions are also involved.
> The
> boundary at spatial infinity is Mach's "distant star's",
No, it's quite different.
> in a real universe.
Look back and note that my theoretical context was Newtonian mechanics.
It is well known that that cannot possibly apply to cosmological things
like spatial infinity.
> 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".
There is no mysticism about boundary conditions -- they are essential to
solving differential equations.
> I think Mach's Principle is a boundary condition,
> but IMHO, (agreeing with TR) is mystical.
Mach was not discussing boundary conditions at all, he was discussing
mass 'way out there.
> [Ken S. Tucker inserts an irrelevant and erroneous diversion about
> E&M]
You keep getting the basics wrong:
> E x B = c
In your notation, both E and B are 3-vectors, so E x B is also a
3-vector, but c is not. This equation cannot possibly be correct.
In fact, E x B is known as the Poynting vector, and for a light ray is
proportional to its momentum. In particular, a more intense light ray
has a larger momentum and a larger Poynting vector; it cannot possibly
be constant as you suppose. And as a 3-vector, it also has a direction.
Tom Roberts tjro...@lucent.com
Harry
> I guess there are 2 versions (at least) of Newton's bucket experiment.
> The one I had I mind was the experiment of the bucket connected to a
> rope, and this twisted rope when released provides torque to the bucket
> causing it to spin on its axis.
>
> Question: Is different analysis required between the overhead bucked
> rotation, and the spin on a rope experiment?
Newton's version was the twisted rope one. I think that is indeed the best
and simplest one to illustrate "absolute" rotation effects, as the problem
is perfectly symmetrical for the inertial and accelerated frames of
reference.
Harald
Ken S. Tucker
>Ken S. Tucker wrote:
Tom, I doubt the EM stuff you deleted would appeal
to you, it's quite advanced.
>> E x B = c
I should add is the DIRECTION of TRAVEL,
as the context suggested.
>In your notation, both E and B are 3-vectors, so E x B is also a
>3-vector, but c is not. This equation cannot possibly be correct.
>In fact, E x B is known as the Poynting vector, and for a light ray is
>proportional to its momentum. In particular, a more intense light ray
>has a larger momentum and a larger Poynting vector; it cannot possibly
>be constant as you suppose. And as a 3-vector, it also has a direction.
Right I should have specified c as a direction only of
the light-ray, without the magnitude. I did that because
it was the direction that was the principle argument.
Sorry for the confusion. (We at C-dyn, use short forms,
and I forget others don't).
>Tom Roberts tjro...@lucent.com
Hayek
Daniel Weston wrote:
You can't have one without the other. :-)
If you would put the bucket at the north pole, and
the water was fixed wrt to the stars, it would be
rotating because the Earth's mass drags the buckets
frame by a very little amount :
http://www.xs4all.nl/~notime/inert/gravp548.html
This is the essence of the Gravity Probe B experiment.
Read these pages from the MTW :
http://www.xs4all.nl/~notime/inert/gravp543.html
Hayek
Bill Hobba wrote:
> "Daniel Weston" <dani...@webtv.net> wrote in
> message
> news:26292-40...@storefull-3137.bay.webtv.net...
>
>
>
>> I have carefully read all the above posts, for
>> which I thank all the contributors. My
>> question now is; Is it possible to reasonable
>> conclude that an object is spinning without
>> reference to any frame of reference, or
>> reference to absolute or non-absolute space? Is
>> this a legitimate simplification of what
>> appears to be a somewhat intractable problem?
>>
>> Consider the following: In deep inter-galactic
>> space, there is a massive disk that appears to
>> be rotating to a passing rocket.
>
>
> Rotating relative to what - the rocket, a
> conceptual inertial frame or the fixed distant
> stars?
You put a droplet of water on it, near the center,
and the droplet accelerates away to the edge.
There is also a pendulum in the middle that seems to
ignore the roatation. And a Gyroscope, and some
brain cells that resist any motion towards Mach's
Principle. :-)
Hayek
Bill Hobba wrote:
> "N:dlzc D:aol T:com (dlzc)" <N: dlzc1 D:cox
> T:n...@nospam.com> wrote in message
[]
>> Well, just a point, GR invokes geometries.
>> Geometries that are the product of mass/energy.
>> So saying that "frame dragging" is a
>> prediction of GR is saying that not-quite-local
>> matter might affect local inertia... no?
> To be truthful it is not something I have really
> investigated. I must devote a bit of time to
> looking into the details now the gravity probe is
> up there.
[jaw dropping]
Yet you dare to answer me with these words :
Bill Hobba:
[HUP - Matrix solutions historical sequence]
> It is a matter of historical fact that the above
> is false. Hayak, why do you not actually learn
> the facts before running off at the mouth? What
> is it about crackpots that compels then to not
> check on their facts first? See page 249 Pias -
> Inward Bound.
I read Heisenberg's reasoning for the HUP, and there
where no matrices involved. I think it was dated
1927. The research with matrices to approach QM
continues and is improved to this day. Gentlemen do
not discuss facts, so you can score this one.
But the last days you have been discussing GR and MP
, and now it turns out that "it is not something
you have really investigated".
So it turns out that YOU have been wasting my time,
and I have been trying to entertain your views, and
I know realise that your views where based only
ignorance. I was suspecting that, but out of
politeness, and since I considered you a serious
poster, I have giving you the benefit of the doubt,
which honestly you did not deserve at all.
