"Androcles" wrote in message
...

"Bill Miller" wrote in message
...
|
| "Timo A. Nieminen" wrote in message
| ...
| On Mon, 23 Jun 2008, Bill Miller wrote:
|
|
| "Timo A. Nieminen" wrote in message
| ...
| On Sat, 21 Jun 2008, Bill Miller wrote:
|
| snip
|
| Correct. And as long as the interaction is of a contact nature, then
| eveything is OK. But when there is a delay between the action and the
| reaction, then *for that delay period* momentum is not conserved. But
we
| know that momentum MUST be conserved, so we must look at Newton with
an
| eye
| to modifying it to deal with what amounts to a time dependency.
|
| This is not a new idea. We have long recognized, for EM that
electrostaic
| representations break down when time dependency is present.
|
| Heaviside suggested this in 1893 but never took it all the way to its
| logical conclusion.
|
| Heaviside's Maxwellian gravitation? There is no modification of
Newton's
| laws of motion in it. Newton's law of universal gravitation,
describing
| gravitational forces as interactions between distant bodies, is
replaced
| by a field theory, wherein all interactions are local - body interacts
| with local field, not body with distant body.
|
| You must be looking at a different copy of Heaviside's 1893 article. In
it,
| he clearly (to me at least) understood concepts of time-dependancy, the
| gravitational equivalent of the Poynting Vector (that he claimed partial
| credit for) and others. I agree that he did NOT deal with retardation.
| Neither did/does Maxwell!
|
| This "action at a distance" has always been an Achilles Heel.
|
| It is resolved, I believe by understanding and applying Causality. We
need
| to understand that if two events occur at the same time, neither can
cause
| the other. Instead, at least one must be caused by some other (hidden)
| event.
|
| Recognition of this simple concept would, as one example, have stopped
| generations of instructors from teaching their students that E causes H
and
| H causes E.


You mean this magnet turns on only when the operator throws a switch
because it is a simultaneous but independent event?

http://www.global-b2b-network.com/di...ctromagnet.jpg

Because?
So, what is happening? The switch is thrown and low and behold, Both an H
field and a Current appear simultaneously?
Throwing the switch puts the circuit into direct communication with a
sustained electric potential. As it's an electric potential electrons begin
to flow, and as there are now moving electrons these cause a corresponding H
field?
Ok, so now we move to magnetic induction and we end up concluding that the B
field is now causing the electrons to flow?
If Albert can combine time/space (you can't have one without the other) why
not current and H?
Doesn't sound silly to me at all. Can they actually be separated? Can one
exist without the other?
Vince

On Wed, 25 Jun 2008 18:32:46 GMT, "Bill Miller"
wrote:


"Timo A. Nieminen" wrote in message
.. .
On Mon, 23 Jun 2008, Bill Miller wrote:



That leaves hordes of non PG students still believing this rubbish. And it
begs the question of why, in UG classes, the instructors don't say
*something* about how theses two parameters don't cause each other, but that
they always appear simultaneously. I suspect its because the instructors
don't know it!

I fervently hope you're not teaching anyone. You're too ignorant to be
in the business of physics which is that of discerning cause and
effect. Instead of denying cause and effect, you should be analyzing
for the underlying science.

Is there a single UG EM textbook that correctly categorizes the relationship
between E and H? Even ONE?

Tell us, omniscient one, what exactly what is this precious
relationship, of which you are evidently the exclusive franchisee?

Here's how I think it works: Volts applied to a coil build up H
ampturns/meter which when multiplied by mu store momentum B in
webers/m^2. Upon opening the circuit, momentum B divided by mu
generates a sizeable voltage back at the original terminals. The field
B is successively the sink and the source. Yes V causes B and B causes
V.

Cheers, Bill

John Polasek

On Jun 25, 10:25 pm, John C. Polasek wrote:
On Wed, 25 Jun 2008 18:32:46 GMT, "Bill Miller"

That leaves hordes of non PG students still believing this rubbish. And it
begs the question of why, in UG classes, the instructors don't say
*something* about how theses two parameters don't cause each other, but that
they always appear simultaneously. I suspect its because the instructors
don't know it!

I fervently hope you're not teaching anyone. You're too ignorant to be
in the business of physics which is that of discerning cause and
effect. Instead of denying cause and effect, you should be analyzing
for the underlying science.

And I, John, fervently hope that YOU are not teaching "faith-based"
physics anywhere. There is already enough "dumbing down" in science!

Is there a single UG EM textbook that correctly categorizes the relationship
between E and H? Even ONE?

