McEwan's Snow Job

18jan00. McEwan, after four years incommunicando (he only ever wrote once, in 1996, under instruction from is boss, and then ignored all further communications from third parties and instructions from his boss to write again), now does a snow job, garnished with the 'confidential' card, and salted with grovels to Pepper FRS, a Southerner. [McEwan should have grovelled to Pepper FRS's boss Howie FRS, who, like McEwan, is a Westerner. I.C.1feb00]

Dear Mr Catt,

I am offering a reply to your recent correspondence. I do hope you will

accept that this is entirely friendly and disinterested, and that I have

honestly tried to explain the problem.

I'd just like to first make a few personal comments about myself.

[About 600 'confidential' words erased by I Catt.]

………

I hope you will understand therefore that I simply can't afford to get

involved in a lot more correspondence on this issue, but I offer below some

thoughts which I hope will help.

……….

I must say that I don't think you are doing anything useful by stirring up

issues of north versus south, east etc

I will trust to your integrity to treat my above comments, especially about

my own circumstances, as totally confidential.

[See p55 of the book "The Catt Anomaly", on this website, quoting Catt's 10sep96 letter to McEwan's boss; "I promise that his [McEwan's] response, and my further comments on him, will appear in future issues of this book." Should I now break my promise? These 'scientists' *always* play the 'confidential' card.]

Now let me make a few comments for public consumption:

*********************************************************

"I previously offered to Mr Catt a simple explanation of how the charge is

conveyed along the transmission line. I used an uniform array of N

electrons and N positive ions spaced out along a section of line of length

L. I then pointed out that if we push in one extra electron at the left of

this section, and redistribute the N + 1 electrons uniformly over that

section, there appears a net unbalanced charge of one unit which is

distributed nearly uniformly over that section, but none of the charges

involved had to move a distance greater than L/N within the time it took to

redistribute the charges. The large values of N actually involved explains

why the particle velocity really is so small. This is the gist of my

explanation which I won't repeat in detail as I assume Mr Catt has already

included it and will recap it as necessary.

I still stand by this as a basic explanation of how the charge is carried

along the line. As I explained before, I think the anomaly only appears to

exist because there is a confusion about the identity of the charges

involved. The charge which actually supports the line voltage is actually a

very slight unbalance between very large densities of positive and negative

charges which are already in any given section of line before the

propagaing wave reaches them. (Note the italics!)

My description shows that a pattern of unbalanced charge can move far more

rapidly than the individual charges involved. (I could make the obvious

analogy with sound waves; after 1 second I hear the sound from a lightning

stroke 340 metres away but it is perfectly obvious that none of the

atmospheric molecules that were around the original discharge have arrived

at my ears. Putting it a bit facetiously, I don't smell any ozone at the

same time as the sound arrives and there certainly aren't any 340 m/sec

winds blowing round my head. But surely the idea of particles transmitting

stress to other particles is already clear enough.)

I would like to emphasise that my description using N charges in a line was

a deliberately simplified one intended to get over the key concept without

a lot of detail. This leads me to my next point.

I am prepared to take slight issue with Prof Pepper - again in a completely

friendly way I hope - about the main component of the velocity of the

charges. My recollection is that he agreed with me that the required

charges are already in the section of line to start with, but I think he

implied that the charges move laterally outward to generate the surface

charge as the wave moves over them. I would assert that the main component

of particle velocity is longitudinal.

In fact it is easy to show that the current flow must have both lateral and

longitudinal components, so I agree with Prof Pepper that there are lateral

charge movements but I do assert that the longitudinal velocity components

are the larger ones. We can go into this in a little more detail:

The surface charges on the metallic conductors exist only in a very thin

surface layer. Classical theory doesn't give any indication of the

thickness of this layer. To do it properly means solving the wave

mechanical equations for the states of the electrons near the surface. This

I am not competent to do. However, this distance scale is obviously an

atomic one.

Within the conductor deeper than the surface charge layer, we will find

there is no unbalanced charge density. We now have to introduce the

concept of skin depth. The current flow along the conductor occurs within a

layer near the surface whose thickness is the skin depth. Because the skin

depth varies inversely as the square root of frequency, we are obliged to

consider individual frequency components in the propagating pulse. However

the skin depth is very much greater than the surface charge layer thickness

up to very high frequencies, as (for copper) it is about 9 mm at 50 Hz and

about 2 microns at 1 GHz.

The implication of this is that the moving electrons must have both

transverse and longitudinal components of velocity. They have to arrive at

the surface of the metal, yet flow within a much thicker region. To arrive

at the surface, they must, as Prof Pepper says, move sideways. However, if

they only moved sideways, there would still not be any net charge imbalance

in any small section of line. So here I am saying that Prof Pepper's

description is incomplete, there have to be longitudinal motions as well.

You can imagine the lines of the current flow field (at a single frequency)

as like semi-loops in which one end of the loop starts on a patch of

positive surface charge, bends round very sharply within the skin depth,

then goes longitudinally along and terminates on a negative surface charge

patch. I emphasise again, however, that no individual charge originally at

one end of the loop has to arrive at the other end; only small individual

velocities are involved.

