Black hole is a former featured article. Please see the links under Article milestones below for its original nomination page (for older articles, check the nomination archive) and why it was removed.
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	This article appeared on Wikipedia's Main Page as Today's featured article on September 23, 2004.
Article milestones Date Process Result July 27, 2004 Featured article candidate Promoted November 19, 2006 Featured article review Demoted January 7, 2007 Good article nominee Not listed August 31, 2010 Good article nominee Listed This article was on the Article Collaboration and Improvement Drive for the week of March 7, 2007. Current status: Former featured article, current good article

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• https://news.osu.edu/black-hole-is-closest-to-earth-among-the-smallest-ever-discovered/

Write both observed AND theorized (if you hide theory vs data science doesn't evolve).

Replace the dashes for commas. Introduce John Michell and Pierre Simon in the beginning of the second paragraph. Meaning put the subjects who discovered it first.

I'm planning on taking this article to WP:PEERREVIEW to get some comments on it before proposing it for promotion to WP:FA. Anyone have any last comments/concerns/suggestions before I take it there?

Tagging some people who have been working on the article: @Johnjbarton, @Parejkoj, @L3erdnik, @EatingCarBatteries, @Hexad Shocksingularity (talk) 05:16, 23 December 2025 (UTC)[reply]

It might be helpful if you summarize which sections you've mostly worked on recently so that we can maybe focus on those. L3erdnik (talk) 16:38, 23 December 2025 (UTC)[reply]

I have been working top-down, so the "in science fiction" and "open questions" sections are those I've been working on most recently. Thank you, btw! Shocksingularity (talk) 19:30, 23 December 2025 (UTC)[reply]

I'll commit to one of the three reviews, which every one you think would help the most. Johnjbarton (talk) 18:23, 23 December 2025 (UTC)[reply]

The peer review (currently ongoing) would probably help the most, but anything would be appreciated! Thank you for taking your spare time to help with the article. (The peer review will probably be happening for a few weeks, as I'm busy in real life, so no need to rush) Shocksingularity (talk) 02:42, 24 December 2025 (UTC)[reply]

Based on the source

• Lü, H., & Lyu, H. D. (2020). Schwarzschild black holes have the largest size. Physical Review D, 101(4), 044059.

the various meanings of "size" or "radius" could be mentioned. I think that ambiguous word should be avoided here and made some changes accordingly. Johnjbarton (talk) 00:46, 24 December 2025 (UTC)[reply]

The source itself specifically measures the radius, and uses that as a measure of size: "If the radius of the horizon measures the actual size of a black hole, photon spheres and shadowy disks give the apparent sizes. The Schwarzschild black hole saturates all the 24 inequalities; therefore, for given mass, by both contents and appearances, it is the biggest of all." It also measures the radii of the event horizon and photon sphere rather than the area bounded by them, finding and .

Is there anything ambiguous in the text itself, or just the source title? I can also look for a different source (or just remove it altogether since everything it's used for already has another reference), add an inline comment, or add a quote to the citation. Shocksingularity (talk) 02:40, 24 December 2025 (UTC)[reply]

The source is fine. Note "If the radius...": lots of sources will tell you funky things about the event horizon not being a "thing". So my interpretation here is "If one accepts the radius of the horizon as a size, ..." But ignore that, here is my point: the many new papers on BH imaging use the other radii and the article should discuss them as well using that source or another one IDK. We'll never measure the horizon size, it's just a parameter in a model, not a thing. Johnjbarton (talk) 03:44, 24 December 2025 (UTC)[reply]

What other radii in particular? The Schwarzschild radius? The shadow radius? Shocksingularity (talk) 06:05, 24 December 2025 (UTC)[reply]

In particular, radii that are or might be derived from observations like EHT. This well cited review

• Perlick, V., & Tsupko, O. Y. (2022). Calculating black hole shadows: Review of analytical studies. Physics Reports, 947, 1-39.

implies that the shadow radius is key. It also has a detailed definition of the shadow and a list of alternative terms. Our article uses the word "shadow" but fails to define it or discuss it directly, another thing to fix. Johnjbarton (talk) 18:43, 28 December 2025 (UTC)[reply]

I also think we should move the section on Radius. How about:

1. Move "Event Horizon" to the first subsection under "External geometry"
2. Move "Radius" below "Event Horizon" but include the last lonely sentence, move it into the Radius.
3. Add some content foreshadowing the ergosphere/photosphere sections.

Johnjbarton (talk) 19:35, 7 January 2026 (UTC)[reply]

I've listed this article for peer review because I am trying to get it to featured article status. I'd particularly appreciate critiques on:

• Anything that is scientifically inaccurate
• Any section or topic that could be shortened or is given undue weight
• Anything that is too technical

Thanks, Shocksingularity (talk) 00:14, 24 December 2025 (UTC)[reply]

• Update: see my review below. I mentioned in the Talk page: size is a unique topic which could use more coverage.
• The section "Properties and structure" has two introductions: three paragraphs below that title and "Physical parameters". Mass is discussed three different places in that section. I would reorg. The first paragraph is Definitions. The next two are "No hair theorem". Mass being the most basic property should be first; I would rename "Physical parameters" to "Mass" and "Mass" to "Mass ranges" underneath Since the no-hair section used angular momentum, so should the section title.
• Some sentences here have too many sources. More than two sources always makes me wonder what is going on. One reliable source and one popular source is enough. For example "It is unlikely that black holes with masses greater than 50-100 billion times that of the Sun could exist now, as black hole growth is limited by the age of the universe." had four sources. None of these sources verify the claim. I deleted two and changed the content to match the sources.

