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Would either (both) of you care to define exactly what you each mean by the term 'displacement current' (in vacuo).
Q1 Is it for instance:
Q2 In which direction does it flow if it exists?
I feel that a lot of the preceding disagreement may be due to lack of clarity in your definitions and explanations. Once you have both answered all the above questions, I think the discussion can be focused on any remaining disagreements you may have.-- Light current 05:32, 24 February 2006 (UTC)
Just so we all know who's saying what, I suggest we all follow these simple rules:
Thanks!-- Light current 18:54, 24 February 2006 (UTC)
One proviso I forgot to mention is that we're not discussing dispalcement in dielectrics, because we all? believe in that. What we're discussing is displacement in vacuo. Agreed? -- Light current 21:40, 26 February 2006 (UTC)
Charge aint got time to accumulate at RF!-- Light current 21:55, 25 February 2006 (UTC)
Since Maxwell was apparently unaware of em radiation he had to find a fix for Kichoffs laws. It is now agreed of course that Kirchoffs laws are but an approximation to the real happenings and that field theory tells the complete story in circuit analysis. In regard to your reply, Im happy to accept your defn (dD/dt) of displacement in vacuo. Im going to try to avoid use of the term current as this implies a flow of something.-- Light current 18:30, 24 February 2006 (UTC)
Im happy to accept your defn here Kevin. Lets call it dD/dt. Question is, does Nigel agree with this?-- Light current 23:05, 24 February 2006 (UTC)
Im a little concerned about your statement 'an accumulation of charge'. What exactly do you mean by this? Where does this charge come from? Or do you maen a separation of charge?-- Light current 02:37, 25 February 2006 (UTC)
I agree that we must not move the debate unnecessarily into the realms of quantum mechanics. We must be careful to limit the discussion to the salient points. Actually, I don't believe anything flows normal to the plates- so its not a problem for me!!-- Light current 21:43, 25 February 2006 (UTC)
I agree with the second part of your post-- Light current 21:10, 26 February 2006 (UTC)
When you say accumulation of charge, you mean not real charge carriers, but charge created from nowhere?(or the em wave) Yes?-- Light current 22:22, 26 February 2006 (UTC)
Light Current: Maxwell has all sorts of mechanical "displacement current" theories of the aether, but the facts are resolved by quantum field theory, which is experimentally confirmed. If you charge up one plate, the other charges by induction, which means energy flows across to it as determined by quantum field theory (which should be considered the underlying mechanism for Maxwell's equations, and is more general).
So
The TEM wave is not however the mere charging of one conductor, but the charging of one conductor with positive charge and the charging of the other one with an equal amount of negative charge. This is a very special situation, which allows a propagating wave to go, because each conductor is then sending an equal amount of displacement current energy to the other. Nigel 172.212.141.83 16:34, 24 February 2006 (UTC)
OK Nigel. Thanks for making your position clear. This is what I thought you were saying. But best to make sure. Ive just spaced out your post to make these answer easy to see. --Light current 18:54, 24 February 2006 (UTC)
Yes Nigel could you oblige please?-- Light current 23:02, 24 February 2006 (UTC)
So, Nigel, when we have a very special situation, which allows a propagating wave to go, because each conductor is then sending an equal amount of displacement current energy to the other. doesnt this add up to zero? I think ther must be a way of explaining this without recourse to quantum mechancis which tends to obscure the issue I feel.-- Light current 21:12, 26 February 2006 (UTC)
Im interested to know what Nigel means by 'induction' in the context of travelling waves and TLs. Does this mean that one current induces the other, or that both currents are induced by the em energy flowing between the conductors?-- Light current 22:10, 26 February 2006 (UTC)
Light current: yes the exchange of energy from one conductor to the other at the front of the logic step (during the rise) is symmetric, so the net transverse flow of energy is zero in the transmission line. (A net result of zero also results when you spend as much as you earn, or when you add up the total charge in a typical - not ionised - atom.) It is quantum field theory which underlies electromagnetism, so any alternative (non-quantum field theory) explanation is likely to be crackpot. Nigel 172.201.199.96 11:05, 28 February 2006 (UTC)
Start with the capacitor, two parallel metal plates. Charge up one plate with a spark from a comb. The other plate then charges by induction, which is a polarisation of charge created by the electric field. The electric field lines in quantum field theory are not real lines, but just mark the paths of radiation ("gauge bosons", force-causing photons) which create electric forces. In this situation, where you charge one plate in a capacitor and the other plate charges by induction (charge polarisation), there is a net flow of energy, but if you simultaneously charge one plate with positive charge and charge the other plate with negative charge, then you find that they exchange equal amounts of energy, which is the transmission line situation. Ivor Catt incorrectly (see [1]) uses a picture of a logic step, which blocks proper understanding of the underlying mechanism. Nigel 172.201.199.96 11:05, 28 February 2006 (UTC)
Light current: Catt is based on Heaviside who had the current in the wire being caused by events in the surrounding space. QED was founded in 1929 by Dirac's prediction of the positron which was confirmed experimentally in 1932 by Anderson, and the vacuum polarisation effect was first correctly calculated by Feynman, Schwinger, and Tomonaga in 1949, giving the 1.00116 Bohr magnetons for the magnetic moment of the electron which had been found experimentally in 1948. So this isn't new stuff. Catt told me that Heaviside's unpublished papers (for his famous never-published "fifth volume") had been found by the mathematician H. J. Josephs to contain ideas of relevance to this quantum theory.
