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Modified Newtonian dynamics

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This article does a wonderful job of covering all the major points in a in-depth yet accessible way. It also explains the underlying mathametics for the expert. Even for the layman, the topic is described both conceptually and with equations. Every point is addressed in a methodical and analytical manner, a great example being the section Consistence with Observations. In short, it is a great example of what an encyclopedic article should be, both accessible and in-depth, offering something for everyone. There could hardly be a candidate more suited to being a featured article. I nominate Modified Newtonian dynamics. Loom91 07:54, 1 September 2005 (UTC)[reply]

Tally: The current opposition tally is- 6 Loom91 18:35, 6 September 2005 (UTC)[reply]



  • Object. No references. Lead secion is a brief mention of the name and author rather than a summary, see this page. 119 08:53, 1 September 2005 (UTC)[reply]
    Responding to the submitter's request I reconsider, I still object on the lead section. It does not summarize the rather weighty sections 'Consistence with the observations' and 'Discussion and Criticisms' and so is not a complete summary, in my opinion. 119 04:50, 4 September 2005 (UTC)[reply]
    Your wish is my command. I've added yet another paragraph to the intro, briefly touching on the main points of the two sections mentioned by you. I'm afraid of making it too lengthy. Loom91 17:57, 4 September 2005 (UTC)[reply]


  • Object 1) The lead section is too short to adequately summarize an article of this length. 2) Cite your sources in a References section. 3) The image captions in the first section do not adequately describe the images. 4) The image placement in the first section leaves too much whitespace. 5) The mathematical description in the second section doesn't need to show every algebraic step from the initial equation to the last; show the initial equation, state assumptions (e.g. "We assume that, at this large distance r, a is smaller than a0 and thus..."), then show the solution for the variable that you are reducing to (i.e. "Solving for v, the equation is reduced to..."). 6) There are several places in the prose that need a copyedit for grammar (e.g. "As an effective theory, it describe the dynamics of accelerated object with an equation, without any physical justification." from the beginning of the Discussion and Criticisms section). slambo 16:01, September 1, 2005 (UTC)
Has Slambo gone on a vacation or forgotten this page. He has made no changes to his objections since the first day! Loom91 18:02, 4 September 2005 (UTC)[reply]
It seems Slambo has abandoned this discussion. What can be done about this? Loom91 18:35, 6 September 2005 (UTC)[reply]


  • Object, per above: no references. Phoenix2 17:20, September 1, 2005 (UTC)
    • Good enough for me, now that there are references. Images/diagrams seem well placed. Support. Phoenix2 21:12, September 1, 2005 (UTC)


Slambo's objections 1 through 5 addressed(i hope adequately). However my first language is not English and therefore I'm ill equipped to do grmmatical and spelling corrections(6th objection). A little help in this direction from anyone will be highly appreciated. On the two objections raised by Carnildo, the first image is nothing more than line diagrams which can be drawn by anyone and no copyright can be claimed on them anymore than a copyright can be claimed on a drawing of a circle. The objection raised about the second image is a valid one, thus I'm removing the image. Please help me in correcting grammer and change your votes to accept. Thank you. Loom91 18:45, 1 September 2005 (UTC)[reply]

It is certainly possible to claim copyright on an image such as Image:Newtonianfig3.png. --Carnildo 19:38, 1 September 2005 (UTC)[reply]
It seems CArnildos is the only objection remaining, and I could solve it in 5 minutes but unfortunately I have lost my copy of Microsoft Paint to a virus attack on my XP. If anyone mails me a copy of MS Paint at loom91@yahoo.com then I will upload an alternate image. Alternatively, someone kind can do the image themself and upload it. Thanks.Loom91 07:00, 2 September 2005 (UTC)[reply]
The final objection has been addressed! I've replaced Newtonianfig3.png with a public domain drawing by me, DarkMatterHalo.png. That takes care of the lot. Now will you please change your votes to support? Loom91 07:59, 2 September 2005 (UTC)[reply]


I have rectified the grammer and spelling errors. I believe that takes care of all existing objections. Anyhing else? Loom91 19:21, 1 September 2005 (UTC)[reply]



Repaired? How? I don't get what's wrong with the link.Loom91 17:09, 5 September 2005 (UTC)[reply]
Oh, I get it. Alright, fixed the link well and proper. Loom91 17:22, 5 September 2005 (UTC)[reply]


  • Support. I didn't know this theory. I've learned something. Why haven't you put a nice picture of the universe to make it a bit more appealing and allow the administrators to put it on the main page. Vb19:00, 5 September 2005 (UTC)[reply]