It is you who should withdraw, and investigate the
link between GR and MP.
In another thread I read you liked " a lot of
connected ideas in one place" (free quote).
I concentrated a lot of ideas in one phrase : "a
clock is an inertiameter".
I repeat "N:dlzc.." David Smiths's post:
"Well, just a point, GR invokes geometries.
Geometries that are the product of mass/energy.
So saying that "frame dragging" is a prediction
of GR is saying that not-quite-local matter might
affect local inertia... no?"
The geometries, the result of the mass/energy in GR
give you the clock rate at a point in space. Mach's
Principle gives you the inertia at a point in space
as a result of mass/energy.
The conclusion is very simple : Einstein and Mach
where talking about the same thing : time as in
clock rate and inertia are the same thing, and a
clock is an inertiameter.
There is a lot of other evidence that indicates
this, the mechanism of a clock, my reasoning with a
rotating disc, electrons in a cyclotron, etc..
Remember the words of JJ Thomson, given as a toast
at the "discovery of the electron"-party : "the tiny
little electron, may it be of no use whatsoever".
The realisation that a clock is an inertiameter may
indeed be of no use whatsoever. :-)
Hayek
N:dlzc D:aol T:com (dlzc) wrote:
> Dear Daniel Weston:
>
> "Daniel Weston" <dani...@webtv.net> wrote in message
> news:26291-40A...@storefull-3137.bay.webtv.net...
>
>>Not all spin is relative. Some spin is not relative and is therefor
>>absolute. Take 14 buckets on a rope and wind them up in such a manner
>>that when they are released, 7 spin clockwise, and 7 counter clockwise.
>>All 14 cannot be spinning only relatively. The same idea is at work in
>>our solar system with clockwise and counter clockwise spinning of the
>>planets.
>
>
> All 14 could be set to spin on different axes. Their rotation would EACH
> still be relative.
>
>
>>On a different approach, let there be a sphere in deep inter galactic
>>space. And in the center of the sphere let there be a round table 10 ft
>>in diameter. It is noticed that there is relative spin between the
>>sphere and the table. Which is spinning though? Then place a marble 1
>>ft from the center of the table and note what happens. If the marble
>>moves away from the center spiraling out toward the edge, then we know
>>that it is the table that is spinning. If the marble does not move,
>>then we know that the sphere is spinning.
>>This looks like spin which can be called absolute.
>
>
> Still only relative. And still a glorified version of an accelerating
> frame.
Now I understand why you do not understand.
A frame that is almost litteraly "UNIVERSE-ALL" can
be called absolute.
For the Earth the score absolute-relative is
2.0*10^13 to one.
http://www.xs4all.nl/~notime/inert/gravp548.html
dlzc1 D:cox T:net@nospam.com N:dlzc D:aol T:com (dlzc)
"Hayek" <hay...@nospam.xs4all.nl> wrote in message
news:40ad07c9$0$568$e4fe...@news.xs4all.nl...
You really are bored, aren't you?
> A frame that is almost litteraly "UNIVERSE-ALL" can
> be called absolute.
>
> For the Earth the score absolute-relative is
>
> 2.0*10^13 to one.
Means nothing. Even an inertial frame at rest wrt the CMBR *now* is
different than such a frame two minutes from *now*. The second frame has
accelerated, Universal curvature has changed. So all measurements are
relative to *now*, whenever those measurements might be. "Absolute" works
fine in philosophy...
David A. Smith
Hayek
Who cares about CMBR ?
> The second frame has accelerated, Universal
> curvature has changed.
Does not matter. It will stay an inertial frame.
And the frame will follow curvature. To the frame
the curvature is an absolute reference.
Take two black holes, "relatively" nearby eachother,
and rotating in two different directions.
Two penduli placed at their "North poles" will
rotate wrt to eachother and wrt to the stars.
But that does not mean that we can talk of "relative
rotation". Penduli do not rotate their plane of
swing, penduli follow the metric. So they follow a
reference, and that reference can be called
absolute. All pendulum at the respective the North
poles will not rotate wrt eachother.
I am willing to admit that the whole relative and
absolute discussion is moot, as long as we all agree
on what is real : the inertial metric defined by the
mass distribution. Gentlemen do not discuss facts.
And as I said in another post : the hypothetical
"flat space", a prerequisite of SR, *IS* an absolute
frame. All penduli in flat space will *NOT* rotate
wrt to eachother.
> So all measurements are relative to *now*,
> whenever those measurements might be. "Absolute"
> works fine in philosophy...
Also in practice, if you do not accept the road as
an absolute frame of reference you gonna get a lot
of speeding tickets. :-)
Hayek
Tom Roberts wrote:
> Ken S. Tucker wrote:
>
>> Tom Roberts <tjro...@Lucent.com> wrote in
>> message news:<40A0E780...@Lucent.com>...
>>
>>> 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.
>
>
> No. Mach's principle is rather vague, mostly
> because he made about a dozen different
> statements that are similar, but are all lumped
> together as "Mach's principle". But its essence
> is that all the matter in the universe is
> inherently involved, AND NOTHING ELSE. My point
> above is that boundary conditions are also
> involved.
Maybe not all the matter, as not all matter might be
in gravitational/inertial contact with us.
This translates also in some initial boundary condition.
[..]
> Tom Roberts tjro...@lucent.com