Tell us, omniscient one, what exactly what is this precious
relationship, of which you are evidently the exclusive franchisee?

Here's the dogma: We start with Maxwell's equations and note that the
curl of E is given by the time rate of change of B and then we also
observe that the curl of H is given by J plus the time rate of change
of D. Well that's simple enough isn't it? Clearly E causes H and H
causes E! Hence we all are fat and happy imagining EM waves plunging
through space with E creating the H vectors and H creating the E
vectors as it goes along! Everybody knows this is how it works! It's
right there in the equations!

Too bad it's all wrong. The form of Maxwell's equations we are using
here are NOT "causal"! That means that one side "equals" the other but
one side does NOT "cause" the other! The truth that Bill Miller finds
so seldom among those who pretend to be the ultimate source of EM
knowledge to others, is that E doesn't cause H and H doesn't cause E.
BOTH are cause by a THIRD source, namely charge! This is where
"retarded" potentials come from. But this is exactly why "modern"
physics is so primitive and so wrong. Physicists are too lazy to
bother with the actual situation and always try to use models that are
linear, without any feedback (which nobody understands anyway) and do
not consider retarded causality. Hey that kind of math is just too big
of a pain in the ass anyway, so why bother. You can get useful answers
the other way (most of the time). And where your faith-based physics
fails, just sweep that under the rug. If anyone complains, fire them.

Here's how I think it works: Volts applied to a coil build up H
ampturns/meter which when multiplied by mu store momentum B in
webers/m^2. Upon opening the circuit, momentum B divided by mu
generates a sizeable voltage back at the original terminals. The field
B is successively the sink and the source. Yes V causes B and B causes
V.

Lookee here. THIS is EXACTLY the problem. We have thought with total
disregard of causality! You've constructed a model that appears to
make sense, but is in fact explaining nothing. A 'true" explanation
would involve a careful delineation of each "retarded" effect. True
causality leads to true retardation. The problem here is that you are
not considering retarded effects which makes you retarded!

On Jun 18, 5:59*pm, Benj wrote:
I just saw Ben Stein's documentary "Expelled: no intelligence allowed"
over at the $1 theater and it was a great piece of work. Namely those
promoting the dogma of establishment science. *This is a subject near
and dear to my heart upon which I have been known to post here
repeatedly, but it always bears bringing the subject up one more
time.

Although this film is on the subject of publishing papers on
"intelligent design" and the attacks upon one career that occur if
such transgressions against establishment dogma are even suggested let
alone advocated, the same actions can be equally seen if one chooses
to discuss a whole host of "anti-establishment" topics. I leave it as
an exercise for the interested student to make a list of topics upon
which any attempt to publish credible research will be a fast track to
the unemployment line.

The attacks always take the same form. The author is accused of
"pseudoscience". The authors find that grants and support dry up.
Papers are rejected. Jobs suddenly become unavailable. You get fired.
You get denied tenure and not for the normal reasons like being a
woman or not willing to grovel before the tenured faculty. Attacks
often extend to being accused of mental illness or incompetence.

So what is going on? I'll tell you. The problem, dear reader, is YOU!
You are simply too smart and too perceptive to be allowed free reign
in a world ruled by mass politics. You can too easily see through the
myriad political scams designed to keep those who rule, in power and
rich! Hence, a way had to be found to control you and keep you in
line! And what is that way? It's the "university" system that has been
developed along with "peer review" and government and other
"controlled" funding of research that makes sure that certain topics
and certain ideas are never given free and open discussion. *You ALL
know this is true. But most of you can't say a thing though because
unlike me, you still have a career in science that can be lost.

This documentary is especially interesting to me in that it pulls very
few punches. It makes the connection between communist doctrine and
establishment dogma. It makes the connection, for example between
Hitler's death camps for the disabled and other "defectives" and the
American "Eugenics" research at Cold Harbor (which by the way, changed
its name but still exists) that Hitler was so taken with. It points
out the connection between atheism (the state religion of leftist
regimes) and Darwinism. And best of all it shows the draconian
punishment awaiting any research who steps even a little bit out of
line! *Yes, Virginia they WILL "make an example of you" if you drift
even a little bit into a "forbidden zone"!

All of you out there, listen to me. If you are just the least bit
interested in REAL science, this documentary is required viewing. It
should soon be out on DVD so go steal a copy from a friend or if you
must, rent it from Blockbuster. Your first lesson in science boys and
girls is that science is NOT the pure exercise of intellect and free
inquiry you thought it was. It is about making sure that aspects of
knowledge that threaten the power of the elite stay tightly
"controlled". There is POLITICS right down at *the core of modern
science and sorry to say, politics operates best with lies. And it's
high time you all learned how this politics works whether you choose
to join in the lies or work to eliminate them.

