Talk:Non-standard cosmology

Recent non-standard cosmology theories?

This [1] article explains that non-standard cosmologies (arguments against the Big Bang) are much less and less published in mainstream science journals as time goes on. I believe this is true. In the last ten years if you look for non-standard cosmologies hardly any appear in established peer-reviewed science journals. They always appear in fringe journals. The Wikipedia article on Non-standard cosmology doesn't mention any new theories. Nothing in the last 30 years etc.

There is a long list of non-standard cosmologies here. These are extreme fringe ideas published by mostly non-scientists in fringe journals or self-published. Psychologist Guy (talk) 11:53, 3 February 2021 (UTC)

Remember, the article lists MOND, f(R) gravity, and TeVeS. These are genuine theories. They are fringe compared to Lambda-CDM, but they are still genuine theories. You claim they are not published in established peer-review science journals, are you claiming the Astrophysical Journal is not an established peer-reviewed science journal? It published this paper [2] just a few months ago. What about this, published in Physical Review Letters? [3] If they are published less it's because fewer cosmologists work on them, not because they are bad science. You could make the argument that the article should not list these theories, but if you claim that they are "extreme fringe ideas published by mostly non-scientists in fringe journals or self-published", you are incorrect. Banedon (talk) 12:05, 3 February 2021 (UTC)

There is a distinction to be made between alternative theories for parts of Lambda-CDM and completely new cosmologies. Historically, there were a variety of cosmologies which denied the FLRW metric which neither MOND/TeVeS nor f(R) do. Also, it's important to acknowledge that the alternatives do not get the same level of exposure as the standard CDM explanations. jps (talk) 12:13, 3 February 2021 (UTC)

I still cannot accept the paragraph - it says "Big Bang opponents often ignore well-established evidence from newer research ..." but how many of the theories listed on the page are actually denying the Big Bang? It's extremely unfair to associate people working on many of the theories on the page with denying the Big Bang, some of them might even treat that association as an insult. Tying things to "denying the FLRW metric" does not work either, because you can still have the Big Bang without FLRW, e.g. this paper which challenges one of the core assumptions of FLRW is absolutely respectable science and was published in a respectable journal [4]. Again as long as the article lists respectable non-standard cosmologies, it should not have that paragraph. Banedon (talk) 12:28, 3 February 2021 (UTC)

No, I did not say they are never published in established peer-review science journals. The source I cited said that alternatives to the Big Bang are less and less frequently published in peer-reviewed journals. This is exactly the case. The papers you have listed are not what I would have in mind as a non-standard cosmology, they are just modified gravity theories. I don't think we should confuse non-standard cosmological models which challenge the Big Bang with modified gravity theories which are alternatives to just the cold dark matter model. I believe the "alternative gravity" section should edited to reflect this. The Tensor–vector–scalar gravity is not an alternative to the Big Bang. It's originator Jacob Bekenstein is a supporter of the Big Bang. Nor is f(R) gravity an alternative to the Big Bang etc. These are modified gravity theories, they are not alternative cosmologies to the Big Bang they are compatible with it. Of course, non-standard cosmologies sometimes make use of alternative or modified gravity theories but it is incorrect to this cite these as non-standard cosmologies. None of the authors you cited dispute the Big Bang and are proposing an entirely new cosmological model. Can you actually show a paper in a well respected peer reviewed journal that disputes the Big Bang specifically and proposes an alternative in the last 5 years? Very few papers of this kind have been published in the last 10 years. I see a lot of electric universe stuff but none of it makes it to peer review. Psychologist Guy (talk) 12:30, 3 February 2021 (UTC)

Are you arguing that modified gravity theories are not non-standard cosmologies? If so, are you also arguing that they don't belong on this page and therefore should be deleted? Banedon (talk) 12:33, 3 February 2021 (UTC)

It's hard to say. There are extravagant extensions to MOND which are absolutely non-standard cosmologies and, to be sure, many MOND papers and talks start out with a reference to cosmology rather than dark matter (which I've always found weird, but anyway). I think MOND, f(R), and TeVeS deserve inclusion here, but they are more successful at straddling the mainstream/fringe divide than essentially all the other topics on the page. This is the problem with a page where the inclusion criteria is just "not standard". jps (talk) 13:28, 3 February 2021 (UTC)

Also, challenging late-time isotropy does not, in itself, challenge the FLRW metric. Indeed, the paper authors you cite assume FLRW background because, I suppose, they have nothing else to replace it with. This is hardly "Big Bang denial" of the same sort then. jps (talk) 13:38, 3 February 2021 (UTC)

Banedon I think it depends on how we define non-standard cosmology, I am defining it like the author of the article I linked to, basically an alternative to the Big Bang model. Technically you are right because any model that challenges the ΛCDM model might be termed a "non-standard cosmology" by default, such as modified Newtonian dynamics, entropic gravity or any theory of modified gravity but I don't think that is what is in mind when readers check out our article on non-standard cosmology which talks about alternatives to the Big Bang such as the steady state theory. I also checked a bunch of textbooks that mention "non-standard cosmology", that term is not always used but when it is, it refers to cosmological models that challenge the Big Bang not just one aspect of it. We have an article Alternatives to general relativity. Maybe we need to create an article "Alternative to the Big Bang" where we list the Steady-state model, plasma cosmology and others. However, is there really any point because it would be a historical article. There doesn't appear to be any recent scientific alternatives that we can add references for.

