Talk:Universe

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Former good article Universe was one of the Natural sciences good articles, but it has been removed from the list. There are suggestions below for improving the article to meet the good article criteria. Once these issues have been addressed, the article can be renominated. Editors may also seek a reassessment of the decision if they believe there was a mistake.

The Universe as a sentient sense organ[edit]

It is strange that nobody involved in religion, or anyone interested in religious thought and who has helped compile this article, to date, has thought of the Universe itself as actually being the physical neurons connecting themselves together in God's brain? Or quite possibly it isn't that surprising, given the subject matter, although the person who wrote the movie script for Men in Black was quite near to doing it. And he could have been on anything, not just dopamine. Anonymous (talk) 13:31 2 may 2015 (UTC) — Preceding unsigned comment added by 31.51.13.202 (talk)

This sounds like the panpsychism concept. It probably belongs on the Cosmology article, since that covers philosophical viewpoints. Praemonitus (talk) 17:24, 19 June 2015 (UTC)

It could be that the as per the multivers theory we are actually a cell or even just a atom or particle of the One Above All (the one true god a being that is both good and evil. yes i am a fan of marvel comics.) as true perspective distance of the universe is next to impossible to determine as it is constantly expanding. --Guyver92 (talk) 06:06, 8 May 2015 (UTC)

An issue with the definition[edit]

The 'totality of existence' is a rather facile definition. Not only is that taking the position—in violation of WP:NPOV—that physicalism and atheism are correct, but it's also ignoring the fact that many viewpoints in mathematical philosophy regard non-physical abstract objects (sets, numbers, etc.) as existing as well. This is compounded by the fact that the sources cited for that definition are mere dictionaries(the Encyclopedia Britannica entry of "universe", which was also cited, does not regard it is the "totality of existence"), which are certainly not reliable for a topic clearly requiring a specialized, scholarly definition.JDiala (talk) 01:42, 15 April 2015 (UTC)

So, are you saying the definition is too inclusive or not inclusive enough? Although this Talk page constantly goes round and round about it, there has been a sort of consensus that the definition should be limited to the astronomical concept, and should not include philosophical or religious concepts such as God, or abstractions (ideas, numbers, etc.). In agreement with that, I feel 'totality of existence' is a little too inclusive. --ChetvornoTALK 02:12, 15 April 2015 (UTC)
In recent years I notice the definition has switched back and forth between versions of 'totality of existence' and the more limited 'totality of spacetime', which would more clearly exclude the philosophical stuff like God. I think I prefer the latter. --ChetvornoTALK 02:12, 15 April 2015 (UTC)
It is too inclusive. Spacetime is sufficient for a simple definition. JDiala (talk) 02:38, 15 April 2015 (UTC)
At the risk of igniting another endless "lede" discussion, how does everybody feel about switching back to a lede that defines the Universe as the "totality of spacetime and all it contains" as it was in January [1]? --ChetvornoTALK 20:23, 16 April 2015 (UTC)
If you haven't noted it, do see the discussion above; the current wording in the lede was in place in January 2014 and was largely restored in January 2015. However, I'd be fine replacing "existence", since it's a bit fluffy and metaphysical (though I disagree that there are any NPOV issues, and I think dictionaries are the best sources for definitions like this). I think the dictionary definitions at the beginning of the discussion above are helpful, particularly the Oxford and Merriam-Webster ones. How close can our wording be without being plagiarism? "Totality of spacetime" doesn't seem as clean to me as "the sum of everything that exists" (Oxford) or "all of space and everything in it" (Merriam-Webster). —Alex (Ashill | talk | contribs) 21:40, 16 April 2015 (UTC)
I think we need to avoid something that is exclusively astrophysical.Isambard Kingdom (talk) 21:42, 16 April 2015 (UTC)
How about this (which was also used in the january version): We use the "spacetime" definition in the lede, but add the sentence: "The term is also used more broadly for concepts such as the cosmos, the world, reality, and nature." further down in the lead section. That way we indicate the broader meanings to the word are strictly separate from the "astrophysical" definition. --ChetvornoTALK 22:09, 16 April 2015 (UTC)
I suggested removing that sentence in February, with my reasoning in the discussion above. I now see that those terms are discussed in the article itself, which does argue for including them in the lede. However, I think the context they were in before (immediately after the contents of the Universe) isn't quite right. I also note that there's no mention of the fairly extended section about historical models in the lede. Perhaps we should add a new paragraph to the lede that goes into historical models, etymology, and synonyms? The lede could probably benefit from some discussion of the difference between the scientific/astrophysical entity (what I'd call the Universe, though that's controversial from a grammatical point of view but I think very useful from a meaning point of view) and the more philosophical concept of the universe (which those terms are more related to). —Alex (Ashill | talk | contribs) 14:28, 17 April 2015 (UTC)

