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Sick of ridiculous KVL infighting
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Simon:
If I remember rightly it was lewen that tried to show the theory does not hold up by going beyond it's scope. As much as I respect the man as an inspiring lecturer in this case he delved into something outside of his sphere and did not make clear why it was happening.
Siwastaja:
A really good teacher needs to keep their head cool in case of objection, and continue the quest of making people learn; spend all the time necessary to help student find the source of their error. Lewin colossally failed in that, possibly because of personality issues, possibly because he did not consider Mehdi as his students. But there is a third possibility, that he understood from day one that Mehdi's being intellectually dishonest with no intention of learning, and "skip" the whole game as unfruitful waste of time. Such is risky behavior, but so is sexually harassing one's students. Lewin's definitely is not a model character. When you say it like this directly, everybody will agree that it's irrelevant when it comes to the physical discussion. Yet, it's very usable tool to create suitable impressions. Lewin's not trustable. Mehdi's a very nice guy, who just makes a rational argument...


--- Quote from: tszaboo on January 14, 2022, 09:45:49 am ---Guess what, KVL also doesn't hold, when a wire is hot, and thermionic emission happens.
It doesn't mean it is useless. And who cares. Let grey haired physics professor rant on their own lectures. When I had a prof like this at university, I just stood up and took the class with another one, that was an engineer.

--- End quote ---

This comment is fascinating, I think it kind of proves my point exactly.

Imagine Mehdi's video never existing in a first place.

I'm rephrasing tszaboo's comment in my own words, and I hope I don't significantly change the meaning, as if this comment appeared after attending Lewin's lecture with the demonstration shown:
"Oh, Lewin demonstrated a case where KVL does not hold, I understood it, and it's correct. There are other cases where KVL fails, too, like thermionic emission. So what? No one ever called KVL useless, but I still want to make it super clear, that it is not useless. I don't like the character of Lewin and due to that, will prefer other lecturers."

See how ridiculous this is in this changed Mehdi-free context? Lectures are full of demonstrations. I have never heard anyone say "so what, there are others as well".

But we see many comments like tszaboo's, and why is that? Because a straw man exists, a straw man of "KVL being useless", which is just ridiculous, no one ever claimed that. This strawman also includes the idea that Lewin somehow claimed that KVL is unusable for most everyday engineering tasks, or something like this.

This strawman is especially appealing to those who never attended university, and as a result, not understand basic university-level mathematical notations and more importantly, admit the importance of basic terminology. Which is fine, but Lewin's lecture videos are in university context. Mehdi's reply isn't.

But this strawman clearly is also appealing to some who did attend university, like tszaboo, or myself.

But where did this strawman originate? I'll give tszaboo benefit of doubt, his intentions are at least neutral.

Hence the "Mehdi's a social manipulator theory". Believe it or not, it's not important, but important is to think what's happening.
instrumental:
Hey folks!


--- Quote from: dunkemhigh on January 13, 2022, 05:43:30 pm ---
--- Quote ---Any sensible comment gets lost in the noise in a matter of a day, which is probably exactly the reason for such smoke screen.
--- End quote ---

What will prevent this thread also suffering the same fate once it's been discovered?

If someone is disrupting a discussion through foul means then surely the answer is to ask a mod to deal with them. I don't see that giving them more threads to disrupt achieves much. Of course, perhaps the mods will be too busy, fail to see your point or otherwise let things run, but you don't know unless you ask.

But, on the whole, I am not averse per se with skimming the crust off into another smaller and newer thread. It was just the "Listen, my explanation is the right one, so I'm a special case" which poked me.

--- End quote ---

Firstly -- no, I'm not a sock-puppet, I'm a longtime lurker who happened on this thread yesterday while skiving off documentation. I'd already been somewhat aggravated at the YouTube scene over this dispute, and made an account to post about this (and also to complain about the SCPI interface on the RS-KEL103, but that's another matter). Nice to meet you all :-).

Secondly -- yes, it's a bit presumptive of me to come and post an "authoritative" explanation instead of posting in the other thread, where it would be more on-topic. Firstly, I was hoping more for a meta-discussion about the argument, and wanted to bracket off the problem itself. Secondly, I'd like to understand what exactly about this problem is so tricky to understand; if my explanation of the problem is unsatisfactory, perhaps you have a more intuitive explanation.