Johnjbarton (talk) 03:22, 24 December 2025 (UTC) [reply]

(Don't know how these reviews are supposed to work. I'm just going to keep posting here I guess) Johnjbarton (talk) 03:26, 24 December 2025 (UTC)[reply]

Thank you for the feedback. I will get on that. Shocksingularity (talk) 06:03, 24 December 2025 (UTC)[reply]

Review I've read the article and verified many claims, fixing a few that were a bit off. From the technical point of view the article is solid to a general physics reader. I've posted a number of Topics on the Talk page suggesting improvements or additions. If we can address (or decide not to address) these I would a recommend Featured Article. Johnjbarton (talk) 03:24, 12 January 2026 (UTC)[reply]

@Shocksingularity: It has been almost a month since the last comment on this PR. Are you still looking for feedback? Z1720 (talk) 03:56, 11 February 2026 (UTC)[reply]

@Shocksingularity - If you still want more input I'm happy to do a peer review... I'm a big fan of black holes. I have not looked at the article in depth, but I note that it is over 13,000 prose words which rather large. The WP:SIZERULE guideline suggests 9,000 .. for important topics like black holes, maybe 10,000 or 11,000 is understandable. But 13,000 suggests the article is not making appropriate use of sub articles per WP:SUMMARYSTYLE. I've had to trim a couple of my FA nominations, like James Cook, down to 10,000 words and I know how painful it can be, But it's the right thing to do for the reader's sake. Noleander (talk) 05:05, 11 February 2026 (UTC)[reply]

@Noleander: That would be awesome, thank you! I'm really not sure what else to cut.

@Z1720: yes, I am still looking for feedback. User:Johnjbarton has been the one primarily peer reviewing the article and has been putting suggestions on the article talk page, not here. Shocksingularity (talk) 06:22, 11 February 2026 (UTC)[reply]

I added a lot of suggestions on the Talk page and I think all have been addressed. Johnjbarton (talk) 14:26, 11 February 2026 (UTC)[reply]

• Overall impression: prose is engaging and professional; images are outstanding. Lots of reliable sources.

• Alt text: see WP:ALT - Some of the images do not have proper "alternative" text for blind users . E.g. For image File:Black Hole Desktop & Phone Wallpapers (SVS14146 - BH accretion disk viz desktop).png the alt text says "See caption". That does not meet WP:ALT requirements. Blind users of Wikipedia use "screen reader" apps that read the alt text and speak it outloud to the user (or display it in large font). The alt text needs to paint a visual picutre of what is in the image. Example alt text for the above image: "A glowing orange-red disk, swirling around a black sphere; on a solid black background". For most images, the alt text should be quite different from the caption.

• Alt text: another example that needs work: Spacetime curvature schematic - needs to describe the visual contents of the image (mention mesh, etc)

• Source title capitialization: WP:CITESTYLE requires all source titles to use a uniform capitalization style. Usually, that means all titles should use either

Title case: "Observation of Gravitational Waves from a Binary Black Hole Merger"

or

Sentence case: "The tidal disruption of a star by a massive black hole".

Suggest you pick one style and apply it to all source titles. WP:CITESTYLE says to ignore how the sources capitalize their own title.

• The biggest issue, as I mentioned above, is the size: WP:SIZERULE suggests 9,000 prose words is a good maximum size. Some articles are approved for FA at 11,000 words, but that is the exception. The problems with 11,000 or higher is (a) it runs afoul of the WP:SUMMARYSTYLE guideline which asks editors to create a "tree" structure of articles; (b) it is unpleasant for readers to read a huge, intimidating article; and (c) it is unfair to FA reviewers to ask them to approve a huge article that is otherwise good quality: you are putting them on the spot. The reviewers will say "The article is too big". Nominator replies "All the info is important, what should I remove?". Reviewers reply: "I dunno, you read the sources, not me". It's better to avoid all that and trim it down to 11,000 or so before nominating.

• To trim the article down, there are a few techniques:

1. Footnotes: Identify sentences that contain rather obscure facts, and wrap them in an template:efn footnote. The sentences stays in the article, but does count towards the "prose count" 11,000 (approx) goal
2. Sub-articles. The Black hole article already has a dozen or more sub-articles: Accretion disk, Photon sphere, Ergosphere, Event horizon. Use them. Push any minor facts down into those sub-articles (if the fact is already in the sub-article, just remove from the BH article).
3. New sub-articles. If you look at great FA articles on major topics, like Solar System, they usually have a sub-article for each major top-level section. Yet the Black hole article does not. Consider new sub-articles for:

• History of black.holes
• Structure of black holes
• Evolution of black holes
• ... etc...

Implementing approach (3) is a simple procedure: (a) Create new new sub-article, empty, e.g. Structure of black holes (b) copy the entire section from Black hole#Structure into that new sub-article; (c) go thru the section Black hole#Structure and delete all minor/obscure material.

I have created a new article, History of black hole physics, and copy-pasted the section in per your suggestion. (I called it history of black hole physics rather than history of black holes to clarify that it is specifically about the history of research on black holes, not the history of the black holes themselves). Shocksingularity (talk) 05:35, 19 February 2026 (UTC)[reply]

• "See also" - There is no need to list articles in the "See Also" section if they are already listed in one of the NavBoxes at the bottom, e.g. Sonic black hole is in the See Also list, but also in the bottom Navbox Template:Black holes

• Ideally, the article would have no "See also" section because all important articles are either (a) linked in the body text; or (b) in a bottom NavBox. But if the article must have See Also, WP:SEEALSO says the links should be followed by a brief hint about the article's content.

• Cite bundling ... and squeezed by an infinite amount.[235][239][238] or .... electric mixer would have on dough.[254][197][255] Having multiple superscript footnotes like that is generally considered ugly, especially when there are 3 or more. WP guidelines do not prohibit it, and many FA articles have 2 superscripts adjacent. Three or more is rarer in FA. But, IMHO, articles nominated for FA should be exemplary, and the best FA articles use cite bundling techniques to package multiple cites into a single superscript [52]. See WP:CITEBUNDLE. I use the Template:multiref approach to bundling: you can see how that template is used in my recent Bridge FA article. But there are also other ways to bundle cites.

