Talk:Dark matter

Dark matter and black holes

The following discussion is closed. Please do not modify it. Subsequent comments should be made in a new section.

Draft table

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Dark matter candidate Support for Evidence against Observed? Cold MACHOs Black holes Intermediate mass Frampton et al.[1][2][3] Please see also below. Garrett and Duda (2011)[4] Carr et al (2010)[5] Yes; dozens since 2009[6] Stellar mass Hawkins (2011)[7] etc.[8] Yes; from supernovae Micro Frampton et al (2010b)[9] Possibly as gamma ray bursts Other (Brown dwarfs, RAMBOs) No recent support Garrett and Duda (2011)[10] Yes, in insufficient quantities WIMPs Exotic neutrinos Garrett and Duda (2011)[11] D'Amico et al (2009)[12] Can not explain mass distribution in galactic halo centers and dwarf galaxies; not observed No Axions No Other No (less than 3 sigma[13]) Other (Hot, Warm, Mixed) No recent support No I welcome edits directly to the draft above from anyone who would like to add material from peer reviewed sources. If, however, you wish to delete material or make additions which are not supported by peer reviewed sources, please copy the table and make another one below. Thank you. 67.6.175.184 (talk) 21:20, 9 February 2012 (UTC) This gives a totally biased and non-NPOV view. The fact that black holes have been observed is not evidence that they can compose a significant component of DM. Many swans have been observed; are they dark matter? Any such table must be based on a published source by a reputable researcher, not on your OR and invalid synthesis. Waleswatcher (talk) 23:09, 9 February 2012 (UTC) This is not a synthesis, it's a collection of facts from the peer reviewed literature arranged in a tabular format. Please go ahead and create a different one if you disagree with it. Is there some aspect of it that you believe is not supported by reliable sources? 67.6.175.184 (talk) 23:31, 9 February 2012 (UTC) Here's a review by three experts http://arxiv.org/pdf/0907.1912v1.pdf . Kamionkowski is a leading expert in cosmology, a long-time professor at Caltech that recently moved to Johns Hopkins, and obviously a reliable source (the other two as well, but he's the most eminent). The review doesn't even so much as mention black holes. Due weight? Zero, according to that. Another review: http://arxiv.org/pdf/hep-ph/0404175v2.pdf The authors are well-established experts in the field. Silk is at Cambridge or Oxford, I forget, and is one of the dons of the field. It mentions MACHOs once, in passing, and never mentions black holes as a dark matter candidate. Due weight? Zero, according to that. Another review: http://arxiv.org/pdf/astro-ph/0301505v2.pdf again by an established expert. MACHOs are mentioned, with about 1/3 of a page devoted to them. He says they are directly ruled out by microlensing experiments as being less than 25% of DM at 95% confidence. That was 2003, the constraints have since gotten much stronger, as Carr et al show. Another review, this time in Nature, perhaps the premier science journal: http://www.nature.com/nature/journal/v468/n7322/pdf/nature09509.pdf It never mentions either MACHOs or black holes. It says clearly that WIMPs are the favored candidate, and then lists other possibilities (which don't include MACHOs or black holes). Lastly, one more review. http://downloads.hindawi.com/journals/aa/2011/968283.pdf Direct quote: "MACHOs can only account for a very small percentage of the nonluminous mass in our galaxy, revealing that most dark matter cannot be strongly concentrated or exist in the form of baryonic astrophysical objects. Although microlensing surveys rule out baryonic objects like brown dwarfs, black holes, and neutron stars in our galactic halo, can other forms of baryonic matter make up the bulk of dark matter? The answer, surprisingly, is no..." I found all of those via google, as the first few hits for a search on reviews of dark matter. I didn't in any way pre-select them or filter them. They make it blindingly obvious that MACHOs of any kind, and black holes in particular, are not taken seriously by the field as a dark matter candidate. By wiki's policy of due weight, black holes can therefore receive at most a passing mention, and only to say that they are believed to be ruled out (ref Carr 2011 for instance). Waleswatcher (talk) 23:33, 9 February 2012 (UTC) Certainly there are many papers about WIMPs which mention MACHOs only in passing or not at all. Drawing conclusions from that is forbidden synthesis, and absurd because the papers we have been discussing about MACHOs conversely mention WIMPs only in passing or not at all. Thank you for the additional sources. I will add them to the table. 67.6.175.184 (talk) 23:39, 9 February 2012 (UTC) Total nonsense. Four of those papers are reviews of dark matter, full stop. They are not papers about WIMPs, they are overall reviews of dark matter. Not one says that black holes can be dark matter - those that mention it at all say it's ruled out, and with time the evidence has gotten stronger than stronger. The other papers above are reviews of DM that indeed focus explicitly on particle candidates. They do so for a reason. It's very clear that you are unreasonable and will not be convinced no matter what the evidence. If you insist on inserting your OR, non-NPOV, and due weight violating material into this article, I will request intervention from other editors. Meanwhile, when I have the time I will edit the article to include a list of properties DM must have, that explains why WIMPs or other particles are regarded as the leading contenders, with material based on one of those reviews by experts. Waleswatcher (talk) 23:56, 9 February 2012 (UTC) I'm sorry, you are mistaken: Your second source above, for example, is entitled "Particle Dark Matter...." Of course it isn't going to mention MACHOs in any detail. Some of your other sources say that MACHOs are ruled out by CMB and wide binaries. You can learn that those data have been found to be obsolete if you read Frampton and his several colleague's papers, which I gather you are not inclined to do. It's a good thing their reviewers and editors did not share your absolute predisposition, because the results of those peer reviews hold sway in Wikipedia, not your personal opinion, no matter how steadfast. In any case, I look forward to your list when you find the time to make it. I have added the three most recent of the reviews you found to the table. I thank you for pointing out my errors. I hope in the future you will continue to do so, but more in the spirit of editorial cooperation instead of with incessant personal attacks and without assuming good faith. You don't happen to work for a lab which receives funding for WIMP searches, do you? I would urge others to read the abstract of the Nature paper you cited and the discussion in its comments. 