Ok. Now all you with the GS rating can start posting the suggestion
that I go look for my "tinfoil hat". Of course you haven't viewed this
movie and never will, but I'm sure you are nevertheless convinced that
it's all "pseudoscience", lies and right wing Christian tripe. [All
perpetrated by the well-known right wing Christian evangelist Ben
Stein! *:-) ]

Our profession is in dire need of a good housecleaning! *I say this
documentary is one good step in the right direction.

How did you guys pass your exams? Almost all of this discussion is
off topic. This seems to be the fate of too many of these general
questions.

"Benj" wrote in message
...
On Jun 25, 10:25 pm, John C. Polasek wrote:
On Wed, 25 Jun 2008 18:32:46 GMT, "Bill Miller"

That leaves hordes of non PG students still believing this rubbish. And
it
begs the question of why, in UG classes, the instructors don't say
*something* about how theses two parameters don't cause each other, but
that
they always appear simultaneously. I suspect its because the instructors
don't know it!

I fervently hope you're not teaching anyone. You're too ignorant to be
in the business of physics which is that of discerning cause and
effect. Instead of denying cause and effect, you should be analyzing
for the underlying science.

And I, John, fervently hope that YOU are not teaching "faith-based"
physics anywhere. There is already enough "dumbing down" in science!

Is there a single UG EM textbook that correctly categorizes the
relationship
between E and H? Even ONE?

Tell us, omniscient one, what exactly what is this precious
relationship, of which you are evidently the exclusive franchisee?

Here's the dogma: We start with Maxwell's equations and note that the
curl of E is given by the time rate of change of B and then we also
observe that the curl of H is given by J plus the time rate of change
of D. Well that's simple enough isn't it? Clearly E causes H and H
causes E! Hence we all are fat and happy imagining EM waves plunging
through space with E creating the H vectors and H creating the E
vectors as it goes along! Everybody knows this is how it works! It's
right there in the equations!

Too bad it's all wrong. The form of Maxwell's equations we are using
here are NOT "causal"! That means that one side "equals" the other but
one side does NOT "cause" the other! The truth that Bill Miller finds
so seldom among those who pretend to be the ultimate source of EM
knowledge to others, is that E doesn't cause H and H doesn't cause E.
BOTH are cause by a THIRD source, namely charge! This is where
"retarded" potentials come from. But this is exactly why "modern"
physics is so primitive and so wrong. Physicists are too lazy to
bother with the actual situation and always try to use models that are
linear, without any feedback (which nobody understands anyway) and do
not consider retarded causality. Hey that kind of math is just too big
of a pain in the ass anyway, so why bother. You can get useful answers
the other way (most of the time). And where your faith-based physics
fails, just sweep that under the rug. If anyone complains, fire them.

Here's how I think it works: Volts applied to a coil build up H
ampturns/meter which when multiplied by mu store momentum B in
webers/m^2. Upon opening the circuit, momentum B divided by mu
generates a sizeable voltage back at the original terminals. The field
B is successively the sink and the source. Yes V causes B and B causes
V.

Lookee here. THIS is EXACTLY the problem. We have thought with total
disregard of causality! You've constructed a model that appears to
make sense, but is in fact explaining nothing. A 'true" explanation
would involve a careful delineation of each "retarded" effect. True
causality leads to true retardation. The problem here is that you are
not considering retarded effects which makes you retarded!



Benj...

You said it better than I could!

And the thread that has occurred as a result of my examples demonstrates the
dogmatic nature of many physicists better than anything that I could
possibly SAY!

Bill

On Wed, 25 Jun 2008, Bill Miller wrote:


"Timo A. Nieminen" wrote in message
...
On Mon, 23 Jun 2008, Bill Miller wrote:


"Timo A. Nieminen" wrote in message
...
On Sat, 21 Jun 2008, Bill Miller wrote:

snip

Correct. And as long as the interaction is of a contact nature, then
eveything is OK. But when there is a delay between the action and the
reaction, then *for that delay period* momentum is not conserved. But we
know that momentum MUST be conserved, so we must look at Newton with an
eye
to modifying it to deal with what amounts to a time dependency.

This is not a new idea. We have long recognized, for EM that electrostaic
representations break down when time dependency is present.

Heaviside suggested this in 1893 but never took it all the way to its
logical conclusion.

Heaviside's Maxwellian gravitation? There is no modification of Newton's
laws of motion in it. Newton's law of universal gravitation, describing
gravitational forces as interactions between distant bodies, is replaced
by a field theory, wherein all interactions are local - body interacts
with local field, not body with distant body.

