Talk:Dark matter/Archive 4

This is an archive of past discussions about Dark matter. Do not edit the contents of this page. If you wish to start a new discussion or revive an old one, please do so on the current talk page.

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Dark matter proved unnecessary by frame-dragging effect(spinity)

I tried to modify the dark matter main page, but somebody deleted it. I am very diasppointed. But, I think I find out the truth. Dark matter is unnecessary!! Considering the frame-dragging effect derived by general relativity, dark matter is not neeeded. The frame-dragging force(I call it Spinity) is SJm/r^2, S=2G/c^2. If spinity is considered in deduction of virial mass, the newly modified virial mass will become 2RV^2/(G+SWr^2). The discrepancy of virial mass and mass estimated by light-to-mass ratio is greatly reduced. In Mily Way galaxy, newly modified virial mass is 10^6 less than original predicted virial mass. Thus, dark matter is unnecessary in the Milky Way galaxy. Please go the website Http://www.phy.ntnu.edu.tw/demolab/phpBB and type wanchung in search box. Or, please type frame-dragging and dark matter in google search box. You will find the title-dark matter proved unnecessary by spinity for detailed deduction. Wanchung Hu 15:37, 1 March 2007 (UTC)

I corrected a typo you made in your recent addition, but I can't otherwise comment on the content of your new text because I'm a non-expert. I have the article on my watchlist solely to watch out for blatant vandalism and/or mistakes in grammar. I'll leave it to the experts to debate the inclusion of this new information or not. - Itsfullofstars 17:46, 1 March 2007 (UTC)

I propose removing this, as it is clearly an advertisement for original and unvetted research. Speaking as a dark matter researcher I find the result pretty dubious, but that's irrelevant. If this work stands up to scrutiny it could be included in this article at some future date, but at least for now it doesn't fit in. —The preceding unsigned comment was added by JPFlip (talk • contribs) 18:25, 1 March 2007 (UTC).

Please see WP:OR. Wikipedia is not an appropriate place to publish your original research. --Reuben 20:00, 1 March 2007 (UTC)

Rewording last sentence (and other sentences in) the opening paragraph.

September 2007

Comment: this sentence:

"Fritz Zwicky used it for the first time to declare the observed phenomena consistent with dark matter observations as the rotational speeds of galaxies and orbital velocities of galaxies in clusters, gravitational lensing of background objects by galaxy clusters such as the Bullet cluster, and the temperature distribution of hot gas in galaxies and clusters of galaxies."

is confusing, in the normal English sense of being difficult to parse. I wish it could be reworded. My comment has nothing to do with the content. I don't feel qualified to edit this highly technical page, even in an attempt to clarify its use of language.

After comparing it to Fritz Zwicky#Dark matter, I think what the sentence means is: "Fritz Zwicky was the first to assert that dark matter accounts for observations of rotational speeds of galaxies..." continuing as before. But I'm not sure if that sentence would be true. Art LaPella 20:32, 16 September 2007 (UTC)

March 2007

"All these lines of evidence suggest that galaxies, clusters of galaxies, and the universe as a whole contain far more matter than is directly observable, indicating that the remainder is dark."

Any doubts about the evidence are covered by the word 'suggest' in the beginning of the sentence.

The last bit of the sentence could be stronger. "...observable, indicating that the remainder is dark." could be replaced with "...observable, making the remainder dark." Suggestions for other wording are welcome. Pukkie 10:43, 3 March 2007 (UTC)

That could work. It could also be "observable, and the remainder is dark" or "observable, and that the remainder is dark," so that the "remainder is dark" is already covered by the first "suggest." Right now the "remainder is dark" is sort of doubly-hedged, by "suggest" and "indicating," and I think you're right to try to change that. --Reuben 17:58, 3 March 2007 (UTC)

I changed it to "observable, and the remainder is dark". Pukkie 11:44, 7 March 2007 (UTC)

Question from a layman

Does this dark matter stuff relate in any way to the old Aether concept? —The preceding unsigned comment was added by 142.161.181.175 (talk) 20:00, 3 March 2007 (UTC).

There were several old Aether concepts, but Aether theories says "In physics there is no concept considered exactly analogous to the aether. However, dark energy is sometimes called quintessence due to its similarity to the classical aether." Dark energy is a lot like dark matter - neither can be created and studied in a laboratory. Enemies of dark matter enjoy comparing dark matter to aether or to any discredited theory, but of course that doesn't prove dark matter is real or unreal. Art LaPella 20:28, 3 March 2007 (UTC)

Yes. I believe that Dark matter is another Aether theory. Please see my above article(Dark matter proved unnecessary by frame-dragging effect). Dark matter is a wrong theory, especially in milky way galaxy. If dark matter really exists, it should exist in ellipical galaxies as well. But, there is no dark matter in ellipical galaxies from a research result in Science 2003,301(5640):1696 by Romanowsky AJ. Dark matter doesn't exist!!!!!!!Wanchung Hu 18:19, 6 March 2007 (UTC)

whether dark matter turns out to be another Aether theory is yet to be seen. however if you take out dark matter in cosmological models, its very hard to find good fits to cosmological data such as Sne IA and Cepheid red shift observations, cosmic microwave background, and matter distribution in the universe today. As you can imagine, these equations can be quite complex and often have degenerate consequences from changing variables such as the % of dark matter in the universe.

as of now, dark matter is just a word. there is no set definition; it is "defined" by its properties that it needs to have (i.e. nonrelativistic energy today) to not be detected and give the gravitational pull needed in spiral galaxies (or better worded , interpreted from observation). there is no particle in the standard model of particles that would fit this bill, although extensions do explain some of it like SUSY WIMPS or Axions. However, it might not exist at all and then we will have to look into General Relativity or Statistical Mechanics or experimental errors or etc etc. to explain this. This topic is current research, so we'll have to wait and see.

i believe that observational interpretation of some elliptical galaxies do show dark matter, although not at the level a lambdaCDM universe would like. NGC 3379 survey was the most recent one i believe; you can look it up on arxiv.org Wanchung, you have already presented you view along with a link. wikipedia is not a scientific forum as stated before. please write up a scientific paper and present it for publishing or pre-print online libraries such as arxiv.org so the scientific community can discuss you research. --Blckavnger 19:40, 6 March 2007 (UTC)

questions from a scientifically inclined laymen

Is it perhaps logical to think that dark matter/energy is perhaps only quasi real or maybe 1 dimension out of phase with our universe? —The preceding unsigned comment was added by Avatar of Nothing (talk • contribs) 23:01, 3 March 2007 (UTC).

Most any such Star Trek theory is arguable, as long as we can't catch the stuff and analyze it. Art LaPella 23:44, 3 March 2007 (UTC)

But isn't it to cover this sort of situation that Popper came up with his criterion of falsifiability. For any hypothesis to be given houseroom to start with it has to be open to falsification. If it's not falsifiable, it's not properly within the realm of science. Davy p 03:47, 4 March 2007 (UTC)

Sometimes lack of falsifiability is a function of lack of understanding. When Copernicus first penned De Revolutionibus he roughly proposed that there was no falsifiable way to distinguish between his model and Ptolemy. If strict Popperians had been around then, they would have roundly criticized him for being "extra-scientific". It was only after Kepler repositioned the Copernican model into the 3 laws of planetary motion and Galileo developed frame dynamics that people could see why the arguments used against heliocentrism were incomplete or based on misunderstanding of physics. Telescopic evidence that would falsify key-features of the geocentric model would follow only afterwards. --ScienceApologist 13:59, 4 March 2007 (UTC)

ok. So the concensus is I may be right, but at the current stage it must be assumed I am wrong because it can't be falsified, right? I wasn't originally thinking of ST but now that you mention it I am pretty sure they mentioned something about it a few times. Avatar of Nothing 15:26, 5 March 2007 (UTC)Avatar of Nothing

Dark matter 'proof' called in doubt

The Dark matter 'proof' has been called into doubt: http://space.newscientist.com/article/mg19125684.200-dark-matter-proof-called-into-doubt.html and http://www.eurekalert.org/pub_releases/2006-09/ns-dm090606.php Jazzman123 22:33, 23 April 2007 (UTC)

A few thoughts:

New Scientist is not a very authoritative source. It tends to put a very positive spin on anything outside the scientific mainstream, uncritically overlooking even very serious flaws. It's not a science journal, it's a popular magazine about science, with a particular editorial bent.
The Eurekalert link is just a copy of the article from New Scientist.
John Moffat's work on the Bullet Cluster hasn't been published in a peer-reviewed journal as far as I know, so it's also hard to use that as an authoritative source.
Moffat's work on MOG and other MOND-related work are good science, and are in no way "fringe" theories. Wikipedia should take them seriously.
We do need to be careful about uncritically using phrases like "direct proof of dark matter."

--Reuben 23:17, 23 April 2007 (UTC)

This is just another round in the dark matter vs MOND debate. One method adds extra matter, the other modifies the laws of gravity to make it look like there is more matter. --h2g2bob 01:15, 24 April 2007 (UTC)

Moffat has written 2 articles on astro-ph, neither of which he appears to be submitting to journals. If you're going to quote a results of a researcher, you should quote the papers and not news coverage of the paper. You can see the history of this article about how these results have over time been added, deleted, added, modified, deleted, etc. Wikipedia does not cover original research, only reports on refereed, published results, and astro-ph by itself is not publishing a result. 132.235.24.91 21:03, 29 April 2007 (UTC)

Can this unknown huge mass in cluster of galaxies proceed from dark holes? or can this huge mass of universe attached to dark matter do not exist almost at all?

Sounds a little crazy(or an answer) but what if the number of dark holes are more spread in the universe that we are thinking, if it number in a galaxy is huge(relative of course), they are (invisible)hard detectable even in our milky way - in far off galaxy almost impossible(at this time). Their presence can explain the needy mass in galaxies and cluster of galaxies and no wonder that this can do so distortion of behind light.