• Page numbers for cites: format consistency? What is the approach used for page numbers in the cites? I see some use template:rp as in {{rp|p=266}} which produces a superscript like .[139]: 266 But other cites use the "page" attribute within template:cite book as in: |page=110 The FA criteria require consistent style & format for all cites, so articles use one approach or the other. I don't recall seeing an FA article that had a mixture of the two styles.

• Italics for technical terms: Physicists termed these oscillations "Mixmaster dynamics" or ... during a supernova explosion in a process called "fallback". suggest use italics in situations like that, per MOS:TECHNICAL and MOS:WORDSASWORDS e.g. Physicists termed these oscillations Mixmaster dynamics. That is not a hard rule, but double quotes are more appropriate when quoting a phrase from a particular source.

• •  Done Ran through a CTRL+F to check.

• I ran the article through the Earwig Copyright tool, and it showed one yellow warning: https://plato.stanford.edu/entries/spacetime-singularities/ I looked at the details, and it appears to be a false positive, so nothing to worry about.

• Generalize section: Black holes#In science fiction - suggest generalize that section title to be "In culture", which would encompass literature, movies, art, memes, etc. I can think of several usages of "black hole" in art/culture that are not within science fiction (e.g. in politics or workplace: "black hole" is place ideas/tasks go and are never seen again, etc) Not saying the section should discuss all cultural uses (need to get the article size down :-) but the section title should be inclusive, not exclusive.

• Large number of authors in a source: Cromartie, H. T.; Fonseca, E.; Ransom, S. M.; Demorest, P. B.; Arzoumanian, Z.; Blumer, H.; Brook, P. R.; Decesar, M. E.; Dolch, T.; Ellis, J. A.; Ferdman, R. D.; Ferrara, E. C.; Garver-Daniels, N.; Gentile, P. A.; Jones, M. L.; Lam, M. T.; Lorimer, D. R.; Lynch, R. S.; McLaughlin, M. A.; Ng, C.; Nice, D. J.; Pennucci, T. T.; Spiewak, R.; Stairs, I. H.; Stovall, K.; Swiggum, J. K.; Zhu, W. W. (2019). "Relativistic Shapiro delay measurements of an extremely massive millisecond pulsar".Nature Astronomy. 4: 72–76. I don't believe WP has a guideline encouraging or discouraging dozens of authors. Personally, when I have sources with 3 or more authors, I display only the first two names then use | display-authors = etal which makes the above look like: Cromartie, H. T.; Fonseca, E.; et al. (2019). "Relativistic Shapiro delay measurements of an extremely massive millisecond pulsar". Nature Astronomy. 4: 72–76. and gives a cleaner look. It's not like WP is a primary source academic journal that must list all 27 authors.

• ID numbers (ISSN, Bibcode, JSTOR, DOI, etc) for journal sources. The display of ID numbers across the cites is not showing a strong consistency. WP does not have a hard rule on which to display, because various sources have various ID numbers available: e.g. the ISSN may only be available for 90% of the journal sources; or the BibCode maybe available for only 40% of the sources, etc. Different FA reviewers will have different opinions; I know some will say "include as many ID #s as you can". My personal rule for journals is: (a) always include ISSN; (b) always include DOI if available; and (c) include other #s (BibCode, etc) only if DOI is not available. But that is just me. Bottom line: do what you can before nominating to maximize consistency in the info displayed in the sources, because it is a hassle to remedy it during the review.

• That's all I have for now. Ping me when you've considered the above and I'll start going through the text of the article. Noleander (talk) 14:20, 11 February 2026 (UTC)[reply]

  In my opinion footnotes are even more reader-hostile than their equivalent content. In my experience they force the reader to a side trip and very often hide incorrect or unsourced claims. I prefer to cut content or split into full articles. Johnjbarton (talk) 16:12, 11 February 2026 (UTC)[reply]

  Yes, those are good points. Footnotes certainly should not be used as mechanism to sneak-in questionable material. Personally, when I use footnotes I always provide a citation with each footnote but, some editors do not. Noleander (talk) 16:35, 11 February 2026 (UTC)[reply]

  Are you ok if we markup your list with  Done? We can discuss the options in the Talk page, resolve them, then clear the list? Johnjbarton (talk) 19:50, 11 February 2026 (UTC)[reply]

  Yes, mark it up any way you want. If you have any questions or comments u can intersperse them below the bullets. But please leave the original bullet points intact so I can refer to them. Noleander (talk) 20:16, 11 February 2026 (UTC)[reply]

  ... Regarding the Talk page, I only have this peer review page watch-listed. So I'll only be notified of comments you make here in this PR page. Of course the PR page is trancluded into the Talk page so it also appears there, but I don't have the Talk page in my watch list. Noleander (talk) 20:23, 11 February 2026 (UTC)[reply]

  Thanks for the tips. I have a couplequestions:

  • For WP:CITESTYLE, do you know of any good userscripts or bots that could make this uniform? The article has over 400 sources, and although not all of those are papers, a good chunk are and I'd rather not manually change every title to conform to the guideline.

