Firstly, I want to apologize for the tone of my previous reply; I could, and should, have made the main point - that this is no longer the chain model Veritasium was speaking of - in one short paragraph.
Beyond that, I think there is an issue here in the relationship between analogy and explanation.
If we draw an analogy between two different phenomena, we have not, at that point, explained either. If the analogy is between one phenomenon we understand, and one that we do not, it does not follow that the explanation for the former also explains the latter; that is an additional premise that has to be justified independently. It may be that the analogy points us towards a justification, but we cannot assume that.
Analogies can also be helpful as what Daniel Dennett calls 'intuition pumps' - a point of view that may help us form intuitions about what is going on (they can also pump incorrect intuitions, however, so we have to be careful.) With regard to electricity, there was a time when it just seemed impossible to me that AC could send power to a distant lamp or motor, and the chain analogy helped me get around that block (I sometimes wonder if Edison, who held a strong and largely irrational antipathy towards AC, could have benefitted from it!)
This analogy gives useful intuitions with regard to simple DC and low-frequency AC circuitry, but it rapidly breaks down if we try to push it too far. The simple analogy fails as soon as we get to transformers, for example.
At this point, we might be tempted to patch it up this way: imagine that the chain drives a sprocket, which in turn drives a second sprocket with a different number of teeth, which is moving a second chain.
There are several problems with this, such as there being no obvious reason for conflating the transformer turns ratio with the sprockets' teeth ratio, and that, taken as an explanation, it implies that transformers work for DC. Furthermore, it is just an ad-hoc patch to the chain-loop 'theory' of electricity.
Maybe you can come up with something that avoids the second of these problems (e.g. use a lever instead of sprockets), and perhaps even the first (but if you go with the lever, now you have added the problem of why a lever but not gears), but the third will always be there - as it is in the increasingly complex models you have presented in this discussion. The fundamental problem is that there is no analog, in the mechanics of matter (including acoustics), to the interaction between electric and magnetic fields in the vacuum.
There is an interesting historical connection here: I am told that as Maxwell struggled with EM, he filled his notebooks with many mechanical models, having space filled with tiny gears meshing with one another, but they did not make it into the theory. They seemed to have served as intuition pumps, or as a Wittgenstein's ladder - a sort of scaffolding that gets you to where you are going, but which you can throw away once you are there - though physics did not completely abandon the luminiferous aether until Einstein's theory of special relativity showed it to be unnecessary.
In this light, I take the argument in Veritasium's video to be structured this way: the chain model (i.e. the simple one, in which the links stand for electrons) breaks down for more complex situations, such as what happens in the first second of his proposed experiment. In EM theory, however, there is a construct - the Poynting vector - which shows the flow of energy and which is completely general, providing a single unified picture of what is going on in all cases. It works for the first second of the experiment as well as the cases where the chain analogy is an effective intuition pump, such as the steady state of the experiment. Thus I, personally, have no problem with Veritasium saying that it is a strictly better explanation than the chain model, and also than your ad-hoc additions and alternatives to it (though he did not, of course, take any position on those.)
One other point: the transmission-line model itself contains an analogy, between the distributed properties of the line and a circuit of discrete components. In that case, however, the discrete model was developed, by Heaviside, rigorously from first principles, so we know it can be used in explaining what is going on. That is how you do analogies that will serve as explanations!
Finally, here's an insightful essay by Freeman Dyson, entitled "Why is Maxwell's Theory so hard to understand?"
I took no issue with the tone of your replies, and I hope my own tone has been civil as well - I am in fact enjoying this conversation! Also, thank you for the link to the Freeman Dyson essay, I had not read it before.
Related to the matter of explanations vs analogies - I think I agree with most of your points. It's also true that Veritassium was dismissing a different chain model than the one I used.
However, I would say that, to me but also many other people, the Poynting vector is not an explanation of what is happening - it seems to be much more of a property of the system rather than an explanation of why the system does what it does. The mechanical analogies help give this insight - why is it working the way that it is? - as do the (classical) field-based explanations.
In fact, as far as I understand, Maxwell's theory works quite well as a mechanical theory of (mechanical) waves propagating in a medium. The problem with this isn't that the maths don't work out - it's that the theories also hold for propagation in outer space or man-made vacuum, where we have been unable to find such a medium.