67.6.175.184 (talk) 00:55, 10 February 2012 (UTC) No, you are mistaken. There are four (count them) reviews that are general reviews of DM. None of them have "particle" or "WIMP" in the title, because they are general reviews. Not one supports the view that MACHOs of any kind, and black holes in particular, can be DM. On the contrary. The are several other reviews that focus on particle DM - for obvious reasons. And no, I don't work in a lab, nor have I ever received any funding that has any relation to dark matter. I have no stake in this, but you quite obviously do. Waleswatcher (talk) 01:50, 10 February 2012 (UTC) Here's yet another general review of DM, from 2008: http://arxiv.org/abs/0901.4090 Those are notes from a summer school course on dark matter for Ph.D. physics students learning about cosmology and astrophysics, written and delivered by an expert in the field. Guess what? In the entire 57 page document, Hooper never so much as mentions MACHOs or black holes as a DM candidate. That's what, eight (I'm losing count) different DM reviews, all of which either say that MACHOs are ruled out or ignore them entirely? Do you want me to post the due weight guidelines again? Here they are: From Jimbo Wales, paraphrased from this post from September 2003 on the mailing list: If a viewpoint is in the majority, then it should be easy to substantiate it with reference to commonly accepted reference texts; If a viewpoint is held by a significant minority, then it should be easy to name prominent adherents; If a viewpoint is held by an extremely small (or vastly limited) minority, it does not belong in Wikipedia (except perhaps in some ancillary article) regardless of whether it is true or not; and regardless of whether you can prove it or not.Waleswatcher (talk) 01:58, 10 February 2012 (UTC) Suppose I start counting the adherents of Frampton's results prominent enough to pass peer review either as a coauthor of his or citing him approvingly. That will indeed be easy. We have both read the names of at least a dozen of them in the past day, I am sure. Will those be sufficient if I reiterate them for you, or should I also include the names of the editors who have accepted those papers? Where do you draw the line between accepting the judgement of the editors and reviewers of prominent journals and treating science as a popularity contest? Also, isn't it true that there has been more than $130 million poured into WIMP detectors in the past few months, while black hole studies require no special equipment other than what is already available on the Planck satellite, for example? How do you think that fact should influence how we judge the conflicting proposals? 67.6.175.184 (talk) 02:20, 10 February 2012 (UTC) Hawkins cites one Frampton paper (not the one you said he did) as evidence for a model that could potentially produce stellar mass BHs. He doesn't count, and neither do the authors on that paper, because it doesn't espouse your view either. A dozen? Nope, more like one. Not to mention that there are hundreds or thousands of dark matter researchers, and their views are made very, very clear in the EIGHT reviews I've provided, not one of which supports your contention. I'm sorry, but it doesn't get any more open-and-shut than this. If you persist in inserting material that violates wiki's policies I will open a case or request help from other editors. Waleswatcher (talk) 02:26, 10 February 2012 (UTC) "Also, isn't it true that there has been more than $130 million poured into WIMP detectors in the past few months, while black hole studies require no special equipment other than what is already available on the Planck satellite, for example? How do you think that fact should influence how we judge the conflicting proposals?" This isn't a NASA panel, it's wikipedia. Whoever you are (Paul?), give it a rest, please. Go write some papers, that will have much more impact than this silliness. Waleswatcher (talk) 02:26, 10 February 2012 (UTC) Thank you for reminding me that Royal Observatory Research Fellow Mike Hawkins is another prominent adherent of this theory you are baselessly calling fringe. I am most certainly not Paul, as you can see from my IP address that I am in Colorado. I am a statistician, not an astrophysicist, but still very well qualified to judge your absolutist stance as biased to the point of POV-pushing. At this point I have no reason to believe that a conflict of interest is not involved given the way you responded to my last question. You had the easy opportunity to deny that you are financially interested in these questions and you did not, striking out and accusing me of being Professor Frampton instead. I have had it with your continual personal attacks and threats. I have reported you to the Fringe Theory Noticeboard. Good day! 67.6.175.184 (talk) 03:02, 10 February 2012 (UTC) I think it would help the article if it included a second table (or perhaps a new section) that summarizes for all known gravitationally attracting particles, objects and energies (protons, neutrons, electrons, photons, large black holes, etc.) why they cannot comprise dark matter, for those that have been rejected as candidates. SEppley (talk) 15:07, 19 February 2012 (UTC) Good idea, but quite a bit of work to do without OR and with proper referencing. Waleswatcher (talk) 05:06, 21 February 2012 (UTC) I believe the controversy here is due to a strong disagreement about the extent to which microlensing studies have ruled out compact objects as dark matter. From my preliminary study, the belief that "our available statistics is still too small to draw definite conclusions on the dark matter content in the form of compact halo objects" (from http://arxiv.org/pdf/1001.2388v1.pdf) is currently the prevailing view, meaning that black holes of any mass are again allowed as viable dark matter possibilities. I'm very interested in others' understanding of this situation, as I've only recently started reading on it. Npmay (talk) 07:24, 6 March 2012 (UTC) That's not the case - the prevailing view among experts is that MACHOs are conclusively ruled out. Waleswatcher (talk) 04:44, 7 March 2012 (UTC) Source? Npmay (talk) 06:23, 7 March 2012 (UTC) There are at least six listed immediately above, starting with "Here's a review...". Waleswatcher (talk) 06:53, 7 March 2012 (UTC) I've looked at the first so far, and it doesn't have a description of why it doesn't consider compact objects; it just doesn't. I'll look at the others, but in the mean time, if you know, would you please help find the answers to the related questions at Wikipedia:Reference desk/Science#Do gravitational microlensing studies rule out compact objects as dark matter? Npmay (talk) 15:00, 7 March 2012 (UTC) If you want to see a summary of the evidence against black hole MACHOs, Carr et al (linked to above) is very recent and pretty complete. For baryonic MACHOs (brown dwarfs etc.) some evidence comes form microlensing, and there's also very strong evidence from cosmology (dark matter really cannot be baryonic). Waleswatcher (talk) 16:40, 7 March 2012 (UTC) I will look at Carr. I missed that one but I did find a discussion in Olive (2003) at the top of page 21 which only says MACHOs less than one solar mass had been excluded at that time. The other three sources I looked at don't seem to have any discussion of the reason why MACHOs have been excluded. Npmay (talk) 18:24, 7 March 2012 (UTC) The first thing I found when I searched for MACHOs in Carr et al (2009) was: "there are no constraints excluding PBHs in the sublunar range 1020 g < M < 1026 g [19–21] or intermediate mass range 102 M⊙ < M < 104 M⊙ [25, 40, 90]" but as it doesn't seem to go in to any further detail, I will track down those references and see what they have to say. Npmay (talk) 18:39, 7 March 2012 (UTC) Iocco et al (2011) has a fascinating discussion of avoiding various inconsistencies such as cuspy halos. It rules out adiabatic compression and shows that the expected ranges of density and galactic interior slopes are consistent with baryonic dark matter. Novati (2012) conclusively rules out compact objects under 0.l solar mass, isn't sure about 0.1-1.0 solar masses, and frustratingly doesn't say a thing about larger masses before abruptly concluding that more data is necessary. Npmay (talk) 06:12, 8 March 2012 (UTC)