(This can be put a bit more formally using some mathematics. Because there

can be no unbalanced charge density within the conductor, the current flow

field must have zero divergence, i.e. if we use an x - axis along the

cable axis and a y - axis normal to the conductor surface, then we must

have dUsubx)/dx + dUsuby/dy = 0. Here Usubx and Usuby are the x and y

components of the current density flow vector. Now the first term is

certainly non - zero because the velocity does exist on the left of the

wave front and not on the right of it. This implies that Usuby can't be

zero. I include this only as shorthand for the benefit of those who are

familiar with this kind of maths, but it isn't essential.)

For the high frequency components within the propagating pulse, the ratio

of the longitudinal velocity components to the transverse ones will be the

approximate ratio of the wavelength of the guided wave to the skin depth.

For components at sufficiently low frequencies where the skin depth becomes

larger than the conductor transverse dimensions , the corresponding ratio

will be of the order of the ratio of the wavelength of the wave to the

transverse dimension of the appropriate conductor. I believe that in all

virtually all practical cases this ratio is very much greater than unity.

I am sure Prof Pepper will not be in the least offended by my raising this

contention, and anyway I am quite prepared to be shot down about it if I

myself am wrong.

Within the approximations of the classical equations, the problem of the

step wave propagating along a line made of conductors of finite

conductivity can in principle be solved numerically using the

finite-difference time domain method. I am not certain that the software

that is actually around can cope well with the different length scales of

the skin depth and the inter-conductor spacings. I don't have time to look

into this, but if anyone else would like to have a go (or maybe even has

done it already and I am not aware of it) I believe they will be able to

demonstrate a current flow field similar to what I described: I think it

will show almost purely longitudinal velocity components, uniformly

distributed across the conductors, a long way behind the wave front, and

transverse components that increase as you approach the propagating wave

front.

I have noted Mr Catt's comments where he says that one explanation of the

wave transmission (and I believe it is correct) is that the electrons

transmit the wave by each one "nudging" the next. [Nothing to do with Catt. Catt's co-author Dr. Lynch said this idea was presented by the lecturer at the IEE 1997 Wheatstone Lecture.] The point he [Lynch] raises here is that the spacing between the electrons is very much greater than the

radii of the particles. I hope I am correct in interpreting his problem as:

"how do they nudge each other if they are a long way from touching?" I have

to say that I believe this is a total red herring. The particles don't have

to touch each other to transmit the force; if you push one electron closer

to another, the second one gets a nudge because the electrostatic repulsion

acting on it increases. The increase, however, is not felt instantaneously

by the second, but only after the time taken for light to travel from one

to the other.

(At this point we could now get into several very interesting further

questions, but they are really sidelines as far as the resolution of the

Catt anomaly is concerned. One is the question of what is meant by the

radius of the electron. One possible definition is the radius at which the

electrostatic field ceases to obey the inverse square law. There is also a

classical definition based on the electromagnetic scattering cross section,

and a quantum radius which I don't understand. I don't believe these

quantities are connected, but I would be most interested in the comments of

expert physicists. Another fundamental problem is what keeps particles

together under their internal repulsion. This certainly isn't dealt with by

Maxwell's equations, as they stand, but neither is it a problem for

explaining the wave transmission problem. Again I simply don't know what

the present state of knowledge is about these points, and would be

interested to hear about recent developments from experts who are up to

date. At extremely high frequencies, there are indeed effects due to the

finite rate of acceleration of electrons in conductors under applied force.

I believe the characteristic frequency at which this becomes important is

the plasma frequency of the metal, normally somewhere in the X-ray region,

I think. Finally a still higher level of description is to treat the

electron movement using quantum mechanics.)

To show there is a problem with an existing physical theory, you either

have to show that is logically self-inconsistent or that is fails to agree

with experimental observations. My conclusion is that, although Mr Catt's

problem does provide many interesting exercises in applying the available

theories, it still doesn't manage to meet my criteria for showing that

there is a problem with them."

*********************************************************

(end of "public" material)

To conclude, I hope you will think carefully about my comments and accept

them as my best and most honest attempt to explain the issue, within the

limits of my knowledge.

Approx. 200 more 'confidential' words erased by Ivor Catt

Very best wishes,

Neil McEwan [18jan00]

Co-author Dr. A. Lynch to Ivor Catt, 30jan00

Dear Ivor,

My physics dates back to the 1940's, since when I have usually called myself an electrical engineer. But I think the spacing of atoms in a solid or liquid is about 0.3nm, and the size of an atomic nucleus is less by a factor of thousands, so that energetic particles are able to pass through a thin film of solid with few collisions. The size and shape of an electron are, I believe, unknown. McEwan discusses the "nudging" sensibly, but he appears to assume that the electron is spherical - otherwise why "the" radius? ….

….

….

…. There are, however, no doubts about J.J.'s discovery [which J.J. described to young Arnold Lynch, now aged 83, - I.C.]: electric charge is associated with inertia, and this is what matters for your Anomaly.

Yours sincerely, Arnold Lynch

Comment by Ivor Catt, 1feb00.

Lynch first pointed out in our joint IEE paper that electrons are too far apart to nudge each other. Here, he points out that they must be far apart, not only in diameter, but also in their power to influence events, with large unaffected spaces between, "so that energetic particles are able to pass through a thin film of solid with few collisions." He is moving towards the suggestion that if electrons nudged each other, then X-ray photography would not work. - I.C. 1feb00.