We've gone this way now, and I'm happy to be having this discussion. Please excuse me! I lost the plot a bit, writing the screed, then (in a slightly hungover state) forgetting to return to the raison d'etre of the thread in the first place -- asking why this disagreement is occurring, and what can be done to put an end to it.


--- Quote from: Simon on January 14, 2022, 10:23:31 am ---If I remember rightly it was lewen that tried to show the theory does not hold up by going beyond it's scope. As much as I respect the man as an inspiring lecturer in this case he delved into something outside of his sphere and did not make clear why it was happening.

--- End quote ---

Lewin's demonstration is not the clearest. I'm still scratching my head over it! Most of his demos are excellent; this is trying to demonstrate a counterintuitive phenomenon with counterintuitive, roundabout testing. I think this also leads to so-called"experimentalists" changing the free parameters of the demo and disagreeing about the interpretations of the results -- a sign of a bad experiment!

Perhaps to sketch an alternative, I'd opt to attach the ground clip to the tip of an oscilloscope probe and demonstrate that I can still sense "voltages" when time-varying magnetic flux is running through the loop -- it's a handy trick to know for qualitative EMC, and simple enough that the odd interpretations around Lewin's demo ("what if we move the resistors around the loop") are evaded. No free parameters this way, hard to get it wrong :-).


--- Quote from: Siwastaja on January 14, 2022, 10:47:54 am ---A really good teacher needs to keep their head cool in case of objection, and continue the quest of making people learn; spend all the time necessary to help student find the source of their error. Lewin colossally failed in that, possibly because of personality issues, possibly because he did not consider Mehdi as his students. But there is a third possibility, that he understood from day one that Mehdi's being intellectually dishonest with no intention of learning, and "skip" the whole game as unfruitful waste of time.
--- End quote ---

This is a great point. From Lewin's perspective, this is a settled matter; EM theory has hung around for over a century, and he'd been working in the field for over half a century at the time. He runs into the issue of communication with a student who doesn't quite get it. It's made more difficult by the fact that Mehdi himself is positioned as an educator, who frames "disagreeing with a master" as regular in the ordinary course of science.


--- Quote from: bdunham7 on January 14, 2022, 12:06:08 am ---
--- Quote ---So, any time we have a changing field or current (e.g. AC at any frequency), we can no longer define voltage.

--- End quote ---

with "there are multiple possible definitions of voltage" or something like that.  Proving that we can't define voltage by measuring something with voltmeters seems a bit silly.

--- End quote ---

I appreciate this! I meant this more in the context of the definition of the voltage as the potential function of the electric field (in which case the maths breaks) -- this should definitely be clarified. Thanks!

Many thanks for the discussion, all!
RoGeorge:
Might be Prof. Lewin's account.   :-//

Can't tell about others, but I'm very well and happy about my nerdyness.  To me, being called a nerd is a compliment, thank you!  :D

About Prof. Lewin, I think he is correct, no doubt for me now.  Makes sense in every aspect I am aware of, thought I'm only an amateur physicist.

At first, my "mind conditioning" unintended induced by years of tinkering with electronic circuits made me think Mr. Lewin was joking, especially since one of his papers about the subject was dated 1st of April.  ;D

But then, I've put aside the EE approach and tried to look only in terms of physics laws and physics and definitions (Voltage is the work needed to drag a charge from A to B), and it was clear like day and night that the professor is correct.  Also, what he was pointing out and his mind blowing demonstration doesn't brake Electrical Engineering in any way.

EE deals with the same results by "blaming" the induction in the voltmeter's cables.

Overall, I'm grateful he pointed out to non-conservative fields with a click bait title and a mind blowing experiment.  Otherwise I would have missed that aspect of non-conservative fields entirely.  Though, the biggest lesson to me was how strong brainwashing can be (here a case of unintended brainwash).

The strongest cage to break is the mind conditioning that slowly grows to imprison us.
Simon:
My memory is that Lewin demonstrated that the law did not hold, but gave no further explanation as though he had proved someone wrong. As a lesson that is a failure.
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