Do gravitational microlensing studies rule out compact objects as dark matter?

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I'm copying this here from the Science Reference Desk since I wanted to follow up on the nucleosynthesis reasoning. Npmay (talk) 20:43, 10 March 2012 (UTC) Recently I noticed that there is quite a controversy about the composition of dark matter (see Talk:Dark matter#Draft table for instance) and while looking in to it, I found that there is some disagreement about the extent to which gravitational microlensing studies have ruled out compact objects as dark matter. I noticed that [14] specifically says that small numbers of microlensing events observed by the many searches "does not allow us to draw definite conclusions on the content of compact halo objects" as dark matter. That paper cites [15] which is by authors famous for mapping dark matter in the universe. It has this to say: "There have been extensive and sustained efforts to characterise the number of MACHOs in the halo of the Milky Way, its satellites the Large and Small Magellanic Clouds, and our neighbouring galaxy Andromeda (M31). Even though MACHOs are not visible themselves, whenever one passes in front of a star its gravitational microlensing briefly brightens the star. Since the volume of space along lines of sight that would cause microlensing is tiny, many millions of stars need to be continually monitored. Looking towards 12 million stars in the Magellanic Clouds for 5.7 years, the MACHO survey [306] found only 13–17 microlensing events (and some of these have been challenged as supernovae or variable stars). At 95% confidence, this rules out a model in which all of the Milky Way’s dark matter halo is (uniformly distributed) MACHOs. However, if all events are real, the rate is still ∼ 3 times larger than that expected from a purely stellar population, indicating either that they contribute up to 20% of the Milky Way halo’s mass [307], or a larger fraction of the Magellanic Cloud halo, in less massive bodies [308]. Also looking towards the Magellanic Clouds, the Experience pour la Recherche d’Objets Sombres (EROS) project [309] found only 1 event in 6.7 years of monitoring 7 million stars, compared to the 39 expected were local dark matter composed entirely of 0.6 × 10−7–15 M⊙ MACHOs. Looking towards the Magellanic Clouds and the densely populated central bulge of the Milky Way, the Optical Gravitational Lensing Experiment (OGLE) [310, 311, 312] detected only 2 microlensing events in 16 years, and even these events are consistent with self-lensing by stars, rather than MACHOs [313, 310]. The OGLE results conclude that at most 19% of the mass of the Milky Way halo is in objects of more than 0.4 M⊙, and that at most 10% is in objects of 0.01–0.2 M⊙. The POINT-AGAPE experiment [314, 47] observed unresolved (pixel) microlensing in the more distant Andromeda galaxy, and found that at most 20% of its dark matter halo is in 0.5–1.0 M⊙ mass objects (at 95% confidence)." Those seem like relatively narrow ranges, but my question is about conclusions regarding mass ranges which are open-ended upwards. If dark matter was composed of objects which were, say, 100,000 M⊙ on average, wouldn't that result in far fewer microlensing events -- because there would be so many fewer total MACHOs -- than could have ever expected to be observed in those studies? What is the reasoning involved in ruling out any compact objects larger on average than a couple dozen solar masses with any of these studies? Npmay (talk) 20:54, 6 March 2012 (UTC) Off the top of my head, if the (or some of the) hypothetical MACHOs were dozens of solar masses or more, it's difficult to see what they could be other than stars (in which case they wouldn't be dark – we'd see at least some of them) or black holes, in which case one might expect to see some (perhaps intermittent) recognisable radiation from any infalling gas and/or dust they surely would encounter occasionally. {The poster formerly known as 87.81.230.195} 90.197.66.254 (talk) 02:22, 7 March 2012 (UTC) Does anyone know where the numbers on the expected radiation from infalling gas radiation are compared to observation? Certainly accretion disks do not last forever, and once a black hole has cleared out its immediate vicinity, it is not clear to me how often matter would likely wander in to replenish it. Surely someone has calculated this? Npmay (talk) 02:49, 7 March 2012 (UTC) For black hole MACHOs, Carr et. al. is a good start. For baryonic MACHOs, the strongest constraints come from light element abundances etc. that rule out baryonic dark matter of any type. Waleswatcher (talk) 16:42, 7 March 2012 (UTC) I'm looking through the references cited by Carr et al which on page 3 says, "there are no constraints excluding PBHs in the sublunar range ... or intermediate mass range 102 M⊙ < M < 104 M⊙" but where can I find a discussion of light element abundances? I don't see why hiding matter in black holes or any other kind of MACHOs would imply a change in nucleosynthesis ratios, but I don't know where to start to read about that. Npmay (talk) 22:11, 7 March 2012 (UTC) If you change the ratio of non-baryonic, non-electromagnetically interacting dark matter to baryonic matter, you mess up all sorts of things in early universe cosmology. You can read about that in any modern cosmology textbook, like Weinberg or Mukhanov. Basically, those constraints rule out the possibility that dark matter is baryonic. As for primordial black holes in those particular mass ranges, I'm not sure what the other constraints might be. One thing I do know is that there is no plausible mechanism to create them. Also, if they get too light they would have evaporated by now. Waleswatcher (talk) 05:14, 8 March 2012 (UTC) Where should I look in Mukhanov (2005) for this? The discussion on page 70 ("The CMB fluctuations imply that at present the total energy density is equal to the critical density. This means that the largest fraction of the energy density of the universe is dark and nonbaryonic") doesn't exactly explain what would get messed up with baryons. What is the mechanism by which supermassive black holes are thought to have been created? Npmay (talk) 06:34, 8 March 2012 (UTC) Deuterium abundances are probably the place to start. That's very sensitive to the baryon density (because a proton and a neutron have to collide to produce it), and its measured value rules out the hypothesis that there are enough baryons to be dark matter. As for supermassive BHs, are you asking an entirely new question now (about the black holes at the center of galaxies), or about MACHO dark matter? If it's the latter, the answer is there isn't one. Waleswatcher (talk) 02:16, 9 March 2012 (UTC) I took a close look at that section, and honestly I am having difficulty finding the line of reasoning which eliminates the possibility of greater numbers of baryons in the same ratios. If you could walk me through that or point me to the page numbers, I'd appreciate it. My question about black holes is: Since it is widely accepted that supermassive black holes exist in about the same abundance as galaxies, are there any reasons that smaller black holes comprising some substantial portion of dark matter may have also formed in the same manner? Also, since we don't have any information about the composition of black holes, how do we know they are baryonic at all, and not mostly composed of electrons or mesons, or perhaps even the missing proportion of antimatter? Supermassive_black_hole#Formation cites [16] supporting the existence of a large population of IMBHs. Npmay (talk) 10:55, 9 March 2012 (UTC) Walking you through is too much to ask. The basic reasoning is simple - light elements form at a certain phase of the universe (when it's at the right temperature). The density of protons at that time determines their abundance (the greater the proton density, the more collisions and therefore the more elements other than hydrogen). So the abundance tells you the density of protons at that time, and it's much too small to account for the total matter density as measured today. Waleswatcher (talk) 15:25, 10 March 2012 (UTC) That is a great help to understand. Thank you! It also helps explain the inflation rate changes used to hypothesize a means of IMBHs formation: Since density is units per volume, if post-inflation expansion was not as much as a smooth transition (it's already speed up and slowed down once, so why not twice?) that would explain how the same temperature could produce more baryons from more matter at the same density. Npmay (talk) 20:52, 10 March 2012 (UTC) After reading on this question for a little while, it seems that while the overall rate of expansion in the post-inflation early universe is generally well understood, there is absolutely no way to tell whether fluctuations in that rate occurred or not, and thus the argument that the absence of fluctuations is preferred, limiting the extent of baryonic dark matter, for no other reason than that it is the simplest description of events. That seems extraordinarily flimsy reasoning, unless there is a way to quantify the relative likelyhoods. Does anyone know of anything more on the subject than that? Npmay (talk) 04:47, 11 March 2012 (UTC) Since this worked well last time, I have asked this question in greater detail at Wikipedia:Reference desk/Science#Is any evidence against fluctuations in the early universe expansion rate allowing baryonic dark matter? Npmay (talk) 05:17, 11 March 2012 (UTC) Fluctuations in the rate of inflation have a direct impact on the cosmic microwave background and are among the most precisely measured quantities in cosmology. A big part of the evidence against baryonic dark matter comes directly from that measurement. Waleswatcher (talk) 13:18, 11 March 2012 (UTC) You are certainly correct that the inflation rate is well measured by quantum effects resulting in large scale structures. I have edited my question using italics to show that I mean the post-inflation expansion rate before or during nucleosynthesis. My apologies for the confusion. Npmay (talk) 07:03, 12 March 2012 (UTC) If you change the post-inflation expansion rate, you could certainly alter those conclusions. But to change the post-inflation expansion rate you'd have to modify general relativity. Modified theories of gravity are an interesting and much-explored alternative to dark matter, but peripheral to this article. Waleswatcher (talk) 12:48, 12 March 2012 (UTC) I see; or, the strength of dark energy which is used to explain the initial rapid inflation? Npmay (talk) 22:40, 12 March 2012 (UTC) As for supermassive black holes in galactic centers, there are two theories. 1) Many individual mass concentrations (or density fluctuations, if you like) in the very first formations of clouds eventually becoming galaxies resulted in rather massive, however stellar-size primordial black holes, which collided while the galaxy was still in its formation. 2) After the big bang (or rather in the course of it), a significant amount of dark matter (theory according to supersymmetry, sparticles) formed in the first instances of the creation of the first particles (before protons and neutrons were formed) and joined to form both supermassive black holes as well as the first ever structure filaments of the universe. There is a string-theoretical description of black holes, named "fuzzballs". When you look down the article and look at the sources, there are four lectures on the subject by Samir Mathur (held at CERN), the third being the calculation of a stellar black hole, the fourth an extrapolation of these findings to the big bang and the likely development of the universe in string-terms. Hope this helps! 87.184.27.249 (talk) 13:37, 9 March 2012 (UTC) In both cases, are the supermassive black holes formed from aggregates of smaller black holes? Npmay (talk) 20:52, 10 March 2012 (UTC) That's hard to say, but black holes as dark matter are permitted and with luck we will know for certain soon. 71.212.246.55 (talk) 07:39, 25 May 2012 (UTC)