──────────────────────────────────────────────────────────────────────────────────────────────────── After thinking about the relationship between the lede and the article, I've boldly reordered the article to be

  1. Etymology
  2. Synonyms
  3. Historical concepts
  4. Chronology
  5. Properties and laws
  6. Shape
  7. Theoretical models

(Synonyms and Historical concepts were between shape and theoretical models, which broke up the modern scientific description.) I ordinarily prefer to leave historical models and synonyms to the end, but I think this is appropriate for this particular article, since the word "universe" does have significant non-scientific meaning. It also flows better, particularly since the historical models section ends with "The modern era of physical cosmology began in 1917, when Albert Einstein first applied his general theory of relativity to model the structure and dynamics of the Universe.", which flows very nicely into the modern scientific description. —Alex (Ashill | talk | contribs) 14:39, 17 April 2015 (UTC)

@Ashill: You have not given a convincing reason as to why dictionaries should be used to define what "universe" is(note that it doesn't matter what you "think"; you require an argument based on Wikipedia policy), nor have you (or Isambard Kingdom) explained why an astrophysical definition is not preferable. Cosmology is the scientific study of the universe, and is a sub-category of astrophysics. This is a scientific article. Why, then, should our definition not be based on the mainstream view of experts on the subject (rather than dictionaries)? In the above discussion neither of the several sources linked describe the definition of "universe" as "the totality of existence". Are they less reliable than dictionaries? I suggest you may need to read through WP:RELIABLE. — Preceding unsigned comment added by JDiala (talkcontribs) 23:45, 30 April 2015 (UTC)
@JDiala: Dictionaries are absolutely reliable sources for simple definitions. What makes you think otherwise?
The cited Webster's New College Dictionary definition (#1) is "the totality of all the things that exist; creation; the cosmos", which mostly supports the current definition (though maybe "existence" has a subtly different meaning that "all things that exists"). And the second sentence ("This includes planets, stars, galaxies...") makes it very much astrophysical. But as I stated above, I'm not wild about the "existence" bit either.
Rewriting the sentence without plagiarizing one of the sources is a bit difficult, since they've found most of the ways to say the same thing. A suggestion: "The Universe is all of time, space, and its contents. This includes planets, stars, galaxies, the contents of intergalactic space, the smallest subatomic particles, and all matter and energy, the majority of which are most likely in the form of dark matter and dark energy."
Though I generally do prefer to keep scientific and non-scientific stuff in separate articles, this article does have a fairly extended set of sections with well-sourced and (I think) relevant content. The lede should reflect that instead of being entirely focused on the modern scientific aspects as it currently is.
As to "think": I do try to use words like "think" on talk pages to distinguish my opinion from what sources say. What editors think is absolutely relevant in editorial decisions about what to include in an article and which sources are relevant (within policy); Wikipedia isn't written by automatons. I suggest that you read the box at the top of the guideline you linked to: "This page documents an English Wikipedia content guideline. It is a generally accepted standard that editors should attempt to follow, though it is best treated with common sense, and occasional exceptions may apply. Any substantive edit to this page should reflect consensus. When in doubt, discuss first on the talk page." I think that what editors think is very relevant to using common sense. —Alex (Ashill | talk | contribs) 13:56, 1 May 2015 (UTC)
@Ashill: A simple definition may suffice for a simple topic--say, Pizza--but not for "Universe". An overly simplistic definition, evident in the case of this article, can be an imprecise one. If plagiarism is an issue, why not the following definition from the July 2014 version: "The Universe is all of spacetime and everything that exists therein, including all planets, stars, galaxies, the contents of intergalactic space, the smallest subatomic particles, and all matter and energy."? Notwithstanding the non-scientific stuff included in the article, I am still not convinced that the lead should encompass these non-scientific views. Consider, for example, life. The lead sentence is clearly totally scientific, even though there is a large amount of non-scientific discussion on the issue of life (ie. meaning of life). Moreover, since practically all of the sources describe and discuss the universe scientifically, should Wikipedia not do the same? If this is a major point of contention, why not have a separate sentence or a separate paragraph discussing broader, non-scientific conceptions of the "universe". JDiala (talk) 00:48, 2 May 2015 (UTC)
I think there's more miscommunication than disagreement here. Our proposed definitions are, as far as I can tell, nearly identical. The main difference is that I prefer to split it up into two sentences to avoid a run-on. I'm not suggesting incorporating the historical models and etymology into the definition in the first paragraph of the article; I'm suggesting adding a fourth paragraph to the lede that summarizes those sections of the article. —Alex (Ashill | talk | contribs) 02:03, 2 May 2015 (UTC)
Okay fair enough. If we're largely in agreement, shall we make a change? JDiala (talk) 23:58, 3 May 2015 (UTC)
OK, I've done this. I used "time and space" instead of "spacetime" because none of the sources with definitions actually say "spacetime". —Alex (Ashill | talk | contribs) 16:26, 4 May 2015 (UTC)
Alex, thank you for these thoughtful edits. Isambard Kingdom (talk) 14:48, 17 April 2015 (UTC)
I agree, looks great. A nice simple clear definition. Agree "space and time" is better than the technical word "spacetime". Nice job. --ChetvornoTALK 18:49, 4 May 2015 (UTC)