I think it is confusing to list MOND, f(R) gravity, and TeVeS with the steady state and plasma cosmology etc because those researchers are not denying the Big Bang like plasma cosmology theorists. Even if you disagree, one observation of mine that I don't think you will deny is that this article is grossly out of date. Are there any modern alternative cosmology models that challenge the Big Bang? Our article mentions Fred Hoyle and Jayant V. Narlikar on a revised steady state model but that was 25 or 30 years ago and Eric Lerner's plasma cosmology was 20 odd years ago. What new information could be added to the article to improve it? Ethan Siegel talks here about how there are no recent alternatives to the Big Bang [5] "The last adherents to the ancient, discredited alternatives are at last dying away. The Big Bang is no longer a revolutionary endpoint of the scientific enterprise; it's the solid foundation we build upon. Its predictive successes have been overwhelming, and no alternative has yet stepped up to the challenge of matching its scientific accuracy in describing the Universe". The non-standard cosmology I am talking about appears to be a dead field. The source I originally added to the article notes that it rarely is published in peer review. Hopefully you agree on that. Psychologist Guy (talk) 15:35, 3 February 2021 (UTC)

Arguably eternal inflation-like theories are anti-Big Bang as would any theory that avoided a Big Bang singularity, but these are technical differences which probably do not deserve lumping. To be honest, I've always been a little uncomfortable with this article. It started out as a holding place for people who wanted their "alternatives to the Big Bang" ideas expounded upon (and you can see them scattered throughout the archives). There is a place for this kind of contextual information, but most of the article's topics were firmly fringe 15 years ago and today it's such a backwater as to be almost quaint. To the extent that anything is relevant to modern scholarship, it is those ideas that focus on niggling doubts regarding small parts of the theory... quantum gravity considerations, problems with the dark sector, inflation, etc. We may very well be looking at two different subjects here and spinning out might not be terrible. An article on dark sector alternatives might accommodate the F(r), TeVeS, and MOND ideas more naturally than "nonstandard cosmology". We can include a very brief mention of them and link over there. jps (talk) 16:02, 3 February 2021 (UTC)

I agree, for me the article is confusing certain topics together as one. I think someone needs to sort this mess out. I would support the creation of a new article or merging certain content into another. It seems this article was quite controversial 10 years ago but now has low-traffic, so I don't think it would be controversial to move content into another article. Interestingly I looked at the creation of this article, its been around since 2003 and the first editor defined non-standard cosmology as "any cosmological theory which argues that the big bang theory is incorrect" [6], over the years many different editors have lumped together many different theories. The outcome is a confusing article. Most users probably don't have time to fix this issue but I believe it should be sorted. Psychologist Guy (talk) 16:20, 3 February 2021 (UTC)

Just to chime in, I think splitting this into "old, totally fringe, and/or nonsense ideas" and "modern legitimate alternatives" is a good idea. What exactly to call those articles I'm less certain. I've been a Wikipedia astronomy/cosmology page watcher since the mid-2000s and the last few years have had a marked reduction in fringe peddlers. It's been rather pleasantly boring, and means that cleaning these up should be easier. I think such a separation would be worthwhile from an encyclopedic standpoint: Arp, Tired Light, and Plasma Cosmology really don't belong on the same page as MOND and the original steady state, for example. - Parejkoj (talk) 20:03, 3 February 2021 (UTC)

I have a soft-spot for Zwicky's original flavor tired light, but that story is less well-known than original flavor steady state, for sure. jps (talk) 20:39, 3 February 2021 (UTC)

It will be hard to draw a clear line between the two, because as jps mentioned, eternal inflation is also currently a legitimate theory without a "Big Bang" (in the traditional sense of the word). How about doing this: focus on the reputable alternative theories on this page, and have a small section with "old/debunked theories" with links to the main articles? Banedon (talk) 11:58, 4 February 2021 (UTC)

This has normally been the "fringe" article and I think its name indicates as much. While I am all in favor of WP:WEIGHTing the saner proposals in Wikipedia generally, I'm not sure this is the article to do that. Unless there has been movement in the literature towards using the term "non-standard cosmology" to mean anything vaguely at odds with vanilla Lambda-CDM. jps (talk) 12:19, 4 February 2021 (UTC)

I gotta say, although I still believe the sentence should not be included (and I think associating MOND, TeVeS etc with "non-standard cosmology" is defensible), I also think there are bigger priorities than fixing this article, e.g. a standalone article on Hubble tension. It doesn't look like any of us can actually spare the time to rewrite this article, either. Banedon (talk) 01:16, 9 February 2021 (UTC)