You must be looking at a different copy of Heaviside's 1893 article. In it,
he clearly (to me at least) understood concepts of time-dependancy, the
gravitational equivalent of the Poynting Vector (that he claimed partial
credit for) and others.

Of course he looks at time-dependent situations - otherwise his
finite-speed Maxwellian model of gravitation just reduces to Newton's law
of universal gravitation. But the whole essence of his approach is to
replace Newton's law of action at a distance with a local field theory,
starting firmly on this path right at equation (1).

I agree that he did NOT deal with retardation.
Neither did/does Maxwell!

Heaviside deals with retardation, but not so transparently. He introduces
a finite (constant, i.e., frequency independent) speed v of gravitation,
and goes from there.

Maxwell knew that his theory could be described in terms of retardation -
he recognises the mathematical equivalence between his theory and Lorenz's
in a footnote in his Treatise. I don't know when he realised this, or that
he had a retardation compatible theory. Perhaps when he gets the wave
equation with a constant speed?

Which brings me to a related, but not-so-related, point. Maxwell was, IMO,
a good enough mathematician so that he could have done the Hertz-Heaviside
simplification of his equations himself. Why didn't he? Since he
identifies the field quantities in his version as physically meaningful
(e.g., vector potential as momentum of the ether), there isn't any point
in getting rid of them. He's not just trying to describe forces on charged
bodies or currents (which Hertz and Heaviside seemed to be content with),
but wanted to know what the ether was up to. If you want an instantaneous
snapshot of the ether, you don't want a retarded formulation of the
theory. I don't know, but perhaps this influenced him.

This "action at a distance" has always been an Achilles Heel.

It is resolved, I believe by understanding and applying Causality. We need
to understand that if two events occur at the same time, neither can cause
the other. Instead, at least one must be caused by some other (hidden)
event.

Shades of Aristotle.

Recognition of this simple concept would, as one example, have stopped
generations of instructors from teaching their students that E causes H and
H causes E. It would have also stopped generations of mathematical
physicists from publishing articles in peer-reviewed publications that
"proved" that E causes H or vice versa. And it would have stopped
generations of experimental physicists from spending countless hours and
dollars in building apparatus to measure the non-existent H between the
plates of capacitors.

Not so many papers, hours, or dollars. The existence of electromagnetic
waves, transverse (i.e., div(E) = 0, div(H) = 0) solutions of the vector
Helmholtz equation, is pretty good evidence that the dD/dt term really
belongs in the Maxwell equations, so perhaps a more direct "proof" isn't
seen as essential.

If I have understood your position on this, Timo, it is that the teaching of
this is expeditious & that once one gets to the PG leve, the "true facts"
are revealed and everything is fine.

Well, for better or for worse, what is taught is necessarily simplified.
Alas, while a small number of misconceptions might be corrected in later
undergrad or postgrad education, many are not. With limited time, and
limited initial knowledge, there are limits to what can be taught. I
woulnd't say that everything is fine, just that it isn't easy to do
much better. One particular problem is that many (most?) courses lead to
just cramming for an exam, followed by forgetting. Emphasis on techniques
and proofs over any real understanding. One problem is that understanding
comes with experience, and a 1 semester course allows very little time for
that.

I don't think that the current issue (E, H, and causality) is such a big
deal. It's mostly harmless as far as beliefs go, and only one of very many
various misconceptions that students pick up. They learn far worse ones
along the way. It also isn't enough to just tell them in lectures -
students don't learn from lectures, they learn from assessment and
preparing for assessment. It's hard to assess understanding, so
understanding tends to not be assessed strongly, so students don't get
really motivated to understand.

That leaves hordes of non PG students still believing this rubbish. And it
begs the question of why, in UG classes, the instructors don't say
*something* about how theses two parameters don't cause each other, but that
they always appear simultaneously. I suspect its because the instructors
don't know it!

Likely enough.

Is there a single UG EM textbook that correctly categorizes the relationship
between E and H? Even ONE?

Probably. Very likely. But specialised EM texts are the stuff of advanced
(or at least intermediate) undergrad courses. Those who do just 1 or 2
physics courses ay uni, or only do high school physics never get to see
them. There might well even be generic introductory textbooks that don't
get it wrong, by not mentioning it at all. If I have time in the near
future, I will look.

Newton 1 and 2 are pretty much just definititions of inertial motion and
force, while Newton 3 is (as above) conservation of momentum. How can these
be modified sensibly?