Proposed Definition update-add "contents" per the sources The Universe is all of time and space and its contents, [8][9][10][11] which includes the planets, stars, galaxies, the contents of intergalactic space, the smallest subatomic particles, and all matter and energy, the majority of which are most likely in the form of dark matter and dark energy.[12][13]Jcardazzi (talk) 00:06, 2 June 2015 (UTC)jcardazzi

Okay with me. --ChetvornoTALK 00:20, 2 June 2015 (UTC)
Per which source? None of the four cited sources include the word "contents". Though Merriam Webster does say "and everything in it including stars, planets, galaxies, etc", but that's already covered (almost verbatim) in the next sentence. I prefer keeping the first sentence concise. —Alex (Ashill | talk | contribs) 01:05, 2 June 2015 (UTC)
I think Ashill is being too technical here. We don't necessarily need dictionary-like definitions, and we don't need a lead that strives for consistency with such verbatim distinctions ("contents"). It is okay if the lead is a sensible summary of the content of the article. Isambard Kingdom (talk) 06:44, 2 June 2015 (UTC)

Sorry,sources: per Meriam Webster: "the universe : all of space and everything in it including stars, planets, galaxies,

per American Heritage: All space-time, matter and energy, including the solar system, all stars and galaxies, and the contents of intergalactic space, regarded as a whole.

per Oxford: All existing matter and space considered as a whole; the cosmos.

per oxford Advanced: The universe: the whole of space and everything in it, including the earth, the planets and the stars

When I read the definition "The Universe is all of time and space", I wondered "what about the contents? why are the contents not included in the Universe?" the Universe's matter and energy, et al. The next sentences explain after the definition the Universe includes matter and the contents, but the contents are not in the 1st sentence definition. Thank youJcardazzi (talk) 03:03, 2 June 2015 (UTC)jcardazzi

