[SI-LIST] Re: Circle bus topology; Circular Firing Squad?
- From: "Ihsan Erdin" <erdinih@xxxxxxxxx>
- To: "olaney@xxxxxxxx" <olaney@xxxxxxxx>
- Date: Fri, 3 Aug 2007 06:08:48 -0400
Orin,
My answers follow in-line.
Regards,
Ihsan
On 8/2/07, olaney@xxxxxxxx <olaney@xxxxxxxx> wrote:
>
>
> Ihsan:
>
> Yours was a disappointing answer. The use of the term "action at a
> distance" was a specific reference to a quote in a previous email. For the
> *3rd* time: "As discussed in Lesson 2, some forces result from contact
> interactions (normal, frictional, tensional, and applied forces are examples
> of contact forces) and other forces are the result of action-at-a-distance
> interactions (gravitational, electrical, and magnetic forces)."
> http://www.glenbrook.k12.il.us/GBSSCI/PHYS/CLASS/newtlaws/u2l4a.html
> If you read the previous emails containing this, did you forget or not
> understand them? There is no point in trying to have a discussion if your
> only memory is the last email. Suffice to say, those who cling to a
> collision (contact interaction) model are using the wrong paradigm. Yet,
> there are respondents who keep speaking of electrons colliding (which due to
> repulsion cannot happen at ordinary energies), and yes, even of billiard
> balls smacking into each other.
All I'm trying to tell is that action at a distance is one of the
fundamental principles of classical physics that gave birth to
Maxwell's equations in the 19th century. It is doing an excellent job
for our macro world but fails to explain some bizarre phenomena in the
micro cosmos. Modern physics helps here by bringing a new
interpretation to the field theory (or action at a distance as you
prefer to call it) with its "standard model." Everything: weak force,
strong force, gravity and EM force are explained by particles. When
you talk about electrons in the micro cosmos I was surprised to see
you can also make reference to the action at a distance with the EM
fields in mind. I'm sorry but this mix-and-match will not work in the
quantum world. If Maxwell's equations were successful in the subatomic
region there would be no need for QED.
>
> Second, your brief tour of 20th century physics is not a line of reasoning.
> You make several statements that amount to proof by assertion, which is
> really just a polite way of having a back and forth "Is too! - Is not!"
> argument. The photoelectric effect lacks relevance here, but if it does,
> explain it.
The relevance of photoelectric effect... This is just to give a
historical background to the fact that EM energy is made up of photons
and that photoelectric effect is the first proof of this fact. In the
last two years of my subscription to this list I don't remember EM
energy has ever been mentioned in terms of its particle nature.
Considering the broad audience spectrum of this list, I think citing a
reference to dig deeper is a justifiable attempt to some suspicious
minds.
It is not necessary to invoke QED to understand the phenomena
> under discussion, but if it is, explain it.
It was originally asked whether the wave-particle duality helps to
resolve the issue here. Answering this question without mentioning QED
is like solving the wave propagation on a transmission line without
referring to Maxwell's eq.s.
Do (you) really believe that the EM
> fields that we are dealing with on a transmission line require invoking a
> particle nature? Or that photons don't pass through each other
> effortlessly?
Probably not. But I didn't jump in waving the QED flag right from the
start. Indeed, I had no intention of even mentioning it until the
wave-particle duality was raised and your explanations came in. I
simply raised my objections to some of your ideas and tried to explain
the problem as far as the particle nature of the EM force is
concerned.
I see your rhetorical arms waving in the general direction of
> physics beyond what is relevant or needed to competently deal with the waves
> under discussion. This is mere obfuscation.
Let me rephrase what I said before: interference is not a well
understood phenomenon in the micro cosmos and using the particle
nature of the EM force wouldn't take us anywhere further than the EM
field theory would do. Is this statement clear enough to dispel the
confusion here?
>
> To contribute to this discussion, you need to speak to the kernel of the
> controversy. First, the physics. We started with two identical waves
> meeting from opposite directions on a uniform transmission line, but as soon
> as a variant in one wave was proposed as an identity tag, the fallback
> position was that the *difference* would continue around the loop, but that
> you still couldn't tell whether the identical portions rebounded or not.
> When asked why there should be any difference between the two cases, the
> response was more along the lines of "you still get the right answer", and
> to my ears, seemed mumbled.
I think in an earlier posting I made myself very clear that this is a
matter of perception and modeling. For an unbiased observer it doesn't
matter whether the waves are bouncing or passing through each other.
I've seen some very good postings that phrase this better than I did
and need to add no more.
> Orin
>
>
> On Thu, 2 Aug 2007 08:09:35 -0400 "Ihsan Erdin" <erdinih@xxxxxxxxx> writes:
> > Good summary, Orin. But the term "action at a distance" or
> > mathematically " the field concept" is more of a macroscopic
> > property
> > that could be better explained at the subatomic level with the
> > quantization of matter and energy.