The existence of this medium, in which EM waves are simple mechanical waves, was actually the main scientific theory for quite some time (the luminiferous aether). However, as experiments probed deeper and deeper at the necessary properties, especially with the locality bounds imposed by special relativity, the luminiferous aether became impossible to accept and the need for a medium had to be abandoned in favor of the field-based explanation - without any change to the actual maths, though.
It's also important to note that the Poynting vector is itself a consequence of applying two simple laws - special relativity and the conservation of energy - to EM theory. These two simple laws lead to a basic observation: energy can't move from point A to point B without moving somehow through each point in space between A and B. The Poynting vector tells you, for any point, which direction the energy is moving in that point. The general concept is not tied to EM, just the particular magnitude and direction is dependent on Maxwell's equations. Equivalent vectors would exist for any phenomenon that can transfer energy - strong force, gravitational effects, mechanical waves, oil trucks etc.
Thanks! - this discussion has led me in directions I have not given any thought to before, and maybe it's not finished...
The questions of what it means to understand something and what constitutes a good explanation seem related, and are both issues that I wish philosophy of the mind would spend more time on (but I'm probably just reading the wrong authors...) Formally speaking, science is not concerned with either of these issues, yet, paradoxically, it seems to have vastly expanded humanity's knowledge of, and ability to explain, the natural world.
This is off the top of my head, and perhaps it is an idea that's already been thoroughly trashed, but suppose understanding is a matter of developing intuitions that work? Until we have those intuitions, we have no idea what's likely to happen next, and that makes us feel uneasy and unprepared, but once we do, we feel more certain that we can handle whatever happens.
Putting aside our intuitions about other people, which are a huge part of being human, most of our other intuitions about the natural world are in Freeman Dyson's second layer - the layer of tangible, rather than fundamental, things. If we spend some time boating, for example, we develop intuitions about what might go wrong in stepping from a dock into a small boat. One way - perhaps the only way - to develop intuitions about things on the first layer is to work with them enough that we can begin to anticipate how things will work out before we have worked through the analysis (I say analysis, because, as Dyson is pointing out here, we have reached the point where most of our fundamental knowledge is abstract.)
This is not the whole picture, however, as there are many things, such as the Poynting vector, that are neither fundamental nor tangible. I imagine that if you work with the Poynting vector enough, you will develop intuitions about where it points before you have done the math. If you can look at a situation and say something like "Well, the Poynting vector will initially go this way, so there will be current in the load as soon as L/c seconds of the switch turning on", then you have provided an explanation (not the explanation) that works for yourself, and also other people with a similar familiarity/understanding of the Poynting vector.
At this point, you may well be thinking that this shows Veritasium was wrong to talk about the Poynting vector, as, presumably, few in his audience have this sort of familiarity with it (I don't.) Personally, however, I feel that what he was doing was useful, and also a very common, and perhaps unavoidable, pedagogical approach: he seems to be saying, in effect "it so happens that there is this abstract concept, that stands in this relationship to electromagnetic fields [also abstract concepts, by the way, but ones with which his audience are presumably more familiar] and which answers the questions we are concerned with here: how does energy get to the lamp, and when does it get there?" It is not a from-the-fundamentals, layer-one explanation, but, unless we are being unduly (and probably inconsistently) skeptical of science and scientists, we can be confident that it can, in turn, be explained from the fundamentals. Transmission-line theory is even further removed from layer one, yet it similarly offers a stepping-stone to it. These are useful abstractions that save us from figuring out everything from first principles all the time, which would be impossible for most people (such as myself), and inordinately burdensome for those who could.
I am not sure that Maxwell's theory works in the mechanical domain: while there are variants of the wave equation for transverse waves in solids and along material boundaries, is there a material or a mechanical analogy to the perpendicular interacting electrical and magnetic fields of Maxwell's theory? (Maybe there's a hybrid situation with piezoelectric materials or materials that do not follow Hookes law?)