So this effect is not so hard proof for existence of influence of dark matter's attraction(or dark matter's huge mass) in cluster galaxies.

When we want to count the mass of universe of course we need to take in consideration not only the mass of the galaxies (including this invisible black holes) but and the mass of small particles like all radiation kind - alpha, beta, gamma.... photons (not sure about radio wave influence to mass but .......)

But... If is a little funny about the big influence of so small particles like light (photons) to the mass of universe what to say about dark matter particles much smaller like neutrino... ???...

Let's take some example:

Supposing, that universe represent an aquarium and we are some kind of life being in that aquarium that has the technology of an optic microscope and we try to calculate the mass off universe.... Oh ! this explain ... the mass of water is huge to other things BUT... let's think again the water can't be seen but it is sensed...

Supposing, that universe represent in this case a greenhouse where in the place of water is air and we have the same life being with technology of optic microscope and they try to calculate the mass off universe ..... ???.. . this is not the same thing, in this case the mass of invisible air (less sensed) is not huge...

Let's return to our problem, with our technology we hardly hardly discovered neutrino that isn't sensed at all...... maybe this small particles don't contain this mass that we try to attach to something (in we don't find it in this undiscovered black holes) or maybe it don't exist almost at all => maybe this can explain Why galaxies are estrange(remove, go away) from each other with acceleration ! (this deficiency of gravitation may be the reason why it can't keep galaxies together so they are estrange with acceleration having their angular acceleration from moving) or do you think is more real the theorem of some kind of "dark forces" pushing them away.

I'm not a scientist, just a ordinary student :) but waiting comment from real scientist :)

sorry if there are grammatical mistakes, but I hope you understand me :) Mark md4 16:56, 18 May 2007 (UTC)

I'm not a real scientist, but I believe their answer would boil down to: We've thought about things like that, but we just don't know. This page is intended to help us improve the Dark matter article, which is intended to report prevailing scientific opinions, so a better place to discuss theories like yours would be at blogs like [1] [2] [3] etc. (Warning: In general, there are a lot more theories from newcomers, than interest in them from experts.) Art LaPella 17:50, 18 May 2007 (UTC)

Hi Mark, you can also ask questions like this at the Wikipedia:Reference desk, where there is a "Science" category. I've found that very obscure and strange questions will usually get an impressively quick and complete answer there. For a short answer to your questions, cosmologists try to be as thorough as possible in studying the mass and energy budget of the universe. This includes radiation (photons are currently a very small part of the total), neutrinos (constrained to < 10% or so, probably much less), black holes (which are not completely ruled out as dark matter if they have certain mass ranges, but I don't know of models where this happens), etc. Electrons (a.k.a betas) and helium nuclei (a.k.a. alphas) are found in cosmic rays, so they are up there. There just don't seem to be enough of them to solve the dark matter problem. There could be dark matter particles much lighter than neutrinos: axions. They are a very good candidate, in fact. --Reuben 18:29, 18 May 2007 (UTC)

Art LaPella you are right, but I saw there up a "discussion" tab(I didn't understand it in the right way), thanks for links ;Reuben, I understand question for the desk, no debate on wiki. Mark md4 19:30, 18 May 2007 (UTC)

Dark matter=Celestial ether?

Is dark matter just another name for the celestial ether that was thought up in the 1800's and early 1900's and was later proved to not exist by relativity theory? —Preceding unsigned comment added by 72.69.85.212 (talk) 12:55, 21 June 2007

No. the central features of Luminiferous aether was that it was an all-pervading backdrop to the universe that was thought to interact (i.e. transmit) light. Dark matter, however, is much more lumpy, and only interacts with other objects by gravity. Mike Peel 19:16, 21 June 2007 (UTC)

Yes. At least according to the modern theoretical research of the dynamic aether fluid crystal-like structure (compare to this recent discovery) that permeates all space, accounts for the creation of matter and regulation of quantum activity and, in the macro scale level, for observed cosmological phenomena that defies the constantly patched standard model and derived popular theories.

Should you perform an analysis to the historical of a few articles, i.e. aether theories, you will also notice that editors around have been deliberately opposing-erasing the addition of these type of current data-research into the articles (allowing only historical references to what all know to be misconceptions of the 19th century physicist about an [inexistent] static or luminiferous aether, obviously discarded through the 1887 MMX). The direct relation between the term Dark matter, as expression[s] of our ignorance (see source) and the dynamic Aether subtle medium/substance is established (see link) by researchers as Dr. Harold Aspden, a physicist and electrical engineer (see background) whose Aether theory and derived predicted values (of proton-electron mass ratio, alpha, muon g-factor, electrostatic spin, etc.) is recorded in some of the major peer-review journals (i.e. Lettere al Nuovo Cimento and Physics Letters A); however data about this researcher, as all current data about the dynamic aether, was also recently banished as "fringe" and "non-notable" by Wikipedia's relativists science editors (see deletion log).

Yet, in order to discard the Aether they would have to erase not only Dark matter but all that is already experimentally termed as the vacuum energy and related vacuum fluctuations, the zero-point energy and more or less related effects, such as the Casimir effect, Van der Waals force, etc., and all currently ongoing experimental research in these fields. Well, but these relativists, along with the majority of the world, and in spite of all the recent observational results, still fanatically [my pov] adhere to the space-time, the big bang and the expanding universe wild stories... Cheers, from a truly layman in these fields of science. —The preceding unsigned comment was added by 213.58.99.29 (talk • contribs) 22:10, 12 August 2007 (UTC).

Molecular Hydrogen hypothesis

An article here: http://www.journals.uchicago.edu/cgi-bin/resolve?id=doi:10.1086/421111 appears to state that the authors detected large amounts of intergalactic(?) molecular hydrogen which they submit could constitute a significant part of the baryonic dark matter. I'm not able to look at it myself since it's behind a paywall, but I am wondering if this should be mentioned as one of the possible explanations of/sources for baryonic dark matter in the article.

I am aware that this hypothesis that dark matter is nothing more than H2 is promoted by various people who do not accept the Big Bang as a valid explanation for the origins of the universe (many of whom are cranks or else legitimate physicists who are clinging to old theories), but the article appears to be reporting on actual findings, rather than speculation... were those findings later found to be flawed? Glaurung quena 16:46, 24 August 2007 (UTC)

There's nothing wrong with those findings, and molecular hydrogen can be a big part (or the bulk) of the baryonic dark matter. There are also some people who claim that hydrogen clouds make up all the dark matter - and sometimes also claim that the same molecular clouds can explain away all kinds of other things, like cosmological redshifts. But leaving those theories aside, the finding that baryonic dark matter can be made up of molecular hydrogen clouds is perfectly real. Then we come to an issue of imprecise terminology. The term "dark matter" is often used to mean nonbaryonic dark matter in particular, since it's by far the most dominant component. The Wikipedia article is an example, as it only makes a few mentions of the baryonic kind. There's no separate article for baryonic dark matter, although there is a red link from this article. If you'd like to try clarifying the status of baryonic dark matter in this article, that would be great! --Reuben 18:30, 24 August 2007 (UTC)

Good reference?

I was recently pointed at this paper: Report on the Direct Detection and Study of Dark Matter, from "The Dark Matter Scientific Assessment Group (DMSAG), A Joint Sub-panel of HEPAP and AAAC." It looks like it would be a pretty good source for the article, as it summarizes many of the recent developments in the field. Since it is something of a funding recommendation, I suppose it might have a particular bias to it in that respect. --Starwed 09:28, 2 September 2007 (UTC)

Out of date? / Future events warning?

I found something that was out-of-date. Do you think we should tag this article as future events? {{future}} or something to indicate it needs constant updating, or perhaps keep a list of things that may be outdated very soon? How about moving all the discussions of potential future research and papers to a new section to make it easier to maintain? Or is just something generally accepted for this topic? Sentence in question: "In research due to be fully published in spring 2006, researchers from the University of Cambridge Institute of Astronomy claim to have calculated that dark matter only comes in clumps larger than about 1,000 light-years across, implying an average speed of dark matter particles of 9 km/s, a density of 20 amu/cm³, and temperature of 10,000 kelvins.[17]" -- Netdragon 19:14, 23 September 2007 (UTC)

As I understand it, scientific matters shouldn't be reported at all on Wikipedia until they've gone through peer review. It should be possible to find the publication and cite it properly in this case. If not, perhaps it should be deleted. That could apply to other preliminary results that have been announced but not published. Discussion of future experiments or research should be fine, but preliminary results are somewhat questionable. --Reuben 03:47, 24 September 2007 (UTC)

Here's one publication from Gilmore and others, covering part of the announcement. I haven't checked whether everything's there or not. astro-ph/0608528. This paper goes with their presentation from the 2006 UCLA dark matter conference, where Gilmore presented remotely. You can also find his slides here: gilmore.pdf. It will be published in Nuclear Physics B along with the rest of the conference proceedings, probably out ~ early 2008. --Reuben 04:01, 24 September 2007 (UTC)

Dark matter as Matrioshka Brains

It is equally reasonable, given the age of the universe and the possible evolution of civilizatiosn billions of years older than ours (see the work by Lineweaver's group), that there are many civilizations which have evolved to the Matrioshka Brain stage and which have decided to leave their galaxies, thus giving ruse to an abundance of "dark matter". Such civilizations which radiate energy at temperatures very close to the CMB temperature would be undetectable using current methods. Discussions of "dark matter" which do not take into account the end stage evolution of advanced technological civilizations (and what they would look like) are inherently incomplete.