Evidence for intermediate mass black holes

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http://arxiv.org/pdf/0910.1152v1.pdf -- Frampton and Ludwick's 2009 basic 100,000 solar mass peak calculation for primordial IMBHs. http://www.sciencedirect.com/science/article/pii/S0920563210001003 -- Frampton's 2010 explanation of why 100,000 solar mass dark matter IMBHs are consistent with the orbits of wide binaries, microlensing, and galactic disk stability. (WIMPs still struggle with the cuspy halos, not to mention dwarf galaxies.) http://iopscience.iop.org/2041-8205/720/1/L67/pdf/2041-8205_720_1_L67.pdf -- Lacki and Beacom's 2010 "Almost All Or Almost Nothing" paper indicating that most all of the WIMPs would have fallen into black holes if there are more than a very small number of them. http://arxiv.org/pdf/1205.4012v1.pdf a very new paper explaining the conditions under which primordial black holes are allowed by nucleosynthesis element ratios; basically if inflation didn't happen at a constant rate. http://arxiv.org/pdf/1204.3619v2.pdf another very recent paper showing "new pathways to PBH dark matter candidacy" using reduced dimensional analyses. http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2966.2006.10801.x/abstract -- Lodato and Natarajan's 2006 theory of supermassive black hole formation which someone cited in opposition to the existence of IMBHs, but which actually describes the production of 100,000 solar mass black holes. http://arxiv.org/pdf/1205.6467v1.pdf -- this brand new paper suggests that supermassive black holes' early quasar behavior kept the other black holes from being able to grow. 71.212.249.178 (talk) 08:30, 10 July 2012 (UTC) I don't know about the others, but the Lacki and Beacom paper doesn't say what you say it does. It uses WIMP annihilations to set limits on the number of primordial black holes with compact WIMP halos. I don't see anything about WIMPs falling into black holes as such. --Amble (talk) 05:27, 11 July 2012 (UTC) "Our analysis does not apply if all of the dark matter is made of PBHs (e.g., Frampton 2009), because there will not be any WIMPs to annihilate." 71.212.249.178 (talk) 15:27, 11 July 2012 (UTC) That does not in any way support your incorrect summary of the paper. Respectfully, I'm not sure you've correctly understood these articles. That's part of why Wikipedia shies away from relying on primary sources: it takes quite a bit of specialist knowledge to understand them and gauge their significance. --Amble (talk) 21:31, 11 July 2012 (UTC) Where do you think the WIMPs would go? With about one atom per cubic centimeter in the interstellar medium, how often do you think any of the million IMBHs at 100,000 solar masses (about 1 per 300,000 stars) would be visible in our galaxy? 71.212.249.178 (talk) 21:58, 13 July 2012 (UTC) Sorry, but these questions have no bearing on whether your summary of the paper is accurate. It isn't. Could you say a little bit about what specific changes you'd like to see in the article, and how you expect the list of papers and preprints to be useful to that end? --Amble (talk) 22:26, 13 July 2012 (UTC) What in particular do you think my summary of Lacki and Beacom gets wrong? I am in favor of including the #Draft table but first replacing the sources for intermediate mass black holes in this subjection to complement Frampton et al's papers. Also it might be a good idea to wait a month or so for NuSTAR results. 71.212.249.178 (talk) 00:04, 14 July 2012 (UTC) Everything: the paper simply doesn't say any of what you attribute to it. As for the article, there is absolutely no way that we are going to add this table based on your reading of primary sources. And as for NuSTAR, it only launched a month ago. It's not going to have any results that can go into the article within the next month or so. --Amble (talk) 00:14, 14 July 2012 (UTC) Can you please be more specific about what you believe has been misrepresented? 71.212.249.178 (talk) 21:44, 14 July 2012 (UTC) I have already noted that your summary talks about WIMPS falling into black holes, while the paper does not talk about WIMPs falling into black holes. How can I be more specific than this? It's a bit like asking for a list of the people who specifically haven't walked on Mars (with dates and locations). But again, none of this is relevant to the article. You're trying to use primary sources in a way that's not in like with Wikipedia's fundamental policies on verifiability, and no amount of discussion of the sources themselves is going to change that. If you want someone to try to help you understand the papers, you could take it to the reference desk or my talk page. --Amble (talk) 00:10, 16 July 2012 (UTC) Why do you suppose the UCMHs mentioned in the paper would form? It's because they are accreting around a black hole, isn't it? How do you suppose they would manage that without many if not all of them falling in? Those constraints are shown in blue on the right side of Figure 2. 71.212.249.178 (talk) 07:46, 16 July 2012 (UTC) I could suppose lots of things, but then we would no longer be talking about what the paper actually says. Since none of this is relevant to improving the Wikipedia article, I don't see a reason to continue this discussion here. You could try the reference desk or a physics discussion board instead. --Amble (talk) 14:46, 16 July 2012 (UTC) I frequently participate in WP:RDS discussions about dark matter. Why don't you ask whether I have correctly characterized the paper in question there? Why do you think this discussion isn't pertinent to improving the article? 71.212.249.178 (talk) 23:28, 16 July 2012 (UTC) Please see also http://arxiv.org/pdf/astro-ph/0407285v1.pdf, http://arxiv.org/pdf/astro-ph/0602388.pdf, http://arxiv.org/pdf/1008.5147v2.pdf, and http://arxiv.org/pdf/1203.4100.pdf 71.212.249.178 (talk) 15:27, 11 July 2012 (UTC)