  • Object—I'm surprised that it was nominated before a thorough copy-edit: I've made numerous small changes to the opening; the authors should try harder. Tony 13:08, 5 September 2005 (UTC)[reply]
Can you please be a little more specific as to exactly which grammatical errors remain, I unfortunately fail to find them. Loom91 17:05, 5 September 2005 (UTC)[reply]
In any case, I've touched up the intro some more, see embedded comments for rationales. Loom91 17:22, 5 September 2005 (UTC)[reply]
I've edited another section. However, please let me know whether you'll be able to address the concerns below; if not, I won't go ahead with the edit. Why isn't that extraordinary photo on the discussion page in the article? It's an ideal article for photos. Tony 02:19, 6 September 2005 (UTC)[reply]
I'm not inserting the photo as it does not provide copyright information and is thus not suitable for a Featured Article. If you know that it fits in Wikkipedia policy, please let me know and I'll include it. And thank you for your work in the article. Loom91 18:31, 6 September 2005 (UTC)[reply]


The standard applied to (all) other math and physics articles is to have the article start with the words In physics, ..., although in this case, In astronomy, modified Newtonian dynamics is .... Discussions about style and etc. can be carried out at Wikipedia talk:WikiProject Physics. linas 18:53, 5 September 2005 (UTC)[reply]

Addressed! Loom91 17:52, 6 September 2005 (UTC)[reply]


  • Object. My main point is that I believe this theory is not accepted by the community of physicists, not even as an alternative, and this should be noted in the lead section (I'm not a physicist, so I've asked the people at Wikipedia:WikiProject Physics to comment). It's not clear what happens if multiple forces act on a body: should one first add up the forces and then apply the modified second law to find the acceleration, or the other way around; this is the same in Newtonian mechanics, but not in this modification. Some more comments, all from Modified Newtonian dynamics#The change:
    • the difference between and is not explained;
    • the formula should say instead of ;
    • the sentence below does not seem correct English to me;
    • I don't believe that "the form of µ doesn't change the consequences of the theory", only that it does not change some consequences of the theory (like the rotation curve);
    • "doesn't" should be written "does not";
    • "every day world" should be "everyday world";
    • "a is greater than a0" should be "a is much greater than a0" (and why the font tag in the subscript?).
Having so many questionable aspects in such a short fragment does not bode well. -- Jitse Niesen (talk) 19:20, 5 September 2005 (UTC)[reply]
Your first point is addressed. The final sentence in the intro uses almost your exact phrasing. On your second point, it is most certainly not appropriate to explain basic vector notation. The article is long enough already. On your third point, the difference is of spacing, but I'm not familiar with LaTeX. As you know LaTeX, perhaps you can change the formula. The difference is trivial. Your other points are all now addressed. Loom91 18:31, 6 September 2005 (UTC)[reply]


  • Support. Of course, the points noted by Jitse should be addressed. About Jitse's first point: Only a handful of scientists advocate MOND as an alternative to dark matter. But this theory is taken seriously by the rest of the scientific community. They take it as a challenge to try to disprove it. See e.g. Joseph Silk's article cited in this article. So, I suggest that the fact that the theory has only a limited number of advocates be mentioned in the introduction. Another point are the links in the references. If possible try to also link to preprints. You need a subscription to APJ to access Silk's article, but this article is also available on the Arxiv preprint server. Count Iblis 21:24, 5 September 2005 (UTC)[reply]