I have been digging a bit more into MOND to see how to distinguish it from other cosmological approaches. Right now, I'm not convinced it is so easily demarcated from other fringe proposals. Sure, it has far more "mainstream" champions than, say, plasma cosmology, but on the other hand its successes are constrained almost entirely to galactic dynamics and it is entirely unclear how it would be incorporated into a cosmological theory that excised CDM, for example. I just went down a little bit of a rabbit hole in Stacey McGaugh and David Merritt's work and see this as a glaring issue that both of them more-or-less tacitly acknowledge (Pawel Kroupa less so). Interestingly, then, the framing for novel cosmological approaches in terms of MOND really is not being done in the academic journals yet. The sentence, interestingly, still is rather accurate for it. f(R) theories, on the other hand, basically are only bandied about in PRL-type papers so in the context of those ideas there is less of an argument. Interestingly, a lot of f(R) theories ignore MOND entirely since they start from the action on the relativity side which is one of the "aesthetic" arguments against TeVeS. jps (talk) 13:19, 10 February 2021 (UTC)

Yeah, MOND has the glaring problem of "how do you explain the CMB?" with no good answer that I'm aware of. It is possible to come up with theories that reduce to MOND in some limit, though. Example. I would certainly call any cosmology based on this relativistic MOND theory a non-standard cosmology. Banedon (talk) 00:44, 11 February 2021 (UTC)

Wow, what a mess! It would be basically impossible to write a coherent "intermediate level" explanation for structure formation or the CMB on the basis of that. We could, perhaps, reframe this article to make that point explicit: it's the cosmologies that are based on MOND that are non-standard. And, additionally, they are not in the journals. Also, I found this to be as close as possible to a bird's eye view of the situation. jps (talk) 13:35, 11 February 2021 (UTC)

I reorganized the lede to try to relegate Big Bang denial to an era that precedes Lambda-CDM. This may help matters a bit? jps (talk) 13:46, 11 February 2021 (UTC)

Aaand... now I reorganized the entire article. The Big Bang-denying versus Big Bang-accepting cosmologies are now disambiguated for the most part. (Not sure about Dirac Large Number Hypothesis, actually... don't think anyone is taking that idea seriously). jps (talk) 14:21, 11 February 2021 (UTC)

I wrote a fair amount of new text and deleted some others (as jps mentioned I don't think anyone is taking Dirac Large Number Hypothesis seriously). I still think we should not highlight theories that deny the Big Bang in the lede - at this point it is a historical artefact, and the article as it is places (in my opinion fully justified) much more emphasis on modifications to Lambda-CDM and to GR. Banedon (talk) 06:35, 25 February 2021 (UTC)

I think this is fair. To decide whether to excise Big Bang denial completely is an interesting question. We could create a new article such as Historical opposition to the Big Bang where it might be more clearly couched and then we might avoid thornier issues. If/when we spin-out that first section into an article like that, we could reinvigorate an article like alternative cosmologies which could include the ones in the second and third sections. That might be a better way forward? jps (talk) 16:23, 28 March 2021 (UTC)

Alternative organizations

I wonder if there could be a better way to present this material. @OwenX

"Non-standard" is literally negative ("not-standard"), and I think most non-scientist readers will assume that this label is equal to fringe. However we have no theory that explains the finding which lead to the hypothesis of dark matter, including ΛCDM. The 'standard' is just the most conservative one; the alternatives are not necessarily fringe. The article Non-standard cosmology is a hodge-podge of things which necessarily will be incoherent (to be sure it is less incoherent than many articles!).

But what would be better? I think the "Alternatives to XX" approach is more neutral and already in use for Alternatives to general relativity and it is used in the section names here. This immediate points to an issue with this article: one of the sections is "Alternatives and extensions to Lambda-CDM" but Lambda-CDM is supposed to the Standard Cosmology, so that non-standard cosmology would be "Alternatives and extensions to Lambda-CDM" right? Furthermore, Lambda-CDM is described as the mathematical model for the Big Bang theory so are these two things or one thing? Are the alternatives two things or not?

So perhaps breaking out "Alternatives to Big Bang theory" and "Alternatives to Lambda-CDM" and summarizing them here would allow this article to better explain the interconnections between these subjects. Then this article would be "Alternative cosmologies" Johnjbarton (talk) 01:25, 23 December 2023 (UTC)

I'm fine with renaming this page to "Alternatives to Lambda-CDM" or "Alternatives to standard cosmology". Dark_energy#Other_mechanism_driving_acceleration also has some relevant content which may benefit from a "See also" to here. Of course, we'll have to do this all over again once astrophysicists come up with a better model that doesn't require as many fudge factors and cheat days, or in our case, cheat 10⁻³² seconds... Owen× ☎ 12:48, 23 December 2023 (UTC)

I don't really see the problem with "non-standard". It's about ideas that, well, aren't standard. If anything, "Alternatives to..." sounds a bit too positive; it carries the suggestion that the "alternatives" are all viable, which not all of them are. XOR'easter (talk) 17:40, 23 December 2023 (UTC)