@Shocksingularity: - No, I'm not aware of a tool to do that (but one might exist somewhere). I always change them manually. The relevant guidance in WP:CITESTYLE is "For example, the Wikipedia article cannot have a mishmash of capitalization styles because one of the cited newspapers uses title case for its headlines while another one uses sentence case;[note 5] it can, however, have a style that consistently uses title case for all book titles and sentence case for all book chapter titles.... [one should correct] the capitalization of titles to consistently use the chosen style for that article, whether that be title case, sentence case, small caps, etc. (but not all caps, per MOS:ALLCAPS). If title case is used, follow Wikipedia conventions (MOS:TITLECAPS) for which words are capitalized when using title case. Remember that the chosen capitalization style may be complex (e.g., books titles capitalized differently from article titles), but it must be internally consistent (e.g., all newspaper articles should be capitalized the same way, even if book titles get capitalized a different way). " This is a new guideline that was established in summer 2025. Noleander (talk) 22:59, 11 February 2026 (UTC)[reply]

@Shocksingularity: I found a tool that might automatically adjust source title capitalization: User:ZKang123/TitleCaseConverter but I've never used it. Noleander (talk) 18:19, 12 February 2026 (UTC)[reply]

Hello! I'm not sure how I stumbled upon this peer review, but is this really required for FACs? This is really painful to manually change every title at each references. 🍕BP!🍕 (🔔) 04:02, 14 February 2026 (UTC)[reply]

@Boneless Pizza! - Yes it's a new guideline - applies to all articles - not just featured articles. However it's generally not enforced for GA reviews. The new guideline was established in summer 2025 in an RFC...the green text above gives the details. The tool identified immediately above called ZKang123 will automatically convert all source titles to title case, So you don't have to do it one by one. Noleander (talk) 04:11, 14 February 2026 (UTC)[reply]

I apologize If I am making this thread too long @Shocksingularity. @Noleander I already installed and red User:ZKang123/TitleCaseConverter but I don't any see an option to use it sadly. 🍕BP!🍕 (🔔) 04:16, 14 February 2026 (UTC)[reply]

You have to edit the whole article, and when you're in the editor the Tools menu will have three or six New actions for this tool. You may have to Scroll down the Tools menu to find the actions. This tool does not appear on the Tools menu when you're viewing an article, you have to be in the edit page and then use the Tools menu Will contain the action choices. Noleander (talk) 04:20, 14 February 2026 (UTC)[reply]

I found it; however, when I chose one of the options, it capitalized the lowercase letters and made the uppercase letters lowercase. 🍕BP!🍕 (🔔) 05:13, 14 February 2026 (UTC)[reply]

Maybe you should submit a bug report to the tool owner. That tool has a talk page where you can provide feedback. Noleander (talk) 11:24, 14 February 2026 (UTC)[reply]

• • In terms of the page numbers, I believe that most using the rp template are for sources being reused, while most using the page attribute inside the citation templates are for sources being used once. I'd rather do the former so as not to have to recite sources, but I worry that citing page numbers inline for every book might clutter up the page.

@Shocksingularity: - If you use a consistent algorithm, most FA reviewers will be fine with it. I posed the question because it looked inconsistent at first glance. If you leave it as is, be prepared to explain the algorithm to the FA reviewers; e.g. "This article uses plain <ref> citatations (and does not use template:sfn or template:harvnb). The "page" attribute of template:cite is used for page numbers, unless a source is used two or more times, in which case template:rp is used.". The reviewers will want a clear algorithm, consistently applied. Noleander (talk) 22:59, 11 February 2026 (UTC)[reply]

• Shocksingularity (talk) 22:42, 11 February 2026 (UTC)[reply]

  My interpretation is that this article already uses one consistent citation style. The variation in page number indicators is fine, and as you note in the best interest of readers given the technology we have available. Johnjbarton (talk) 22:45, 11 February 2026 (UTC)[reply]

  @Johnjbarton: - My approach to this peer review is simply to offer suggestions on how to get the article to smoothly pass through the FA process. I'm not passing judgment. The best way to get an article thru FA is to anticipate any issues that reviewers might identify, and address them before nominating. If an FA reviewer suggests a change, the nominator will need to decide whether to comply or argue against the change. In my experience - arguing with an FA reviewer can cause the review to get delayed, or even failed. (Again, that advice is for the FA review; here in the PR I'm simply offering tips that you are free to ignore). Noleander (talk) 23:07, 11 February 2026 (UTC)[reply]

  I think most of your suggestions are great. I'm unsure if I'm willing to invest energy in the FA to be honest, simply because the overall cost is not balanced by benefit to the encyclopedia. Thus I'm keen to focus on the most important fixes. Johnjbarton (talk) 23:14, 11 February 2026 (UTC)[reply]

  I understand. I face a similar dilemma: it takes me about four months to polish a single article and get it through the FA process (2 months of preparation + 2 months FA review). But during that same time, I could (a) upgrade 4 to 6 articles to GA status; or (b) create 10 to 20 new articles on minor topics; or (c) make small, but important, improvements to scores of articles. Which is best for the encyclopedia? Noleander (talk) 23:18, 11 February 2026 (UTC)[reply]

  Getting a bit off-topic for PR, but I really wish enwiki would adopt a single mandated reference format. Even if it was one that I personally didn't like, at least it would be a fixed target that everybody could aim for, and that tool writers could cater to. RoySmith (talk) 17:16, 14 February 2026 (UTC)[reply]

  I agree. It could be worded as "Style ABC is strongly recommended (and required for new articles) for the sake of readers' experience, and for helping tool developers". I understand the need to grandfather-in older styles; but a professional encyclopedia like Britannica would never use a multitude of styles. Noleander (talk) 17:21, 14 February 2026 (UTC)[reply]

  Britannia does not even have citations. See eg https://www.britannica.com/science/reaction-mechanism/Unimolecular Johnjbarton (talk) 17:40, 14 February 2026 (UTC)[reply]

  I wan't referring to citations specifically. My point was that a professioanlly-edited book/journal/encycl is uniform in all regards: cites, punctuation, formatting. Wikipedia is very irregular. Not because the irregularity is good, but because WP was forced to accommodate various styles to keep volunteers participating. An understandable choice, because if WP had been strict about uniformity, it would not be as large or popular as it is now. Noleander (talk) 18:25, 14 February 2026 (UTC)[reply]