I'd say that looking at Causality and incorporating what we learn into new
expressions that include factors tor time variation of position and for
timevariation of mass would get the job done.

New expressions for what? My point is that it's easy enough to modify,
e.g., a force law (as Heaviside did Newton's law of universal
gravitation), or Coulomb's law (as per Maxwell), but a very different
thing to try to modify Newton's laws of motion, which are of a very
different fundamental nature.

Naturally, any such additions
must obey conservation of momentum AND must reduce to the original form when
time dependancy is absent.

Well, if you want conservation of momentum, then you're _not_ going to be
modifying Newton 3. Also, if you want retarded interaction at a distance
along with conservation of momentum, then you're going to need fields that
can carry the momentum from point A to point B (or some other "thing" to
have the momentum when the "interacting" objects don't have it).

Or we change our ideas about what conservation of momentum means.

Yes, if we consider two masses as above (or two electric charges) to be
interacting with each other, we have exactly the problem you point out.

Does this mean Newton 3 is wrong? Does this mean momentum is not
conserved? I would say that it means that we simply don't have a
situation
where there are two objects interacting at a distance, but two objects
each interacting with a field. Perhaps the interaction really is as
described by field theory, a local interaction between field and body,
and
we should throw away the classical mechanics idea of interaction at a
distance rather than Newton 3.
That's one way of dealing with it. I believe that a better way would be
to
recognize that Newton's work is not applicable to time dependency. That's
no
different, conceptually, from Maxwell's expansion of Ampere's Law to
include
The rate of Change Of E field in order to deal with magnetic fields in a
time-dependent environment.

I think it is different conceptually. One is a conservation law, and the
other describes a limited set of experimental observations.

It is true that gravity is a whole bunch of orders of magnitude more
difficult to deal with experimentally than EM. Building planetary objects,
setting them rotating, and zapping them past one another is way beyond our
experimental capability.

BUT, we have a handy set of "toys" in our own night sky. And there we have
an interesting set of pre-made experiments already in process. Like, maybe,
does our model explain why the rotational speed of the Sun at the equator is
different from the speed at the poles? Or does it provide some insights into
Mercury's (supposedly) residual precession? Does it support or deny the
existence of black holes? Does it provide some insight into the "missing
mass of the universe" question? What might it say about gravitational waves?
Does it provide a definitive explanation of the process wherein potential
energy is converted into kinetic energy by a falling body? Does it explain
why EM beams are deflected by gravity?

But that's a lotta work. Doing it wrong is a lot easier!

Apart from the rotational speed of the sun, which at first glance is more
a matter of fluid dynamics and plasma physics rather than gravitation, and
perhaps the missing mass stuff, yes, our best models of gravity do answer
these questions. Alas, they don't reduce to Heaviside's model in the
appropriate limit, There was a nice paper by Robert Forward in Proc. IEEE
(or Proc. IRE, if before the name change of the journal) in the 1960s
about the weak-field limit of GR.

--
Timo Nieminen - Home page: http://www.physics.uq.edu.au/people/nieminen/
E-prints: http://eprint.uq.edu.au/view/person/...,_Timo_A..html
Shrine to Spirits: http://www.users.bigpond.com/timo_nieminen/spirits.html

On 26 Jun, 03:25, John C. Polasek wrote:
On Wed, 25 Jun 2008 18:32:46 GMT, "Bill Miller"

wrote:

"Timo A. Nieminen" wrote in message
.. .
On Mon, 23 Jun 2008, Bill Miller wrote:

That leaves hordes of non PG students still believing this rubbish. And it
begs the question of why, in UG classes, the instructors don't say
*something* about how theses two parameters don't cause each other, but that
they always appear simultaneously. I suspect its because the instructors
don't know it!

I fervently hope you're not teaching anyone. You're too ignorant to be
in the business of physics which is that of discerning cause and
effect. Instead of denying cause and effect, you should be analyzing
for the underlying science.



Is there a single UG EM textbook that correctly categorizes the relationship
between E and H? Even ONE?

Tell us, omniscient one, what exactly what is this precious
relationship, of which you are evidently the exclusive franchisee?

Here's how I think it works: Volts applied to a coil build up H
ampturns/meter which when multiplied by mu store momentum B in
webers/m^2. Upon opening the circuit, momentum B divided by mu
generates a sizeable voltage back at the original terminals. The field
B is successively the sink and the source. Yes V causes B and B causes
V.

Cheers, Bill

John Polasek

A charge is the source of E and H which are orthogonal and propagate
independently from it as given by the Lienard-Wiechert field
equations. I think that's all Bill is saying which isn't wrong, is it?