The discussion above is closed. Please do not modify it. Subsequent comments should be made on the appropriate discussion page. No further edits should be made to this discussion.

Assumption of correctness

Ok - I'm not arguing for or against the concept of dark matter. However my understanding is that it is a theory. Granted it's the most commonly accepted theory at this point in time, but it remains a theory does it not? However the article seems significantly biased towards the assumption that the theory is a proven fact ... for example:

"Dark matter came to the attention of astrophysicists due to" (first sentence, second para) which implies that astrophysicists 'found' something rather than observed phenomena and theorized an explanation. Even more so "Though a fourth category had been considered early on, called mixed dark matter, it was quickly eliminated (from the 1990s) since the discovery of dark energy."

I believe that dark energy is another theory, not a proven fact, so it hasn't been discovered ... it's been hypothesized.

I can't do it - I'm not knowledgeable enough in this ... but I really think this article needs to be examined for NPOV by someone who's fully up to speed and can differentiate between most accepted theory and proven fact. 124.168.69.148 (talk) 11:41, 18 April 2012 (UTC)

I think this could be debated, but since it is the only plausible theory to explain observations by far, and has a decent amount of observational evidence, I would fall on the side of keeping it the way it is. Dark energy is another matter, however, I'd suggest taking it up on Talk:Dark energy. -RunningOnBrains^(talk) 17:58, 18 April 2012 (UTC)

Also, you are making a distinction between "most-accepted theory" and "proven fact", when, in reality, no "fact" is ever "proven" in science. Every experiment and observation gathers more evidence until it becomes exceedingly unlikely that all previous experiments have been in error, and all other explanations become less and less likely. Surely, some "facts" can be derived from first principles, like the laws of gravitation and such, but that relies on you accepting those laws. You'd be a fool not to, but we will never get a certified letter from the universe saying "This theory is 100% correct". -RunningOnBrains^(talk) 18:03, 18 April 2012 (UTC)

I think we shouldn't discuss scientific theories here, unless as a means to improve the articles. There's nothing such as "proven facts" in science, the scientific counterpart is very well attested theories. That's the optimum. Rursus dixit. (^mbork³!) 05:08, 19 April 2012 (UTC)

Sorry, forgot I wasn't at the Science Reference Desk for a bit. -RunningOnBrains^(talk) 15:23, 19 April 2012 (UTC)

This person is absolutely correct. I too am looking at the wording thinking for one part how I failed to understand that dark matter was not an observable phenomenon or even hypothesised to be an observable phenomenon. On the other hand, then, I am reading through and phrases like that, "first came to the attention," and I just want to rip the whole thing up and look for patterns in it. I am not one for poetic literature, but I'm all in for literacy. If anyone is writing this article and wants to impart the knowledge usefully upon the unlearned person, this is what you should look at just as closely or moreso than your galactic halos. ~ R.T.G 16:46, 15 May 2012 (UTC)

In the very first sentence it establishes that the existence of dark matter is a hypothesis, "...dark matter is a type of matter hypothesized to account for a large part of the total mass in the universe". Because this is established, we can now infer: "Dark matter came to the attention of astrophysicists due to discrepancies between the mass of large astronomical objects determined from their gravitational effects, and mass calculated from the "luminous matter" they contain" "Discrepancies between the mass of large astronomical objects and the mass calculated from the 'luminous matter' they contain came to the attention of astrophysicists, and they hypothesised the existence of 'dark matter'..." I realise I've not done a very good job of explaining my point. But what I'm trying to say is, the article doesn't imply that the theory on dark matter is proven, it already explicitly stated that it is a hypothesise. I would assume if someone is reading this article they would be intelligent enough to remember that it's only hypothetical, or does one expect too much? — Preceding unsigned comment added by 90.209.165.17 (talk) 03:17, 16 June 2012 (UTC)

Part of the problem is that this article is woefully lacking in citations. It makes statements like "The full calculations are quite technical, but an approximate dividing line is that "warm" dark matter particles became non-relativistic when the universe was approximately 1 year old and 1 millionth of its present size; the horizon size was then 2 light-years, which would expand to 2 million light years today (if there were no structure formation). ...and then backs that up with NOTHING. No citations at all. No other field of study could get away with this, but apparently astrophysicists do. They should look for more respectable work. 24.165.102.99 (talk) 15:00, 5 July 2012 (UTC)Ubiquitousnewt

I agree with you on the section you pointed out. It needs some heavy editing, as well as citations. However, I don't see any deep connection to the state of the field. This article, like other Wikipedia articles, is edited by volunteers rather than by a paid corps of professional astrophysicists. --Amble (talk) 16:20, 5 July 2012 (UTC)

Stellar motion discrepancy

One "Serious blow" link

Here a "Serious Blow to Dark Matter Theories" (Journalist inflated), that examines a discrepancy between the Dark Matter expectations on star dynamics and the conditions in the neighborhood of the Sun (out to 13,000 ly away). Rursus dixit. (^mbork³!) 04:57, 19 April 2012 (UTC)

News article

Why is there no mentioning on the dark matter page of the fact that very recently (the last 1-6 months!), the very existence of dark matter has been called into question. The statement that dark matter is 'generally accepted by the scientific community' is no longer valid. — Preceding unsigned comment added by ParksTrailer (talk • contribs) 13:59, 5 May 2012 (UTC)

I introduced a statement the other day with links to several news articles referring to a study done that cast very many doubts on the very existence of Dark Matter, which was immediately removed from DM's wiki page. Now that I ask specifically why this is going on, and there are no posts, not a single person has anything to say about it? That response is very inappropriate. I posted on the Dark Matter page only after coming to the understanding that this 100% theoretical substance does not have the same respect from the scientific community. I propose someone jump in here and start a real discussion or my entry be inputted again to the wiki page; without either response one can only assume some rather biased editors. EzPz (talk) 17:43, 5 May 2012 (UTC)