I can only echo what Isambard Kingdom and Jcardazzi said. Adding "and its contents" surely does not require an explicit source, and if it does Jcardazzi's is sufficient. --ChetvornoTALK 10:16, 2 June 2015 (UTC)
I didn't mean to say that "and its contents" isn't OK, just that Jcardazzi's argument that it is better "per the sources" is clearly false (based on the currently-cited sources). My substantive objection is that it turns a simple, clear, and complete topic sentence into a run-on. What about "The universe is all of time and space. This includes its contents: planets, stars, galaxies, intergalactic space, the smallest subatomic particles, and all matter and energy, the majority of which are most likely in the form of dark matter and dark energy."? —Alex (Ashill | talk | contribs) 12:50, 2 June 2015 (UTC)

I used a synonym of "contents" for the different words in the cited sources, which refer to the contents of the Universe in different words, "whole of matter and energy", "totality of known..objects:, "totality of all space and time,all that is, has been, and will be." (the 3rd definition seems too vague and mystical to me). I don't think adding "and it's contents" makes the 1st sentence a runon sentence, the sentence goes from 8 to 11 words. Leaving the contents out of the universe seems incomplete to me. None of the current sources state the Universe is only space and time, with no contents.

Current sources cited: yourdictionary.com:The universe is the whole of all matter, energy, planets, galaxies and space

dictionary.com the totality of known or supposed objects and phenomena throughout space; the cosmos; macrocosm.

Introductory Astronomy & Astrophysics (4th ed.): The totality of all space and time; all that is, has been, and will be.

Thank you Jcardazzi (talk) 13:20, 2 June 2015 (UTC)jcardazzi

Again, all of that is in what is currently the second sentence of the lede. You propose merging that second sentence into one long run-on. I prefer a short, first sentence; the second sentence is already on the long side. —Alex (Ashill | talk | contribs) 13:29, 2 June 2015 (UTC)

Hi, I do not propose merging the 2nd sentence. I propose the below text, for consistency of terms and definitions. Reasons: 1. None of the sources cite the universe is only all of time and space. 2. The WP article https://en.wikipedia.org/wiki/Outer_space describes space (outer space) as a void, between celestial objects, and excludes the objects from "space".

Proposed text: The Universe is all of time and space and its contents. The Universe includes planets, stars, galaxies, the contents of intergalactic space, the smallest subatomic particles, and all matter and energy. The majority of matter and energy most likely is in the form of dark matter and dark energy. Thank you, Jcardazzi (talk) 22:33, 2 June 2015 (UTC)jcardazzi

This new proposed text is not what you proposed above (which did merge the two sentences). It's an improvement. I think that space has a subtly different meaning when combined with time that does imply everything in it, but I'm fine including contents in the first sentence if it's split up like this (though I still prefer just "all of time and space" in the first sentence). I'd change the second "The Universe" to "This", but otherwise go for it. Breaking up the second sentence as you suggest is a definite improvement. —Alex (Ashill | talk | contribs) 23:29, 2 June 2015 (UTC)

Scope of article[edit]

To be explicit about something that's come up tangentially in a few other places, what should the scope of this article be? A recent set of edits incorporated the philosophical meaning into the lede. (I think the content as it is should be in the body, not the lede, but that's a side point.)

I don't really think that the scope of the article should be limited to just the scientific meaning of the Universe, but discussion of the philosophical meaning of the word (including mathematics) is really talking about a very different thing than the discussion of the astrophysics, so it's a little hard for me to see how to make the article coherent. Making the topic of the article every meaning of a word that really does have quite distinct meanings in different disciplines seems to err a bit too much on the general side. —Alex (Ashill | talk | contribs) 19:16, 29 May 2015 (UTC)