Robert 11:07, 6 November 2007 (UTC)

Fourth Universal Field

I've removed (for a second time) a section that appears to be original research. The citation given was to a book published by a vanity publisher, rather than a peer-reviewed scientific journal. That is unacceptable for the purposes of Wikipedia. --131.215.123.98 20:32, 11 November 2007 (UTC)

Reply. I was the one who posted this topic. Being new to Wikipedia contributions, I was unaware of the policies upon which the removal was based. I now understand and I have no quarrel with the removal. Nonetheless, the topic is interesting to me and I would be pleased to see some talk related to it. The thesis that I had mentioned has a foundation in the writings of James Clerk Maxwell, but few researchers ever picked up that thread from him. If I posted a brief mention of the topic based on Maxwell's work and a few follow-ups from verifiable sources as a minority view, would the topic likely survive the editor's pen (assuming that the topic then appears relevant)? Ordovico 23:21, 11 November 2007 (UTC)

I still doubt that would pass the test. The equation you mentioned in the article looks a lot like gravitomagnetism to me (a low-order correction to Newtonian gravity which comes from General Relativity). Other scientists know about gravitomagnetism, but haven't suggested that that is an explanation for dark matter.

Nitpick: since this was put under "Alternative explanations", it would explain why DM need not exist. Lars T. 01:05, 12 November 2007 (UTC)

Granted. My point stands, however, in that scientists know about gravitomagnetism, but haven't suggested that it explains why dark matter need not exist. (Precision isn't always my strongest suit.) --131.215.123.98 01:22, 12 November 2007 (UTC)

All additions you make need to be based on material published in reputable sources -- e.g., Physical Review Letters, in this case. For example, a claim that it "obviates the need for QCD or string theory" is a pretty huge claim -- even for an unverified theory -- and would have to be explicitly stated in a very reputable source. Maybe you should introduce these kinds of edits on a talk page, and only move to an article after other editors have chimed in. --131.215.123.98 00:47, 12 November 2007 (UTC)

Orientation Question. Directed to the editor: why was I unable to detect the deletion of the article in the first place? My later changes were not an edit war but simply resulted from confusion about why the article was missing. I checked "related changes" where I expected to see entries disclosing my original addition of text and any later edits that removed my text, but I found neither. Should I have been looking elsewhere? Ordovico 23:26, 11 November 2007 (UTC)

"Related changes" is "a list of changes made recently to pages linked from a specified page". What you are looking for is the "watch" link on the top of the page. Lars T. 23:54, 11 November 2007 (UTC)

I think you want to go to the relevant article itself (not its talk page), then click "History", which is probably right at the very top center. Also, I'll note that I really don't think this was an edit war; I'm sure your edits were in good faith. Welcome to Wikipedia. --131.215.123.98 00:47, 12 November 2007 (UTC)

Small remark. You say that one should cite only reputable sources, well I agree on that. But why then there is still this picture of the ring-like dark matter structure in the article? There is no reputable source in the article. Furthermore, as far as I know, the results yielding this picture are not acknowledged and in wikipedia there should be only information that is correct for certain.
--René 21:17, 13 November 2007 (CET)

I thought it was gone. It shouldn't be replaced until it's cited. If you have a some evidence that it shouldn't be here, that might help convince whoever put it back. --131.215.123.98 01:49, 14 November 2007 (UTC)

Well, maybe the following link would suffice as citation: http://hubblesite.org/newscenter/archive/releases/2007/17/image/a/

However, of course there is no source stating that this is not accepted yet.

--René 08:45, 14 November 2007 (CET)

Are planets Dark matter?

"The composition of dark matter is unknown, but may include ordinary and heavy neutrinos, recently postulated elementary particles such as WIMPs and axions, astronomical bodies such as dwarf stars and planets (collectively called MACHOs), and clouds of nonluminous gas. Current evidence favors models in which the primary component of dark matter is new elementary particles, collectively called non-baryonic dark matter."

Are planets dark matter? Tyr Lord Of Combat (talk) 17:50, 13 January 2008 (UTC)

Look at the Wikipedia article for baryonic which will allow you to discern what non-baryonic means.--Jorfer (talk) 17:54, 13 January 2008 (UTC)

Planets would be classified as baryonic matter.--Jorfer (talk) 17:56, 13 January 2008 (UTC)

Well, I guess he knows and is trying to point out that "astronomical bodies such as dwarf stars and planets (collectively called MACHOs)" and also the following "and clouds of nonluminous gas" should be cut from the paragraph. Lars T. (talk) 20:43, 13 January 2008 (UTC)

Re new gravity model

Looks like this might be worth reading and mentioning in article:

"In a paper in the August 3 online edition of the Institute of Physics' peer-reviewed Journal of Cosmology and Astroparticle Physics, they put forth the idea that scientists were forced to propose the existence of dark energy and dark matter because they were, and still are, working with incorrect gravitational theory.
The group suggests an alternative theory of gravity in which dark energy and dark matter are effects – illusions, in a sense – created by the curvature of spacetime (the bending of space and time caused by extremely massive objects, like galaxies). Their theory does not require the existence of dark energy and dark matter.
“Our proposal implies that the 'correct' theory of gravity may be one based solely on directly observed astronomical data,” said lead author Salvatore Capozziello, a theoretical physicist at the University of Naples, to PhysOrg.com."

Dark Energy and Dark Matter – The Results of Flawed Physics? By Laura Mgrdichian, Copyright 2006 PhysOrg.com Discussion of J. Cosmol. Astropart. Phys. 08 (2006) 001.
http://www.physorg.com/news77190620.html

-- Writtenonsand (talk) 21:36, 31 January 2008 (UTC)

It could potentially be mentioned in the article, along with other modified gravity theories. The PhysOrg article is not a great source, though (and is from 2006). What would be needed is to show that this model has gained notability and been accepted by others in the field as a workable theory of gravity that's consistent with all observations in support of dark matter and dark energy. In particular, it would be good to see whether or not this modified gravity model is still in the running after the Bullet cluster observations. Unfortunately, I don't see a talk on non-Riemannian gravity at next month's UCLA conference [4], but there is one on observational tests of modified gravity theories in general, so perhaps it will come up. I encourage you to look for some current info on the status of the Capozziello et al. model. --Reuben (talk) 05:40, 1 February 2008 (UTC)

i believe this article already has a decent section on modified gravitational theories toward the end. i think its adequate considering the evidence for dark matter and the lack of success current alternative models of gravity have sofar. of course some day that may change, but i believe that the growing consesus is that dark matter is more plausible explanation than any modified theory so far. theoretical work will continue on modified gravity of course, and it could very well be that there is a needed modification as we explore large z>10, but at this point i think its fair to say that the majority of cosmologist agree on a mostly cold dark matter model--Blckavnger (talk) 16:16, 6 February 2008 (UTC)

Gravity

While we don't fully understand gravity we will not be able to understand dark matter, as the latter is so closely connected to first. For all we know gravity might work in a different way that we think and this will make up for the 'lack' of mass. —Preceding unsigned comment added by 195.204.65.2 (talk) 12:05, 7 March 2008 (UTC)

Is this a suggestion for how to change the article? Remember at Wikipedia, it doesn't matter what we fully understand here. Wikipedia is intended to reflect leading scientific opinions worldwide, not just ours. For more details see Wikipedia:No original research and Wikipedia:Verifiability. Art LaPella (talk) 21:13, 7 March 2008 (UTC)

What the gravitational physics community does not realize is that there has been a pretty recent major development in understanding of general relativity from the second order effect of the linearized theory. Dark matters, jets, gravitomagnetism, frame dragging force and Lense-Thirring force are all ill understood concepts in the theory of gravitation. The so called, dipole gravity, named after its origin from the linearized theory of general relativity is responsible for all of these effects.

The rotating sphere is a composition of the two gravitational dipole moments placed in the opposite direction. The domed side of the each hemispheres represents the repulsive gravity force of the dipole gravity which is responsible for the jets. Dark matter is ordinary matter that is in continuous motion following the dipole gravity force lines which comes out of the poles and returns back to the equatorial center. The reason they are not visible is because they are of the size of the rocks and traveling rapidly from the poles to the accretion center. Dark matters are the secondary consequence of the dipole gravity field. And this brings about the flat rotation curves for the spiral galaxies. So the flat rotation curve is the third level consequence of dipole gravity. In this picture, the jets and the dark matter problem are the two sides of the same coin.

I hope someone can revise this Wiki article to incorporate the concept of dipole gravity. It is too important to omit it here.

[5] —Preceding unsigned comment added by 70.128.182.230 (talk) 07:25, 8 April 2008 (UTC)

Once again, Wikipedia is intended to reflect leading scientific opinions worldwide, which I believe is what you mean by "the gravitational physics community". If that "community does not realize...", then I believe it's inappropriate for Wikipedia. Of course if you're right, then I wish you good luck persuading the physics community—but once again, Wikipedia doesn't try to decide, nor is it equipped to decide, who's right. It reports prevailing opinions. "Dipole gravity" doesn't even have a Wikipedia article of its own. A better place to promote ideas like "dipole gravity" is http://www.bautforum.com. Art LaPella (talk) 22:32, 8 April 2008 (UTC)

dark matter and redshift?

Would dark matter or I guess any gravitational field create a redshift in the light that passes through it?

It seems that the farther light travels in space the greater red shift it has. Could this be from the amount black matter gravity that has effected the time space that it has travelled?

--Tommac2 —Preceding unsigned comment added by 69.249.66.67 (talk) 05:26, 22 March 2008 (UTC)

This duplicates Talk:Big Bang#Is the universe expanding?. Art LaPella (talk) 16:44, 22 March 2008 (UTC)

IANA scientist, so.......