I agree we need to concentrate on em energy, which you can call by any name you like without affecting the facts. The name is irrelevant. An electric field arises because of energy exchange in the vacuum, which is well tested fact. Other explanations may seem simpler, but lead to epicycles and falsehoods:
Dr M. E. Rose (Chief Physicist, Oak Ridge National Lab.), Relativistic Electron Theory, John Wiley & Sons, New York and London, 1961, pp 75-6:
The treatment of the problems of electrodynamics is seriously complicated by the requisite elaborate structure of the vacuum. The filled negative energy states [in the Dirac sea of the vacuum] need produce no observable electric field. However, if an external field is present the shift in the negative energy states produces a polarisation of the vacuum and, according to the theory, this polarisation is infinite. In a similar way, it can be shown that an electron acquires infinite inertia (self-energy) by the coupling with the electromagnetic field which permits emission and absorption of virtual quanta. More recent developments show that these infinities, while undesirable, are removable in the sense that they do not contribute to observed results [[[J. Schwinger]], Phys. Rev., 74, p1439, 1948, and 75, p651, 1949; S. Tomonaga, Prog. Theoret. Phys. (Kyoto), 1, p27, 1949]. For example, it can be shown that starting with the parameters e and m for a bare Dirac particle, the effect of the 'crowded' vacuum is to change these to new constants e' and m', which must be identified with the observed charge and mass. ... If these contributions were cut off in any reasonable manner, m' - m and e' - e would be of order alpha ~ 1/137.
These are basic, well tested experimental and theoretical facts. If you want a simple theory of the TEM wave, this is the basis for it. Nigel 172.201.86.143 11:17, 1 March 2006 (UTC)
Under review!
-- Light current 22:30, 26 February 2006 (UTC)
It is well known that a TL can be charged fully from a matched source in the time it takes a step to travel to the far end and back to the source. Its used all the time for pulse charging of lines in radar pulsers etc, and can easily be demonstrated with a piece of coax, a fast switch and a fast scope.
In the case of short lines there is not sufficient time for charged particles to move along the line and take up their new static positions. So, where does this new static charge come form so quickly if not from the em energy fed into the line? (I hope this is not a rephrasing of the Catt Anomaly)-- Light current 21:36, 26 February 2006 (UTC)
I agree with your last paragraph except that: do the electrons in the wire have to move at all?. THey may start moving but they cant move fast enough to make any difference to the 'light speed' charging of the TL. I will need to re read your previous paragraphs.-- Light current 14:33, 27 February 2006 (UTC)
Ive not heard of 'abstract charge' before and although it may convey the idea of charge without charge carriers, Im not sure if this neologism would be accepted. If there was another way to describe this idea using atandard terms, I think this would be preferable.-- Light current 16:34, 27 February 2006 (UTC)
Yes this is something that we as editors must get to the bottom of so that we can present a simplified but accurate version to the readers. We, however cannot include original research so all our explanations must be in terms of currently accepted theory (unless were just reporting someone elses ideas!) BTW Nigel's gone rather quiet! Do you think hes ill? Or just thinking?-- Light current 22:17, 27 February 2006 (UTC)
It doesnt matter what Catt's position is as long as we report what it is to the best of our ability. After all, this page is about Ivor Catt, not Nigel Cook, string theory, Kevin Brunt, Light current or the answer to life, the universe and everything! Lets keep it focussed.-- Light current 01:11, 28 February 2006 (UTC)
This page is an archive of past discussions. Do not edit the contents of this page. If you wish to start a new discussion or revive an old one, please do so on the current talk page. |
Would either (both) of you care to define exactly what you each mean by the term 'displacement current' (in vacuo).