The study behind these news articles seems to be Kinematical and chemical vertical structure of the Galactic thick disk II. A lack of dark matter in the solar neighborhood, a study of the dynamics of about 400 mstars in the neighbourhood of the Sun by a team of Chilean astronomers. It may merit a brief note in the body of the article, but is not significant enough to be mentioned in the lead. Gandalf61 (talk) 11:33, 6 May 2012 (UTC)

The above study has been disputed by Bovy and Tremaine who claim that one of the key assumptions in the reference above is not applicable in a realistic Galaxy model. Bovy and Tremaine's re-analysis is consistent with conventional estimates of the local dark matter density, ~ 0.3 GeV /cm^3 . Wjs64 (talk) 22:50, 19 July 2012 (UTC)

multiple partical dark matter

An old model of the univers applied in a new form indicates that there are over 200 dark matter particals of half the number of diferent masses. it also gave a starting point in calculating the diferent masses.the model also gives a number of interesting definitions for other things — Preceding unsigned comment added by 81.141.114.141 (talk) 19:31, 7 May 2012 (UTC)

Unless it has been published in respected science journals, I'm afraid it's too early to include it in Wikipedia. WP:RS describes the type of reference material that Wikipedia articles are based on. --Christopher Thomas (talk) 00:16, 8 May 2012 (UTC)

Inference of knowledge

People do not actually know anything about dark matter and in the interests of academic development and Wikipedias guidelines this should be made quite clear in this article. Currently it as been written to suggest that dark matter is a blob in the sky we've been watching and do not yet understand. That is deceptive. We do not understand it, but that is because we do not know anything about it. There were discrepancies in the calculations of gravity and motion similar to a denser universe. The exact increase in density was calculated. That's as far as they've got so far. I've made a small edit to the lead section and it could probably be written better but the approach needs to be taken. Dark matter is a total unkown hypothesis, not something you can say your telescopes are missing. You could say your microscopes are missing it too. I hope this makes sense... ~ R.T.G 16:27, 15 May 2012 (UTC)

I could say I haven't heard it on a microphone either... it's just a relevant to anything else about dark matter. It shouldn't really be overly suggested that it is anything more than a discrepancy in the the calculation of gravity in the universe. I mean, when it says that dark matter is not known to emit or absorb light, it's more informative to say, dark matter is not known, and though efforts have been made to detect its absorbtion or emission of light, nothing relevant has been found. Is this unfair? ~ R.T.G 16:35, 15 May 2012 (UTC)

First, it's simply not correct to say that "people do not actually know anything about dark matter" or "dark matter is a total unknown hypothesis." We have a number of observable data from different eras and length scales (the facts) and we understand those facts in the light of what we know about physics (the theory). The article describes the observable evidence we do have, the understanding we can draw from it, and the many open questions. If it said as you say "we do not know anything about it", it would be as wrong as if the article on Julius Caesar said that we don't know anything about him because none of us has met him in person. Secondly: you say that "it [h]as been written to suggest that dark matter is a blob in the sky we've been watching and do not yet understand." I'm having a hard time finding what in the article might suggest this. As I read it, it very clearly says the opposite: "[...] and so cannot be seen directly with telescopes." Could you be more specific? --Amble (talk) 19:36, 15 May 2012 (UTC)

From the article: "As important as dark matter is thought to be in the cosmos, direct evidence of its existence and a concrete understanding of its nature have remained elusive." No kidding. Dark matter is dark and can't be detected by any instruments known to science, as far as I know. So how do we know it exists? It was inferred by Zwicky when he concluded "that there must be some non-visible form of matter which would provide enough of the mass and gravity to hold the cluster together." Honestly, it sounds to me like cosmologists have reached a point where they might as well be discussing how many angels can stand on the head of a pin. Johnnyc (talk) 21:29, 15 May 2012 (UTC)

You quote a sentence from the article. It seems to be correct, well supported, and written appropriately. Is there something you propose to change? As for cosmologists, they have to make do with the facts we have. That's what makes science hard. --Amble (talk) 00:29, 16 May 2012 (UTC)

It seems that dark matter is a category of spatial disturbance, to which any indeterminable cause is assigned. What it is in substance cannot be described with any certainty. It's not a finding. The article says some similar things, but without any implications. It implies the reverse many more times. Is it better to change that or to wait until the majority of studies go out of their way to imply it first? I don't think they will, but I still think it's important in the description. ~ R.T.G 23:45, 20 May 2012 (UTC)

The purpose of this Wikipedia article is to report what literature meeting WP:RS says about dark matter. Right now, most of that literature says "expected to be a form of subatomic particle", with minority opinions saying that it may reflect modified gravity laws or something else. These minority views are already noted in the article, with space appropriate to their weight (per WP:UNDUE). The evidence for particle nature (which admittedly isn't iron-clad) is given in the article, and reflects what the sources say (short version: microlensing maps of it say it acts like an almost-perfect fluid in galactic collisions, and big bang nucleosynthesis calculations say pretty much the same amount has to exist in the form of a non-interacting particle for element ratios to work out properly). Debating the merits of each position is beyond the scope of Wikipedia, per the notice at the top of this page. If you feel that the article does not accurately reflect its cited sources (or other sources meeting WP:RS), point to sources and explain how. More extended discussion or debate belongs on a science forum. --Christopher Thomas (talk) 00:27, 21 May 2012 (UTC)

RTG, could you point out specifically where you think the article says or implies something that's not correct? --Amble (talk) 04:02, 21 May 2012 (UTC)

• "dark matter neither emits nor absorbs light." Well, there is no way to tell, and I can't see why that point shouldn't be made at the beginning where it counts. On another article if an editor said, well it really can't be anything else people can think of, you'd fob them off, especially if people could think of other things.
• "seen directly with telescopes" People search for it with telescopes. It's a little different from not being able to see it. There's no point of me to come up with another theory, it just isn't tangible and particularly the word "directly".
• "came to the attention of," No.
• "observations have indicated the presence of dark matter," No... They have indicated an indeterminate presence. Hypotheses indicate the presence of dark matter. That may seem like a long way around, but isn't it deduction in a large part? Then there is not enough weight to that fact and here is an opportunity.
• "According to consensus,"
• "a new, not yet characterised" I'll not rattle on about these last two except to say that if the approach was considered as I, and I think some others occasionally, are trying to suggest these statements might be worded a little differently.