Because this is out of my field, I simply point out this. Maybe worth some sort of development/mention in this article? Kaiwhakahaere (talk) 23:10, 24 April 2008 (UTC)

IANAS either, but it's already mentioned. Dark matter#Detection of dark matter says "In April 2008, researchers announced at a physics conference in Venice that dark matter had been detected at the Gran Sasso laboratory.[19]", linking the same article. Art LaPella (talk) 23:53, 24 April 2008 (UTC)

Aaaaarrrrgggghhhhh. Ok, it has a mention, but how about a development (like a little bit more info)? Or is it not as earth shattering as I think? Cheers. Kaiwhakahaere (talk) 00:13, 25 April 2008 (UTC)

It is actually the same DAMA/NaI team. They have done experiments with the successor of DAMA/NaI known as the DAMA/LIBRA detector and confirmed the result they found with DAMA/LIBRA. I agree that we should rewrite the paragraph about detection of dark mater. We should say that DAMA LIBRA has now confirmed the DAMA signal. Also the DAMA/NaI page should be updated, the red link to DAMA LiBRA can now be filled in.

The relevant preprints we should refer to are: http://arxiv.org/abs/0804.2741 and http://arxiv.org/abs/0804.2738 Count Iblis (talk) 00:19, 25 April 2008 (UTC)

Not so dark?

Should the conclusions drawn from Danforth/Shull (05/20/08 "The Low-z Intergalactic Medium. III. H i and Metal Absorbers at z < 0.4" http://www.journals.uchicago.edu/doi/abs/10.1086/587127) stating that they have detected up to ~40% of "missing" Baryonic matter be included somewhere in this article? (Basically this supports the hypothesis that DM is made up of baryons that we have not observed) --Hyperion2010 (talk) 00:36, 21 May 2008 (UTC)

That article is about the missing ordinary baryonic matter, not dark matter. Of the matter in ordinary baryonic form, mainly hydrogen, that we know is out there, a lot is very hard to detect. Count Iblis (talk) 00:45, 21 May 2008 (UTC)

Cooperstock and Tieu

The work of Cooperstock and Tieu, several papers that have been peer reviewed and published in reputable journals, and which amounts to a major ongoing research program with considerable interest in the community of relativists, should be mentioned in the "Alternatives" section. I added yesterday a short section to this effect, sticking only to the facts - a short description of the import of their work, its origin in general relativity, and its reception by the community. This was immediately deleted. It is a valid alternative explanation, open to debate, but real work by real physicsts, and should not be suppressed. Antimatter33 (talk) 14:26, 16 May 2008 (UTC)

I'm not taking sides, but you seem unaware of previous debate. Search Talk:Dark matter/Archive 2 for the word "Cooperstock" to find several discussions. Art LaPella (talk) 21:02, 16 May 2008 (UTC)

This argument against their work (abs z and all that) has been specifically addressed by C&T and shown to be fallacious. A similar argument in electrostatics would be equally wrong. Their work remains of fundamental importance and more or less demands to be mentioned! The criticism was launched by a Polish grad student. Cooperstock has been doing GR for decades and has a raft of publications. Who do you trust?Antimatter33 (talk) 18:56, 23 May 2008 (UTC)

That wouldn't proof C&T are right even if it were the only article saying they are wrong - it isn't. And even their refutation has been dealt with [6].

For that matter, I have not been able to find that the original paper has actually been published in The Astrophysical Journal as originally said. Lars T. (talk) 21:16, 23 May 2008 (UTC)

This paper is so off base it hardly needs refuting (again the example of the similar problem in electrostatics can be invoked without implying an infinite charge distribution). Apparently there is a large confusion among researchers about what is a potential and what is a field, because they keep making elementary blunders. In any case C&T have answered this "criticism" as well, long ago now. And again I would point out that Menzies has nowhere near the stature of Cooperstock as a researcher, so it is somewhat embarrassing to see him make a fool of himself with such a completely wrong-headed "argument" such as this one.

http://www.slac.stanford.edu/spires/find/hep/www?rawcmd=find+author+cooperstock

Antimatter33 (talk) 18:58, 3 June 2008 (UTC)

So in which issue of the Astrophysical Journal was this paper published? It says it was "Submitted to Astrophys.J.", but not that it was published - and I couldn't find it at http://www.journals.uchicago.edu/loi/apj either. Why do you think it wasn't published? Is there a vast conspiracy going on? Lars T. (talk) 23:47, 3 June 2008 (UTC)

I know nothing about this particular series of papers, but an ADS search for these two authors yields only arXiv preprints—nothing published in a peer reviewed journal. That makes them appear like fringe theories that do not belong on Wikipedia. ASHill (talk | contribs) 23:55, 3 June 2008 (UTC)

Just click the link to SPIRES provided so kindly by me, above. The latest paper will also will appear in Mod.Phys.Let.A. C&T have a large correspondence with other relativists, myself included, and interest in their work is very keen. That it gets banned from this public page is outrageous. This is not a "fringe idea" - it is a straight application of ordinary GR.Antimatter33 (talk) 07:28, 4 June 2008 (UTC)

LSP?

In the introductory section several candidates for the possible dark matter component are put forward, but notably no mention is made of the lightest super partner (LSP). This candidate is certainly one of the likely favourites amongst scientists and should be mentioned accordingly. I would edit the article but I've just returned home from my 8th exam this month and am too tired to think about supersymmetry in any detail right now! Unfortunately the mass spectrum of SUSY particles does not necessarily have to resemble that of ordinary baryonic matter so there is no concensus as to what particle the LSP actually is, although, as I say, it is certainly a favoured candidate for the dark matter. Dazza79 (talk) 23:55, 29 May 2008 (UTC)

dark antimatter

the opposite of matter is antimatter...
but what is the opposite of dark matter? dark animatter?
or biuld the thee a triplett?

--hanmac —Preceding unsigned comment added by 89.61.67.218 (talk) 18:40, 11 April 2008 (UTC)

Not all matter has antimatter in the sense that they can enialate each other’s. When a particle is created, it is not created alone, but in a pair with another particle. That second particle is the 'anti-matter'. A proton and an anti-proton will enialate, but a photon which is its own antiparticle will not. It is possible that dark matter is made up by equal parts of some particles and their antiparticles coexisiting side by side. On the other hand, the big-bang left a universe with more normal matter than antimatter, so it is fully possible that this is the case for the dark matter as well. —Preceding unsigned comment added by 83.254.67.136 (talk) 17:39, 15 June 2008 (UTC)

It's one thing to understand all the complexities of this type of thing. It's quite another to be able to spell "annihilate" :-) —Preceding unsigned comment added by 79.74.73.242 (talk) 19:30, 26 June 2008 (UTC)

Is it silly to think...

...that as the universe expands large amounts of mass could slowly begin to move in behaviour similar to wavelengths, but on a macro scale? And as those paths reach movement proportionate to light wavelength ranges the total rest mass of a system could begin to slowly lower? If some of our methods of measurement use mass relationships, a disparity may start to occur between parts of the universe moving at different wavelength-type paths and we may not see why because we would be a part of that disparity. --RedFeather1975 (talk) 05:32, 25 June 2008 (UTC)

Some ideas are so ill-formed that they are "not even wrong". See Mu. So to answer your question: yes, it is "silly". WAS 4.250 (talk) 17:32, 25 June 2008 (UTC)

I'm not entirely sure why I said that. D: I think at the time I was so tired and thinking that natural tendencies try to reach phase transitions that follow the path of least resistance. And I may have misread somewhere that the outer systems in spiral galaxies are accelerating faster than they should be. I don't know. I need sleep! :( --RedFeather1975 (talk) 10:10, 26 June 2008 (UTC)

I noticed too that I was using wavelengths in that post. I just don't know what the right words are to describe what I must have been thinking. --RedFeather1975 (talk) 11:11, 26 June 2008 (UTC)

The rate of rotation of the parts of our galaxy do not match what gravity theory predicts if there is no dark matter, but can match if there is dark matter.

Out of Control is an excellent online book (click the links on that page). Read it and you will find out why you "said that". There is no "you". Or rather, you are a "society of minds" as Marvin Minsky puts it. WAS 4.250 (talk) 15:55, 26 June 2008 (UTC)

Ohhh. That book looks interesting. Thanks for linking it. :D --RedFeather1975 (talk) 04:43, 27 June 2008 (UTC)

Could this be the answer?

I'm no astrophysicist or anything but please bare with me. We know that Neutrinos seem to be in a state that one could almost say they were phased partially out of our reality... I mean being that they travel at the speed of light and billions of billions of them pass thru us each second yet they hardly ever react with any matter.

Could Dark matter itself be a form of matter but on the atomic scale part of it be sort of phased out of our reality....in a sort of not quite totally in this reality but not totally out of it either. But at the same time, still a whole of its own and still able to react with other matter of our universe?

Think of those 2 dimensional graphs u see that represent space and how all matter we know of bends that space... What if there were an additional graph that blanketed the space we know of (overlapping our whole universe) and could react with it, but was in itself in a state of being that allowed it to sort of stay fixed between matter and anti-matter?

I know, you think i'm totally insane right? Well, think of it this way. We have 0 and 1 don't we... 0 being the neutral and 1 being a positive. But, we also have -1... Anti-matter would be -1, being only theoretically possible (and possibly catastrophic if ever exposed to matter) to us on the matter side of the universe... but dark matter being the 0 would be in a fixed place between the two... Never being quite a total part of either, yet able to react with both on some things like say gravity?

I know i could be just blowing smoke, but i hope this helps to further the discussion and maybe it'll at least eliminate 1 birdbrained idea from the mix.