My opinion: The article does not need to try to cover every meaning of the word "universe". Similarly, the article does not need to try to summarize all astronomical aspects of the universe. The Universe article is not a specialized article. It is a general article. Specialized subjects can be taken up in specialized articles (that is the beauty of an encyclopedia). What the Universe article should be is a fairly accurate panoramic discussion of what is meant by "universe" across a wide range disciplines. Not easy. I know. And I don't even pretend to be able to do that. So, how to proceed? I think we need to encourage participation in the article's development, especially from editors capable of delivering non-astronomical content (because we seem to have quit a lot of that already). How do we encourage this involvement? Isambard Kingdom (talk) 19:32, 29 May 2015 (UTC)
My feeling is the article already has an appropriate amount of "panoramic" discussion of the meaning of Universe in non-astronomical contexts, in the Synonyms and definitions, Historical models and Philosophical models sections. It is important and valuable, and maybe it could be better written. But I think most readers come here for the astronomical concept. --ChetvornoTALK 21:48, 29 May 2015 (UTC)
Perhaps, then, the thing to do is encourage editors with expertise in religion, history, philosophy, etc. to consider those sections in this article and try improve the existing content. Isambard Kingdom (talk) 21:53, 29 May 2015 (UTC)
What do you think is missing, or needs to be improved? --ChetvornoTALK 22:21, 29 May 2015 (UTC)
Well, notions that the universe encompasses all kinds of things: life, ideas, thoughts, emotions; abstract things like philosophy and mathematics. Plus, I'm sure, lots of other things that are not astronomical. By the way, I don't think people necessarily arrive at this page looking for things astronomical. I don't claim to be qualified to fix the article. Isambard Kingdom (talk) 22:28, 29 May 2015 (UTC)
That definition of "universe" is synonymous with "everything," which is an existing and distinct article. Remember that as an encyclopedia not a dictionary, we have one article per subject not one article per word. VQuakr (talk) 00:32, 30 May 2015 (UTC)
That article everthing is certainly well written. Funny too! Isambard Kingdom (talk) 01:19, 30 May 2015 (UTC)
@Isambard Kingdom: if the redlink is sardonicism, you are over my head. VQuakr (talk) 07:47, 30 May 2015 (UTC)

I think the scope of this article should be the the Universe as a subject in Astronomy/Physics. Text at the top should describe the subject and refer readers to other articles for subjects on other meanings of the word. Thank you,Jcardazzi (talk) 22:39, 2 June 2015 (UTC)jcardazzi

Recent edits[edit]

I've moved, merged some sections, sorted and updated the lede, put Universe into italics. If someone wants to comment on these changes, go ahead. prokaryotes (talk) 11:30, 2 June 2015 (UTC)

I have a few concerns.
  1. The new lede is much more technical (going into details of Euclidean space, manifolds, and Minkowski space in ways that should be in the body, not the lede; using "R(t)" – especially without definition – is also too technical). Moreover, the broad description of the observable universe, including its size and ultimate fate, are moved to a separate section ("Characteristic"). This is particularly inappropriate because that text describes content that's later in the article; we shouldn't have a second, non-lede section that summarizes content elsewhere in the article (per WP:LEDE).
  2. The completely rewritten Definition section is awkwardly short (though what it replaces was pretty bad as well, consisting of choppy, short subsections) and uncited.
  3. I made an argument above as to why I like having the historical models section before the modern scientific description; I still think that, though not strongly.
  4. Putting "Universe" in italics seems inconsistent with MOS:ITALICS and standard English usage; why the change? —Alex (Ashill | talk | contribs) 13:24, 2 June 2015 (UTC)
Definition section - I've removed the italics. —Alex (Ashill | talk | contribs) 13:40, 2 June 2015 (UTC)
  • The definition section was separated, i did not changed the text there, its the remaining parts now. It should be extended. Lede - I will try to make it less technical. Italics, because some words were in italics, some not. I don't care if it is in Italics, or not. Maybe merge all theories and models, than separate them by historic and modern. prokaryotes (talk) 13:44, 2 June 2015 (UTC)
Italics are used, in this article, when discussing the word "universe" as opposed to discussion of the actual "Universe". These are matters of style only, and, so, less important than content. Isambard Kingdom (talk) 13:47, 2 June 2015 (UTC)
They are now, after I removed the italics. They were used for every occurrence of the word universe. —Alex (Ashill | talk | contribs) 13:51, 2 June 2015 (UTC)
Right, and I'm fine with that reversion, but prior to this round of edits, italics were used in the definition/etemology section to emphasize the word "universe" as a word only. Not arguing, just saying. Isambard Kingdom (talk) 13:58, 2 June 2015 (UTC)