It's not a challenge of the theories I am trying, it's all very interesting I think, but it's not portrayed very carefully in some respect in the lead and the overview. Here are some quotes from the article which I think are under water, "Determining the nature of this missing mass is one of the most important problems in modern cosmology and particle physics." ""Cold" dark matter is dark matter composed of [electromag stuff]... ...This is currently the area of greatest interest for dark matter research," "Possibilities range from large objects like MACHOs (such as black holes[67]) or RAMBOs, to new particles like WIMPs and axions. Possibilities involving normal baryonic matter include brown dwarfs or perhaps small, dense chunks of heavy elements." and to reword another sentence, "There is no concrete understanding of dark matter," and so on. It's not a matter of giving exposure to unregarded theories, more about exposure to the mysterious and wide ranging nature of the subject. ~ R.T.G 12:54, 21 May 2012 (UTC)

You've got a long list there, and frankly I can't understand what you are objecting to with any of them. I'll just take the first:"dark matter neither emits nor absorbs light." Well, there is no way to tell - of course there is a way to tell. If dark matter did either, it would be detected with telescopes. Waleswatcher (talk) 18:42, 21 May 2012 (UTC)

• • Point: There's something big up there swishing all the gravity around, but what else it is or does, such as absorbing and emitting light, nobody actually knows. They take an assumption and work from there. An assumption is relevant information. It is in fact key and in that respect should be clear point by point in, at least, the lead and probably the overview as well. It should not be impossible.
  • I don't propose to disagree with that particular assumption, the radiation, not on the article anyway, but only to make it more apparent where we don't know, that we don't know, that an assumption has been made. Personally, it's nonsensical to assume absolutely that no raditation interactions can occur in dark or any other kind of matter. You'd be an eejit if you were trying to find some in that case wouldn't you?
  • If you don't point out the assumptions that a theory is relying on, why should I know there were assumptions to begin with? Should I be firmly aware of the assumptions to understand? Anyway, it wouldn't do to go through the whole article piece by piece noting every little thing as unproven, but it would do in the lead to point out how unproven and changing the theories of dark matter are. Recently it was decided that most of the dark matter supposed to be in the Milky Way would in fact now be baryonic, detectable, matter. There is a major principle of uncertainty and it's not a misinformative aspect. I'm just yakking on about it now but I've conveyed nothing I guess I am doing it wrong. ~ R.T.G 22:34, 21 May 2012 (UTC)

Again, I'm not sure what you're trying to say. You're right that dark matter could interact very weakly with light, but no one assumes otherwise - they just use the data to constrain how strong the interactions (emission and absorption and scattering) can possibly be, and the data shows they have to be very, very weak. As for what we don't know for sure, we don't know anything for sure. We don't know electrons exist. That's the essence of science - all you can do is formulate hypotheses and test them against data. If they hold up, it doesn't mean they're right, but at least they passed some tests. Getting back to this article - why don't you pick one specific passage you object to, and propose alternate language of your own? Remember, wiki articles need to be neutral and reliably sourced. Waleswatcher (talk) 14:55, 22 May 2012 (UTC)

From Dark matter (disambiguation), "Dark matter is matter that is undetectable by its emitted radiation, but whose presence can be inferred from gravitational effects." I'd change it to say, "Dark matter is theoretical matter..." and I think that would make a much clearer start to the article. Ensuring links to cosmology and astronomy are still up there shouldn't be too difficult. "Theories regarding dark matter are of particuar interest in the study of astronomy, cosmology, and particle physics." Thus, "Dark matter is theoretical matter that is undetectable by its emitted radiation, but whose presence can be inferred from gravitational effects. Theories regarding dark matter are of particuar interest in the study of astronomy, cosmology, and particle physics." But, I am sort of iffy about "..whose presence can be inferred..." as it is not a who, and might try instead, "Dark matter is theoretical matter that is undetectable by its emitted radiation, but is generally believed to account for large unexpected gravitational effects on the galactic and intergalactic scale. Due to the subjects hypothetical nature, particular theories are occasionally changed or rejected, but dark matter is generally considered to constitute 84% of the total mass in the universe and 23% of total energy potential. Theories regarding dark matter are of particuar interest in the study of astronomy, cosmology, and particle physics." Something like that? And a bit more then of course. ~ R.T.G 20:42, 22 May 2012 (UTC)

You seem to be objecting to content on a different page (Dark matter (disambiguation)). THis talk page isn't the right place to discuss that. Can you find something in this article you object to, and if so, can you suggest a change? Waleswatcher (talk) 01:36, 23 May 2012 (UTC)

I am suggesting that the passage from there, is more suitable for the page here... and so on. ~ R.T.G 08:29, 23 May 2012 (UTC)

I am suggesting to start changing the lead area on this page with that stuff there. ~ R.T.G 08:31, 23 May 2012 (UTC)

What is it about the lead of this article that you don't like? It states in the first sentence that DM is a "currently unknown type of matter hypothesized to account for a large part of the total mass in the universe." Perhaps not ideal phrasing, but it makes it clear that it isn't know what DM is, or even if it exists. The phrase "theoretical matter" in your proposed wording doesn't make sense - presumably you mean "hypothesized", but that's already in the current wording. Waleswatcher (talk) 13:34, 23 May 2012 (UTC)

I made some minor changes to the first paragraph of the lead, and added a sentence: Instead, its existence and properties are inferred from its gravitational effects on visible matter, radiation, and the large scale structure of the universe. Waleswatcher (talk) 13:44, 23 May 2012 (UTC)

I could go on to say about the emitting light quote, if it were fair to say that dark matter is detectable by studying celestial gravity, then dark matter can only be detected using a telescope rather than cannot, etc, blah :). ~ R.T.G 20:48, 22 May 2012 (UTC)

Calling dark matter "theoretical matter" would be inaccurate. Dark matter is driven by observation, not theory. Specific candidates, such as axions and neutralinos, may be theoretically motivated, as is the Higgs boson. --Amble (talk) 14:55, 23 May 2012 (UTC)

• One problem is the stuff is badly-named. If it doesn't interact with electromagnetic radiation, it's not so much dark as transparent. As transparent as Harry Potter with his magic cape on. Imagine a lens made of material you cannot see. The other problem is that the word "matter" which isn't even defined for regular "matter." Mass is a scientific word, but matter is not a scientific word, even if you leave out the "dark" part.

  So, anyway, there's this "stuff." We presume it's not massless like photons. Perhaps it has rest mass, like neutrinos. Evidently it has more rest mass than neutrinos, or else it wouldn't act as it does (if it was very low mass and coupled with the Big Bang, it would be so fast as to have escaped galaxies completely, but instead it seems to be stuck by the gravity of them; yet how has it "cooled" with no interaction to cool it? Evidently only from the space-expansion of the Big Bang, like the cosmic microwave background). Anyway, it's (as we said) apparently transparent, and worse still, you couldn't "feel" it even if you stuck your hand in it ("feeling" something, means your hand has an electromagnetic interaction with it). Particles of it should go through you, like neutrinos. So, it's at least as "ghostly" as neutrinos, and maybe even ghostlier, if it doesn't undergo weak interactions. It's barely there. We don't have words for that kind of thing. Dark is wrong, as it has a connotation of absorption, instead of transparency. Matter is wrong also, if you mean anything like normal matter. The problem is that this stuff is so odd that we're short of language. SBHarris 02:59, 24 May 2012 (UTC)

Sbharris: some interesting points, it is indeed "transparent" but the term "dark matter" is widely accepted and the article has to reflect this. The general term "Matter" is slightly context-specific, but usually refers to fermions or composites thereof (protons, neutrons etc) with rest mass. Massless photons are never called "matter"; massive bosons e.g. the W, Z and Higgs boson are a grey area: they do have rest mass, but don't obey number conservation laws like fermions, so usually don't count as "matter". (An aside: the mass of a proton or neutron is a lot larger than the summed masses of its three quarks, due to binding energy: but protons and neutrons are definitely "matter", and this binding energy definitely gravitates, so the definition of matter is slightly fuzzy at a deep level.)