On Jun 27, 9:35 am, blackhead wrote:

A charge is the source of E and H which are orthogonal and propagate
independently from it as given by the Lienard-Wiechert field
equations. I think that's all Bill is saying which isn't wrong, is it?

No, Bill isn't wrong.

And I also differ with "Maxwell's" assertion that we've drifted off-
topic. The original topic was the Ben Stein "Expelled" documentary
which probed the issue of "faith-based" physics dogma being protected
by political means. That is still the topic here even though we are
using examples different from the "intelligent design" one of the
film.

What gets me is that when someone "questions authority" the dogma crew
usually first name-calls using the "tinfoil hat ploy" which implies
that if the person with the "new" idea is insane, then what they say
isn't worth even considering, which is often followed by suggestion to
"go read some Freshman textbooks on the subject". The latter assumes
that somehow "freshman textbooks" are the ultimate authority on what
is true and what is not! Obviously that is a lie. EXPERIMENT is the
ultimate authority!

Any of you guys ever talk to authors of freshmen textbooks? First off,
they all admit that copying older books is a way of life, so that the
perpetuation of error becomes an automatic factor built into the
process. And furthermore, being "introductory" guides these books all
have to use a "lowest common denominator" approach. Therefore that
they are bibles of dogma should be no surprise. But given this, many
such texts are still careful to word statements in ways such that when
exactly and correctly read they do NOT present doubt as dogma.
However, most of those reading these books do not take time to examine
such wording with an exacting eye. They simply see what they already
believe and see it all as affirmation of the dogma that they believe
in their hearts.

And the problem is that all this combines to lead students AWAY from
true authority (experiment) and toward a blind acceptance (which is
further reinforced by the necessity of repeating all dogma correctly
at will on exams) of so-called "laws" which are in fact mere
approximations to reality. Finally having lost sight of of the true
science philosophy, the students who eventually advance in position
and power, eventually comes to a point where they can enforce dogma by
political means. It's a standard thing and it is not good for the
advancement of science. It's good that Ben Stein has blown the whistle
on it.

On Jun 26, 1:55*pm, "Timo A. Nieminen" wrote:
On Wed, 25 Jun 2008, Bill Miller wrote:

"Timo A. Nieminen" wrote in message
.. .
On Mon, 23 Jun 2008, Bill Miller wrote:

"Timo A. Nieminen" wrote in message
. ..
On Sat, 21 Jun 2008, Bill Miller wrote:

snip

Correct. And as long as the interaction is of a contact nature, then
eveything is OK. But when there is a delay between the action and the
reaction, then *for that delay period* momentum is not conserved. But we
know that momentum MUST be conserved, so we must look at Newton with an
eye
to modifying it to deal with what amounts to a time dependency.

This is not a new idea. We have long recognized, for EM that electrostaic
representations break down when time dependency is present.

Heaviside suggested this in 1893 but never took it all the way to its
logical conclusion.

Heaviside's Maxwellian gravitation? There is no modification of Newton's
laws of motion in it. Newton's law of universal gravitation, describing
gravitational forces as interactions between distant bodies, is replaced
by a field theory, wherein all interactions are local - body interacts
with local field, not body with distant body.

You must be looking at a different copy of Heaviside's 1893 article. In it,
he clearly (to me at least) understood concepts of time-dependancy, the
gravitational equivalent of the Poynting Vector (that he claimed partial
credit for) *and others.

Of course he looks at time-dependent situations - otherwise his
finite-speed Maxwellian model of gravitation just reduces to Newton's law
of universal gravitation. But the whole essence of his approach is to
replace Newton's law of action at a distance with a local field theory,
starting firmly on this path right at equation (1).

I agree that he did NOT deal with retardation.
Neither did/does Maxwell!

Heaviside deals with retardation, but not so transparently. He introduces
a finite (constant, i.e., frequency independent) speed v of gravitation,
and goes from there.

Maxwell knew that his theory could be described in terms of retardation -
he recognises the mathematical equivalence between his theory and Lorenz's
in a footnote in his Treatise. I don't know when he realised this, or that
he had a retardation compatible theory. Perhaps when he gets the wave
equation with a constant speed?

Which brings me to a related, but not-so-related, point. Maxwell was, IMO,
a good enough mathematician so that he could have done the Hertz-Heaviside
simplification of his equations himself. Why didn't he? Since he
identifies the field quantities in his version as physically meaningful
(e.g., vector potential as momentum of the ether), there isn't any point
in getting rid of them. He's not just trying to describe forces on charged
bodies or currents (which Hertz and Heaviside seemed to be content with),
but wanted to know what the ether was up to. If you want an instantaneous
snapshot of the ether, you don't want a retarded formulation of the
theory. I don't know, but perhaps this influenced him.