Echoing this: Non-standard cosmologies are mostly not viable, that's why they're not the standard model. This has been a dumping-ground for a bunch of fringe stuff (I forgot that the sections on redshift periodicity and plasma cosmology was so long: that should be drastically trimmed), which is unfortunate, and probably wouldn't be fixed by renaming it to "Alternatives", unless you plan to just remove all the fringe stuff with that rename? - Parejkoj (talk) 18:46, 26 December 2023 (UTC)

Not all non-viable alternatives are notable, but some are, for historical, approximate, or pedological reasons, eg Newton's law of universal gravitation ;-) Plus (briefly) discussing the reasons for non-viable theories is itself helpful in clarifying what makes a successful theory. So I think the viability issue can be dealt with. Johnjbarton (talk) 19:47, 23 December 2023 (UTC)

I don't object to covering the empirically disfavored theories; as you say, they can be of historical interest or have other aspects that make them noteworthy. But if we're going to have both the disproved and the respectable-but-niche ideas all in the same page, I'm inclined to "non-standard" more than I am to "alternative". Of course, that's just my sense of the connotations. XOR'easter (talk) 20:34, 23 December 2023 (UTC)

That wording just hides the negation. Logically, it is still there because "alternative to X" implies "is not X". --Hob Gadling (talk) 07:37, 24 December 2023 (UTC)

GRSI merge

@‎Peterjol In my opinion the consensus was merge into Alternatives to general relativity not this page. Johnjbarton (talk) 02:46, 7 January 2024 (UTC)

There were two proposals: "Alternatives to general relativity" and "Non-standard cosmology." Merging into "Alternatives to general relativity" would be patently wrong, as GR-SI claims it is within General Relativity. For example, one of its papers has the title "An explanation for dark matter and dark energy consistent with the Standard Model of particle physics and General Relativity." Therefore, the only choice left was "Non-standard cosmology." If "Non-standard cosmology" is not suitable either for the merger, then the discussion on where to merge the page should be reopened and a suitable page should be identified. Peterjol (talk) 22:14, 17 January 2024 (UTC)

Doing what you think is correct is not what consensus means. It's up to you to reopen the discussion if you don't agree. Johnjbarton (talk) 00:07, 18 January 2024 (UTC)

@Banedon as you see, IMO this content should be on Alternatives to general relativity. It is consistent with GR but it is not GR. It calculates self-energy terms that alter the 1/r^2 so it's not general relativity. Johnjbarton (talk) 03:40, 18 January 2024 (UTC)

@Johnjbarton: I do not understand why you reverted, because the essence of my edit is at best tangential to the above. If this content really should be on Alternatives to general relativity, then my edit is appropriate; if the content should be in this article, my edit is still appropriate. Plus the edit dealt included text on things unrelated to this particular model. Please explain what exactly it is you want to discuss, and also how it is relevant. Banedon (talk) 07:58, 18 January 2024 (UTC)

@Banedon Sorry I know you were trying to make an improvement. Your edits, per WP:UNDUE, were (I gather) intended to scale the section to the other similar proposals on the page. Your edits moved the content, indicating that you too believe that this content belongs with similar proposals for alternatives to general relativity. Absent other information I would agree.

However, there is another choice. The content should be moved to Alternatives to general relativity per our previous consensus and then evaluated. On that page, WP:UNDUE would not require as much cutting, but more important the content would not need to be in a section of non-standard/alternative/other as your edit produced. On that page the work could have a section and another sentence or so and be reasonably represented.

Your edit also added to additional paragraphs without references. Johnjbarton (talk) 17:31, 19 January 2024 (UTC)

I'm with Banedon on this one: GRSI really doesn't appear to deserve more than a few sentences and one or two references, not multiple paragraphs and subsections. The other two topics Banedon added to "Other alternatives" have many many more citations (hence their own pages) and deserve a mention here, but none of them have any broad acceptance in the field. - Parejkoj (talk) 08:35, 19 January 2024 (UTC)

I'm not against reducing the GRSI. I'm against including it on this page. Johnjbarton (talk) 17:32, 19 January 2024 (UTC)

With all due respect, saying "alter the 1/r^2 so it's not general relativity" is not correct. 1/r^2 pertains to Newtonian gravity, not to GR. GR has a more complicated dependence in r. For example, the G^2 order correction beyond Newton is proportional to 1/r^3, see for example Bjerrum-Bohr, et al. Phys. Rev. D, 67, 084033 2003. You can also see that from the Einstein–Infeld–Hoffmann equations (en.wiki.x.io/wiki/Einstein–Infeld–Hoffmann_equations)

The starting point for GRSI is the Einstein-Hilbert Lagrangian, which Deur solved numerically. The only ways it is not GR is either if mistakes were made in solving the equations or if the numerical approximation is too rough. But we should not assume that (whatever our personal opinion may be) since GRSI results are published in top-tier research journals.

