Talk:Electromagnetic field

This article gives an overview...

Some time ago I added this sentence to the intro:

• This article gives an overview of the classical electromagnetic field and introduces many related articles with more details.

It was removed by @Fgnievinski with the edit summary

• see MOS:SELFREF;

At first I thought this was a correct MOS thing, but then I read the referenced page more carefully. See MOS:SELFREF. That page says explicitly:

• This means that while articles may refer to themselves, they should not refer to "Wikipedia" or to the Wikipedia project as a whole (e.g. "this website").

And the side give an example with a green check for "This article discusses..."

Based on my reading I want to return this paragraph to the intro.

1. Is it correct, the article is an overview,
2. It sets expectations for readers that they may need to dig into linked article to get details,
3. It encourages readers to scan knowing they won't be burrow down so much as flying over,
4. It encourages editors to keep to a summary style here and move to linked articles for significant addtions.

Johnjbarton (talk) 22:10, 24 March 2024 (UTC)

Normally, a hatnote is the proper way for warning the reader this page might not be what they are looking for. If this were an introductory article, it could be tagged with Template:Introductory article; but then, what would be the corresponding non-introductory article about EMF? The problem with the disclaimer at hand it's a vacuous truth for readers: of course other articles will give more details about other topics. If there are notable omissions, it's better to leave a hidden comment in the article source or start a to-do list in the talk page. If the goal is to alert editors to adhere to summary style, the best way is to use an editnotice, which is displayed when editing a page (try editing Sport, for example). Based on the motivation described in your edit summary, I've now taken the liberty of requesting the editnotice: Template talk:Editnotices/Page/Electromagnetic field. fgnievinski (talk) 03:35, 25 March 2024 (UTC)

Summary style is exactly what I meant; thanks for the editnotice. Johnjbarton (talk) 14:53, 25 March 2024 (UTC)

Hello. I understand your intention. I agree that I did not see a MOS violation. I think it is more in the spirit of the no disclaimers guidelines. The reader simply does not need to be warned that the article is an overview. That is practically the default for an encyclopedia. But to speak to your points:

• 1. No, it is the usual mishmash of shallow and deep discussion.
• 2. That should be the default expectation.
• 3. The typical reader won't have a clue about the distinction between an overview and something else.
• 4. Please don't be offended, but LOL! WP editors won't give that encouragement even a second thought.

Constant314 (talk) 04:06, 25 March 2024 (UTC)

What is the field?

An introductory line should explain something about photons and virtual photons. The article just goes straight to "how" and not "what". — Preceding unsigned comment added by 14.201.231.48 (talk) 06:49, 19 October 2025 (UTC)

It is not a field of photons, but rather photons are the quanta of the field. It is not a field of any medium so answering the 'what' question is difficult. Jähmefyysikko (talk) 07:10, 19 October 2025 (UTC)

I have added the mathematical definition of the EM field. Constant314 (talk) 20:39, 19 October 2025 (UTC)

@Johnjbarton: I see that number field redirects to algebraic number field, which is not what I intended. Vector field is correct. You are correct as to what Feynman said that chapter of the reference, but in chap 15-4 he says, "A “real” field is then a set of numbers we specify in such a way that what happens at a point depends only on the numbers at that point." Constant314 (talk) 02:17, 20 October 2025 (UTC)

Here is my understanding. Yes, a field, as in a algebraic number field, is a number at every point. A vector field is a vector at every point; in general a tensor field is a tensor at every point. The "electromagnetic field" as a physical concept has several mathematical representations. The most commonly taught one, at least as far as I know, uses a pair of vector fields, E and B, but the electrostatic potential and vector potential are equivalent.

I interpret Feynman's "set of numbers" to be these vectors. Most of 15-4 is Feynman "not discussing" philosophy. Johnjbarton (talk) 02:38, 20 October 2025 (UTC)

When a field travels across to different media

We say

• When a field travels across to different media, the behavior of the field changes according to the properties of the media.

but the field does not travel, it is a mathematical value. I would say:

• The properties of a field and its response to disturbances changes in different media.

However the sentence has a source which I do not have access to. Johnjbarton (talk) 22:55, 19 October 2025 (UTC)

The citation isn't specific, it refers to "Examples and practice problems" instead of a page number. Most likely, it does not contain such description. Jähmefyysikko (talk) 23:10, 19 October 2025 (UTC)

The field is singular and ubiquitous

The electromagnetic field is singular and it fills the universe. The article the should be used with it and never a or an. Charges and currents don't have a field, rather they influence the values of the field in their vicinity. I realize that people do casually say that a charge has a field, but that is just short cut speech for influences the values of the field near their position. I am not going to start a religious war about this, but I will fix it in the lead paragraph. Constant314 (talk) 22:55, 13 May 2026 (UTC)