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"Veritasium" (YT) - "The Big Misconception About Electricity" ?
SiliconWizard:
--- Quote from: bdunham7 on January 01, 2022, 07:50:08 pm ---No, the concept of the localization of the wave function of any particle or object, quantified as its de Broglie wavelength, has been taught in introductory QM for decades and I had to demonstrate it experimentally (for electrons) in one of my undergraduate physics labs via the standard Davisson-Germer experiment. Nothing new, except that the de Broglie wavelength for larger objects is so small and thus the distribution probability so localized that it is much more difficult to observe.
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Uh, yeah. Precisely. The wave function applied to "any object" of any scale is a cute theory, but it just failed for anything other than very small particles. Electrons, sure nothing new about that! The paper I quoted above may reshuffle the cards somewhat, although I'm not hugely holding my breath at this point.
--- Quote from: bdunham7 on January 01, 2022, 07:50:08 pm ---I did not say that the flow of water through a pipe was in any way 'similar' to the flow of electrons in a wire--nor did I say they were dissimilar-- I simply said that they were both valid concepts.
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Both valid concepts, but for describing different things.
--- Quote from: bdunham7 on January 01, 2022, 07:50:08 pm ---
--- Quote ---Well yes! But we still haven't defined while "through the wire" exactly meant, unless I missed it. Can we find a definition?
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Well, if you want a QM definition, I think it would simply be that the spatial probability distribution of the electrons in question at each point in time ( Ψ [x,y,z] (t) ) mostly falls somewhere within the dimensions of the wire.
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Yeah, that's a start. It's already beyond what was bluntly put, without much details, in the original video. (Of course this is still somewhat simplified IMO: the dimensions of the wire, for any practical wire, are a more complex concept, and more difficult to model than it appears.)
But after reading all those various approaches, I'm still under the impression that the question is both unanswered and ill-defined. :)
rfeecs:
--- Quote from: bdunham7 on January 01, 2022, 09:07:32 pm ---Whether the energy is 'contained' in the charge or the field seems a questionable question since both are required. You can have any field you want, but without a charge to work on there's no energy.
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So a Megajoule laser pulse doesn't contain any energy?
Charges gave up energy to create the pulse. Charges will eventually absorb energy when the pulse hits them. But how did the energy go from one location to the other?
Apparently not in the fields, because without a charge there's no energy?
OK, the energy is in photons. That's another model.
Perhaps you are saying that static fields do not contain energy.
It seems like a chicken and the egg thing. All electromagnetic fields are created by charges. The energy was put into the system when the charges were moved. You can't have one without the other.
SiliconWizard:
--- Quote from: rfeecs on January 01, 2022, 10:04:25 pm ---It seems like a chicken and the egg thing. All electromagnetic fields are created by charges. The energy was put into the system when the charges were moved. You can't have one without the other.
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Now I think we're moving forward... =)
bdunham7:
--- Quote from: SiliconWizard on January 01, 2022, 09:56:04 pm ---Uh, yeah. Precisely. The wave function applied to "any object" of any scale is a cute theory, but it just failed for anything other than very small particles.
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QM, QED and QFT are non-intuitive and hard to grasp, but they certainly aren't a cute theory that fails. More than one cynic struggling to understand them has noted that many of simpler mathematically predicted non-intuitive results are either too small or too infrequent to be observed, except of course for those that are observed--tunnel diodes, diffraction and while we're at it, things like incandescent light bulbs. Most of the actual physical phenomena that make the universe work are things classical physics, including EM theory, fails to explain properly. The fact that some of those QM results are difficult to observe directly doesn't invalidate or marginalize the theory in any way. In any case, last I heard someone had managed to demonstrate diffraction in and calculate the de Broglie wavelength of fullerenes, a.k.a. buckyballs which are a spherical C60 molecule.
--- Quote ---But after reading all those various approaches, I'm still under the impression that the question is both unanswered and ill-defined. :)
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If you are referring to whether the energy flows in the wire, OK, I'll agree that there is room for discussion. But if it is whether the electrons flow in the wire, I'd regard that as not really worth debating.
bdunham7:
--- Quote from: rfeecs on January 01, 2022, 10:04:25 pm ---So a Megajoule laser pulse doesn't contain any energy?
Charges gave up energy to create the pulse. Charges will eventually absorb energy when the pulse hits them. But how did the energy go from one location to the other?
Apparently not in the fields, because without a charge there's no energy?
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Context and previous replies (which are context, I suppose) are important. I specifically addressed this a page ago and you are misconstruing what I've said.
https://www.eevblog.com/forum/chat/veritasium-(yt)-the-big-misconception-about-electricity/msg3910100/#msg3910100
--- Quote ---Perhaps you are saying that static fields do not contain energy.
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Perhaps you could read my post that I've linked and the one after it and then see whether you agree, disagree or don't understand my position on that. Can you have a static E-field without charges?
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