Q1 Is it for instance:
Q2 In which direction does it flow if it exists?
I feel that a lot of the preceding disagreement may be due to lack of clarity in your definitions and explanations. Once you have both answered all the above questions, I think the discussion can be focused on any remaining disagreements you may have.-- Light current 05:32, 24 February 2006 (UTC)
Just so we all know who's saying what, I suggest we all follow these simple rules:
Thanks!-- Light current 18:54, 24 February 2006 (UTC)
One proviso I forgot to mention is that we're not discussing dispalcement in dielectrics, because we all? believe in that. What we're discussing is displacement in vacuo. Agreed? -- Light current 21:40, 26 February 2006 (UTC)
Charge aint got time to accumulate at RF!-- Light current 21:55, 25 February 2006 (UTC)
Since Maxwell was apparently unaware of em radiation he had to find a fix for Kichoffs laws. It is now agreed of course that Kirchoffs laws are but an approximation to the real happenings and that field theory tells the complete story in circuit analysis. In regard to your reply, Im happy to accept your defn (dD/dt) of displacement in vacuo. Im going to try to avoid use of the term current as this implies a flow of something.-- Light current 18:30, 24 February 2006 (UTC)
Im happy to accept your defn here Kevin. Lets call it dD/dt. Question is, does Nigel agree with this?-- Light current 23:05, 24 February 2006 (UTC)
Im a little concerned about your statement 'an accumulation of charge'. What exactly do you mean by this? Where does this charge come from? Or do you maen a separation of charge?-- Light current 02:37, 25 February 2006 (UTC)
I agree that we must not move the debate unnecessarily into the realms of quantum mechanics. We must be careful to limit the discussion to the salient points. Actually, I don't believe anything flows normal to the plates- so its not a problem for me!!-- Light current 21:43, 25 February 2006 (UTC)
I agree with the second part of your post-- Light current 21:10, 26 February 2006 (UTC)
When you say accumulation of charge, you mean not real charge carriers, but charge created from nowhere?(or the em wave) Yes?-- Light current 22:22, 26 February 2006 (UTC)
Light Current: Maxwell has all sorts of mechanical "displacement current" theories of the aether, but the facts are resolved by quantum field theory, which is experimentally confirmed. If you charge up one plate, the other charges by induction, which means energy flows across to it as determined by quantum field theory (which should be considered the underlying mechanism for Maxwell's equations, and is more general).
So
The TEM wave is not however the mere charging of one conductor, but the charging of one conductor with positive charge and the charging of the other one with an equal amount of negative charge. This is a very special situation, which allows a propagating wave to go, because each conductor is then sending an equal amount of displacement current energy to the other. Nigel 172.212.141.83 16:34, 24 February 2006 (UTC)
OK Nigel. Thanks for making your position clear. This is what I thought you were saying. But best to make sure. Ive just spaced out your post to make these answer easy to see. --Light current 18:54, 24 February 2006 (UTC)
Yes Nigel could you oblige please?-- Light current 23:02, 24 February 2006 (UTC)
So, Nigel, when we have a very special situation, which allows a propagating wave to go, because each conductor is then sending an equal amount of displacement current energy to the other. doesnt this add up to zero? I think ther must be a way of explaining this without recourse to quantum mechancis which tends to obscure the issue I feel.-- Light current 21:12, 26 February 2006 (UTC)
Im interested to know what Nigel means by 'induction' in the context of travelling waves and TLs. Does this mean that one current induces the other, or that both currents are induced by the em energy flowing between the conductors?-- Light current 22:10, 26 February 2006 (UTC)
Light current: yes the exchange of energy from one conductor to the other at the front of the logic step (during the rise) is symmetric, so the net transverse flow of energy is zero in the transmission line. (A net result of zero also results when you spend as much as you earn, or when you add up the total charge in a typical - not ionised - atom.) It is quantum field theory which underlies electromagnetism, so any alternative (non-quantum field theory) explanation is likely to be crackpot. Nigel 172.201.199.96 11:05, 28 February 2006 (UTC)
Start with the capacitor, two parallel metal plates. Charge up one plate with a spark from a comb. The other plate then charges by induction, which is a polarisation of charge created by the electric field. The electric field lines in quantum field theory are not real lines, but just mark the paths of radiation ("gauge bosons", force-causing photons) which create electric forces. In this situation, where you charge one plate in a capacitor and the other plate charges by induction (charge polarisation), there is a net flow of energy, but if you simultaneously charge one plate with positive charge and charge the other plate with negative charge, then you find that they exchange equal amounts of energy, which is the transmission line situation. Ivor Catt incorrectly (see [1]) uses a picture of a logic step, which blocks proper understanding of the underlying mechanism. Nigel 172.201.199.96 11:05, 28 February 2006 (UTC)
Light current: Catt is based on Heaviside who had the current in the wire being caused by events in the surrounding space. QED was founded in 1929 by Dirac's prediction of the positron which was confirmed experimentally in 1932 by Anderson, and the vacuum polarisation effect was first correctly calculated by Feynman, Schwinger, and Tomonaga in 1949, giving the 1.00116 Bohr magnetons for the magnetic moment of the electron which had been found experimentally in 1948. So this isn't new stuff. Catt told me that Heaviside's unpublished papers (for his famous never-published "fifth volume") had been found by the mathematician H. J. Josephs to contain ideas of relevance to this quantum theory.