Thanks Prokaryotes. A fresh overhaul, such as this, might help jumpstart progress on this article. I think we could still use input on the "Historical Models" section. One thing, my understanding is that the notion of a "model" is kind of new in the history of science, and that ancient scientists either perceived their "models" as actual reality. I believe that Gilbert perceived his terrella as actual "Earth's" (though I'm happy to be corrected). Or, more practically, as simply a means to an end. So, again just my understanding, at first Copernicus was more concerned about practical prediction of the motion of the planets and Sun for purposes of calendar production; whether or not his heliocentric theory was "real" was of secondary concern. On a completely different note, I'd like to see the equations (there are just a few) removed from the article, as I see them as not balanced relative to the whole of the article's content. My thoughts, Isambard Kingdom (talk) 13:27, 2 June 2015 (UTC)

Before Copernics, namely Philolaus should be mentioned, Copernicus mentions him too. See also Nicolaus Copernicus#Predecessors. I renamed the Historic model section to Historic development. prokaryotes (talk) 13:55, 2 June 2015 (UTC)
P, if you feel qualified to add that content (Philolaus), then please do. Isambard Kingdom (talk) 14:02, 2 June 2015 (UTC)

There are a few newly-added sections (dark matter and dark energy) that are straight copy and pastes of the ledes of their respective articles. Summary style is certainly appropriate for this article, but it's not clear what the benefit of this is. The content was already covered (more briefly) in the Contents section, obviously with links to the specific articles. Why duplicate the content again? (I deleted the dark matter section, but thought I'd bring it here before deleting more.) It looks like the particle physics section is largely the same. —Alex (Ashill | talk | contribs) 14:43, 3 June 2015 (UTC)

Dark matter and energy make most in the universe, and the content in the respective sections is only liek 2 paragraphs and elsewhere only mentioned briefly. These topics deserve a sub section entry. prokaryotes (talk) 14:51, 3 June 2015 (UTC)
It's obviously true that they're most of the contents of the Universe, but I really don't see what is gained by duplicating the content. I think that keeping the focus of this article on how things fit together on large scales is much better. An already-large and unwieldy article has gotten much larger (it was about 100K yesterday, about the WP:TOOBIG rule-of-thumb size when it "almost certainly should be divided", and is now 130K). The particle physics details strike me as worse than dark matter and dark energy; instead of short sections, they're quite lengthy sections that go deep into detail that really isn't relevant for the Universe as a whole (or at least the relevance isn't made clear). Particle physics is obviously important for the early evolution of the Universe, but the entire Particle Physics section (as it currently stands) contributes nothing to understanding the early Universe. —Alex (Ashill | talk | contribs) 15:01, 3 June 2015 (UTC)
What do you suggest is missing in the particle section, when you say it is not covering the early universe? The content also mentions that it is not only related to the early universe. I agree that the article should not be bigger. I thought maybe merging the philosophic and astronomy section, and could be trimmed. Some parts in the particle section could be trimmed, but repeating basic info helps to communicate a complex topic. prokaryotes (talk) 15:08, 3 June 2015 (UTC)
I see that there's one paragraph in each section about the lepton epoch, the hadron epoch, and the photon epoch; that's good. It's the rest of each of those sections that isn't on topic. I think it goes beyond repeating the basic info needed to communicate the topic, particularly since the repetition of basic info looks to me like it's 4–6 times as long as the relevant info in these sections. I'll try to trim. —Alex (Ashill | talk | contribs) 15:30, 3 June 2015 (UTC)
Alex, i think you done a good job, except for removing the particle model removal. If we have an article on the universe and a section on models, than the Standard model belongs there. The part really was tiny, please readd, thanks. prokaryotes (talk) 16:34, 4 June 2015 (UTC)
Are you talking about this edit? I didn't remove anything; I just moved it to what I think is a more sensible and less-redundant place. —Alex (Ashill | talk | contribs) 17:47, 4 June 2015 (UTC)
If we have a section on models, then we need to list the particle physics model there too. Or remove the model section, and just outline the BB event. This is important because both models are considered Standard Models, thus it is a bit confusing when you only find the BB SM under Models. Or just add a sub section with a link to the SM page. prokaryotes (talk) 05:33, 5 June 2015 (UTC)
Thanks Ashill for your edits, i think the article is now in a good shape. prokaryotes (talk) 18:18, 9 June 2015 (UTC)
I also think the article looks very good. Maybe it can be nominated for article of the day or something? Isambard Kingdom (talk) 18:27, 9 June 2015 (UTC)
It was nominated as a Good Article a couple months ago and is still pending review: WP:GAN#PHYS. (There's a large backlog.) My guess is that it may well pass the Good Article review (depends very much on the individual reviewer). I think it would have a very hard time passing a featured article nomination; if you're talking about the article being a front page nominee, featured article status is the first step. Though I do think the article is significantly improved (and wasn't bad to begin with), there are still a number of improvements that could be made (and are on my mental list, which I'm slowly making progress on). —Alex (Ashill | talk | contribs) 18:49, 9 June 2015 (UTC)
Alex, there are a couple of equations in the article (Solving Einstein's equations, Geometry). Can these be taken out? I feel that in all the mix of material, these equations, while possibly interesting, are not balanced with the rest of the material. Just my thoughts. Isambard Kingdom (talk) 18:54, 9 June 2015 (UTC)
I too think that equations do not necessarily have to be in this article, but before removal they should be added (if not already) to the related sub article. prokaryotes (talk) 19:03, 9 June 2015 (UTC)
That's on my mental list to tackle. Need to think about whether the content they convey should be in the article in text; when I looked at it, it seemed probably. —Alex (Ashill | talk | contribs) 23:44, 9 June 2015 (UTC)

