On Apr 13, 6:13 pm, Cecil Moore wrote:
Jim Kelley wrote:

Cecil Moore wrote:
It is impossible for a "partially reflective surface"
to reflect 100% of the intensity.

But that's wrong. If it was right, then a partially reflective surface
couldn't be used to prevent reflections either.

That's faulty logic born out of ignorance.

Partially reflective surfaces can (and are) in fact used to prevent
reflections, just as they are used to 100% re-reflect partial
reflections from a load.

The magnitude of a1 reflected by that
impedance discontinuity *DOES NOT CHANGE* from the very
first incidence of a1.

That was the main point of my post, Cecil. The reflective coefficient
DOES NOT CHANGE. You're the one who claims that it does.

What happens to the energy in the canceled waves?

There is no energy "in" cancelled waves. Your ideas in that regard are
faulty. Energy only exists where fields aren't cancelled. That
should be obvious even to someone with propensities such as yours.

ac6xg

On 14 Apr 2007 09:53:11 -0700, "Jim Kelley" wrote:

What happens to the energy in the canceled waves?

There is no energy "in" cancelled waves.

Hi Jim,

How has this inversion arrived? Cecileo offering emphatic testimony
to the Cardinals "It certainly doesn't move!" and no energy "in"
cancelled waves?

Both waves exist as the absence of either would easily reveal. There
may be no power to extract due to their offsetting contributions, but
that doesn't prove they have vanished (which, in the context of sight,
interference, and light diminishing in regions necessarily demands a
load to demonstrate).

The language of photon shuffling and energy re-distribution lends the
logic of divine intervention to scientific theory. These verbs are
active and require an actor. If we were to travel down that path, the
patterns of intelligent design interference would be explained in
epicycles and crystalline spheres of angels' guiding results.

73's
Richard Clark, KB7QHC

On Apr 14, 11:27 am, Richard Clark wrote:
On 14 Apr 2007 09:53:11 -0700, "Jim Kelley" wrote:

What happens to the energy in the canceled waves?

There is no energy "in" cancelled waves.

Hi Jim,

How has this inversion arrived? Cecileo offering emphatic testimony
to the Cardinals "It certainly doesn't move!" and no energy "in"
cancelled waves?

Both waves exist as the absence of either would easily reveal. There
may be no power to extract due to their offsetting contributions, but
that doesn't prove they have vanished (which, in the context of sight,
interference, and light diminishing in regions necessarily demands a
load to demonstrate).

The language of photon shuffling and energy re-distribution lends the
logic of divine intervention to scientific theory. These verbs are
active and require an actor. If we were to travel down that path, the
patterns of intelligent design interference would be explained in
epicycles and crystalline spheres of angels' guiding results.

73's
Richard Clark, KB7QHC

Hi Richard,

I have to admit that I do have difficulty arguing with nonsense, and
you've caught me at it. I've tried explaining this to Cecil in the
context of energy transfer, but without success. So I'm happy to
leave it to you to explain to Cecil how waves cancel but without
anhiliating the energy "in" them.

73, ac6xg

Jim Kelley wrote:
So I'm happy to
leave it to you to explain to Cecil how waves cancel but without
anhiliating the energy "in" them.

But that's just the point, Jim. You seem to believe the
pre-existing energy in those waves has been destroyed.
They obviously possessed energy before cancellation and
you say they possess zero energy after cancellation. If
that pre-existing energy is not destroyed, where did it go?
--
73, Cecil http://www.w5dxp.com

Cecil Moore wrote:
Jim Kelley wrote:
So I'm happy to
leave it to you to explain to Cecil how waves cancel but without
anhiliating the energy "in" them.

But that's just the point, Jim. You seem to believe the
pre-existing energy in those waves has been destroyed.
They obviously possessed energy before cancellation and
you say they possess zero energy after cancellation. If
that pre-existing energy is not destroyed, where did it go?


Cecil,

Now that you have access to a copy of Born and Wolf, you might dig
inside to see if you can improve your understanding of conservation of
energy. It is not quite as simple as you seem to believe.