PS: If someone wins the Nobel using my idea i better get a little recognition. :) Xeroz (talk) 17:20, 27 June 2008 (UTC)

Dark matter is known to interact with us gravitationally so if there was any concentrated form of it, say a dark matter planet in our solar system, we would know due to its gravity effects, but if there were dark matter aliens walking among us we would not. On the other hand, we know dark matter does not interact at all with our kind of matter through electromagnetic forces, so they could not "walk" with us as they would pass right through the Earth without even noticing it. All in all, it looks like dark matter, is something like neutrinos, that is a ghost particle that just does not interact with anything very much except for gravity, so the "real world" is the world we can see with most of its mass in a form we can not see (except though its gravitational effects) in the form of individual particles that do not form any kind of structure - they remain particles gravitationally trapped in orbits around galaxy centers but farther from the center than regular matter which slows when it collides. Dark matter does not collide - basically it just goes right through both dark matter and regular matter like it wasn't there. Since it can't even interact with itself enough to collide, it can't interact enough to form structures like atoms or molecules. WAS 4.250 (talk) 20:15, 27 June 2008 (UTC)

Maybe it's just a force which developed through enough interactions and permutations of existing forces layering over one another. And it persists because it's circumventing particular factors which would interfere with it's natural evolution. Circumvention is potent in potential for preservation. But it can require a complex course of processes to build up to such a state. I just wonder if understanding it, might lie in thinking big over thinking small. --RedFeather1975 (talk) 00:15, 29 June 2008 (UTC)

Understanding it lies in experiments and observations and equations that make predictions that can be tested. WAS 4.250 (talk) 18:44, 29 June 2008 (UTC)

If the observed phenomenon is the result of a cosmic scale system of systems behaviour, is there an avenue of experimentation we can explore at this time? I am worried there isn't as of yet, and we will have to be very patient and prudent in our search for answers. --RedFeather1975 (talk) 01:43, 30 June 2008 (UTC)

We are limited to mathematical modeling and observing whether or not predicted observations are in fact observed for emergent phenomenon on a cosmic scale. WAS 4.250 (talk) 13:55, 30 June 2008 (UTC)

Moved material relating to bullet cluster

I know very little about this subject, but it was clear that the material relating to the bullet cluster was out of place in the lead section on observational evidence. It's placement made the article less readable, and appeared to be a tangent from the question "how do we know that dark matter exists?" I have therefore relocated it to a separate section further down. Someone more familiar with the subject may find a better way to integrate it into the article without disrupting the logical flow.zadignose (talk) 09:04, 30 June 2008 (UTC)

Hey WAS, nice sloppy and lazy revert. Don't revert over two edits without bothering to compare them, and don't revert at all as a short cut to fixing the problem. If you think the bullet cluster needs to be mentioned in the lead of the section, then REWRITE IT to show how it's relevant to the question "how do we know that dark matter exists?" The description of the bullet cluster PRESUMES DARK MATTER EXISTS, and does not explain in what way it serves as EVIDENCE OF THE EXISTENCE OF DARK MATTER. That's why I asked, in clear language, for someone to "find a better way to integrate it into the article without disrupting the logical flow." The revert is NOT a solution. The fact that the earlier edit was also reverted, though it was a clear improvement in presentation without removing or relocating any substance from the article, highlights what's wrong with simply clicking "revert" when you disagree with an edit. Apparently it falls to me to rewrite the text, and I invite anyone with more knowledge of the subject to improve it... not REVERT it.zadignose (talk) 08:07, 3 July 2008 (UTC)

Okay, I probably should have toned down my heated response to the reversion, but in any case I've attempted an edit that will hopefully improve the article. I hope it is found satisfactory.zadignose (talk) 09:22, 3 July 2008 (UTC)

I've revised the rewritten version a bit, but I'm not sure that mentioning the Bullet Cluster in three places (the article lead, the "Observational Evidence" lead, and a separate subsection in "Observational Evidence" is necessary. I also added a transition sentence to the discussion of the Bullet Cluster in the "Observational Evidence" lead to (hopefully) make it more clear why this result is so important. ASHill (talk | contribs) 15:06, 3 July 2008 (UTC)

I agree that the additional section at the end is likely unnecessary. I hesitated to completely remove what may be pertinant, especially the linked references, but I expect another editor could integrate what's most important and remove the rest.

I'm not so sure about some of the most recent edits. Particularly, I question the change of language from electromagnetic interactions (as it is also described in the article on the bullet cluster) to "collisions." It may just be a semantic distinction... when gasses collide, what force, if not the electromagnetic force, will most effect the velocity of the gasses? I don't think a collision mainly occurs between atomic nuclei, but more importantly, the reference to electromagnetic interaction relates directly to the first sentence of the article which defines dark matter as "matter that does not interact with the electromagnetic force."

I'm also very confused by "This is held as direct evidence of the existence of dark matter, independent of Newtonian gravity," though perhaps it's meant to suggest that Newtonian gravity couldn't account for what is observed? I think what's most important is that it is evidence of dark matter. The use of the word "direct" also seems a bit loaded.zadignose (talk) 08:37, 4 July 2008 (UTC)

I've clarified the description a bit. "Collision" is the term normally used in the literature to describe interactions between particles, although in the case of a plasma, it is indeed the electromagnetic force that is responsible for the interactions. My earlier removal of the term "electromagnetic" was because, as it was worded before, I thought it sounded like "electromagnetic" referred to the emission of X-rays. I hope I've clarified this ambiguity.

To my reading, the fundamental thing that's exciting about the Bullet Cluster result is that it shows directly that dark matter does exist; these data can't be explained by modified Newtonian dynamics. That doesn't mean necessarily mean that Newtonian gravity is completely right on large scales, but it does mean that dark matter must exist. I tried to clarify that as well, without giving MOND much weight.

I've also merged the two separate sections back together in one subsection, now within the "Galaxy clusters and gravitational lensing" subsection, with a brief version in the lead of the "Observational evidence" section. This organization seems the most logical to me, but there may be a better way. ASHill (talk | contribs) 15:28, 4 July 2008 (UTC)

Another question about dark matter

I was just wondering why dark matter, even if it exists as an exotic particle that is invisible to the electromagnetic spectrum, is not observed on Earth. I don't mean it like "why, if it's right in front of us, can't we see it", because the challenges of observing a truly invisible form of matter are obvious, but more like "why don't we see gravitational effects of this supposedly massive (in the strictest sense of the word, i.e. 'containing mass') substance in our everyday Earth-bound physics?" The mass of our planet is a known quantity, and we base that not on observed matter plus dark matter, but solely on observed matter. Same goes for our cars, our structures, and so on. Assuming there's more dark matter than observeable matter at a ratio of about 6:1, why doesn't this translate even a little bit (as I realize the argument I might be getting back would be something pertaining to the fact that dark matter is "lumpy") to what we can see? Goland (talk) 18:13, 6 February 2008 (UTC)

Great question! In a "standard" dark matter halo with dark matter made of exotic particles, the density of dark matter in the vicinity of Earth should be about 0.3 GeV / cm^3. According to google calculator, that's about 5x10^-25 times the density of water! So although the dark matter halo is more dense than the ordinary matter when you average over very large volumes (including mind-bogglingly huge empty spaces), it's far, far less dense than a planet. Actually, though, there's another, independent reason why we don't detect the dark matter in things like the mass of the Earth. Assuming the dark matter is not too clumpy, there's as much of it in any other Earth-sized volume as inside the Earth itself. This means that the gravitational tug of the dark matter in our neighborhood is pulling on you equally in all directions, and you can't detect it that way. On the scale of a galaxy, there's more of it in the direction of the galactic center than in the opposite direction, which has a huge effect on the orbits of stars (including the Sun) around the galactic center. --Reuben (talk) 01:29, 8 February 2008 (UTC)

If gravity causes baryonic matter to get clumpy and ultimately condense into stars etc, why doesn't the same happen to dark matter? Qemist (talk) 12:37, 27 July 2008 (UTC)

Illustration as Humor?

Alright, I get it. "Dark matter as it is currently understood." Big black square:

File:Dmatter square.jpg

An image used to represent Dark Matter as it is presently understood.

But is this page really intended for comedy? Or is this a post-post-modern riff on The Life And Opinions of Tristram Shandy? Nothing meaningful can be learned about dark matter from this. Maybe someone needs to make an article called "dark matter humor?" On second thought, no.zadignose (talk) 07:28, 12 July 2008 (UTC)

Archiving

This talk page is enormous, so I'll set User:MiszaBot to archive threads older than, say, 120 days unless there's objection. —Alex (ASHill | talk | contribs) 16:43, 27 July 2008 (UTC)

Alternative Explanations

I removed the statement: "However it is important to remember that if dark matter passes through matter freely, a detector created from matter has little or no chance of either proving or disproving the existence of dark matter or energy." This sounded a bit mystic! Dark matter may not be baryonic, but it is matter nevertheless and while it may interact weakly with baryonic matter, it will interact: the discusion on the DAMA experiment above discusses this. Perhaps the person who wanted to say this wanted to discuss the difficulty of detecting dark matter directly? If so, it should be phrased better.Perusnarpk (talk) 14:23, 28 July 2008 (UTC)

I changed the first line

Dark matter exists only within the Standard Model. We do NOT see effects. We see that the predicitions of the Big Bang are against observation, so if we use the Standard Model we have 2 ways: either the Standard Model is wrong, or there is something we do not see. Why don't you write that this simply?83.103.38.68 (talk) 09:57, 19 August 2008 (UTC)

WOW, nice rollback, completed with the request of explanations. Which are here and you didn't wrote a word here, only in the rollback action. All the netiquette got lost, when needed. But still no answers here. So what's the point of the message on the rollback?83.103.38.68 (talk) 13:30, 19 August 2008 (UTC)

You still haven't explained what this has to do with the Big Bang exactly. Lars T. (talk) 16:51, 19 August 2008 (UTC)

Introductory sentence

"In physics and cosmology, dark matter is matter". Are you sure? Wouldn't it be more fair to say the ONLY thing we know is that spacetime appears to be curved in ways we wouldn't expect? Perhaps it is something that resembles matter, but all we really know at this point is that our physics don't work. --Eleassar ^{my talk} 11:46, 28 August 2008 (UTC)

If it is not matter and the (apparant) extra gravity is caused by some other effect as suggesed by some theories, then we don't call that "dark matter". See e.g. the MOND theory mentioned in this article. Count Iblis (talk) 13:18, 28 August 2008 (UTC)

Perhaps it should say "is hypothetical matter", since it hasn't yet been proved to exist. And if it doesn't interact with electromagnetic radiation, how does it affect the cosmic background radiation? —Preceding unsigned comment added by 70.88.229.196 (talk) 16:31, 28 August 2008 (UTC)

I've changed it as proposed and added a pointer to alternative explanations. --Eleassar ^{my talk} 07:16, 29 August 2008 (UTC)

Dark Matter Pie Image

Uh.. can we take NASA seriously on this?? NASA 1) Doesn't actually know the size of the universe according to their own claims (they guestimate it based on some general assumptions such as the age of the universe) See: http://imagine.gsfc.nasa.gov/docs/ask_astro/answers/971124x.html! 2) Has not charted all of the universe (No need to source this claim, it's a given) 3) Cannot even prove that dark matter and/or energy even exist. (See top of page: It's all hypothetical)

Therefore, I believe the image showing 'Estimated distribution of dark matter and dark energy in the universe' should be entirely removed from the article. Any thoughts? 67.164.7.42 (talk) 06:58, 8 September 2008 (UTC)

Although the relevant portion of this article could be better cited, it is the overwhelming consensus of astronomers today that dark matter and dark energy exist in proportions very close to those indicated in that pie chart. This conclusion is based more or less independently on two different observations: 1) the fluctuations in the cosmic microwave background, which is indeed measuring the entire observable universe at the time of ~~reionization~~ recombination, and 2) uses distances and recession velocities of Type Ia supernovae to measure.