  I believe a core issue with citation style is technological. A uniform citation style would only work if the reader technology was uniform. Across browsers, browser window sizes, mobile, and print we have no uniformity. Johnjbarton (talk) 18:34, 14 February 2026 (UTC)[reply]

  I disagree. The two dominant styles have different strengths and work well for different kinds of topics and reading styles. Article with many claims traced to different sources benefit from the direct and complete information in the popup tooltips for cite/rp style sources. Articles which source entire paragraphs to a single source get less benefit and those articles seem to be ones that attract readers who want to take the whole thing in. (I would probably quit editing if sfn was mandated). Johnjbarton (talk) 17:40, 14 February 2026 (UTC)[reply]

  @Noleander: Thanks for your comments, they are very helpful and I've already started looking and working on them. You mentioned to ping you once we had looked over your comments so that you could read through the article. If you're still willing to do that, it would be super helpful, especially in determining what content to remove. Shocksingularity (talk) 02:14, 16 February 2026 (UTC)[reply]

  I cut ~500 words. The section on "Singularity" is supposed to be a summary and seems too long, "Cauchy horizon" also because it has lots of multiple refs. But my feeling is that we won't reach 11k without splitting out eg the History. Johnjbarton (talk) 02:31, 16 February 2026 (UTC)[reply]

  I'm kind of in the same place as Neoleander when it comes to article size. It rankles me that there's numerical gatekeeping at FAC when it comes to word count. Articles should be judged on their own, not primarily by counting words. But, yeah, this is 16k words which is so far out of the normal range I'm sure you'll get enough pushback at FAC that failure to be promoted is pretty much a foregone conclusion at that length.

  I'll confess to not having read the full article; it is after all, 16k words, and that really pushes my attention span. I do, however, notice a kind of abrupt change in tone between History and Properties. The later is more technical, and is indeed where the first equations show up. It's where (with the exception of a a couple of passing mentions) you start talking about scary topics like angular momentum and curvature of spacetime. So I'm wondering if maybe the whole History section could be spun off into its own History of research into black holes (maybe with a better title), and then just a very short summary of that with a {{main article}} link (like you did with In fiction). The History of ... article could be much more approachable to people without a scientific background, and it would take a whack at reducing the size of this article. You'll still get pushback from the word count weenies at 13k words, but I think you'll at least have a fighting chance of convincing people that this is a big enough topic to justify the size. RoySmith (talk) 03:45, 16 February 2026 (UTC)[reply]

  Regarding tools to measure article size: There are multiple tools to measure page size, see WP:WORDCOUNT. In the word counts above, I'm using Wikipedia:Prosesize tool which is the count used for WP:SIZERULE guideline. That tool showed the article at 13,300 words when I started the PR (now down to 12,300) and I suggest getting down to 11,000. I think @RoySmith: is using a different tool that gives higher counts (16,000 now) which is about 20% higher value than the Wikipedia:Prosesize tool. Roy's suggestion to get "down to 13,000" in his count is about the same as "get down to 11,000" with the Wikipedia:Prosesize tool.

  I concur with Roy: one or two new sub-articles, especially "History of...", would help reach the goal: Move all the History material into the new sub-article, then remove 1/2 or more from this article's History section. Noleander (talk) 04:26, 16 February 2026 (UTC)[reply]

  Hmmm, I already had WP:DYKCHECK installed, so that's what I've always used and never had any problems. Checking against WP:Prosesize, I do see a significant disparity on this article and it turns out (see Special:Permalink/1338654301) that DYKCheck counts equations in <math> tags while Prosesize does not. While that's interesting to know (and I didn't know it before I went down this particular rabbit hole) wordcountitis is a terrible disease and we should not be slave to the specific numbers, so I'm not too concerned about this discrepancy.

  However you count, this is a big article and I strongly suspect people at FAC will object to the size. Whether you or I agree with that assessment is immaterial; if the goal is to collect a bronze star, you need to make the reviewers happy. RoySmith (talk) 12:50, 16 February 2026 (UTC)[reply]

  Thanks for the feedback, Nolenader and Roy. I agree on the history section, I had been leaning that way too but wanted to check in with others first. I just don't want to remove any more from the more sciencey sections, especially since a good chunk of that got cut already. Shocksingularity (talk) 04:34, 19 February 2026 (UTC)[reply]

  I know it's painful. It's as if you have a child and somebody tells you you have to cut one limb off, and you ask which one? I think of it this way: it's better to do the trimming during the peer review process, because if it comes up during the featured article process that can be bad news ... It can lead to a stalled or even failed nomination Noleander (talk) 04:45, 19 February 2026 (UTC)[reply]

In my opinion the early middle part of the History section needs major work. It obscures the history by including too much about general relativity. Both Bartusiak and Throne sources point to Oppenheimer and Hartland as the first paper on black hole physics. But this paper is buried in a paragraph about Einstein. The Bernstein source used in the paragraph is fine, but it is about Einstein's role in the history of black hole physics, not about the history of black hole physics itself. The whole section has a collection of ideas and dates which only a reader aware of the physics could understand is related to black holes.