By the way, I still don't really understand why the original page for GRSI was not kept: the criterion of interest is not the number of citations of the papers in decent scholarly journals, but the interest of people (otherwise, a Wikipedia page on bigfoot or homeopathy would not pass the bar either). GRSI is discussed enough on forums to warrant a Wikipedia page explaining it. Take, for example, the wiki page on Withee (a small village in Wisconsin). A Google search for "Withee, Wisconsin" returns 31,000 hits while Deur "dark matter" returns 68,000. There are many of such Wikipedia pages on subjects that are less interesting (per google counts) to people than GRSI. I think you would agree that it is not easy from the papers and the forum discussion to understand what GRSI does; that (and the many forum discussions) is why I think a description of GRSI on Wikipedia is useful. Peterjol (talk) 16:01, 21 January 2024 (UTC)

If we look at the total cosmological model, what part does GRSI change? It only changes the GR part. The papers take great effort to show that existing cosmological results are explained by GRSI. Even if GRSI is as you claim only a more accurate calculation, the natural comparison is to other calculations of GR rather than to say plasma cosmology.

As for the notability argument, that needed to be made when the discussion occurred. I think generally Wikipedia Physics judges notability for new science almost entirely based on citation record. There is some allowance for popular (Cold fusion) or historical interest (Hollow earth). The critical criteria is discussion in secondary references (scientific review articles). Explaining GRSI to the public is the job of say Quanta magazine or Physics Today etc; wikipedia then summarizes that content. Johnjbarton (talk) 17:21, 21 January 2024 (UTC)

Proposal to delete the section "Exotic dark matter"

As far as I can tell the section "Exotic dark matter" is a repeat of Dark matter. Furthermore, dark matter is already "exotic matter" so "exotic dark matter" is not a thing. The section appearing here under alternatives to Lambda-CDM is confusing: the content is not an alternative at all. Johnjbarton (talk) 16:59, 23 January 2024 (UTC)

It certainly is not. Self-interacting dark matter, warm dark matter, and fuzzy dark matter are all not standard (remember that standard dark matter is CDM, that's why it's Lambda-CDM). If anything we should delete the MACHO sentence (which would indeed behave like CDM), but to be honest I inserted because you inserted it first. Banedon (talk) 02:17, 24 January 2024 (UTC)

The entire first paragraph discusses lambda-CDM. Johnjbarton (talk) 03:18, 24 January 2024 (UTC)

I'm fine with removing MACHOs from exotic dark matter, but now they are not mentioned in the entire article and yet they were/are-ish one of the alternatives. Seems out of whack to mention some stuff barely study and not MACHO. Johnjbarton (talk) 03:34, 24 January 2024 (UTC)

So is this supposed to be the dark matter article or the exotic dark matter section in non-standard cosmology? I don't get it. You seem to be both saying that MACHOs should be included, and saying that if we include MACHOs, we should delete the section, thereby removing MACHOs. Banedon (talk) 09:33, 24 January 2024 (UTC)

Yes, that is my complaint: the section is unclear. I'll just do an edit and let you look, maybe that will be clearer. Johnjbarton (talk) 16:12, 24 January 2024 (UTC)

MACHOs are non-standard cosmology.

I reverted an edit in which @Banedon deleted a section on MACHOs.

The purpose of this article, as far as I can tell, is to survey non-standard cosmology. As discussed in the text, considerable recent work casts doubt on the quantitative ability of the massive compact halo objects to explain the cosmological data that cause some to look for dark matter. Nevertheless these objects exist and are a part of the science of cosmology. The topic is significantly more notable than most of the rest of the article. It is also possible changes in measurement technology or theories could change as the results on MACHOs are still relatively recent. Johnjbarton (talk) 16:36, 26 January 2024 (UTC)

I don't see why MACHOs aren't part of Lambda-CDM. They'd simply be missing baryons. Can you explain? Banedon (talk) 03:09, 29 January 2024 (UTC)

I'm confused by your point of view. According to the missing baryons:

• "In general, the missing baryon problem is a major unsolved problem in physics."

The article Lambda-CDM model never mentions MACHOs. Johnjbarton (talk) 15:55, 29 January 2024 (UTC)

How familiar are you with cosmology? Tell me if the following is too technical.

Lambda-CDM is Lambda (aka Dark energy) + CDM (aka cold dark matter). Dark matter is anything which obeys ρ ∝ a⁻³ where a is the scale factor (see [7]) (Note this phrase can be used to refer to missing baryons too). "Cold" means that it became non-relativistic very early (see [8]), which is necessary to match observations. MACHOs are made of baryons, which means they are cold. Any MACHO that exists today would fall under CDM and therefore Lambda-CDM. Note Lambda-CDM does not require all CDM to be made of the same substance. It could be several different things, as long as they add up to the necessary mass density. Banedon (talk) 00:07, 30 January 2024 (UTC)

Thanks. If dark matter is standard cosmology and MACHOs provide an alternative explanation, then are they also standard cosmology? If MACHOs are standard cosmology, why the big fuss over them?

On the one hand the evidence that "MACHOs don't add up" is news: CDM still needs dark matter. But you are claiming that MACHOs are CDM. So why the news?