We know that nearly all dark matter must be non-relativistic to be bound in galaxy/cluster structures, therefore it has rest mass, and it's almost certainly fermions to obey conservation laws, hence it is "matter-like" though not any Standard Model particle.

As to how it "cooled"... yes it is the expansion of the universe; massive non-interacting particles lose momentum inversely proportional to the universe's expansion factor, in the same way as microwave background photons lose energy. This is sometimes called "Hubble drag"; it is not a real "drag", but due to the fact that a moving particle "overtakes" stuff which was previously expanding away from it. I'll try and add some of this in at some point. Wjs64 (talk) 22:37, 19 July 2012 (UTC)

LSG Line of sight gravity

LSG gravity replaces Dark Matter. MOG, a variation of General Relativity fits data better than any other theory. MOG replaces Dark Matter. You may find the theory (LSG) in a paper "Time and its Properties". The formula for LSG is C*Ng, where Ng is Neutonian gravity and C a multiplier which is a function of distance and perpendicular velocity to the line of sight plus other lesser factors. C's values are 10 - 8 between the centers of galaxies and greater, 2.25 - 1.75 betweeen the certer of a galaxy and any star and between 1.0 and 1.05 between a star and any near by body. C is an inverse function to the magnitude of the cross velocity. This than explains, with C going from 1 to 10, the following. I. Our solar system where everything is C = 1 because the cross velocities are too great, except comets and the spacecraft (Pioneer Anomaly). II. The velocities of stars in spiral galaxies, C = 2. III. This explains 1) warped spiral galaxies, all. 2) The arms , but mostly the bars in Barred Galaxies. IV. The force between galaxies where C = 9. Here in all cases the extra force above Neutonian is only from the center of galaxies, not any where as Dark Matter. — Preceding unsigned comment added by 68.59.150.181 (talk) on 12:56, 26 May 2012 (UTC)

A clear reference required section. Mtpaley (talk) 23:10, 27 May 2012 (UTC)

"plus other lesser factors" - give us some details. I want to calculate the effects of this theory on planetary orbits. Mtpaley (talk) 23:14, 27 May 2012 (UTC)

Per WP:RS and WP:NOR, the only material that should be included in this article is material published in venues that are considered reliable sources (per this subsection of WP:RS). The term "line of sight gravity" appears in scientific literature, but means something completely different that what you appear to be using it for (it refers to doppler data from space probes indicating acceleration due to gravity along the line of sight to the probe). The term "MOG" is used in scientific literature for "Modified Gravity", and does not refer to any single specific theory. Modified gravity is already discussed in the article. --Christopher Thomas (talk) 23:45, 27 May 2012 (UTC)

Obviously dark matter is the matter residing in singularities

Years ago i wrote in here about my theories on dark matter and galactic anomalies. No one took me seriously unfortunately, maybe it was my massive run on sentence...either way its absolutely apparent that dark matter is the core of singularities. It plays a special relationship with dark energy as dark energy is the gravitational pull of singularities. Something very interesting to think about is the nature of absolute zero in all of this. Absolute zero proves the existence of the big bang theory as the only way to obtain a temperature of absolute zero is by removing all matter from an area, thereby making that areas gravitational pull zero. You must understand the nature of light is its attraction to gravity and it being a form of energy radiates heat thereby igniting the fundamentals of nature. — Preceding unsigned comment added by Uberbunk0439 (talk • contribs) 06:00, 18 June 2012 (UTC)

Per WP:NOR and WP:RS, Wikipedia is not the place to present your own new ideas about dark matter. The article is supposed to reflect ideas that have been presented in peer-reviewed scientific literature (per WP:SCHOLARSHIP) or that have otherwise made enough of a splash to satisfy the notability guidelines (WP:N). --Christopher Thomas (talk) 06:12, 18 June 2012 (UTC)

Jan Oort's "discovery" of dark matter

The article currently gives priority to Jan Oort for discovering dark matter in 1932. This is problematic at the least. Oort's results were thrown off by including thick-disk K giant stars in his perpendicular velocity sample. (See, for example, [17]). It's now understood that there is little if any evidence for dark matter in the galactic disk. We don't usually give primary credit for a discovery that's understood later to be incorrect. Indeed, the article mentioned Zwicky as the first discoverer of dark matter until Oort was added in Feb. 2012 by User:Aarghdvaark ([18] and subsequent edits). Oort played a significant role in developing the idea of dark matter, but his "discovery" was spurious. --Amble (talk) 10:17, 3 July 2012 (UTC)

Thanks for checking on this. I wasn't sure of the details of the history, so I didn't say anything. If want to revert to the previous version, or significantly rework that part, I'll back you up. - Parejkoj (talk) 14:43, 3 July 2012 (UTC)

Third Matter?

Is Dark Matter the third type of matter, with matter and anti-matter being the first two? How does Dark Matter interact with matter and anti-matter? What is it composed out of (ex. particles)? P.S. I'm only in Grade 9, k? Not an expert at this stuff yet... — Preceding unsigned comment added by 96.52.41.208 (talk) 03:27, 5 July 2012 (UTC)

The short answer is, "dark matter" is a different type of matter, but still matter. It presumably has its own antimatter counterpart (though some dark matter candidates are their own antiparticle). It does not interact directly with matter or antimatter under most conditions. The best guess at present is that it's a new type of particle (as described in the article).

Further questions about this should go to the science reference desk page, as this talk page is for discussing changes people want to make to the article, not for discussing dark matter itself. The reference desk should be able to help you with anything else you want to know about the subject. --Christopher Thomas (talk) 05:32, 5 July 2012 (UTC)

XENON100 results negative after 225 days

"A blind analysis of 224.6 live days × 34 kg exposure has yielded no evidence for dark matter interactions.... The PL analysis yields a p-value of ≥ 5% for all WIMP masses for the background-only hypothesis indicating that there is no excess due to a dark matter signal.... The new XENON100 result continues to challenge the interpretation of the DAMA, CoGeNT, and CRESST-II results as being due to scalar WIMP-nucleon interactions."[19] Npmay (talk) 19:28, 30 July 2012 (UTC)

"for PBHs with mass from 10² M⊙ to 10⁸ M⊙... The ionization of IGM due to PBHs with such density parameters does not affect the global reionization history of the universe since reionization from each PBH only covers a tiny patch of the universe. Unlike reionization from first stars, therefore, such reionization has little impact on CMB temperature anisotropies. Accordingly the PBH density parameter constrained from WMAP data, that is Ω_PBH < 10⁻⁷ (Ricotti et al. 2008), is several order of magnitude larger than the value we obtained above. In other words, we can conclude that 21 cm fluctuation observations have a potential to probe the PBH abundance which is impossible to access by CMB observations."[20] (emphasis added.) 207.224.43.139 (talk) 03:46, 31 July 2012 (UTC)