This "action at a distance" has always been an Achilles Heel.

It is resolved, I believe by understanding and applying Causality. We need
to understand that if two events occur at the same time, neither can cause
the other. Instead, at least one must be caused by some other (hidden)
event.

Shades of Aristotle.

Recognition of this simple concept would, as one example, have stopped
generations of instructors from teaching their students that E causes H and
H causes E. It would have also stopped generations of mathematical
physicists from publishing articles in peer-reviewed publications that
"proved" that E causes H or vice versa. And it would have stopped
generations of experimental physicists from spending countless hours and
dollars in building apparatus to measure the non-existent H between the
plates of capacitors.

Not so many papers, hours, or dollars. The existence of electromagnetic
waves, transverse (i.e., div(E) = 0, div(H) = 0) solutions of the vector
Helmholtz equation, is pretty good evidence that the dD/dt term really
belongs in the Maxwell equations, so perhaps a more direct "proof" isn't
seen as essential.

If I have understood your position on this, Timo, it is that the teaching of
this is expeditious & that once one gets to the PG leve, the "true facts"
are revealed and everything is fine.

Well, for better or for worse, what is taught is necessarily simplified.
Alas, while a small number of misconceptions might be corrected in later
undergrad or postgrad education, many are not. With limited time, and
limited initial knowledge, there are limits to what can be taught. I
woulnd't say that everything is fine, just that it isn't easy to do
much better. One particular problem is that many (most?) courses lead to
just cramming for an exam, followed by forgetting. Emphasis on techniques
and proofs over any real understanding. One problem is that understanding
comes with experience, and a 1 semester course allows very little time for
that.

I don't think that the current issue (E, H, and causality) is such a big
deal. It's mostly harmless as far as beliefs go, and only one of very many
various misconceptions that students pick up. They learn far worse ones
along the way. It also isn't enough to just tell them in lectures -
students don't learn from lectures, they learn from assessment and
preparing for assessment. It's hard to assess understanding, so
understanding tends to not be assessed strongly, so students don't get
really motivated to understand.

That leaves hordes of non PG students still believing this rubbish. And it
begs the question of why, in UG classes, the instructors don't say
*something* about how theses two parameters don't cause each other, but that
they always appear simultaneously. I suspect its because the instructors
don't know it!

Likely enough.

Is there a single UG EM textbook that correctly categorizes the relationship
between E and H? Even ONE?

Probably. Very likely. But specialised EM texts are the stuff of advanced
(or at least intermediate) undergrad courses. Those who do just 1 or 2
physics courses ay uni, or only do high school physics never get to see
them. There might well even be generic introductory textbooks that don't
get it wrong, by not mentioning it at all. If I have time in the near
future, I will look.

Newton 1 and 2 are pretty much just definititions of inertial motion and
force, while Newton 3 is (as above) conservation of momentum. How can these
be modified sensibly?

I'd say that looking at Causality and incorporating what we learn into new
expressions that include factors tor time variation of position and for
timevariation of mass would get the job done.

New expressions for what? My point is that it's easy enough to modify,
e.g., a force law (as Heaviside did Newton's law of universal
gravitation), or Coulomb's law (as per Maxwell), but a very different
thing to try to modify Newton's laws of motion, which are of a very
different fundamental nature.

Naturally, any such additions
must obey conservation of momentum AND must reduce to the original form when
time dependancy is absent.

Well, if you want conservation of momentum, then you're _not_ going to be
modifying Newton 3. Also, if you want retarded interaction at a distance
along with conservation of momentum, then you're going to need fields that
can carry the momentum from point A to point B (or some other "thing" to
have the momentum when the "interacting" objects don't have it).

Or we change our ideas about what conservation of momentum means.

Yes, if we consider two masses as above (or two electric charges) to be
interacting with each other, we have exactly the problem you point out.

Does this mean Newton 3 is wrong? Does this mean momentum is not
conserved? I would say that it means that we simply don't have a
situation
where there are two objects interacting at a distance, but two objects
each interacting with a field. Perhaps the interaction really is as
described by field theory, a local interaction between field and body,
and
we should throw away the classical mechanics idea of interaction at a
distance rather than Newton 3.
That's one way of dealing with it. I believe that a better way would be
to
recognize that Newton's work is not applicable to time dependency. That's
no
different, conceptually, from Maxwell's expansion of Ampere's Law to
include
The rate of Change Of E field in order to deal with magnetic fields in a
time-dependent environment.