B&W discuss the Poynting vector and its use in an overview in the first
chapter. I don't have the 4th edition. I have a couple of later editions
that contain identical language, so perhaps the same thing is in the 4th
edition.

In any case, here is the relevant quote. My explanations are enclosed in
[...]. Otherwise the paragraph is completely intact.

"It should be noted that the interpretation of S [Poynting vector] as
energy flow (more precisely as the density of energy flow) is an
abstraction which introduces a certain degree of arbitrariness. For the
quantity which is physically significant is, according to (41), not S
itself, but the integral of S [dot] n taken over a closed surface.
Clearly, from the value of the integral, no unambiguous conclusion can
be drawn about the detailed distribution of S, and alternative
definitions of the energy flux density are therefore possible. One can
always add to S the curl of an arbitrary vector, since such a term will
not contribute to the surface integral as can be seen from Gauss'
theorem and the identity div curl = 0. However, when the definition has
been applied cautiously, in particular for averages of small but finite
regions of space or time, no contradictions with experiments have been
found. We shall therefore accept the above definition in terms of the
Poynting vector of the density of the energy flow."

[ S and n are vectors, shown in bold type in the original. ]

Now for my comments.

Two important concepts are contained in the B&W quote. First, the math
involved with Poynting vectors is not quite as simple as many amateur
radio operators seem to believe. It does not make any sense to simply
add and subtract Poynting vectors in elementary fashion and expect to
get correct results. This is true even for your favorite case of a
one-dimensional problem such as a transmission line.

Second, the Poynting vector by itself means little. It is only the
integral over a closed surface that has physical reality. In your
favorite case of reflections and re-reflections the only useful
non-trivial application of the Poynting vector would be the integration
of the Poynting vector over a small region that includes the line
discontinuity inside. And even then, only the total energy balance can
be determined. Put in direct terms, there is no available information,
and no need for any information about what happens to the energy
contained in the various component waves you like to consider. It simply
does not matter. The only energy balance that counts is the net energy
flowing through the surface of the integration volume. Anything else is
merely in your imagination. B&W allow you to add anything you like, as
long as it is the curl of a vector. But there is no physical reality in
doing so.

It has been pointed out numerous times that modern physical theory is
correct by design. Ian again pointed out that fact earlier today. If the
wave equations, the field equations, force equations, or whatever are
analyzed correctly the energy balance will automatically work out
correctly as well. A check of energy balance is sometimes useful to
highlight any errors that might have been made in the math, but no new
physical information should be expected.

Finally, it is well known by all physicists, and I believe most
engineers, that energy considerations by themselves can be very useful
for analyzing physical problems. Much of higher level classical
mechanics and essentially all of quantum mechanics techniques are energy
based. The so-called Hamiltonian formulation is well-known and widely
used. It is no more or less correct than techniques based on forces and
other fields, but the Hamiltonian technique is often much more
computationally convenient.

73,
Gene
W4SZ

Gene Fuller wrote:
quoting Born & Wolf:
"However, when the definition has
been applied cautiously, in particular for averages of small but finite
regions of space or time, no contradictions with experiments have been
found. We shall therefore accept the above definition in terms of the
Poynting vector of the density of the energy flow."

There's the meat of the quote as far as transmission lines
are concerned. Given that transmission lines are "small but
finite regions of space or time", and since there are only
two possible directions in a transmission line, Born and
Wolf seem to give us permission to do exactly what you
are complaining about. Your concerns about light waves
in three dimensional free space just don't exist for the
primarily single dimensional "space" in a transmission line.
Ideally, the power density exists only between the inner and
outer conductors of the coax.

It does not make any sense to simply
add and subtract Poynting vectors in elementary fashion and expect to
get correct results.

Born & Wolf's own words in the quote above provided by you
contradict that assertion.

It simply does not matter.

You sure make a lot of postings about it for it not
to matter to you. :-) It certainly matters to me
and others and we will not stop the discussion
until it is resolved to everyone's satisfaction.
What are you afraid we will uncover if we keep
digging? Your ignorance?

It has been pointed out numerous times that modern physical theory is
correct by design. Ian again pointed out that fact earlier today. If the
wave equations, the field equations, force equations, or whatever are
analyzed correctly the energy balance will automatically work out
correctly as well.