I agree we need to concentrate on em energy, which you can call by any name you like without affecting the facts. The name is irrelevant. An electric field arises because of energy exchange in the vacuum, which is well tested fact. Other explanations may seem simpler, but lead to epicycles and falsehoods:
Dr M. E. Rose (Chief Physicist, Oak Ridge National Lab.), Relativistic Electron Theory, John Wiley & Sons, New York and London, 1961, pp 75-6:
The treatment of the problems of electrodynamics is seriously complicated by the requisite elaborate structure of the vacuum. The filled negative energy states [in the Dirac sea of the vacuum] need produce no observable electric field. However, if an external field is present the shift in the negative energy states produces a polarisation of the vacuum and, according to the theory, this polarisation is infinite. In a similar way, it can be shown that an electron acquires infinite inertia (self-energy) by the coupling with the electromagnetic field which permits emission and absorption of virtual quanta. More recent developments show that these infinities, while undesirable, are removable in the sense that they do not contribute to observed results [[[J. Schwinger]], Phys. Rev., 74, p1439, 1948, and 75, p651, 1949; S. Tomonaga, Prog. Theoret. Phys. (Kyoto), 1, p27, 1949]. For example, it can be shown that starting with the parameters e and m for a bare Dirac particle, the effect of the 'crowded' vacuum is to change these to new constants e' and m', which must be identified with the observed charge and mass. ... If these contributions were cut off in any reasonable manner, m' - m and e' - e would be of order alpha ~ 1/137.
These are basic, well tested experimental and theoretical facts. If you want a simple theory of the TEM wave, this is the basis for it. Nigel 172.201.86.143 11:17, 1 March 2006 (UTC)
Under review!
-- Light current 22:30, 26 February 2006 (UTC)
It is well known that a TL can be charged fully from a matched source in the time it takes a step to travel to the far end and back to the source. Its used all the time for pulse charging of lines in radar pulsers etc, and can easily be demonstrated with a piece of coax, a fast switch and a fast scope.
In the case of short lines there is not sufficient time for charged particles to move along the line and take up their new static positions. So, where does this new static charge come form so quickly if not from the em energy fed into the line? (I hope this is not a rephrasing of the Catt Anomaly)-- Light current 21:36, 26 February 2006 (UTC)
I agree with your last paragraph except that: do the electrons in the wire have to move at all?. THey may start moving but they cant move fast enough to make any difference to the 'light speed' charging of the TL. I will need to re read your previous paragraphs.-- Light current 14:33, 27 February 2006 (UTC)
Ive not heard of 'abstract charge' before and although it may convey the idea of charge without charge carriers, Im not sure if this neologism would be accepted. If there was another way to describe this idea using atandard terms, I think this would be preferable.-- Light current 16:34, 27 February 2006 (UTC)
Yes this is something that we as editors must get to the bottom of so that we can present a simplified but accurate version to the readers. We, however cannot include original research so all our explanations must be in terms of currently accepted theory (unless were just reporting someone elses ideas!) BTW Nigel's gone rather quiet! Do you think hes ill? Or just thinking?-- Light current 22:17, 27 February 2006 (UTC)
It doesnt matter what Catt's position is as long as we report what it is to the best of our ability. After all, this page is about Ivor Catt, not Nigel Cook, string theory, Kevin Brunt, Light current or the answer to life, the universe and everything! Lets keep it focussed.-- Light current 01:11, 28 February 2006 (UTC)