11 Comments

> Alas, no proof for the existence of luminiferous aether could ever be produced

Not everyone agrees with that interpretation of the Michelson-Morley experiments (including Michelson and Morley) and the others that expanded on their work. https://journalofscientificexploration.org/index.php/jse/article/view/873

Particularly amongst folks that are following the cold fusion space (e.g., Bob Greenyer), there seems be a trend towards taking aether seriously.

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Thanks for this way of thinking about it. I am curious, how does this apply to permanent magnets and their fields? Or does it?

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4dEdited

Kinda. In most materials, orbital angular momentums and spins of electrons are either distributed randomly or always paired; but in permanent magnets, a significant fraction of electrons has aligned orbital momentums and spins. So the hand-wavy answer is that you have charges moving in a coherent way, and the magnetic field is a relativistic consequence of that motion.

A more rigorous answer is complicated by two things. First, for orbital angular momentums, you have rotating frames of reference and it just gets pretty wonky. But more importantly, spins just... don't have a good "macro" explanation? They're often explained as rotation around the electron's own axis, and you can get results if you try that interpretation with a "toy" electron shaped like a donut or something like that... but it's not a good model because the electron is supposed to be a point particle.

This is essentially what I was alluding to in the closing paragraph. The basic approach is to assume that spin is magic and that in some cases, it produces observable magnetic fields.

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C'mon man, we gotta have just one ICP joke, for posterity's sake! I'll go:

Q: What do you call a Juggalo whose girlfriend just broke up with him?

A: Homeless

A2: Still clueless, re: magnets

(PS: Adapted from the many bassist/drummer/guitarist jokes I've endured over the years)

(PPS: Speaking of insane people, Google "ICP jokes" for the oddest collection of memes and nonsensical shist you've ever seen)

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Oooh you should write about that magnet-in-copper-tube experiment next.

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I never thought about magnetic fields this way and really like your way of explaining, but I'm wondering: neither the electrons in the conductor nor the moving charge are traveling at a fraction of light speed.

How does relativity apply?

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I think the basic idea is that it's still a fraction - negligible for almost all "macro" intents and purposes, but given the staggering number of mobile electrons and ions you have in a conductor, even a tiny percentage imbalance creates a non-trivial field.

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Seems You really have a rant on hydraulics comparisons being used for explanation of electronics principles, and this article seems a good topic to point the differences.

One of the issues that could have been brought to the readers' attention is the matter how fast does the electron flows into a conductor (wire)?

I remember, that in high school we calculated the speed of electron flow, and -to our surprise - it appeared that it is comparable to two inches per hour and does not correspond in any aspect to the situation, in which the lightbulb instantly lights up when the switch of a 30ft wire loop is closed. According to the result of calculations it would require around a thousand hours to do so.

Here's a good article that explains this phenomenon (pls excuse I've used a translator):

https://teoriaelektryki-pl.translate.goog/jak-szybko-plynie-prad/?_x_tr_sl=auto&_x_tr_tl=en&_x_tr_hl=pl&_x_tr_pto=wapp

As for the electric or magnetic fields, they are described only when static. Whenever they are no longer stationary, they turn into electromagnetic field consisting of a two vectors:

- magnetic field B and

- electric field H

perpendicular to each other that simultaneously rotate.

Since, amongst the comments there are question on the math models behind the fields theorem, the Maxwell's equations are the essence here.

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Is there any nice way to extend this model to describe electromagnetic waves?

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I have a reasonable treatment of the electric component here: https://lcamtuf.substack.com/p/radios-how-do-they-work

Alas, past a certain very hand-wavy level of precision, it all devolves from cutesy models into math.

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7dEdited

I cannot not say the title of this post to myself in Seinfeld's voice.

"What is the deal with these magnetic fields..."

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