Talk:Dark matter

How old is matter?
Motsaathebekhanyisile (talk) 07:45, 18 February 2024 (UTC)
 * 13.8 billion years. Before that everything was energy, and before that it was basically only geometry. But logic is and has been forever. Sandizer  (talk) 05:24, 27 February 2024 (UTC)

21st century history
what is the reason for this deletion? Is there a way to keep the sources? Do you think they can be summarized better? 141.239.252.245 (talk) 08:16, 19 April 2024 (UTC)


 * Thanks for opening this topic.
 * I reverted the edit as I said in the summary because the content is not "History" of Dark Matter. No historian has analyzed the history of Dark Matter and shown how primordial black holes became the alternative. On the contrary, the current consensus is cold dark matter: Lambda-CDM.
 * The sources and a summary are already in the article in the section "Alternative hypotheses". As it stands it appears to be WP:UNDUE: with in the section "Alternative hypotheses" primordial black hole is given an entire paragraph while other alternatives rate a couple of words. Johnjbarton (talk) 15:18, 19 April 2024 (UTC)

Short description
@Banedon the short description for this article currently reads as

Hypothetical form of matter that interacts with gravity, ...

getting cut off. Remember, the short description doesn't need to have as much detail as a lead sentence and is mostly used to disambiguate. Most people see the SD in the search bar, where they've typed in something that is similarly-titled, not similarly-themed.

I believe "Hypothetical form of matter" would scan quickly, as guidelines suggest, and disambiguate well enough from the other articles that have "dark matter" in the name, which are mostly works of fiction. The closest that might cause confusion is Dark matter halo, which has SD "Theoretical cosmic structure". But since you are engaged on this topic I will leave it to your judgement. Wizmut (talk) 04:16, 31 May 2024 (UTC)


 * I think it needs to say more than that, but a little more briefly, such as "Hypothetical form of matter that interacts with gravity, but not with the electromagnetic field" Bubba73 You talkin' to me? 05:01, 31 May 2024 (UTC)
 * That's not a short description, that's a long description. SD's are not load-bearing in the way a scoping statement is, they're purely to lubricate searches. Wizmut (talk) 05:05, 31 May 2024 (UTC)
 * "Hypothetical form of matter" would be ambiguous, there's a lot of hypothetical forms of matter around (Exotic matter). If we need a very short description, then make it "Concept in cosmology" or something. Banedon (talk) 06:35, 31 May 2024 (UTC)
 * That works too. But the short description always appears alongside the title, and a user probably wouldn't be seeing the SD if they weren't already searching for something beginning with "Dark". Wizmut (talk) 06:54, 31 May 2024 (UTC)
 * I don't understand what you mean. Can you elaborate? Banedon (talk) 08:36, 31 May 2024 (UTC)
 * Most people see the short description when doing searches in the search bar. In a search for "Dark" something, they want to know if each result they see is the one they're looking for. Is it a film, a book, a concept, a politician.
 * Think of something to search for up top in the search bar, type in the first few letters, and see how long it takes to tell if each result is the one you're trying to find. If it takes too long or doesn't make sense, it's probably because the SDs aren't clear and concise enough. Wizmut (talk) 08:53, 31 May 2024 (UTC)
 * Here is an example:Wikipedia Search for Dark.png Johnjbarton (talk) 14:06, 31 May 2024 (UTC)
 * Short description says "... is a concise explanation of the scope of the page.". Simply "hypothetical form of matter" does not fulfill that, in my view. Bubba73 You talkin' to me? 22:22, 31 May 2024 (UTC)
 * But the next sentence says: "These descriptions appear in Wikipedia mobile and some desktop searches, and help users identify the desired article." They have no other purpose. They are invisible to normal readers. Johnjbarton (talk) 22:45, 31 May 2024 (UTC)
 * It also says "Short descriptions provide: a very brief (emphasis mine) indication of the field covered by the article" and later "More than 80% of short descriptions use fewer than 40 characters (including spaces)."
 * This article's SD is 100 characters, currently the longest on English WP. Wizmut (talk) 22:53, 31 May 2024 (UTC)
 * How about "Hypothetical invisible gravitational matter."? Johnjbarton (talk) 22:58, 31 May 2024 (UTC)
 * Eh better but 'gravitational' may count as jargon. Wizmut (talk) 23:05, 31 May 2024 (UTC)
 * But I think it fulfills the mission, in view of different opinions. Johnjbarton (talk) 23:13, 31 May 2024 (UTC)
 * "Hypothetical form of matter that interacts with gravity but not with electromagnetism" is only 85 characters, and I think it conveys the concept. Bubba73 You talkin' to me? 00:14, 1 June 2024 (UTC)
 * It should convey the category or field, not be a definition. See WP:SDESC:
 * "Short descriptions provide:
 * a very brief indication of the field covered by the article
 * a short descriptive annotation
 * a disambiguation in searches, especially to distinguish the subject from similarly titled subjects in different fields" Wizmut (talk) 00:18, 1 June 2024 (UTC)
 * Or how about "Hypothetical invisible matter affected by gravity" ? Bubba73 You talkin' to me? 00:18, 1 June 2024 (UTC)
 * The first three words of that are doing most of the work there - the reader can tell by that point if that's the article they want to click on. But 50 characters is an improvement over 100. Wizmut (talk) 00:25, 1 June 2024 (UTC)

I'm for "concept in cosmology" then. "Hypothetical invisible matter", as the current short description is right now, is still not accurate since dark matter is potentially visible, just not with electromagnetic waves. Banedon (talk) 05:56, 3 June 2024 (UTC)


 * I think "visible" means "light" aka electromagnetic waves. However I also like "concept in cosmology", because the overall effect:
 * Dark matter
 * concept in cosmology
 * is less redundant than
 * Dark matter
 * Hypothetical invisible matter
 * in a list of search terms. Johnjbarton (talk) 14:13, 3 June 2024 (UTC)
 * I will third that choice. Fits with guidelines suggesting that SDs can mention the field of the article topic. Wizmut (talk) 14:19, 3 June 2024 (UTC)


 * I don't think that fulfills the "... is a concise explanation of the scope of the page." in the ShortDescription. It doesn't give the scope of the page.  Bubba73 You talkin' to me? 01:37, 4 June 2024 (UTC)
 * The scope of "dark matter" is clearly cosmology and "concept" identifies it as an abstraction. Johnjbarton (talk) 02:44, 4 June 2024 (UTC)