I take your point that there are are analogs of the Poynting vector in other domains, and I assume you are raising this in support of another claim that I am now willing to provisionally accept: that there could be a valid and useful mechanical analog for Veritasium's experiment - it's just that I haven't seen one, yet, that I feel works well. The thing that makes the Poynting vector unique among its analogs is that it is the one in the specific domain that we are concerned with here. The other analogs might be just as abstract and difficult to develop intuitions about, or, if not, to relate to EM.
If my story in my prior post about Maxwell's notebooks is correct, it could be seen as suggesting that mechanical models help, as they certainly seem to have helped Maxwell - but if they are still useful now that we have the theory, I would expect them to be used to help teach it now. There's a cautionary tale, on page two of Dysons paper, about analogical reasoning, in his account of Maxwell's address to the 1870 annual meeting of the BAAS. As Dyson tells it, most of that talk was ostensibly about Kelvin's analogy between molecules and vortices - an analogy that did not lead to any physical knowledge.
Beyond that, I think there is an issue here in the relationship between analogy and explanation.
If we draw an analogy between two different phenomena, we have not, at that point, explained either. If the analogy is between one phenomenon we understand, and one that we do not, it does not follow that the explanation for the former also explains the latter; that is an additional premise that has to be justified independently. It may be that the analogy points us towards a justification, but we cannot assume that.
Analogies can also be helpful as what Daniel Dennett calls 'intuition pumps' - a point of view that may help us form intuitions about what is going on (they can also pump incorrect intuitions, however, so we have to be careful.) With regard to electricity, there was a time when it just seemed impossible to me that AC could send power to a distant lamp or motor, and the chain analogy helped me get around that block (I sometimes wonder if Edison, who held a strong and largely irrational antipathy towards AC, could have benefitted from it!)
This analogy gives useful intuitions with regard to simple DC and low-frequency AC circuitry, but it rapidly breaks down if we try to push it too far. The simple analogy fails as soon as we get to transformers, for example.
At this point, we might be tempted to patch it up this way: imagine that the chain drives a sprocket, which in turn drives a second sprocket with a different number of teeth, which is moving a second chain.
There are several problems with this, such as there being no obvious reason for conflating the transformer turns ratio with the sprockets' teeth ratio, and that, taken as an explanation, it implies that transformers work for DC. Furthermore, it is just an ad-hoc patch to the chain-loop 'theory' of electricity.
Maybe you can come up with something that avoids the second of these problems (e.g. use a lever instead of sprockets), and perhaps even the first (but if you go with the lever, now you have added the problem of why a lever but not gears), but the third will always be there - as it is in the increasingly complex models you have presented in this discussion. The fundamental problem is that there is no analog, in the mechanics of matter (including acoustics), to the interaction between electric and magnetic fields in the vacuum.
There is an interesting historical connection here: I am told that as Maxwell struggled with EM, he filled his notebooks with many mechanical models, having space filled with tiny gears meshing with one another, but they did not make it into the theory. They seemed to have served as intuition pumps, or as a Wittgenstein's ladder - a sort of scaffolding that gets you to where you are going, but which you can throw away once you are there - though physics did not completely abandon the luminiferous aether until Einstein's theory of special relativity showed it to be unnecessary.
In this light, I take the argument in Veritasium's video to be structured this way: the chain model (i.e. the simple one, in which the links stand for electrons) breaks down for more complex situations, such as what happens in the first second of his proposed experiment. In EM theory, however, there is a construct - the Poynting vector - which shows the flow of energy and which is completely general, providing a single unified picture of what is going on in all cases. It works for the first second of the experiment as well as the cases where the chain analogy is an effective intuition pump, such as the steady state of the experiment. Thus I, personally, have no problem with Veritasium saying that it is a strictly better explanation than the chain model, and also than your ad-hoc additions and alternatives to it (though he did not, of course, take any position on those.)
One other point: the transmission-line model itself contains an analogy, between the distributed properties of the line and a circuit of discrete components. In that case, however, the discrete model was developed, by Heaviside, rigorously from first principles, so we know it can be used in explaining what is going on. That is how you do analogies that will serve as explanations!
Finally, here's an insightful essay by Freeman Dyson, entitled "Why is Maxwell's Theory so hard to understand?"
https://www.clerkmaxwellfoundation.org/DysonFreemanArticle.p...