Talk:Electromagnetism

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Animation of lightning at top of page[edit]

Is having a distracting animation of lightning at the top of this page appropriate for electromagnetism? that animation would be better on the lighting article and certainly not at the top of any page. — Preceding unsigned comment added by 124.176.51.109 (talk) 07:06, 13 December 2012 (UTC)

Agreed. I've cut the two images entirely; I don't think the reader really benefits in their understanding of electromagnetism by being shown what a magnet and some lightning look like. --McGeddon (talk) 17:58, 20 February 2013 (UTC)

---

This article, being a gateway, should have some illustrations. I agree that the lightning bolt animation is very distracting, and a image of a bar magnet doing notiong is of no value whatever. I kind of liked the idea of a static lightning bolt, but I'm not sure what its point is relative to electromagnetism. Given that, are there illustrations that would be useful, e.g. a photo of "lines of force" around both a bar magnet and an electromagnet made with iron filings (the point being that electric current makes "magnetism", and this is the same "stuff" as a bar-magnet's "magnetism"), and an equivalent electrostatics photo-image? (Good luck creating that one!) An electromagnet hanging by thin wires in a gravitational field (like a pendulum) and being pulled sideways by another electromagnet? (Easy to do). Ditto for a tinfoil-covered styrofoam ball being repelled by a charged plate? (Not so easy; this one I found as a problem in a physics text in a chapter on the electric field -- to calculate the angle from vertical; cf Sears and Zemanski 1964:564 problem 25-11, also p. 538 problem 24-4). As a kid I learned about "magnetism" from iron-filing making lines of force, and the experience that two magnets either repel or attract. Electrostatics I learned from charged balloons repelling or attracting, and scuffing my feet to make sparks (and to light up a neon light). That they are equivalent "stuff" in different forms is not a trivial factoid -- what you'd need to illustrate the idea is a triboelectrically-charged leaf-electroscope hooked to a Leyden jar that, when discharged through a coil of wire, moves a compass-needle. Thoughts? BillWvbailey (talk) 15:39, 21 February 2013 (UTC)

0 / 10[edit]

Intro fails to clearly describe what the relationship between electricity and magnetism is.

Article fails to clearly describe how much magnetic force is generated from a known quantity of electricity. — Preceding unsigned comment added by 49.181.91.233 (talk) 11:39, 27 September 2013 (UTC)

Inventors[edit]

I was wondering since people like Tesla and troy reed made electro-magnetic vehicles, and I did recently to add a small section on its historical accuracy. TBh, there are a few dozen inventers. Electro-magnetic car inventors are actually in yildiz, troy reed, wasif kahloon, tesla are a few of them. They work with plasma or a highly advanced form of hho (a battery system) with electromagnetic induction motors even. — Preceding unsigned comment added by 69.255.25.193 (talk) 20:55, 6 July 2014 (UTC)

Unraveling a design problem[edit]

One of the design's problems has been antennas in the circuits. However, a team of researchers in university of Cambridge have invented a new way and is to integrate the antenna on the chip. last frontier of semiconductor design would be a massive leap forward for wireless communications.

Read more here:

http://phys.org/news/2015-04-electromagnetism-enable-antennas-chip.html?utm_source=nwletter&utm_medium=email&utm_content=splt-item&utm_campaign=daily-nwletter


MansourJE (talk) 12:40, 10 April 2015 (UTC)

about zero[edit]

Is zero negative or positive? Sandeepsiddu01 (talk) 06:06, 12 April 2016 (UTC)

Your question is not relevant to electromagnetism. Try asking at Talk:Zero. — Cheers, Steelpillow (Talk) 07:00, 12 April 2016 (UTC)
Better still, since this question is not about improving an article, you could try Wikipedia:Reference_desk/Mathematics. RockMagnetist(talk) 15:57, 12 April 2016 (UTC)

Chaotic and emergent phenomena[edit]

This section seems to be fringe or speculative science. Should it be part of the article?

