Talk:Special relativity

"Origins and significance" -> History and intro

The section "Origins and significance" is a hodge-podge. It's not clear to me why these topics are grouped. I think it would be easier and clearer if we had History as in many other articles.

I can see that since the article goes on and on and on that some form of overview would be nice, even if that would invite the essentially impossible task of summarizing special relativity in a few paragraphs. But I think a starting point should be an intro that summarizes the article.

A related idea is to have a "Background" section to lower the entry point for the article. This section would summarize "relative", Galilean relativity, invariance, simultaneity, speed of light, coordinates, change of coordinates.

Feedback? Johnjbarton (talk) 21:50, 21 April 2025 (UTC)

Yes, kind of thing that will improve article readability but is also very complex, heavy and commiting-task.

With your idea, I have came upon some interesting theories.

I propose the following changes:

1. Introducing a history section might be best choice, and it should focus only on the history instead of jumping between stuffs.
2. Adding a "Background" section (as you said) can help to lower the entry barrier for readers unfamiliar with the foundational concepts. This section could briefly introduce Galilean relativity, simultaneity, invariance, coordinate systems, and the constancy of the speed of light—concepts that are crucial for understanding special relativity.
3. Revising the lead/intro section to act as a concise conceptual summary rather than a technical overview. Its role should be to frame the topic—what special relativity is, why it matters, and what key ideas it introduces—rather than attempt to explain it.

Additionally, I think that adding some interlink on formula or specific topics that beginners may fail to fully grasp will help them to explore it more neatly and understand it in-depth.

Altogether, I stand with your plan. But as I said it is both commiting-task and complex, so an experienced hand is also needed. IHitmanI (talk) 00:54, 22 April 2025 (UTC)

Regarding #3, the Manual of Style expects the intro to be an introduction to an article and a summary of its most important contents. Thus to the extent that the article has technical content it should be summarized in the intro. This can be short and should not cause too much of an issue. As a general guideline however, the intro should not have any claims beyond the article content. Johnjbarton (talk) 01:05, 22 April 2025 (UTC)

You are right, i think since this is a Science topic and already have way too much technical words beforehand, summarising it just for its essential content might be a big change, in terms of readability. IHitmanI (talk) 01:08, 22 April 2025 (UTC)

And yes An Intro should be intro just like any other field except wiki. IHitmanI (talk) 01:09, 22 April 2025 (UTC)

I am working on this. Thanks for pointing out. IHitmanI (talk) 08:25, 23 April 2025 (UTC)

OK I made a number of changes, mostly I think successful. The History is pretty ok and I like the Background section as a way of reoriented readers to the particular terminology of special relativity. The Overview is honestly just a long Lead section and it duplicates the content further down to some extent. One the other hand is covers the basic material without the derivation approach that makes it hard to see the picture. Maybe it makes more sense to remove the two-postulate bits from the Lead and Overview, merge some of the Overview content into the Lead as article summary, and use the overview to expand the points raised in sources like Hughes/Kersting on differences between visual observations and event measurements. Johnjbarton (talk) 00:06, 30 April 2025 (UTC)

Definition of “inertial frames of reference”

The definition given here is wrong, even though the one given in the article linked to is correct. 2600:6C4E:3000:3232:1DE5:44DA:E218:656E (talk) 04:39, 3 June 2025 (UTC)

I can't make out which part of the article you are concerned with, but I found one problem and made a change. Johnjbarton (talk) 15:26, 3 June 2025 (UTC)

@Johnjbarton Surely he is talking about this in the Chapter Background:

"inertial reference frame: a region of spacetime within which all objects move with the same acceleration,[4]: 44" 

This is incorrect. The word acceleration should be replaced with velocity 2A02:1210:44D0:5700:75C3:D3AB:EFF7:185A (talk) 14:14, 15 June 2025 (UTC)

Ok thanks, I made an update. "same velocity" is not a requirement. The key is for all the objects to be subject to the same gravitational acceleration. This limitation is what separates "special" relativity. In general gravitational fields vary so only the uniform parts obey special relativity. Johnjbarton (talk) 17:15, 15 June 2025 (UTC)

"Technical discussion of spacetime"

The long section "Technical discussion of spacetime" is out of place here. The article topic is not "spacetime". I found only four sentences with sources. The content is out of sync ("This will be used below in the section on electromagnetism." but its at the bottom of the article). It is written in the "we define" style. We already have Basic introduction to the mathematics of curved spacetime, Complex spacetime, Metric space, Minkowski space, among others. Johnjbarton (talk) 17:03, 13 September 2025 (UTC)

Background / terminology section

In a discussion at WT:MTAU, User:Stepwise Continuous Dysfunction pointed out that the background section of this article was difficult to understand. I've rewritten it, renamed it as 'Terminology'. Two questions:

1. Is there anything else that's overly complicated or that should be explained?
2. Are there remaining parts of that section that need simplifying?

