Electricity is magnetism

By: --- (---.delete@this.redheron.com), December 16, 2021 12:19 pm
Room: Moderated Discussions
Brett (ggtgp.delete@this.yahoo.com) on December 15, 2021 11:12 am wrote:
> Anon (no.delete@this.spam.com) on December 14, 2021 5:16 pm wrote:
> > Brett (ggtgp.delete@this.yahoo.com) on December 14, 2021 3:01 pm wrote:
> > > Electricity is magnetism:
> > > https://youtu.be/bHIhgxav9LY
> > >
> > > The electrons barely move and it is the magnetism doing all the work.
> > > This should be mind blowing for at least half the people here.
> >
> > Do not rate people according to your own ignorance.
> About half the people here are double EE’s and know this, I am a software guy,
> I found this information interesting and like most non-EE’s I had no clue.

The question is: do you trust physicists or EEs to have the best understanding of electricity?
The primary value, in my experience, of reading histories of science is that by understanding the conflicts of the past, you can understand what to dismiss in modern conflicts. In other words, by understanding what people were arguing about when, eg, they were arguing about "vis viva", or about "nature abhors a vacuum", or about "heat", you not only understand the past, you
- understand why those past concepts were wrong (or, if we are going to be more PC, why those understandings have been eclipsed by more modern understandings)
- you ALSO understand why those past concepts live on as zombies, not just in our language, but also as concepts with varying degrees of liveness in various minds. Most of us are respectful enough to others around us that when we hear certain ideas being repeated over and over, we assume there must be some content to them; part of the final step in one's education in a field is learning to tune out this babble as unhelpful and content-free.

Electromagnetism has gone through evolution no less than other parts of science, with a pool of ideas and language ("electricity", "induction", "emf") stranded in the past but still live in the minds of many practitioners (less so in EE's, least of all in physicists).

I have neither time nor interest to say any more than this, except:
- is "electricity" "magnetism"? Well, I have no idea what "electricity" means. What we can say is that all electromagnetic phenomena are described by an object, the electromagnetic field tensor. The point about this tensor that's significant right now is that it is a 4-tensor, meaning that it transforms in a particular way under boosts, and this transformation intermingles the "electric field" and "magnetic field" components of the tensor. In other words what looks like a pure electric field to one observer can look like a mixed electric and magnetic field to a different observer moving at constant velocity relative to the first.
Special relativity is, of course, part of the basic geometry of the universe.

- Weber presented an alternative view of electromagnetism to (and before) Maxwell, in which relative acceleration is part of the force law. You can explain some things with this in a way that's different from Maxwell, but pretty much every physicist would say that you don't get as far, or as conveniently. I would not consider Weber a good starting point for understanding.
Ultimately (like so many things) this turns into a combination of taste and competence.
If you are content to operate at the 17th century level of Newtonian particles in motion, so your building blocks are forces and positions, then Weber may seem great, you don't have to add in the additional new concepts of an electromagnetic field. By the time of Maxwell you could argue this is still a point of aesthetics, nothing more. But physics moves beyond Maxwell, to X-rays, to the photo-electric effect, to the Bohr atom, the quantum mechanics then QED and QFT. And Weber (and points and forces) do not accompany us on this journey; this is the land of (at the very least) fields and Lagrangians, not Newton's concepts.

- EM continued to have live controversies over various issues ("the shape of the electron", what *exactly* is radiation and why do radiation laws appear to have second and third derivative terms in them, various unedifying technical arguments about stresses in materials under extreme EM fields) at the start of the 20th C, much of which was resolved by QED.
The common thread in these issues is that you do not *maximally* understand a concept like radiation by working downwards (from forces and points to fields to ???), you start by working upwards from QED. If you *insist* on working downwards you can achieve engineering understanding, via phenomenological equations, but you don't (and cannot) get deeper than that. You can build, even analyze, a steam engine based on caloric (as did Carnot), but you can't understand something like magnetic cooling until you go beyond caloric to statistical mechanics.

So, yeah, lots of things have been said in this thread. How many of them were accurate?
Well, like I said, for the deepest picture IMHO trust physicists the most, EE's somewhat less, and randoms on the internet least of all.
I won't tell you whom to believe, but if someone is telling you xxx doesn't work when we try to use Maxwell's equations, what they are saying may (in some sense) be true -- but is your take-away from that "Maxwell is dumb, Weber roolz!" or is it "Yeah, we know. That's why the greatest minds of the 40s through the 70s put together the successor to Maxwell, in the form first of QED, then QFT, then the Standard Model"?
This stuff is REALLY HARD, astonishingly hard, the hardest subject humanity has yet tackled. That's sad, and some of us are approaching the problem from different angles to make it easier to understand. But it's the mountain that has to be climbed if one wants to understand these issues.
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TopicPosted ByDate
Electricity is magnetismBrett2021/12/14 04:01 PM
  *facepalm* (NT)Ray2021/12/14 05:16 PM
    in fairness what started out trollish turned into a really informative thread (NT)anonymous22021/12/15 06:55 PM
  Electricity is magnetismAnon2021/12/14 06:16 PM
    Electricity is magnetismLightning2021/12/14 06:47 PM
      Electricity is magnetismDavid Hess2021/12/14 10:47 PM
    Electricity is magnetismBrett2021/12/15 12:12 PM
      Electricity is magnetismSimon Farnsworth2021/12/15 02:30 PM
      Electricity is magnetismAnon2021/12/15 03:03 PM
      Electricity is magnetism---2021/12/16 12:19 PM
        Electricity is magnetismAdrian2021/12/16 03:51 PM
  Electricity is magnetismAdrian2021/12/15 05:06 AM
    Sorry for a few typos, I was in a hurry, but the typos do not affect the meaningAdrian2021/12/15 05:40 AM
    Electricity is magnetism2021/12/16 06:22 PM
      Electricity is magnetismEtienne Lorrain2021/12/17 02:44 AM
        Electricity is magnetismBrett2021/12/17 01:44 PM
      Electricity is magnetismAdrian2021/12/17 05:24 AM
        Electricity is magnetism2021/12/17 02:49 PM
          Electricity is magnetismAdrian2021/12/18 03:54 AM
            Electricity is magnetismAdrian2021/12/18 04:17 AM
              Electricity is magnetismanon12021/12/19 03:51 AM
                Electricity is magnetismAdrian2021/12/19 05:13 AM
                Electricity is magnetismDavid Hess2021/12/19 06:54 PM
  Electricity is magnetismzArchJon2021/12/15 11:53 AM
  This video is just really totally wrong..., sorry.Hans de Vries2021/12/15 06:26 PM
    This video is just really totally wrong..., sorry.anon2021/12/16 05:03 AM
  Electricity is magnetismBrett2021/12/19 06:02 PM
    Electricity is magnetismDavid Hess2021/12/19 07:11 PM
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