I think it is different conceptually. One is a conservation law, and the
other describes a limited set of experimental observations.

It is true that gravity is a whole bunch of orders of magnitude more
difficult to deal with experimentally than EM. Building planetary objects,
setting them rotating, and zapping them past one another is way beyond our
experimental capability.

BUT, we have a handy set of "toys" in our own night sky. And there we have
an interesting set of pre-made experiments already in process. Like, maybe,
does our model explain why the rotational speed of the Sun at the equator is
different from the speed at the poles? Or does it provide some insights into
Mercury's (supposedly) residual precession? Does it support or deny the
existence of black holes? Does it provide some insight into the "missing
mass of the universe" question? What might it say about gravitational waves?
Does it provide a definitive explanation of the process wherein potential
energy is converted into kinetic energy by a falling body? Does it explain
why EM beams are deflected by gravity?

But that's a lotta work. Doing it wrong is a lot easier!

Apart from the rotational speed of the sun, which at first glance is more
a matter of fluid dynamics and plasma physics rather than gravitation, and
perhaps the missing mass stuff, yes, our best models of gravity do answer
these questions. Alas, they don't reduce to Heaviside's model in the
appropriate limit, There was a nice paper by Robert Forward in Proc. IEEE
(or Proc. IRE, if before the name change of the journal) in the 1960s
about the weak-field limit of GR.

--
Timo Nieminen - Home page:http://www.physics.uq.edu.au/people/nieminen/
E-prints:http://eprint.uq.edu.au/view/person/...,_Timo_A..html
Shrine to Spirits:http://www.users.bigpond.com/timo_nieminen/spirits.html

Excellent response, Timo. It's thoughtful posts like this that make
trawling these groups worthwhile.

On Fri, 27 Jun 2008 06:35:23 -0700 (PDT), blackhead
wrote:

On 26 Jun, 03:25, John C. Polasek wrote:
On Wed, 25 Jun 2008 18:32:46 GMT, "Bill Miller"

wrote:

"Timo A. Nieminen" wrote in message
.. .
On Mon, 23 Jun 2008, Bill Miller wrote:

That leaves hordes of non PG students still believing this rubbish. And it
begs the question of why, in UG classes, the instructors don't say
*something* about how theses two parameters don't cause each other, but that
they always appear simultaneously. I suspect its because the instructors
don't know it!

I fervently hope you're not teaching anyone. You're too ignorant to be
in the business of physics which is that of discerning cause and
effect. Instead of denying cause and effect, you should be analyzing
for the underlying science.



Is there a single UG EM textbook that correctly categorizes the relationship
between E and H? Even ONE?

Tell us, omniscient one, what exactly what is this precious
relationship, of which you are evidently the exclusive franchisee?

Here's how I think it works: Volts applied to a coil build up H
ampturns/meter which when multiplied by mu store momentum B in
webers/m^2. Upon opening the circuit, momentum B divided by mu
generates a sizeable voltage back at the original terminals. The field
B is successively the sink and the source. Yes V causes B and B causes
V.

Cheers, Bill

John Polasek

A charge is the source of E and H which are orthogonal and propagate
independently from it as given by the Lienard-Wiechert field
equations. I think that's all Bill is saying which isn't wrong, is it?
You are right; retardation is adequately represented by the
Lienard-Wiechert field, which I also see referenced in my 1962
Panofsky Philips. They are much cleaner and simpler than Jefimenko's
which can be seen in Wiki.

For Lienard, yes, if you postulate a moving charge it will have
complex field effects. But in free space the only current J would be
Ddot and there is no overt charge density to put in Jefimenko's
equation.

This topic is of little practical effect, retardation being a very
slippery item, and there is enough other disinformation going around
to bother with these sophomoric maunderings.

For example, it is unconscionable that there are physicists today
still embedded in cgs, a legacy from their professors with these
consequences:
1. They have given up the coulomb in favor of the esu.
2. It is not possible to assign units to equations e.g.:
D = E please, assign units
3. they gave up capacitance which should be coulomb/volt (or
farads) in favor of
4. capacitance in centimeters, a clue to the naive "peas on a
knife" view of electrostatics.
5. It is not possible in cgs to intelligently discuss a vacuum
capacitor.

Enough. More dismal is the idea that most students do not even know
the difference between cgs and rmks or SI which have assigned the
properties of eps0 and mu0 to the vacuum.

The main idea is that there are forces that can store energy in the
vacuum which energy then turns around and becomes a source itself in a
completely reciprocal fashion. And this, without the intervention of
charges.
John Polasek