—Femke 🐦 (talk) 09:42, 9 November 2025 (UTC)

@Femke Did you verify your changes against the cited sources? Johnjbarton (talk) 16:19, 9 November 2025 (UTC)

Yes, I did (hence the source change for one explanation) —Femke 🐦 (talk) 16:22, 9 November 2025 (UTC)

Overall the changes look good. However

• What does "a frame of reference with no acceleration" mean? Since a frame of reference is a coordinate system how can it have the attribute "acceleration"?
• We need to include clocks. Most of the difficulty in special relativity arise because people assume time is universal and the fix adopted in sources on special relativity is to focus on clocks.

Johnjbarton (talk) 16:29, 9 November 2025 (UTC)

I found the preexisting text quite clumsy on clocks:

• clocks: relativity is all about time; in relativity observers read clocks.

Is there something more pertinent we can say about them?

I struggled with paraphrasing the source for the frame of reference. Would the following work? "is a viewpoint where objects move in straight lines at constant speed unless a force acts on them". (this would require a source change). —Femke 🐦 (talk) 18:11, 9 November 2025 (UTC)

I agree about the clocks content and I will try to find something better.

A "frame of reference" is just a coordinate system and an "inertial frame of reference" is an idealized or hypothetical coordinate system outside of any gravitational field or mass. More practically or physically, it is a coordinate system in a region of space very far from any mass. The confounding aspect is that low friction 1,2-D surfaces perpendicular to strong gravitational fields (pool tables, famous trains) are adequate approximations. But a frame is not a "viewpoint" and I don't think it should be described in terms of observations (move in a straight line). A frame is a constraint or assumption or axiom of a theory which leads to predictions about objects moving in straight lines. Johnjbarton (talk) 18:30, 9 November 2025 (UTC)

Well Taylor and Wheeler shows I'm wrong. The describe inertial frames empirically, as frames within a region of space where objects float freely. Johnjbarton (talk) 19:33, 9 November 2025 (UTC)

I just want to add here that I think this article is a poster child for the problem Make technical articles understandable. I think a great article on special relativity is extremely difficult despite the technical simplicity of the concept. Mermin or Taylor and Wheeler only cover basics but these works are hundreds of pages. Everyone who contributes probably has a different idea of what is clear and simple. Johnjbarton (talk) 19:38, 9 November 2025 (UTC)

Thanks. In terms of the bit about clocks. Is the last bit of that sentence grammatically correct? I'm not sure I understand it. 'and moving clocks for other objects give different measurements' --> specifically the word 'for' is ambiguous here. Maybe the last sentence should be "Clocks in motion relative to an observer record different time intervals.", but I can't verify with the source. —Femke 🐦 (talk) 07:56, 12 November 2025 (UTC)

The tricky bit here is that physicist view time as a local parameter of a frame of reference. So I used clocks attached "objects" to avoid this abstract notion. Taylor and Wheeler use "wristwatch time" for a similar reason, creating a clock physically attached to a person. So "for" was intended to mean "the clock conceptually attached to that object". But I agree its not great.

I think we should avoid "observers" because many misconceptions about special relativity relate to claims of "apparent" affects. I used least damaging version: "Moving clocks run slower". Johnjbarton (talk) 17:23, 12 November 2025 (UTC)

References

Overview paragaph

I added a paragraph to the overview section above "Basis". It attempts to describe special relativity compactly without technical words. It deliberately omits all caveats, superlatives, history, and applications. While I think brevity is important here, if something is especially unclear please let me know. Johnjbarton (talk) 18:23, 11 November 2025 (UTC)

Can we define "primed"?

I think most (reasonably well educated) laymen would enjoy a definition of what is meant by "primed", since looking it up in a dictionary will not help ~2025-33561-45 (talk) 16:41, 14 November 2025 (UTC)

 Done Johnjbarton (talk) 16:58, 14 November 2025 (UTC)