> > At the turn of the 20th century, it was understood that energy is
> > quantized just like matter is made up of atoms. With his seminal
> > paper
> > on photoelectric effect, Einstein showed light (electromagnetic
> > energy) is made up of particles called photons. Quantum
> > electrodynamics (QED) which was pioneered by R. Feynman deals with
> > photon-matter interaction and attempts to resolve the wave-particle
> > duality by considering the particle nature of the electromagnetic
> > energy rather than its wave nature which we are all used to as
> > electrical engineers. QED successfully accounts for reflection,
> > refraction and photoelectric effect but falls short of explaining
> > other EM effects like interference, polarization and diffraction
> > which
> > are successfully accounted by the wave nature of the light. Quite
> > interestingly, wave theory can't explain the photoelectric effect...
> > Since the issue we're discussing here seems more in the domain of
> > interference, I don't think treating the EM energy with its particle
> > nature will help us resolve whether the photons are bouncing like
> > Arpad's billiard balls or passing through. Having mentioned that
> > example, later on a personal correspondence, Arpad corrected me for
> > the conservation of kinetic energy and momentum in an elastic
> > collision. So, yes his example would be the perfect case for the
> > interaction of two particles where you can't tell whether they hit
> > each other or pass through due to the symmetry.
> >
> > Regards,
> >
> > Ihsan
> >
> > On 8/1/07, olaney@xxxxxxxx <olaney@xxxxxxxx> wrote:
> > > I've added an additional note to forestall a dead end line of
> > reasoning.
> > > You are headed in the right direction. The electrons only drift
> > slowly
> > > with the current. Meanwhile, they wander all over the place under
> > > thermal influence. Note that being electrons, they mutually repel
> > and
> > > never actually collide. To do that, electrons require energies
> > typical
> > > of a particle accelerator. The temperature would have to be so
> > high that
> > > the metal would have long since vaporized.
> > >
> > > For solid metals at room temperature (and considerably higher),
> > the sea
> > > of electrons in the metal acts like a 3D mesh of tiny masses
> > suspended by
> > > electrostatic "springs". The wave is transmitted at close to the
> > speed
> > > of light by the electrostatic forces in the mesh (action at a
> > distance).
> > > The response of the mesh to disturbances is linear and
> > superposition
> > > applies. Waves can pass in all directions simultaneously and
> > > independently.
> > >
> > > Note: The electric wave propagation is so fast compared to the
> > electron
> > > drift, that though the electrons will wiggle slightly in response,
> > their
> > > nominal positions are as if they are frozen in a snapshot. Drift
> > > movement is of no consequence to the wave propagation. The
> > thermal
> > > portion averages to zero, and the slow drift with current is a
> > response,
> > > not a cause.
> > >
> > > Orin
> > >
> > >
> > >
> > > On Wed, 1 Aug 2007 12:03:15 -0700 "Muranyi, Arpad"
> > > <Arpad_Muranyi@xxxxxxxxxx> writes:
> > > > Now that I think of it, the electrons in the copper lattice
> > > > are moving in all different directions, not just in the
> > > > direction of the wave, so they not only hit the electrons
> > > > of the other wave where the waves meet, but they also hit the
> > > > electrons of their own wave... So the bouncing will basically
> > > > follow a random pattern allowing some to go through, some
> > > > go sideways, others to turn around, etc...
> > > > =20
> > > > Arpad
> > > >
> > > > -----Original Message-----
> > > > From: Muranyi, Arpad=20
> > > > Sent: Wednesday, August 01, 2007 11:13 AM
> > > > To: si-list@xxxxxxxxxxxxx
> > > > Subject: RE: [SI-LIST] Re: Circle bus topology; Circular Firing
> > > > Squad?
> > > >
> > > > This is why we need to use coloring dye... :-)
> > > >
> > > > Seriously, I wonder about the particle and
> > > > wave duality of electrons. Remember, the
> > > > drift velocity of electrons is not the same
> > > > as the propagation velocity of the EM waves.
> > > >
> > > > So what happens at the "collision" point (i.e.
> > > > the electrical midpoint of the loop)? Do=20
> > > > the electrons hit each other and bounce back
> > > > like balls with the drift velocity speeds,
> > > > while at the same time the waves go through
> > > > each other (at speeds close to c) without
> > > > changing directions?
> > > >
> > > > Another analogy comes to my mind, when two laser
> > > > beams on different path cross each other. After
> > > > the cross point we are still going to see their
> > > > original colors without any mixing. However,
> > > > if you did the same with two water streams,
> > > > the cross point will result in a splash in all
> > > > different directions...
> > > >
> > > > Is there someone out there with a good physics=20
> > > > background who could shed some light on this?
> > > >
> > > > Thanks,
> > > >
> > > > Arpad
> > >
>
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