Let me put it to you a different way: should we have a paragraph on MACHOs here or in the Lambda-CMD article? Since there are not enough MACHOs, does that count for or against CMD? If MACHO failure is good for CMD, then its an alternative right? Johnjbarton (talk) 03:01, 30 January 2024 (UTC)

Boy, we have a massive disconnect here. Let's be clear, some number of MACHOs clearly exist, just not in sufficient numbers to explain Dark Matter. But that's not surprising, we have independent measurements that show that baryons account for no more than 5% of the universe's energy content. Since MACHOs would be made of baryons, and since Dark Matter is 27% of the universe's energy content, it's obvious that MACHOs cannot account for all of Dark Matter. (Phrased alternatively, it would have been shocking if we detected enough MACHOs to account for all of dark matter, since it implies an error in the CMB measurements.) Therefore MACHOs do not provide an "alternative explanation" for dark matter.

• should we have a paragraph on MACHOs here or in the Lambda-CMD article -- neither, the topic is kind of tangential.
• Since there are not enough MACHOs, does that count for or against CMD -- neither, it doesn't affect the conclusion at all. CDM still exists. What would have affected the conclusion is if there were enough MACHOs to account for >5% of the energy density, since as mentioned above it implies an error in the CMB measurements.
• If MACHO failure is good for CMD, then its an alternative right? -- again it doesn't really matter. There's no impact unless there are enough MACHOs to account for >5% of the energy density. Any number for MACHOs between 2.5% [because we can account for slightly less than half of the baryons in the universe] and 5% would attack the missing baryon problem, but not Lambda-CDM.

Banedon (talk) 03:24, 30 January 2024 (UTC)

Further point: MACHOs were potentially a big deal in the 90s and early 2000s, before we had as precise a measure of the cosmological parameters as we do now. We knew there was dark matter, but we didn't know it was mostly non-baryonic until roughly WMAP (2005). Since then, MACHOs have been mostly ruled out as contributing to dark matter (from CMB experiments and micro lensing) and from being a significant contribution to the missing baryons (from micro lensing). They're not non-standard (since we know some do exist and they would have fit within the standard paradigm) and they're not really "alternatives" (since we know there's definitely not enough mass in MACHOs to make much difference to various "missing" things). There's some mention of them in Dark matter, which seems appropriate to me. The recent chatter about primordial black holes is interesting, because black holes aren't really baryonic, but we've also never expected there to be a large enough number of them to matter; there are a few regions of parameter space left from micro lensing surveys for primordial black holes to matter (ha!) for dark matter, but not much. - Parejkoj (talk) 08:08, 30 January 2024 (UTC)

I appreciate that you are both trying to make solid physics arguments, and I'm sure that they make sense to you. I'm looking at this issue as a reader of wikipedia.

Are MACHOs notable? @Banedon indicates No: so we move to should delete Massive compact halo object? I believe we would agree that this would fail: MACHOs are notable.

Are MACHOs cosmological? Surely we can agree yes.

Are MACHOs standard cosmology or not standard cosmology? Here I cannot understand your logic.

• "What would have affected the conclusion is if there were enough MACHOs to account for >5% of the energy density"

So you are saying that MACHOs were non-standard until they were ruled too minor, at which point they became standard? I think you are then concluding that they are "historical" and not part of the current viable non-standard cosmology? I'm fine with that, but this non-standard cosmology article is >50% in the same category. To me you are making an argument based on physics but it does not line up with the article.

Our notable topic should be logically related to the cosmology articles. If MACHOs are non-standard, then we are done. If they are historical and thus not standard, then the rest of the historical material here should also be removed. If they are standard, then the short summary paragraph from this article should appear in one of the standard cosmology overviews. Johnjbarton (talk) 16:38, 30 January 2024 (UTC)

How do I explain it ... Are MACHOs standard or not standard cosmology? I doubt this question is well-posed, because you likely meant something different for 'cosmology' than what cosmologists would understand when they read your question. For cosmologists (and I don't think this is terminology most cosmologists use, but it is something they will understand), a "cosmology" is a cosmological model. Lambda-CDM is this particular set of parameters within the homogeneous & isotropic universe of the Friedmann equations, which is in turn derived from General Relativity [9]. In this context, then, MACHOs are not standard cosmology, no more than stars are standard cosmology, because they are not cosmologies. You likely mean something different, so you'd have to spell out what it is. Banedon (talk) 03:04, 31 January 2024 (UTC)

You explanation makes perfect sense to me. However it is not relevant. By "non-standard cosmology" I mean whatever this article means, which I can only gather from the material in the article.

How would your cosmologists greet Steady state, Tired light, periodic redshift?

I also think you are considering MACHOs like say "red dwarf stars", a category for astronomical observations. I agree it looks like that now, but imagine if the observations stumbled upon much more mass than they did? If you "believe" Lambda-CDM that is inconceivable, but of course that is why we have experiments in the first place. As far as I can tell the MACHO search was motivated entirely by the idea that more such mass would challenge CDM. I am wrong about that?