Thanks @Constant314 :-) if you had to single out specific points about the section, what aspects in particular do you find to be too speculative or fringe? Previous edits claimed that QED could explain all aspects of electromagnetic phenomena, which I would be concerned about. How do we show readers that there are many electromagnetic phenomena which cannot be explained by (even by the quantum) linear electromagnetic equations i.e. Aharonov–Bohm effect, Beltrami plasma vortices, phase changes associated with superconductivity etc.Sparkyscience (talk) 21:30, 4 November 2016 (UTC)
I don’t know, so I am flagging the section for others to examine. But my concerns are two. In any article there is always the tension between not enough information and too much. An article about electromagnetism, reasonably could go into the QED under-pinning. A “something is wrong with QED” section is two steps removed from the subject of the article. It rightly goes into an article on QED. That’s my opinion. Secondly, a “QED doesn’t work” statement is extraordinary. I would want to see solid secondary references such as main line university physics text books. Let’s examine the statement that Aharonov–Bohm effect cannot be explained by QED. Scientific theories never explain anything; they make predictions. From my admittedly dated readings about the Aharonov–Bohm effect was that it was predicted by QED and that is what led to the experiment. Are you suggesting that AB is not predictable from QED? Constant314 (talk) 22:06, 4 November 2016 (UTC)
Hi Constant314, thanks for going through your valid points and sorry its been a while to get back to you. I completely understand the concerns raised. I suppose the real point that I'm trying to get across is not that "QED is wrong" or a point which is two steps removed from electromagnetism. I agree such things would be too far down the rabbit hole for this article; if this is how the current revision appears to the reader then current version must be changed. What i'm trying to do (...rather badly?) is emphasise an aspect about electromagnetism that is orthogonal to both classical and quantum electrodynamics, the aspect of nonlinearity.
The thing that is of note about the AB effect is not that it it is a quantum phenomena... but that it is non-local. i.e. the effects occur when there is a nontrivial field potential leading to forces which are not local in nature and therefore we sometimes require non-Abelian commutation relations, where potentials can be used to create local-to-global effects, to make accurate predictions. Beltrami plasma vortices can be understood on purely on classical terms (i.e not a two steps removed quantum phenomena), but again cannot be understood through your typical linear equations, same thing with superconductivity phase transitions and the Tesla circuit example... There's more to electromagnetism then Maxwell's equations (or quantized versions) would have you believe, and these effects should be highlighted, because they make electromagnetism interesting!
As an aside, I did not make a "QED is wrong" statement, but i can see why you might have interpreted the above remark as such, QED works great if you can apply perturbation theory, i.e. nonlinearity converges to a simplified linear problem, but this isn't always the case. In my edit on the page, I corrected the article from "All electromagnetic phenomena can be explained in terms of quantum mechanics, specifically by quantum electrodynamics" to "[QED gives] extremely accurate predictions of quantities like the Lamb shift and measurement of the magnetic moment of the electron...[and] is one of the most accurate theories known to physics in situations where perturbation theory can be applied.
I would recommend skimming over Barret & Grimes (1995)[1] to get a clearer picture of what I'm trying to get across with respect to nonlinearity. The forward by Roger Penrose seems prescient to our current conversation:
"There can be little doubt that Maxwell's equations constitute one of the great landmarks in physical theory. Their basic accuracy has been confirmed innumerable times, in many different types of experiment. Their invariance properties led Einstein to his special theory of relativity. Moreover, their gauge-theoretic interpretations led to non-Abelian generalizations, fundamental to modern particle physics. Their elegant mathematical form has provided several important influences on the development of mathematics itself.
These facts should not, however, deter theoretical or experimental physicists from seeking alternative descriptions, unconventional formulations, surprising electromagnetic effects, or radical generalizations. The various articles in this book provide the reader with a great variety of different kinds of approach to developments of this nature. We have historically motivated accounts, suggestions for new experiments, unconventional viewpoints and attempts at generalizations. We also see novel and ingenious formulations of electromagnetic theory of various different kinds.
I am sure that this book will make it clear that electromagnetism is a subject that is in no way closed to simulating new developments. It is very much alive as a source of fruitful new ideas."
Perhaps some rewording to this effect would be useful in highlighting to the reader that what we know about electromagnetism has had a huge impact but that it is not a closed subject? I'm not sure I've done that by any means. As for what i've already written, I certainly don't mind re-edits if not complete revision. The electromagnetism article does need a lot of work. I would be wary of wholesale deletion of the section. So long as we make it clear in the article what is well established within electromagnetism (which of course should be the majority of the article) and what is not well established i feel this subject matter which you have termed "fringe" or "speculative" (...I can't see any overtly dodgy references?) is in fact the "cutting edge" and does have a place on the article. Science, after all, is not a set of facts in textbooks but a method and process of discovery. Sparkyscience (talk) 11:42, 7 November 2016 (UTC)
I'm not suggesting that theoretical or experimental physicists should be deterred from seeking alternative descriptions, unconventional formulations but that rather that alternative descriptions don't belong in this article until they become main stream.
But lets look at Aharonov–Bohm effect. What about this is not local?Constant314 (talk) 18:12, 7 November 2016 (UTC)
Aharonov et al. (2016) "We have shown that the Aharonov-Bohm effect has two distinct aspects, one continuous and one instantaneous. The latter is manifestly nonlocal; it underlines the necessity of describing quantum systems via gauge-dependent quantities rather than local forces, which cannot account for abrupt changes in modular velocity."[2]
You seem to be offering very little in the way of references to back up your (currently subjective) opinion that this is fringe, speculative or not mainstream. If it is a peer reviewed journal, or it is a published article by a univeristy professor in a textbook, I think most would agree that you can not just dismiss the scientific points raised in the edit with the hand-waving you have thus far done; it needs to debated with countering peer reviewed argument of equal merit. To my mind gauge theories, non-abelian groups, nonlinearity are very well developed scientific concepts and have a place in electromagnetic theory and have many interesting and surprising results that a reader may be interested in... If you have any references to back up your opinion that they have no place in electromagnetic theory... that's great... but so far you've said you "don't know" what parts in particular you want to flag...I fear you are merely operating on a hunch...or because you are not familiar with this aspect of the subject matter that must mean it is somehow wrong...
I apologize if I sound like I'm cross examining you. I'm just asking you what the references say since I don't have access to them.Constant314 (talk) 17:10, 8 November 2016 (UTC)

References

  1. ^ Barrett, Terence William; Grimes, Dale M. (1995). Advanced Electromagnetism: Foundations, Theory and Applications. World Scientific. ISBN 9789810220952. 
  2. ^ Aharonov, Yakir; Cohen, Eliahu; Rohrlich, Daniel (2016). "Nonlocality of the Aharonov-Bohm" (PDF). Phys. Rev. A. 93 (4): 042110. arXiv:1502.05716Freely accessible. doi:10.1103/PhysRevA.93.042110.