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Nigel. Maxwell's Aether theories and his interpretation of displacement current as a movement in the Aether were relegated to history by Michelson and Morley. He didn't know the "nature of electricity" because he died two decades before the discovery of the negatively-charged sub-atomic particle that we call the electron. If memory serves, Maxwell's "electron" was a vortex in the Aether. And "vector calculus" evolved because Maxwell, and other physicists, were finding problems that needed it. You are looking at Maxwell's work out of context. -- Kevin Brunt 21:40, 18 February 2006 (UTC)
For all of Catt's assertions, Maxwell's Equations work. The fact that in a "real" capacitor it takes a finite length of time for charge to spread across the plates does not invalidate displacement current; it just means that you have to work out in detail what the charge is doing at each point on the surface of the plate and then integrate across the surface. At which point you'll find that the total comes out the same as if you had just assumed that the charge was uniformly spread across the surface. Because that is what the Ampere-Maxwell Equation implies - if you enclose a volume of space, the net flow of "true electric current" into (or out of) the volume must be zero. When the amount of charge leaving is not equal to that entering there must be a balancing "displacement current", which means that the electric field passing through the boundary of the enclosed volume must be changing. The speed of propagation is irrelevant - it merely limits where the field can be changing in relation to the flow of charge. -- Kevin Brunt 21:40, 18 February 2006 (UTC)
Nigel, you are still mixing up the layers of abstraction. You need to distinguish between Maxwell's amendment to Ampere's Equation to complete the description of electromagnetism, and his attempts to construct a theory to explain electromagnetism in terms of an Aether. Incidentally, you see unaware that his trial-and-error approach is precisely what is meant by "heuristic". -- Kevin Brunt 00:08, 21 February 2006 (UTC)
Since Catt's work is not dealing with extremes of scale neither the Uncertainty Principle, nor non-linearity at 80GeV are relevant. If you look at the voltage step travelling up and down Catt's transmission line, you will find that anywhere between the supply end and the voltage step a current of identical magnitude is flowing; between the voltage step and the open end there is no current flowing; and at the voltage step itself (where the current flow is starting or stopping, depending on which way the step is travelling at the time) there is a changing electric field, (and hence there is displacement current.) Thus any volume that encloses a part of (one conductor of) the TL that includes the voltage step has an imbalance of current flow plus displacement current, and any volume that does not include the voltage step has identical current flows in and out, and no displacement current. -- Kevin Brunt 00:08, 21 February 2006 (UTC)
Furthermore, the stepwise voltage increase at the supply end of the TL is not some sort of "quantisation", it is merely an artifact of the finite length of the TL - if it were quantised, the steps would not be infinitely variable in both time and voltage by varying the length and the supply resistance. And if Catt had used the full form of the Telegrapher's Equations, not the approximations that assume that the resistance of the conductors can be ignored, he would have found that the dispersion would eventually smear the edge of the step into indetectability. -- Kevin Brunt 00:08, 21 February 2006 (UTC)
LC, I see you've a bit of my text about Catt and Exclusive-OR. This probably is useful, but the text needs a good deal of work to be done to it - I'll have a think about it. -- Kevin Brunt 23:48, 23 February 2006 (UTC)
What does need some radical attention, I'm afraid, is the section referencing Gerardus 't Hooft. To the extent that it refers to Catt's work it is merely repetitious, and it then heads off into Nigel's quarrels about quantum mechanics and string theory, which simply don't belong on a page that is specifically about "Ivor Catt". -- Kevin Brunt 23:48, 23 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. |
Nigel. Maxwell's Aether theories and his interpretation of displacement current as a movement in the Aether were relegated to history by Michelson and Morley. He didn't know the "nature of electricity" because he died two decades before the discovery of the negatively-charged sub-atomic particle that we call the electron. If memory serves, Maxwell's "electron" was a vortex in the Aether. And "vector calculus" evolved because Maxwell, and other physicists, were finding problems that needed it. You are looking at Maxwell's work out of context. -- Kevin Brunt 21:40, 18 February 2006 (UTC)
For all of Catt's assertions, Maxwell's Equations work. The fact that in a "real" capacitor it takes a finite length of time for charge to spread across the plates does not invalidate displacement current; it just means that you have to work out in detail what the charge is doing at each point on the surface of the plate and then integrate across the surface. At which point you'll find that the total comes out the same as if you had just assumed that the charge was uniformly spread across the surface. Because that is what the Ampere-Maxwell Equation implies - if you enclose a volume of space, the net flow of "true electric current" into (or out of) the volume must be zero. When the amount of charge leaving is not equal to that entering there must be a balancing "displacement current", which means that the electric field passing through the boundary of the enclosed volume must be changing. The speed of propagation is irrelevant - it merely limits where the field can be changing in relation to the flow of charge. -- Kevin Brunt 21:40, 18 February 2006 (UTC)
Nigel, you are still mixing up the layers of abstraction. You need to distinguish between Maxwell's amendment to Ampere's Equation to complete the description of electromagnetism, and his attempts to construct a theory to explain electromagnetism in terms of an Aether. Incidentally, you see unaware that his trial-and-error approach is precisely what is meant by "heuristic". -- Kevin Brunt 00:08, 21 February 2006 (UTC)
Since Catt's work is not dealing with extremes of scale neither the Uncertainty Principle, nor non-linearity at 80GeV are relevant. If you look at the voltage step travelling up and down Catt's transmission line, you will find that anywhere between the supply end and the voltage step a current of identical magnitude is flowing; between the voltage step and the open end there is no current flowing; and at the voltage step itself (where the current flow is starting or stopping, depending on which way the step is travelling at the time) there is a changing electric field, (and hence there is displacement current.) Thus any volume that encloses a part of (one conductor of) the TL that includes the voltage step has an imbalance of current flow plus displacement current, and any volume that does not include the voltage step has identical current flows in and out, and no displacement current. -- Kevin Brunt 00:08, 21 February 2006 (UTC)
Furthermore, the stepwise voltage increase at the supply end of the TL is not some sort of "quantisation", it is merely an artifact of the finite length of the TL - if it were quantised, the steps would not be infinitely variable in both time and voltage by varying the length and the supply resistance. And if Catt had used the full form of the Telegrapher's Equations, not the approximations that assume that the resistance of the conductors can be ignored, he would have found that the dispersion would eventually smear the edge of the step into indetectability. -- Kevin Brunt 00:08, 21 February 2006 (UTC)
LC, I see you've a bit of my text about Catt and Exclusive-OR. This probably is useful, but the text needs a good deal of work to be done to it - I'll have a think about it. -- Kevin Brunt 23:48, 23 February 2006 (UTC)
What does need some radical attention, I'm afraid, is the section referencing Gerardus 't Hooft. To the extent that it refers to Catt's work it is merely repetitious, and it then heads off into Nigel's quarrels about quantum mechanics and string theory, which simply don't belong on a page that is specifically about "Ivor Catt". -- Kevin Brunt 23:48, 23 February 2006 (UTC)