Histories are generally easier in chronological order, so the one approach is to delete the content until we get to Oppenheimer/Hartland since that is where the topic starts. As an alternative fix would start the section with a paragraph on the Oppenheimer/Hartland paper and its key ideas, then the cover the history of those ideas one by one. Johnjbarton (talk) 02:59, 26 December 2025 (UTC)[reply]

 Done I rewrote the early history so now someone else needs to review it ;-) Johnjbarton (talk) 18:21, 4 January 2026 (UTC)[reply]

I think this one is  Done. Shocksingularity (talk) 22:30, 5 February 2026 (UTC)[reply]

- — Preceding unsigned comment added by ~2026-49543-8 (talk) 19:18, 23 January 2026 (UTC)[reply]

"Laplace omitted his comment about invisible stars in later additions of his book"
perhaps meant to say
"Laplace omitted his comment about invisible stars in later editions of his book" ~2025-43243-09 (talk) 05:07, 27 December 2025 (UTC)[reply]

Done thanks! Johnjbarton (talk) 16:59, 27 December 2025 (UTC)[reply]

This article is not what it seems.

• Petrescu, R. V., Aversa, R., Apicella, A., & Petrescu, F. I. (2018). NASA has found the most distant black hole. Journal of Aircraft and Spacecraft Technology, 2(1), 31-39.

I don't know that the content is wrong The 36 citations are all from either R. Petrescu or F. Petrescu. The publisher, "Science publications" proudly announces "A leader in scientific publishing with over 10,000 articles published". I delete the source from the article. Johnjbarton (talk) 04:08, 30 December 2025 (UTC)[reply]

We need a section on black hole thermodynamics, even if it a summary of that article. Johnjbarton (talk) 02:07, 3 January 2026 (UTC)[reply]

Good idea; should it be a subsection or its own section? Shocksingularity (talk) 23:01, 4 January 2026 (UTC)[reply]

Maybe just before evaporation? Johnjbarton (talk) 01:08, 5 January 2026 (UTC)[reply]

Ok I put something down, please review  Done Johnjbarton (talk) 01:31, 1 February 2026 (UTC)[reply]

Reviewed, mostly some minor copyediting. Let me know if I changed the meaning of anything and I'll fix it.  Done Shocksingularity (talk) 06:34, 1 February 2026 (UTC)[reply]

The article has a paragraph that focuses on this sentence:

• However, in 1965, Roger Penrose proved that general relativity without quantum mechanics requires that singularities appear in all black holes.

Then it says:

• For his work, Penrose received half of the 2020 Nobel Prize in Physics, Hawking having died in 2018.

but the source given for this last sentence says:

• The Nobel Prize in Physics 2020 was divided, one half awarded to Roger Penrose "for the discovery that black hole formation is a robust prediction of the general theory of relativity",

Of course Nobels often go for a bunch of related work, but for me the "robust prediction" is much more notable for the article. Johnjbarton (talk) 00:40, 4 January 2026 (UTC)[reply]

 Done The Nobels are now together at the 2020 point in the History. Johnjbarton (talk) 19:10, 16 January 2026 (UTC)[reply]

Currently we say:

• In 1907, Einstein published a paper describing the equivalence principle, previously studied by Galileo Galilei and Isaac Newton, which states that gravitational and inertial mass are identical.

This puts emphasis on the hypothesis of common cause, but historically the sources put emphasis on the numerous physical observations. Galileo and Newton did many experiments to first disprove the prevailing theory and then solidify evidence for the equivalence. These experiments were central to the shift from philosophy to science dating to that era. Johnjbarton (talk) 17:35, 4 January 2026 (UTC)[reply]

You can change the wording back, it just seemed a little awkward/hard to read to me which is why I changed it. Shocksingularity (talk) 23:00, 4 January 2026 (UTC)[reply]

I tried again, maybe you can improve this one. Johnjbarton (talk) 01:03, 5 January 2026 (UTC)[reply]

Looks good to me now.  Done Shocksingularity (talk) 00:54, 23 January 2026 (UTC)[reply]

The section on "Gravitational collapse" starts off with a bit of dynamics then has two paragraphs of statics and finally returns to dynamics. These should not be mixed up because the sourcing and concepts are different. For example, the source

• Janka, H. T., Langanke, K., Marek, A., Martínez-Pinedo, G., & Müller, B. (2007). Theory of core-collapse supernovae. Physics Reports, 442(1-6), 38-74.

is about dynamics: it only applies to high mass stars above the Chandrasekhar mass limit.

I think the sources for the statics should be moved into Classification and new content about dynamics added. A summary of Supernova § Core collapse would be fun.

The section confuses further because speculative Direct collapse black hole have a very different story. So "Gravitational collapse" should be replaced by the two subsections, "Supernova" and "Direct collapse" Johnjbarton (talk) 20:20, 4 January 2026 (UTC)[reply]

 Done I think we solved this one. Johnjbarton (talk) 19:09, 16 January 2026 (UTC)[reply]

The ""Ergosphere" section says

• This is because frame dragging is so strong near the event horizon that the space around the black hole is moving faster than the speed of light.

citing Carroll, Sean M. (2004). Spacetime and Geometry. 6.6. The lecture notes don't have subsections and chapter 6 is not about black holes. Chapter 7 doesn't say this. I can't access the book.

I would like to delete the sentence because it distract the reader from the article topic. "What does it mean to measure speed in this case? Space is curved and rotating." "Does this matter?" and so on. This is a topic for frame dragging not black hole IMO. Johnjbarton (talk) 20:07, 5 January 2026 (UTC)[reply]

I agree. I have removed the sentence.  Done Shocksingularity (talk) 22:33, 5 February 2026 (UTC)[reply]

The section "X-ray binaries" is about an astronomical classification related to but not limited to black holes. Our topic should be "Binaries" and include content about X-ray binaries. The various kinds of binaries with black holes should be mentioned and their accretion onto black holes / or merger discussed. Johnjbarton (talk) 03:28, 6 January 2026 (UTC)[reply]

There is currently information about black hole binaries in the classification section. Should I move it to the binaries section? Shocksingularity (talk) 19:25, 6 January 2026 (UTC)[reply]

I think the last two sentences, yes. the accretion one seems to ok as is. Johnjbarton (talk) 19:36, 6 January 2026 (UTC)[reply]