The statement at the top of the page that dark matter is all hypothetical (which was recently added) is not really supported by sources. There's not much debate in the scientific community about the existence of dark matter, although its nature is largely unknown. —Alex (ASHill | talk | contribs) 11:45, 8 September 2008 (UTC)

How much gravity does dark matter produce?

With relation to galaxies, do we have any idea how much gravity is missing ( associated with dark matter ) in an average galaxy? Can this be worked into a linear or volume density? Like 1 light year ^ 2 produces x amount of gravity on average. --Tommac2 It can be theorized that dark matter is the gravitational pull from the supermassive black holes in the universe. so in effect the singularity can be looked at with significantly more insight. strange matter may be the seperative pulls from one black hole to the next. It really all comes down to the bath water experiment: excite the water around the drain and a funnel occurs, this will effect all remaining water in the tub. —Preceding unsigned comment added by MrH3MinuteMile (talk • contribs) 05:53, 19 September 2008 (UTC)

Outer Surfers

Dark matter in spiral galaxies but not in globular clusters??? Are the outer stars of spiral galaxies surfing on some kind of gravity wave effect caused by the rotating centre (creating only the illusion of the presence of mysterious dark doughnuts)? --Vibritannia (talk) 12:51, 12 September 2008 (UTC) (Alex, I inserted the underlined words.)

Essentially all of the mass in globular clusters is in the stars, so they are held together by their own gravity. I'm not sure what you're asking. —Alex (ASHill | talk | contribs) 18:52, 10 September 2008 (UTC)

Error in 1st pagargraph

In the second sentence it states "According to present observations of structures larger than galaxies, as well as Big Bang cosmology, dark matter and dark energy account for the vast majority of the mass in the observable universe."

In fact the presence of Dark matter was first inferred from Zwicky's studies of the rotation of the Milky Way Galaxy, which showed the centre of the Milky Way rotated as if it were a solid, and that this could not be explained if visible sources of matter comprised the major composition of the Milky Way Galaxy. This needs correction. John D. Croft (talk) 13:12, 8 November 2008 (UTC)

You're mistaken on several points. Zwicky studied galaxy clusters, notably the Coma cluster, and not individual galaxies. Much later, it was shown that the Andromeda galaxy has a rotation curve with constant velocity at large radius. This was convincingly demonstrated by Vera Rubin using her own observations and those of other astronomers. Note that rotation as a solid body would have velocity proportional to radius, which is not what's observed. Finally, the rotation curve of the Milky Way galaxy has been especially difficult to determine, since our view is obstructed in parts, and because the radius includes extra uncertainties from the conversion from geocentric to galactocentric coordinates. --Amble (talk) 20:36, 10 November 2008 (UTC)

The rotation curve of the Miky Way is very precisely measured, and is the better measured rotation curve of any galaxy, but it is hard to measure it any better than that for the reasons Amble mentios above. —Preceding unsigned comment added by 58.240.157.37 (talk • contribs) 15:23, 30 November 2008

The velocity measurements for the Milky Way may be precise, but we have better rotation curves for other galaxies. You need both v and r to make a rotation curve v(r). We can measure v well for objects in the Milky Way, but r is difficult, since it folds in the uncertainty in the distance of Earth from the galactic center. For other galaxies, this is not a problem. See for instance astro-ph/0603143: "Surprisingly, the two nearest massive galaxies, the Milky Way (MW) and M31 (at an adopted distance of 780 kpc from McConnachie et al. 2005), have very poorly defined RCs. Our position inside the Milky Way’s disk makes it very difficult to interpret the HI outside the solar radius [...]" --Amble (talk) 01:45, 1 December 2008 (UTC)

warp in the disk of the Milky Way

The text: would explain the previously mysterious warp in the disk of the Milky Way by the interaction of the Large and Small Magellanic Clouds and the predicted 20 fold increase in mass of the Milky Way taking into account dark matter. is unclear to me. Does it mean that the "interaction of the Large and Small Magellanic Clouds" also accounts for "the predicted 20 fold increase in mass "? Or is the part of the sentence after "and the" constitute a partially formulated additional idea? Brews ohare (talk) 16:45, 8 December 2008 (UTC)

Dark Matter, in Prospective

Although I am not a student of astronomy or physics, is the theory of Dark Matter mostly attributed to this pattern?: Our moon, as all natural satellites, rotates around a planet; the planet rotates around it's parent star; A star rotates around it's parent galaxy's super-massive black hole; Galaxies, which travel, are caused by an unknown force, perhaps it is the dark matter that causes galaxies to movie? Or is it simply the gravity by it's neighboring galaxies that cause the movement? Or Both? I ask this simply because the article does not delve into this. Mdriver1981 (talk) 12:06, 19 September 2008 (UTC)

When on the topic of black holes, does that article, or perhaps the article about Micro black hole have any relevance for this article? —Preceding unsigned comment added by RBM 72 (talk • contribs) 00:11, 16 December 2008 (UTC)

Dark matter in the Earth?

What is known about dark matter within the Earth? Some upper limit must have been determined on the amount - if nothing else, it doesn't pile up past the mundane surface or else the space program would have been in trouble. ;) I suppose only cold dark matter is eligible to stay in such a confined space? Wnt (talk) 00:44, 17 December 2008 (UTC)

Shape of galactic dark matter

Sometimes I've seen illustrations that seem to suggest that a planar, rapidly revolving spiral galaxy would have a nearly spherical cloud of dark matter surrounding it. Is that so, or does the dark matter have a distribution reflecting an equivalent angular momentum? Wnt (talk) 00:44, 17 December 2008 (UTC)

Merger of Nonbaryonic dark matter

Merge. Nonbaryonic dark matter lacks context and is does not merit its own article.

Agreed. SwordSmurf (talk) 12:32, 8 November 2008 (UTC)

Agreed as well. The Nonbaryonic Dark Matter article has nothing that this article does not already contain. Not sure if that means the merger has been executed already, because Nonbaryonic Dark Matter still exists as a separate article. Verkhovensky (talk) 18:51, 11 December 2008 (UTC)

Agree, support merge as per above. AC+79 3888 00:44, 30 December 2008 (UTC)

Disagree. There is a separate article for baryonic dark matter, so there should also be one for nonbaryonic dark matter. UMinnAstro (talk) 21:29, 3 January 2009 (UTC)

Disagree Nonbaryonic dark matter is a notable topic in itself and well-suited for its own article. It can be mentioned in this article, but further details about it would be invited if it had its own article. Themfromspace (talk) 16:07, 23 January 2009 (UTC)

Agree with merge. That baryonic dark matter has its own article (which it still does at the moment) does not entail that nonbaryonic dark matter should. Nonbaryonic dark matter is the 'important' kind of dark matter, and is frequently what is actually meant in casual uses of the more general term. It is what this article should be (and is) mostly about. False vacuum (talk) 22:37, 3 February 2009 (UTC)

Discussion superseded by new actions: The contents of the Nonbaryonic dark matter article have been integrated into this one (after being improved somewhat), and the redundant article has been proposed for deletion. False vacuum (talk) 00:26, 4 February 2009 (UTC)

I'm no Scientist

But using Occam's Razor, isn't it much more likely that the "Virial Theorem" was just flawed? If I'm reading this right, when scientists applied their theorums and formulas to the real world they found that they weren't getting the results they thought they would, so rather than review their long accepted theories, they invented an invisible omnipresent entity to explain how the world works. Ironic, coming from scientists. 69.3.84.236 (talk) 14:52, 5 January 2009 (UTC)

This and the above are probably deletable forum chatter, but I should say that the point is that people didn't understand why a theory didn't seem to add up. If you come up with a theory that seems to explain many things and then it doesn't work on others, you have to fix it - you have to figure out what's wrong and by how much. So decade after decade people figured out what the theory said had to be there, how to measure it - all the while not having any "faith" that it really existed - and then finally deciding that there was some consistent evidence to support it existing after all. Really, science is full of invisible entities deduced by indirect means - atoms, germs, radiation, magnetic fields, (formerly) the rotation of the earth and such - and people have had to go through all this every single time. Wnt (talk) 16:30, 8 January 2009 (UTC)

Introduction should mention alternatives

Dark matter is not universally accepted as even being something that exists. There is a section about alternative explanations in the article. But the introduction makes no mention of this. The possibility that dark matter does not exist should be mentioned in the introduction - this is a key attribute of dark matter. —Preceding unsigned comment added by 71.112.21.41 (talk) 20:08, 10 February 2009 (UTC)

Lack of proof

This article has been written in a manner which leads one to believe that dark matter is non-theoretical, and rather something which is proven as fact. I would like to see greater mention of alternative theories, and would like to have the theoretical nature of dark matter mentioned throughout. While it has its merits, dark matter has not yet been proven, and so should be described in a way which states its nature as theory, its merits, and its shortcomings. While there is evidence to support that dark matter may exist, it should still be treated as theory, rather than what seems to be implied fact. Astroblah —Preceding undated comment was added at 08:10, 13 February 2009 (UTC).