The assertions that reflected waves don't exist or if they
do exist, they contain no energy, are false assertions. Trying
to sweep them under the rug by mealy-mouthing some automatic
energy balance religion is just another copout.
--
73, Cecil http://www.w5dxp.com

Cecil Moore wrote:
Gene Fuller wrote:
quoting Born & Wolf:
"However, when the definition has been applied cautiously, in
particular for averages of small but finite regions of space or time,
no contradictions with experiments have been found. We shall therefore
accept the above definition in terms of the Poynting vector of the
density of the energy flow."

There's the meat of the quote as far as transmission lines
are concerned. Given that transmission lines are "small but
finite regions of space or time", and since there are only
two possible directions in a transmission line, Born and
Wolf seem to give us permission to do exactly what you
are complaining about. Your concerns about light waves
in three dimensional free space just don't exist for the
primarily single dimensional "space" in a transmission line.
Ideally, the power density exists only between the inner and
outer conductors of the coax.

It does not make any sense to simply add and subtract Poynting vectors
in elementary fashion and expect to get correct results.

Born & Wolf's own words in the quote above provided by you
contradict that assertion.


Cecil,

You conveniently chopped out the part of the B&W quote that matters. You
continue to claim that energy associated with each of the myriad of wave
components that exist at the point of interest must be reconciled. The
correct application of the Poynting theorem, as noted in the full B&W
quote, says that your requirement is not correct. Only the net energy
flow into that small integration volume has any physical reality.

Unless there is a source or sink at the point of interest, the net
energy flow will be exactly zero. Further analysis is futile.
Conservation of energy, specifically the Poynting theorem, does not
support you or anyone else who tries to atomize the waves in an attempt
to balance energy contribution from individual wave components. You are
on your own.

By the way, a very similar statement about the application of Poynting
vectors appears in Classical Electrodynamics by Jackson. This is not
some strange interpretation by a single author.

73,
Gene
W4SZ

On Apr 14, 8:57 pm, Cecil Moore wrote:
Jim Kelley wrote:
So I'm happy to
leave it to you to explain to Cecil how waves cancel but without
anhiliating the energy "in" them.

But that's just the point, Jim. You seem to believe the
pre-existing energy in those waves has been destroyed.
They obviously possessed energy before cancellation and
you say they possess zero energy after cancellation. If
that pre-existing energy is not destroyed, where did it go?
--
73, Cecil http://www.w5dxp.com

As I said, Cecil, your ideas about waves 'possessing energy' need a
little work.

ac6xg

Jim Kelley wrote:
As I said, Cecil, your ideas about waves 'possessing energy' need a
little work.

Complete lack of technical content or technical defense
of your assertions is noted - nothing but a bunch of
hand-waving.

One more challenge for you, Jim. If you can prove that
an EM wave can exist without the associated ExB energy, you
will no doubt win a Nobel Prize in Physics.

Here's what Hecht says: "Any electromagnetic wave exists
within some region of space, and it is therefore natural
to consider the *radiant energy per unit volume*, or
*energy density*. We suppose that the electric field itself
can somehow store energy. This is a major logical step
since it imparts to the field the attribute of physical
reality - if the field has energy, it is a thing-in-itself."

Maybe it's past time for you to take that logical step
that Hecht took so long ago?

"To represent the flow of electromagnetic energy associated
with a traveling wave, let 'S' symbolize the transport of
energy per unit time (the power) across a unit area. ...
it has come to be known as the *Poynting vector*."

Hecht labels the energy per unit time in an EM wave as
"power". Hecht's Poynting vector equations contain cosine
terms. Hecht shoots down virtually every one of your
assertions and objections.

I notice you carefully avoided my S-Parameter example.
--
73, Cecil http://www.w5dxp.com

On Apr 15, 11:58 am, Cecil Moore wrote:
I notice you carefully avoided my S-Parameter example.

I try to comment only on technical things that you say with which I
disagree, Cecil. Though as it happens, most of the objectionable
comments you make are not techincal.

ac6xg