 Done section could be a bit clearer in identifying all binary partners, but I did not find a source which did that. Johnjbarton (talk) 19:07, 16 January 2026 (UTC)[reply]

I deleted this sentence:

• Properties of black holes can also be detected from the gravitational waves they emit.

which cited

• Poisson, Eric (1996). "Measuring black-hole parameters and testing general relativity using gravitational-wave data from space-based interferometers". Physical Review D. 54 (10): 5939–5953. arXiv:gr-qc/9606024. Bibcode:1996PhRvD..54.5939P. doi:10.1103/PhysRevD.54.5939. PMID 10020601.
• Echeverria, Fernando (1989). "Gravitational-wave measurements of the mass and angular momentum of a black hole". Physical Review D. 40 (10): 3194–3203. Bibcode:1989PhRvD..40.3194E. doi:10.1103/PhysRevD.40.3194. PMID 10011687.

The story is more complicated. These are two theory papers, and I believe they rely on stars falling into black holes. Reynolds discusses waves from mergers that have been measured. We could have some content around this, maybe in "Binaries". Johnjbarton (talk) 03:33, 6 January 2026 (UTC)[reply]

Black hole § Detection of gravitational waves from merging black holes covers this.  Done Johnjbarton (talk) 23:24, 16 January 2026 (UTC)[reply]

I took a paragraph under Properties which described measuring properties and distributed it to Mass/Spin/Charge. However another organization would move the property measurements to Observations > Basic Properties. Opinions? Johnjbarton (talk) 19:05, 7 January 2026 (UTC)[reply]

I think that the organization you did is fine. Shocksingularity (talk) 01:18, 10 January 2026 (UTC)[reply]

Thanks.  Done Johnjbarton (talk) 19:08, 16 January 2026 (UTC)[reply]

The first paragraph in the section "Black hole information paradox" ends with 6 citations. The paragraph is clearly not a summary of these sources. Three of the sources are from the 1990s, one is not reviewed, Hawking only obliquely discusses the paradox, Stoica from 2018 has relatively few citations. One can enjoy these sources but I can't verify our content from them. It's not that they contradict the content as much as they say a great deal more making verifying our content difficult.

On the other hand some things these sources say are more interesting to me than the content in the other three paragraphs in the section. Paragraph 2 is about black hole complementarity and paragraph 3 starts with " modern physics has discovered that black hole complementarity is still problematic,". Paragraph 4 introduces the firewall paradox. These three paragraphs are a selection of three topics on the subject black hole information paradox, which is where they belong in my opinion.

I suggest we merge paragraphs 2-4 in to black hole information paradox, pare the list of 6 sources, and add a paragraph based on newer reviews:

• Bose, S., Fuentes, I., Geraci, A. A., Khan, S. M., Qvarfort, S., Rademacher, M., ... & Wanjura, C. C. (2025). Massive quantum systems as interfaces of quantum mechanics and gravity. Reviews of Modern Physics, 97(1), 015003. Page 11 has a one paragraph summary of black hole information paradox. It is a just bit deeper than the summary we have in our first paragraph.
• Raju, S. (2022). Lessons from the information paradox. Physics Reports, 943, 1-80. The summary section starts The information paradox is not one paradox but part of a web of interconnected puzzles about black holes. These puzzles are of interest, not just in their own right, but also because they illuminate several general features of quantum gravity. In terms of encyclopedic knowledge, I think this is what we should summarize about the black hole information paradox rather than trying to delve into any one of the issues in this highly technical and unresolved space.

I await opinions before doing the damage. Johnjbarton (talk) 02:58, 8 January 2026 (UTC)[reply]

I'm good with that. Thanks! Shocksingularity (talk) 17:59, 8 January 2026 (UTC)[reply]

 Done please review Johnjbarton (talk) 19:44, 8 January 2026 (UTC)[reply]

 Done thank you! Shocksingularity (talk) 00:07, 9 January 2026 (UTC)[reply]

This source discusses the (amazing!) role of black holes in galaxy formation.

• Cattaneo, A., Faber, S. M., Binney, J., Dekel, A., Kormendy, J., Mushotzky, R., ... & Wisotzki, L. (2009). The role of black holes in galaxy formation and evolution. Nature, 460(7252), 213-219.

I've seem similar material but this one is the clearest to me. I think we should have a paragraph or so on this topic. Johnjbarton (talk) 20:20, 10 January 2026 (UTC)[reply]

I'll work on it. Shocksingularity (talk) 03:34, 11 January 2026 (UTC)[reply]

Your addition looks great, thanks!  Done Johnjbarton (talk) 16:49, 20 January 2026 (UTC)[reply]

Thanks! I will try to get to your other suggestions asap, I've been a bit swamped with the start of the semester but hopefully soon things will lighten up and I'll be able to edit more soon :) Shocksingularity (talk) 05:12, 22 January 2026 (UTC)[reply]

Our section Black hole § Photon sphere emphasizes the relatively confusing idea of unstable orbits. The cited sources however talk about a lot of other things

• Cramer, C. R. (1997). Using the uncharged Kerr black hole as a gravitational mirror. General Relativity and Gravitation, 29(4), 445-454. Photons emitted towards the BH boomerang. Does not verify the sentence it is associated with.
• Qiao, C. K. (2022). Curvatures, photon spheres and black hole shadows. arXiv preprint arXiv:2208.01771. Emphasizes practical value of photon sphere and black hole shadows techniques for BH image analysis.
• Lü, H., & Lyu, H. D. (2020). Schwarzschild black holes have the largest size. Physical Review D, 101(4), 044059. Compares radius calculations

I'm going to try to capture more of what I see in these and other sources. Johnjbarton (talk) 02:39, 11 January 2026 (UTC)[reply]

I think this section is find, please review. Johnjbarton (talk) 23:18, 16 January 2026 (UTC)[reply]

Looks good  Done. Shocksingularity (talk) 06:51, 1 February 2026 (UTC)[reply]

The section on "Observational evidence" is a mix of history, technology, and results. Should we move the history to History? Is this level of detail appropriate?