The article isn't about the alternative theories, it's about Dark Matter. For that simple fact alone it already gives enough room to those alternatives — which are anything but proven themselves. Lars T. (talk) 22:24, 13 February 2009 (UTC)

There is now a very large amount of evidence in support of dark matter and few cosmologists seem to doubt its existence. I agree with the previous poster. Plenty of room is given to the alternatives, which are very unpopular amongst cosmologists anyway. C3lticmatt (talk) 19:37, 11 March 2009 (UTC)

EGRET update

Egret admitted that the overabundance in their spectrum was caused by a calibration problem in the high energy region. They withdrew the DM signature claims. Maybe somebody could update the article? —Preceding unsigned comment added by 134.61.14.52 (talk) 18:35, 25 March 2009 (UTC)

Please feel free to edit the article yourself, and especially to contribute references to sources for new information. Thanks! --Amble (talk) 18:38, 25 March 2009 (UTC)

Dark Matter and Dark Energy similarity

(this has nothing to do with the physics, just the words in the names) Since Dark Matter and Dark Energy have such similar names, I suggest there be a line at the top of the article to help the uninitiated differentiate between them (I don't know the difference (yet) and I actually visited solely to see that they were different). I suppose I'll add this to both articles I suppose.

To be clear, I'm suggesting something like:

This article is on Dark Energy, for Dark Matter see Dark Matter

I suppose the difference is fairly obvious now that I think on it though. --illumi (talk) 04:00, 12 April 2009 (UTC)

The article mixes the two concepts one of which is much better understood than the other. To introduce how much matter of the universe we are able to sense, the article could refer to the often repeated figures that the matter that we know about only is about 4% of the total mass of the universe, and the other 96% is unknown, or dark energy. That 96/4 split is a great lead and grabs people's attention. Instead the article places an unnecessary prerequisite on understanding the concept of energy density. "Only about 4% of the total energy density in the universe (as inferred from gravitational effects) can be seen directly. About 22% is thought to be composed of dark matter. The remaining 74% is thought to consist of dark energy, an even stranger component, distributed diffusely in space.[2]" Does this best serve the layperson attempting to understand the basic idea of dark matter? Not only must they understand energy density, but that we make inferences about "energy density" (not matter) by looking at gravitational effect. They would expect that gravitational effects could be used to make inferences about matter, and the article could leverage that information. Instead, it adds the broader consideration of energy. While achieving greater technical accuracy, we've lost the audience. I propose we bury the discussion of the relation to dark energy in the latter portion of the article, and instead use the 4%- 96% number, focusing on the matter/ dark matter distinction first- leveraging ideas about matter that are more generally understood. -J JMesserly (talk) 17:18, 22 April 2009 (UTC)

But the 96% is made up of several different things; only a fraction of it is dark matter. So the 96%/4% split doesn't tell you anything about the subject of this article. The important thing is to show that dark matter is much more abundant than ordinary matter, but still less abundant than dark energy. --Amble (talk) 18:44, 22 April 2009 (UTC)

Right. My mistake about numbers. The 4/96 split usually worded: "96% of the universe which leads to confusion since people associate universe with matter only. Anyway, 4% versus 22 percent is stunning- but not if worded that way. It means that for every 6 parts of matter in the universe we can only perceive 1 part. 5 times as much matter as we know in the universe is invisible. That grabs the imagination of the lay reader. Anyway, the energy of that piqued interest will carry most readers along a trajectory of understanding the gravity lensing and the behavior of spinning clusters stuff. All that is understandable enough, but you lose them when too much spooky stuff is thrown into the osterizer at one time. I still recommend not bringing up the dark energy concepts until the much more comprehensible dark energy is fully explained. -J JMesserly (talk) 06:36, 23 April 2009 (UTC)

Can I object to the use of "dark" in dark energy (end of para 3)as comparable to "dark" in the dark ages. It has nothing to do with human ignorance and everything to do with the darkness of the matter and so our inability to see it. Dark energy is different, there the darkness is one of ignorance. Whealgrace (talk) 13:07, 4 June 2009 (UTC)

Dark Matter is a new current event!

http://www.newscientistspace.com/article/dn9809-cosmic-smashup-provides-proof-of-dark-matter.html

— Preceding unsigned comment added by 83.95.217.27 (talk) 14:40, 22 August 2006 (UTC)

Technical tag

I have added a "This article is too technical" tag to the talk page. Because dark matter is a subject sometimes mentioned in mass media and popular culture, I think it needs an article that is layman-friendly, with the more-advanced information placed in more-specific articles or towards the bottom of this one.

The main problem with this article is that it suffers from Lazy Wikilinking Disease, in which editors feel they don't have to explain terms that are wikilinked. For example, one sentence reads, "Many of these (motions) appear to be fairly uniform, so by the virial theorem the total kinetic energy should be half the total gravitational binding energy of the galaxies." The sentence doesn't explain what the "virial theorem" or "gravitational binding energy" is. There's two problems with that. One is that readers shouldn't be sent on a wild goose chase through the encyclopedia to understand a single article. The other problem is that the unexplained wikilinked terms probably lead to even more-complicated articles, and if the reader can't understand dark matter, he or she probably won't understand virial theorem. (Indeed, clicking on virial theorem leads to an article filled with mathematical equations that will be incomprehensible to anyone without a physics or math background.)

This article needs someone familiar with the topic and is a good writer to rewrite it so it is aimed at a "general audience," -- people who know what a galaxy is but not what supersymmetry is. None of the more-technical information should be deleted from the encyclopedia, but it can be reorganized into more-specific articles, such as galaxy rotation curve. -- Mwalcoff (talk) 00:53, 23 June 2009 (UTC)

Observational evidence

Since the 1970:th until recent, studies of the speed of the satellites traveling through the solar system shows their speed to be slightly different from what could be expected. One of the most well know examples of this is the Pioneer anomaly. Some kind of force seem to act as if gravity were somewhat stronger than the theory of relativity predicts, or else, the solar system has a mass slightly larger than the sums of all objects taken into count. It is still unknown if this effect is due to dark matter interference, but that is listed as one of the possible explanations. RBM 72 (talk) 23:48, 27 June 2009 (UTC)

Detection section

I just rewrote this section. It was a bit of a scrapbook with lots of snippets on different experiments but no coherant structure. I fixed some of the points made above. It still needs improving - for example some more details of the general principles of dark matter detection.1414rwbt (talk) 20:59, 5 July 2009 (UTC)

Dark chemistry ?

If dark matter exists, we must suppose the existence of a dark chemistry. It is likely that in the future, there may be an article on such a hypothetical chemistry. 69.157.229.14 (talk)

Please sign your contribs by writing ~~~~ to date your signature. And no, for weakly interacting dark matter, we don't need to presuppose such a "dark chemistry", because it might be nonexistent. ... said: Rursus (^mbork³) 07:24, 6 October 2009 (UTC)

In texas?

The article begins "In texas and cosmology . . ." - - - tongue in cheek, what about the other States? I would fix this but am unsure of editing on WikiPedia, and am also unsure what the opening phrase is really supposed to say, being a book editor, not a physics major.

J. Kulacz 24.117.91.92 (talk) 06:51, 10 September 2009 (UTC)

Hi, that's already been fixed. It now says 'In astronomy...' - get yourself an account and learn to edit. There are ways of finding out what the article said before the vandalism. Let me know when you get an account (click on my name and then my talk page). Dougweller (talk) 08:06, 10 September 2009 (UTC)

Merging Dark matter in fiction

The concept is not something that requires an entire article. It should be placed here and kept down to two or three paragraphs. The lists are pointless and do not need to be kept, though a few important examples can be taken to be used in the paragraphs. TTN (talk) 18:26, 13 August 2009 (UTC)

Oppose per recent AfD. Artw (talk) 18:51, 13 August 2009 (UTC)

How does using a "no consensus" AfD to oppose something make any sense? If you believe that the information cannot fit here, please just state that instead. TTN (talk) 18:57, 13 August 2009 (UTC)

There was no consensus for deletion, which is what the merge would effectively be - or are you suggesting that anything actually be added to the article beyond the paragraph that is already there? Artw (talk) 19:02, 13 August 2009 (UTC)\

I'm thinking the beggining paragraphs and a decent number of examples for now. Either way, the current article would have to end up in that shape anyway. TTN (talk) 19:17, 13 August 2009 (UTC)

If it's going to be here, will this article's editors actually permit it? I get the feeling that article was created as a spinout of this one. Jclemens (talk) 18:53, 13 August 2009 (UTC)

Generally, they are only created because people keep piling on every single trivial reference to the topic they can find. They aren't usually split if they are actually kept down to a decent size. TTN (talk) 18:57, 13 August 2009 (UTC)

Right, but there's a tangibly greater resistance to WP:IPC sections in hard science topics than there are in general arts/literature articles. I've already gone through and pared the list down during the AfD, and flagged about half of the rest as unreferenced. If only the referenced sections were kept, that would still be substantially larger than the target size you advocate. In my mind, another AfD in a month or two would be a more straightforward way to handle it: either the list meets notability guidelines or it doesn't, but calling it a "merge" and deleting 90+% of the content is not the right way to get rid of the article. Jclemens (talk) 19:02, 13 August 2009 (UTC)