contents- what about ordinary energy?[edit]

regarding: "The Universe is composed of dark energy, dark matter, and ordinary matter." Why is ordinary energy not mentioned? for example: light, heat, radio waves et al. If dark energy is specifically mentioned, should ordinary energy be mentioned to be consistent? Thank you,Jcardazzi (talk) 23:14, 9 June 2015 (UTC)jcardazzi

Ordinary energy (meaning electromagnetic radiation) is a tiny fraction of the energy density of the present Universe. Add up the contributions of dark energy, dark matter, and ordinary matter to the mass–energy of the Universe, and <0.1% is left over. And essentially every source lists those three as the dominant constituents of the Universe, so we'd be going against the sources to include radiation. The article correctly notes that radiation was the dominant component during the photon epoch, most of the first 380,000 years. —Alex (Ashill | talk | contribs) 23:43, 9 June 2015 (UTC)

Hello Ashill, ordinary energy being <0.1% of the universe is still greater than zero, and is a content of the universe, per all sources I checked. Plus, ordinary energy is an important and necessary content to humans. For example: If the sun stopped emitting light and heat, all humans would die. If there was no electricity, there would be no electronics, no computers, no wikipedia.

Ordinary energy, while not dominant, is worth stating, I believe. I suggest a revision: "The Universe is composed of dark energy, dark matter, and ordinary matter and energy."...Ordinary energy is less than 0.01% of the content of the Universe. Thank you,Jcardazzi (talk) 12:00, 10 June 2015 (UTC)jcardazzi

This image (part of Dark energy) https://commons.wikimedia.org/wiki/File:DMPie_2013.svg should be updated then too? prokaryotes (talk) 12:09, 10 June 2015 (UTC)
If that image were updated, there would be no change. The sliver that is radiation is thinner than the thin lines that separate the significant constituents. At the highest resolution PNG rendering (2000 pixels), ordinary energy would take up less than half a pixel.
Radiation is discussed a good bit in the chronology section, as it was dominant during the photon epoch. A radiation section in Contents would probably be good. To the introduction to the Contents section, I think that appending something like this to the paragraph would be better than including radiation in the list of significant constituents: "At present, electromagnetic radiation is a small portion of the mass–energy density in the Universe, but it was the dominant form of mass–energy during the photon epoch." But that just duplicates content that is (appropriately) in the chronology section.
(Note that "ordinary energy" is not a commonly-used phrase; I think that "radiation", "electromagnetic radiation", or "light" are all better.) —Alex (Ashill | talk | contribs) 13:48, 10 June 2015 (UTC)