• In April 2017, EHT began observing the black hole at the centre of Messier 87. Using petabytes of data from eight different radio observatories over a ten-day observation period, the EHT team created a composite image of the black hole, which they debuted in April 2019.

We don't give similar details about other measurements. Johnjbarton (talk) 20:41, 11 January 2026 (UTC)[reply]

I have removed some of the history stuff, and added more technological details to the GW-detection and EHT sections.  Done Shocksingularity (talk) 00:32, 9 February 2026 (UTC)[reply]

While I'm not keen on this, it has been suggested that the article ought to be split. The simplest split would be at History. More material in the article could be moved into History also. Eg Mixmaster content. WDYT? Johnjbarton (talk) 23:02, 11 February 2026 (UTC)[reply]

The source:

• Carroll, Sean M. (2003). Spacetime and Geometry: An Introduction to General Relativity. Addison-Wesley. ISBN 978-0-8053-8732-2.

does not have page numbers. I would like to change to

• Carroll, S. M. (2019). Spacetime and Geometry: An Introduction to General Relativity. Cambridge: Cambridge University Press.

which is available via the Wikipedia library with page number. Johnjbarton (talk) 01:47, 12 February 2026 (UTC)[reply]

• As predicted by general relativity, the presence of a mass deforms spacetime in such a way that the paths taken by particles bend towards the mass.

Is sourced to Carroll-2004 5.4 and 7.3. However I see no such content to match this claim. In addition the paragraph uses this source on general relativity combined with a source on causality structure of spacetime near black holes. I dropped Carroll and rewrote the paragraph based on the causality source. I'm unsure if it makes sense. Johnjbarton (talk) 02:46, 12 February 2026 (UTC)[reply]

To a distant observer, a clock near a black hole would appear to tick more slowly than one further from the black hole.

I'm not finding this in Carroll-2014. He does not seem to discuss gravitational time dilation in the 2019 edition. Generally Carroll is very technical, it does not seem like a great ref for this qualitative stuff. Johnjbarton (talk) 03:01, 12 February 2026 (UTC)[reply]

I added:

Wheeler, in a 1967 lecture to the American Association for the Advancement of Science, "Our Universe, Known and Unknown", used the phrase:

[B]y reason of its faster and faster infall [the surface of the imploding star] moves away from the [distant] observer more and more rapidly. The light is shifted to the red. It becomes dimmer millisecond by millisecond, and in less than a second is too dark to see...[The star], like the Cheshire cat, fades from view. One leaves only its grin, the other, only its gravitational attraction. Gravitational attraction, yes; light, no. ... Moreover, light and particles incident from outside [and] going down the black hole only add to its mass and increase its gravitational attraction.^{[1]: 256–257}

I think Wheeler's quote is worth noting. He is credited with popularizing the term black hole, and this is where he did it. And the image of a black hole as a cosmic Cheshire cat, leaving only its gravitational grin, shows up in popular science.

Thorne's book is without a Good Article, although it surely merits one. Let's work on that. Charlie Faust (talk) 15:16, 13 February 2026 (UTC)[reply]

I'm not a fan of quotes in science articles generally. Encyclopedia entries are typically concise and must stay close to the key aspects of the topic. Quotes are often without sufficient context to be fully correct and understood. This is a case on that point: Wheeler is describing the implosion process, not a static black hole. We could have an entire article on the formation dynamics. Your claims about the connection to popularization and to the cat are known to you but not necessarily to readers. Adding that leads us further away from the key aspects of the topic.

I think significant quotes in biographies make more sense. Johnjbarton (talk) 23:09, 13 February 2026 (UTC)[reply]

Well, fair enough. (The quote is found on Wheeler's page, where it's perhaps more apt. He is credited with popularizing, if not coining the term black hole). Charles Darwin, which is a Featured Article and which I have edited, features several quotes by and about the man. But a biography article has different standards than an article on a scientific topic.

I first encountered the analogy of the black hole as a cosmic cheshire cat from Carl Sagan's Cosmos, in "The Lives of the Stars". It stayed with me. But Wheeler's page may be the place. Charlie Faust (talk) 00:34, 14 February 2026 (UTC)[reply]

User:Shocksingularity suggested condensing, rather than eschewing, the quote. The heart of the matter, it seems to me, is: "[The star], like the Cheshire cat, fades from view. One leaves only its grin, the other, only its gravitational attraction. Gravitational attraction, yes; light, no. ... Moreover, light and particles incident from outside [and] going down the black hole only add to its mass and increase its gravitational attraction." There you have Wheeler's first mention of "black hole", and the first comparison of it to the Cheshire cat.

The Alice books have been a fruitful source for scientists and mathematicians. Eddington likened quantum theory to "Jabberwocky": "Something unknown is doing we don't know what." Charlie Faust (talk) 15:05, 14 February 2026 (UTC)[reply]

Should there be something about Penrose in the lead? He showed that "black hole formation is a robust prediction of the general theory of relativity",^[2] per his Nobel citation. What about Reinhard Genzel and Andrea Ghez?

I think condensing the Wheeler quote would be worthwhile: Here is the heart of the matter: "[The star], like the Cheshire cat, fades from view. One leaves only its grin, the other, only its gravitational attraction. Gravitational attraction, yes; light, no. ... Moreover, light and particles incident from outside [and] going down the black hole only add to its mass and increase its gravitational attraction." Charlie Faust (talk) 16:59, 17 February 2026 (UTC)[reply]