The problem with going back to AfD is that the system is completely hit or miss. If you get the right people, it is certainly possible to get this deleted on the second go, but at the same time, it is also possible that this could get to the fifth nomination without anything more the five "no consensus" results. Merging in the few decent references and a few of the examples is much better, as it allows for more control. TTN (talk) 19:17, 13 August 2009 (UTC)

Eh, I guess I'd rather see the entries that currently fail WP:V sourced or removed and the list kept as a separate article, so I guess that means I Oppose this merger as stated. Jclemens (talk) 19:49, 13 August 2009 (UTC)

The separate lists will have to be removed eventually, so there is really no benefit in keeping it. Even if you were to add references to every one of the current pieces of trivia, they would still be take up undue weight, and it would have to shift into paragraph format eventually. The proper way is to cite one or two for each different kind of media, and in a properly sourced article, they could probably be used to identify things like the first real use of Dark Matter in fiction and the like. TTN (talk) 20:07, 13 August 2009 (UTC)
- That eventuality isn't obvious to me from my reading of WP:SAL and WP:IPC. Jclemens (talk) 20:31, 13 August 2009 (UTC)

We do not have any featured lists that follow this kind of format (unless you can point any out), so that is one definite sign that these are doomed to either sit forever, be deleted, or actually be used to fill in the parent topic. Despite the fact that these are never sourced, it would actually be quite easy to do so if someone felt like it, and such a list would probably still be flat-out rejected for being trivial. TTN (talk) 20:40, 13 August 2009 (UTC)

Oppose merge. Good list that could be improved. Best, --A Nobody^{My talk} 20:36, 13 August 2009 (UTC)
Oppose. Almost all the examples in the 'Dark matter in fiction' article are very different to dark matter in astronomy. They are better as separate articles. Putting the fiction stuff here would distract attention away from the science and discourage experts from contributing to the article. 1414rwbt (talk) 11:58, 15 August 2009 (UTC)
Encourage separate in pop culture article(s) This problem arises regularly. Example: We have an article on Time travel (a serious subject in physics), but Time travel in fiction would totally take over the article if we allowed it to remain, so per WP:SS we make this a short section with the fiction article as the {main}. It could as well be called Time travel in popular culture. In fact, I recommend the essay WP:POPCULTURE for a realistic view of sorting out and off-loading these things to their own articles where they can grow. In fact WP:TRIVIA suggests that even separate "trivia" dedicated articles are not necessarily a bad thing (one man's trivia is another man's pop culture reference).
Now, we have this issue of spinning off articles from embedded lists. There's nothing wrong with an embedded list per se; not everything needs to be converted to paragraphs (WP:EMBED). If the subject is a valid one (and neither pop culture OR trivia are verbotten or against policy-- again see WP:TRIVIA) then the question of whether these things should exist as paragraph articles or lists, is entirely a matter of appropriateness. Some things are better put in both-- lists and paragraph articles are complementary. So, not only is there a Time travel in fiction paragraph article, but also the following "stand-alone" list articles, created as per WP:LIST. There is no shame in any of them, and they are more appropriate to the sort of focused and related facts they contain and catalog:
List of time travel science fiction
List of games containing time travel
List of video games with time travel

You see? Since WP is not paper, we can put all this stuff in, make room for it, categorize it, make sure it's not lost, and still not bother people who just want to read about physics. S B H arris 06:47, 27 October 2009 (UTC)

please provide the informatin about the dark matter ....

I need some information about the dark matter ... can anybody please give me that if you have effective information please please send me the emil address below... (Email Removed) —Preceding unsigned comment added by Pravinthe1st (talk • contribs) 19:45, 31 October 2009 (UTC)

Ring of Dark Matter

As far as I know, the community is rather certain that this ominous ring is an artifact, based on bad data analysis, namely circular correlations of noise. This assumption is also supported by the fact, that the group's description of their work in their paper was very fishy and partly self-contradicting. Therefore, I suggest to delete this part in the article.
--René 20:50, 17 October 2007 (UTC)

Some dark matter = Dyson sphere?

Anybody ever thought that perhaps life is more abundant in the Universe than we think, and the reason why we can't see a lot of the matter, is because any sufficiently technologically advanced civilization would capture all the energy of their star, or central reactor, and use it for life purposes, Dyson sphere style? Background microwave radiation would be the only "heat" radiation given off from the sphere. We neither know of materials or technologies of sufficient material strength for a Dyson sphere, nor technologies to radiate off "waste" heat in microwave, not infrared. But an O'Neill cylinder is quite within our technological reach today. Perhaps it's already constructed, but only people with special privileges get to live on it. Sillybilly (talk) 09:47, 8 November 2009 (UTC)

Dyson spheres as dark matter would be a form of MACHO, detectable by microlensing observations. The MACHO collaboration has observed very few microlensing events, after observing for long enough that many should have been seen if our galaxy's dark matter halo were actually made of MACHOs. Therefore, we can rule out Dyson spheres as a large component of galactic dark matter. Also, if they were radiating in microwave, they should light up the sky - and there are many telescopes observing in microwave. --Amble (talk) 17:04, 8 November 2009 (UTC)

GA Sweeps: On hold

This article has been reviewed as part of Wikipedia:WikiProject Good articles/Project quality task force in an effort to ensure all listed Good articles continue to meet the Good article criteria. In reviewing the article, I have found there are some issues that may need to be addressed, listed below. I will check back in seven days. If these issues are addressed, the article will remain listed as a Good article. Otherwise, it may be delisted (such a decision may be challenged through WP:GAR). If improved after it has been delisted, it may be nominated at WP:GAN. Feel free to drop a message on my talk page if you have any questions, and many thanks for all the hard work that has gone into this article thus far.

The references need to be tightened substantially. I count 16 paragraphs with no references whatsoever. There are a few specific instances of unsourced, possibly contestable statements that definitely need a citation; there may be still more that I have missed:
- "In the Bullet Cluster, lensing observations show that much of the lensing mass is separated from the X-ray-emitting baryonic mass."
- "For 40 years after Zwicky's initial observations, no other corroborating observations indicated that the mass to light ratio was anything other than unity (a high mass-to-light ratio indicates the presence of dark matter)."
- The first four paragraphs of the "Galactic rotation curves" section are full of uncited assertions
- "In the dozens of cases where this has been done, the mass-to-light ratios obtained correspond to the dynamical dark matter measurements of clusters."
- "The correspondence of the two gravitational lens techniques to other dark matter measurements has convinced almost all astrophysicists that dark matter actually exists as a major component of the universe's composition"
- The entire section: "Structure formation"
- "Hot dark matter cannot explain how individual galaxies formed from the Big Bang."
- "At present, the most common view is that dark matter is primarily non-baryonic, made of one or more elementary particles other than the usual electrons, protons, neutrons, and known neutrinos"
- "Experiments with the Large Hadron Collider near Geneva may be able to detect the WIMPs."

Ref added. Puzl bustr (talk) 20:06, 1 December 2009 (UTC)

- "The PAMELA payload (launched 2006) may find evidence of dark matter annihilation."
- "The Fermi space telescope, launched June 11, 2008, searching gammawave events, may also detect WIMPs."
- "In 2014 the LSST will be operational, one of the main goals of the telescope is to discover and learn more about dark matter."
- "An experiment planned to be carried out deep within a formerly abandoned mine in or near Sioux Falls, ND in 2016 hopes to further prove the existence of dark matter using a process called LUX (or Large Underground Xenon) detection."
- "A proposed alternative to physical dark matter particles has been to suppose that the observed inconsistencies are due to an incomplete understanding of gravitation."
- "Some M-Theory cosmologists also propose that multi-dimensional forces from outside the visible universe have gravitational effects on the visible universe meaning that dark matter is not necessary for a unified theory of cosmology."
The references should be in a consistent format, using {{cite web}} and similar templates if possible. Specifically, bare links such as ref #29 are unacceptable, and online sources should include information on the access date (in case the links go dead).
Stub sections such as "Popular culture" need to be expanded.
"These cosmological models predict that if WIMPs are what make up dark matter...." What cosmological models?
The second paragraph of "Structure formation" alternates between past and present tense.

These are minor concerns to be addressed, I will still likely pass this article without these changes, but they should be fixed before going up for Featured Article candidacy:

There are several instances of Words to avoid, such as "claimed," "however," "although," etc. Not all of these are necessarily bad, but look to avoid them in certain instances.
Single-sentence paragraphs in the "Detection" section should be merged into larger paragraphs.
The lead section is quite long; try to shorten it, possibly by introducing a new section below. The lead should also not contain any information not contained in the main article; it should be a summary, not a tease (see WP:LEDE)

I will leave a notice at the appropriate WikiProjects/userpages to hopefully get attention to these problems. This article should be fixed, or substantial, ongoing progress be made, by July 9. I plan on adding more problems later; I will extend the deadline if need be.-RunningOnBrains^{(talk page)} 17:13, 2 July 2009 (UTC)

Unfortunately, while a few improvements have been made, as of July 11, 2009, this article fails to satisfy the Good Article criteria. For that reason, the article has been delisted from WP:GA. However, if improvements are made bringing the article up to standards, the article may be nominated again at WP:GAN. If you feel this decision has been made in error, you may seek remediation at WP:GAR. -RunningOnBrains^{(talk page)} 07:03, 11 July 2009 (UTC)

A matter of style and mathematical correctness needs be addressed. In the article I find this: "there are 10 to 100 times fewer." It seems to me that "one time less" would be zero. If I have 5 widgets, one times five is five which, when subtracted from the original number of widgets leaves zero. So "there are 10 to 100 times fewer" leaves some kind of large negative number. It would be more precise to say that there are "one-tenth to one-one hundreth as many" or "1/10 to 1/100 as many" or "fewer by a factor between 10 and 100." 24.125.58.26 (talk) 20:20, 20 October 2009 (UTC)kjdamrau