Your argument has convinced me that we shouldn't have the MACHO summary where it is. Which spot in which overview article is the right spot? Johnjbarton (talk) 17:00, 31 January 2024 (UTC)

Steady state cosmology is a different cosmology, in the sense of the word above. It leads to a noticeably different universe from Lambda-CDM, in particular one that adheres to the perfect cosmological principle when Lambda-CDM only obeys the cosmological principle. Tired light is also a different cosmology, since it overturns Hubble expansion. Redshift quantization would also modify Lambda-CDM, since it's not easily explained within the model and presumably involves modifying Hubble expansion.

MACHOs on their own have no impact on Lambda-CDM, in fact as pointed out above, some number of MACHOs surely exist. These would fit into the missing baryons segment of Lambda-CDM. The claim that MACHOs account for all of dark matter, however, would be non-standard. (In fact claiming that MACHOs account for more than >3% of the energy density would be nonstandard since the missing baryons are no more than 3% of the energy density. Naturally the higher this number goes the more non-standard it gets.)

I can't say why people started searching for MACHOs, but it's the obvious thing to do. A priori dark matter can span the entirety of parameter space, and it's very helpful to exclude portions of it with microlensing. (See also [10] Fig 2).

I don't think MACHOs should be in this article. A mention in dark matter is appropriate. Banedon (talk) 02:35, 1 February 2024 (UTC)

"I can't say why people started searching for MACHOs, "

According to Bernard Carr's 1994 article, it was an alternative to CDM:

• For a while "hot" dark matter was popular, but soon "cold" dark matter took center stage and many people still regard this as the "standard" model. In the past few years, however, attention has returned to the baryonic candidates-partly because of perceived problems in the cold model and also because there may now be direct evidence for baryonic dark matter. Carr, B., 1994. Ann. Rev. Astron. Astrophys., 32, 531.

So the people started searching for MACHOs as an alternative to CDM. Johnjbarton (talk) 03:38, 1 February 2024 (UTC)

While I was prepared to move the MACHOs paragraph to dark matter on your advice, the article currently explicitly excludes any baryonic alternative.

• ...the term "dark matter" is often used to mean only the non-baryonic component of dark matter, i.e., excluding "missing baryons".

Johnjbarton (talk) 03:42, 1 February 2024 (UTC)

In 1994, that was possible, yes. CMB acoustic peaks didn't come till WMAP (2005), then Planck (2013), which constrained the amount of baryonic dark matter to 5%. I don't see the relation with this article, however. Banedon (talk) 03:44, 1 February 2024 (UTC)

I moved the content to dark matter; please review. Johnjbarton (talk) 03:50, 1 February 2024 (UTC)

Post-fringe-y stuff removal discussion

Well, we're now well into the WP:BRD cycle... Looking at that paragraph again, I think it's a good fit for this article (possibly with tweaked text). MACHOs are not viable to account for dark matter, so they're "non-standard" in that sense and we should at least mention that non-viability here. There's I think an already appropriate amount of discussion of them in the dark matter article, which also says that they're not viable in the section on Baryonic matter. I think part of the problem is that this article itself is a bit of a mess (as reflected in various talk topics over the years). It's split between legitimate historical alternatives, mostly junk proposals, and legitimate current alternatives, roughly in article order. I think we could maybe just remove the entire "observational skepticism" subsection. In fact, I'll do that now and see who objects. - Parejkoj (talk) 18:58, 1 February 2024 (UTC)

I object, I don't think it's unreasonable to at least mention PC, Arp, and tired light, although they could probably be greatly cropped since they each have their own articles and can use {{main}}. Also, there's no mention of John Moffat's STVG/MOG work, which is at least as interesting as MOND/TeVeS, and well-published. — Jon (talk) 20:24, 1 February 2024 (UTC)

In the short term I object too, but in the long term I think we need to figure out what exactly this page is about. If this page is about concepts that were at one point in time plausible cosmological models that were later ruled out, then MACHOs would certainly fit. Banedon (talk) 00:23, 4 February 2024 (UTC)

I'm curious what the objection to the removal of Plasma Cosmology and Arp are? Neither of those was ever a viable alternative (PC was always a joke, and Arp never had a workable model, even if he did get citations). Tired Light maybe deserves a historic mention from the ~30s, but not really anything later than that. STVG probably does deserve a mention, yes. - Parejkoj (talk) 08:38, 4 February 2024 (UTC)

Well if we take the interpretation of "Non-standard Cosmology" as cosmological models that are currently considered non-standard, then one certainly can argue that plasma cosmology and redshift quantization deserve to be included. So the question ultimately comes down to: what do we want to include in this article? There's a similar discussion above [11]. It might be preferable to settle this via a RfC or something. Banedon (talk) 03:19, 6 February 2024 (UTC)

Except plasma cosmology (PC) and redshift quantization (RQ) were never really even remotely feasible. They barely even qualified as "science", even when they were introduced, with glaring holes in their statistics, observations, and models. The various iterations of RQ didn't really form a proper cosmology, that I'm aware of, just a bunch of "look at this collection of objects, it must be interesting because they're grouped together!" At least one version of PC had some math behind it and a vaguely coherent cosmology, except it always had a scaling problem and never really did a good job explaining anything rigorously.