  • Object. I haven't contributed to this article, but I work in the field. The article could one day be good, but there are lots of small scale problems. For example, just to take the introduction, what does "Although Milgrom and others have demonstrated consistently ratifying evidence in favor of MOND, there has been little truly conclusive research" mean? It leaves the reader (and me) 100% confused about the observational status of MOND. How about "(beyond the mitigating influence of the Sun's gravitational field)"? What is "mitigating" about the Sun's field? There are also lots of examples of improperly informal language.
"Overview" section needs rework. The image of the dark matter halo is ugly and needs to be redone.
The mathematical derivation of the predicted rotation curve is too technical for an encyclopedia article, and also is rather laborious.
"Consistence with the observations" is a bit too much editorializing for my tastes, and misrepresents the scientific process as a form of "box checking". A good version of this section would focus on the actual criticisms and responses on the question of MOND, not just rehash a debate on the scientific method (imagine if every article on controversal science had this section.) That would be very interesting and encyclopedic: what were the actual methodological criticisms laid against MOND over its history?
An important fact is only obliquely mentioned: that MOND, as it was first stated, violates the (considered fundamental principle of) Lorentz invariance by postulating a preferred frame of reference. This has been rectified by the TVS paper, very recently, which recasts MOND in terms of a Lagrangian. A classic objection to MOND was that it could not explain the cosmological evidence for dark matter (e.g., spatial flatness); it remains to be seen whether or not the TVS formulation can do it.
In any case, I find the discussion of the impact of TVS on MOND, and the general question of general and special relativistic effects in MOND, to be severly lacking.
My general suggestion here is that this article could be great, but it needs serious work. A problem is that it is rather cluttered and poorly organized. I would suggest future editors start by cutting out lots of stuff, and trying to get a better outline format.
All the best, Sdedeo 02:53, 6 September 2005 (UTC)[reply]
The intro has been reworked, all the sentences you objected to removed. Can you be more specific about which points in Overview need to be reworked? It's very difficult for me to edit if you give only vaugue impressions about your objections. I can not see how MOND postulates a 'preffered' frame of reference. Which frame does it prefer? How can you call that simple algebra techinical when articles on physics routinely make use of exotic and little-undertood mathematics such as Hilbert Spaces, Bra-ket notation and that sort of things? That's what I call techinical! About TeVeS, I know little about it. As you said you are working in the field, how about adding what you know to a new section about TeVeS? Also perhaps TeVeS should be treated as a separate matter, since it deviates from MOND in its native form.A good article is born from many people working together, everyone adding to the part they know most about. Please consider taking some time to improve the article. I have edited out the preamble about scientific method and instead placed a link to the original article for reference. Please let me know your thoughts Loom91 18:31, 6 September 2005 (UTC)[reply]
Hi Loom. My feeling is that this article is quite a ways from being a featured article candidate, which is why some of my objections are broad.
The algebra demonstrating that MOND gives flat rotation curves is not necessary. You don't have to prove statements in the article; you can just state them, and (hopefully) provide a reference if the statement is in any way contentious. Similarly, in the "mathematics of MOND", you should really not be busting out with the gradient operator. This is just a general tradition in popular science articles: avoid equations unless absolutely necessary; describe results with words and metaphor. It should be possible to describe the essentials of MOND without using the gradient, e.g..
As I've said (and so has SCZenz), one of the major objections to MOND was its conflict with Relativity. Another (connected) objection is the fact that "classic" (i.e., non-TVS) MOND could not make any cosmological predictions. Since cosmological evidence for dark matter has been a major thing since the early 1990s (at least), MOND's failure there is extremely notable, and not covered in the article.
The discussions of MOND vis a vis scientific methods are still pretty contentious. As I've said, you should really source any statements that suggest MOND is criticised because of a conflict with Occam's Razor. AFAIK, astronomers have not really challenged MOND on such broad grounds, but you might be able to find references.
Re: preferred frame stuff. This is part of MOND's conflict with General Relativity I've discussed above. In a nutshell, the local physics inside a freely-falling reference frame should be universal. However, MOND says that some freely falling reference frames (e.g., that of a spaceship free-falling into the Sun) are different from others (e.g., one on the outskirts of the galaxy.) The two experimenters will measure different values of the inertial mass of (e.g.) the electron, according to MOND. You would be able to distinguish the two reference frames, which is a violation of relativity even in the weak field limit.
I hope this helps you improve the article. Unfortunately, I don't think it will make FA status this time around, but perhaps in the future. I'll definitely put it on my list of things to look at later in the year.
All the best, Sdedeo 00:48, 7 September 2005 (UTC)[reply]
  • Object, as per Sdedeo. In particular, I am concerned with the treatment of the scientific method in the article. And inconsistency with General Relativity is not to be ignored lightly. -- SCZenz 04:42, 6 September 2005 (UTC)[reply]
Ignored lightly? How? MOND is not a relativistic theory, niether does it claim to be one. That is the ream of TeVeS. Loom91 18:31, 6 September 2005 (UTC)[reply]
It seems quite strange to have a large-scale theory of gravity and motion that's not compatible with GR. We already have one theoretical divide, between QM and GR--we don't need more unless absolutely necessary. But this really comes back to treatment of the scientific method. To say MOND is a phenomenological model that may give quantitatively accurate values for the rotation curves is one thing, but the article's claims are considerably stronger. -- SCZenz 21:34, 6 September 2005 (UTC)[reply]


References are not correctly cited; missing are the volume and page numbers. Authors should be given a first name as well as a last name. Suggest using the WP reference templates to provide a uniformity of style. See Wikipedia:Cite sources for pointers to templates. linas 18:53, 5 September 2005 (UTC)[reply]

You might even want to organize references according to whether they are historical or popular, etc. See Riemann hypothesis for such an example. linas 19:01, 5 September 2005 (UTC)[reply]
The section called "external links" should be merged with the section "references". The external links should be credited with authors and dates as well. The reason for this is that many journal articles are now available on pre-print/reprint servers on the web; and so there is often no real difference between a print reference and a web reference. It also eliminates the bad habit of citing random web links wihtout given an author credit or dating the thing. linas 19:06, 5 September 2005 (UTC)[reply]
I take it that you are commenting rather than making a formal objection since you haven't used an Object to begin, but I will try to answer your concerns anyway. First off, page numbers? You are being too strict. The featured article criterias are not that strict! I have mentioned the date in each case, which makes finding the issue trivial, and from there the mentioned article can be tracked from the Index.I'm taking your suggestion and merging "external links" with "references", and the links are credited with authors whenever appropriate. I can't cite an author for a pre-print server! Loom91 17:52, 6 September 2005 (UTC)[reply]
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