What fraction atoms?[edit]

In response to a few recent edits on this article, I'm wondering if there is an estimate of the mass fraction of the Universe that is composed of electrically neutral atoms (not ions, not free electrons). It would be interesting to put this into in this article. Isambard Kingdom (talk) 03:41, 25 June 2015 (UTC)

I would think that would be a difficult question to answer accurately. See for example. Praemonitus (talk) 16:40, 23 July 2015 (UTC)

Magnetic effects on cosmic scales[edit]

@Ashill, I think I'm okay with your reverting my edit here: [2], but let me ask for some clarification. Galaxies can have their own dynamos, what with the electrically conducting plasma of stars and gas acting through motion to generate large-scale magnetic fields. Sounds interesting to me, but I don't know for a fact that a galactic dynamo can have a (dynamic) back-reactive effect on the structure of a galaxy -- thus qualifying under the "cosmological length scales" discussed in this part of the article. Let me know. A possible nuanced edit of the article might avoid confusion from people like me who know enough to get confused. Isambard Kingdom (talk) 16:23, 26 June 2015 (UTC)

Also, note the role of magnetic fields in jets (even large ones): Astrophysical jet. The term cosmological scale "level of galaxies and larger-scale structures" might need some adjustment to fix this. Isambard Kingdom (talk) 17:14, 26 June 2015 (UTC)

Yes, galaxies can produce dynamos and have magnetic fields in the interstellar medium (in fact, that's largely what I study professionally and thus something I avoid on Wikipedia ;) ) which may well impact what galaxies look like, but the magnetic fields don't control the formation of cosmic structure; the electromagnetic forces are much smaller than gravity on those scales. So magnetic fields may affect what galaxies look like (though even there, probably only as a secondary effect except on observational tracers like polarized radio emission that are very sensitive to magnetic fields) but probably don't affect what the Universe looks like. So I think just glossing over it is appropriate here. Magnetic fields may be created in jets but probably don't control jets. —Alex (Ashill | talk | contribs) 17:29, 26 June 2015 (UTC)
Understood, I also don't edit Wikiarticles on what I actually do! Isambard Kingdom (talk) 17:31, 26 June 2015 (UTC)
But that whole paragraph should be referenced better.... —Alex (Ashill | talk | contribs) 17:45, 26 June 2015 (UTC)

History section[edit]

I notice that the classical Chinese school of thought regarding the universe, dating as far back as the 4th century BCE is not mentioned here, why is that?

The Chinese term for Universe is 宇宙, the first character meaning all of space, infinite and without bounds, and the second meaning all of time, without beginning nor end.

The classic saying goes:

“四方上下曰宇,往古来今曰宙。”

The four directions and up and down are called yu, from ancient to modern is called zhou, thus the universe yuzhou (宇宙) is the totality of all space-time.

Though I understand that other cultures have other ideas regarding what the universe really is, this seems to be a rather gaping omission in this article.

71.202.100.77 (talk) 12:00, 28 June 2015 (UTC)

Interesting. I don't know how or if foreign language issues like this are handled (I can't read more than about a dozen Chinese characters). Ideally, we have a citation to a reference article that discusses (say) ancient Chinese notions of space and time, and everything that existed, exists, or will exist. Isambard Kingdom (talk) 17:02, 28 June 2015 (UTC)
Some interesting articles:
1. Gernet, J., 1993-94. Space and time: Science and religion in the encounter between China and Europe, Chinese Science, 11, 93-102.
2. [3]
3. [4]

Isambard Kingdom (talk) 17:15, 28 June 2015 (UTC)

Done. Isambard Kingdom (talk) 14:31, 9 July 2015 (UTC)

Big Rip[edit]

The article only briefly mentions the Big Rip scenario in the GR section. A new study gives further info, model of cosmic stickiness favors 'Big Rip' demise of universe prokaryotes (talk) 08:28, 2 July 2015 (UTC)

At this point the result is just a paper study.[5] It will need to predict verifiable results that can be tested. Praemonitus (talk) 16:43, 23 July 2015 (UTC)