You and I both participated in that discussion above from 2021! I think a distinction we should make is that this page is about alternatives that have serious scientific backing (e.g. MOND proponents acknowledge the problems it has and try to back it up with real math); I don't know if we need a central clearing house for all the other hodgepodge ideas that people have published over the years (including PC and RQ and a variety of others)? - Parejkoj (talk) 08:43, 6 February 2024 (UTC)

One problem I have with the page is the curious "burrowing" outline. The outer level matches the article title: non-Big Bang cosmology. But then we step down into one aspect of cosmology, non-standard-LCDM, followed by another step down into one aspect of LCDM, non-standard-GR. The non-Big Bang part was not very strong and the non-GR part is better handled in Alternatives to general relativity.

May be the goal should be more content on "Extensions and alternatives to Lambda-CMD?" Johnjbarton (talk) 21:35, 6 February 2024 (UTC)

If it's extensions & alternatives, MACHOs would still not be viable since they're currently observationally ruled out. If it's history, there's already a history section in the Lambda-CDM article. I'm leaning towards breaking this article into a "History of Cosmology" article, and an extensions article, then deleting this one. Banedon (talk) 02:56, 9 February 2024 (UTC)

I see that WP:BRD is a strategy. A strategy should have a clear aim or aims to be effective. Is that expressed anywhere for what this article should be about? I don't see it in the 'Article Policies' at the top of this page. Should I be looking elsewhere? (other that the lead section of the article itself) Hewer7 (talk) 10:54, 25 March 2024 (UTC)

Shockwave cosmology

We deleted the article on GRSI which was backed by a long series of articles touching on many aspects of cosmology. But now we have Shockwave cosmology based on one paper and the news articles spun out of it. Johnjbarton (talk) 17:06, 16 March 2024 (UTC)

Ooof, yeah, that one is similarly poorly supported. The original paper at least has more than a handful of citations, but I haven't looked at those cites to see if they're of any value. - Parejkoj (talk) 06:39, 17 March 2024 (UTC)

Shockwave cosmology first came to my attention in a book by Luke Barnes and Geraint Lewis, referenced in the article. They appear to say it is plausible, but not able to be tested. However the linked theory about an alternative to dark energy does have a possible test, although I haven't been able to find out what the status of that test might be. Do you know? Hewer7 (talk) 18:11, 23 March 2024 (UTC)

"The Cosmic Revolutionary's Handbook" by Luke Barnes and Geraint Lewis has a chapter called "BALLS FROM LEFT-FIELD" They use the shockwave model to illustrate their point "One popular misconception of the big bang model is that it describes an explosion." They point out that the shockwave cannot be tested and "This makes the model, from an observational standpoint, an unnecessary complication of the big bang theory.

The paper "An instability of the standard model of cosmology creates the anomalous acceleration without dark energy" linked in the shockwave cosmology article has 8 citations in Google Scholar, and zero of these are notable. Johnjbarton (talk) 18:40, 23 March 2024 (UTC)

Reading through "The Cosmic Revolutionary's Handbook" by Luke Barnes and Geraint Lewis, what stands out is how the descriptions of the majority of alternatives to the big bang theory end with a statement about how 'a rival falls'. Unusually, for this book, there is no similar statement about shockwave cosmology. Other ideas covered in the 'Balls from left field' chapter are also shown to fall due to evidence. Barnes and Lewis point out that there is no test for Smoller and Temple's 2003 paper, but they do not mention the related paper on dark energy that does include a proposed test, the one I ask about above. Hewer7 (talk) 11:01, 24 March 2024 (UTC)

IMO you are reading a lot into a minor omission. You are missing the most important overall point of the Barnes/Lewis book: the standard big bang theory is very well supported by standard physics models and no alternative model is really a contender. Johnjbarton (talk) 16:23, 24 March 2024 (UTC)

Well, this article is about non standard cosmology. I think the fact that Smoller and Temple have made a testable prediction related to shockwave cosmology is notable. Hewer7 (talk) 10:49, 25 March 2024 (UTC)

Dark Energy is Flawed or Nonexistent?

Seems recent studies suggest that Dark Energy thinking is seriously "Flawed" - or that Dark Energy doesn't even exist at all - if interested, my related pubished NYT comments may be relevant - in any case - Worth adding to the main "Dark Energy Spectroscopic Instrument" article - or Not? - Comments Welcome - Stay Safe and Healthy !! - Drbogdan (talk) 16:04, 8 April 2024 (UTC)

Advertising the discussion on multiple talk pages is ok, but it would be better to keep the discussion itself on a single page; I suggest WT:PHYS#Dark Energy is Flawed or Nonexistent? since it usually gathers the largest audience of interested editors. Jähmefyysikko (talk) 17:13, 8 April 2024 (UTC)

NOTE: A related discussion has been centralized on "physics Wikiproject", and can be found at the following link => "Wikipedia talk:WikiProject Physics/Archive April 2024#Dark Energy is Flawed or Nonexistent?" - iac - Stay Safe and Healthy !! - Drbogdan (talk) 22:24, 8 April 2024 (UTC)

References

Drbogdan (talk) 16:04, 8 April 2024 (UTC)