Talk:Nutation

Frisbee

I just think it's hilarious that an explanatory article on nutation doesn't mention frisbees. — Preceding unsigned comment added by 205.153.180.229 (talk) 16:43, 8 November 2011 (UTC)

Wrong Orientation

The precessing North pole of the earth should follow a clockwise path around the axis of the ecliptic when viewed from above the ecliptic, which is the opposite of what we see in the illustration that accompanies this article —Preceding unsigned comment added by 188.118.69.232 (talk) 11:17, 24 October 2010 (UTC)

You are, of course, correct. However, the direction of precession is entirely correct for the direction of rotation of the hypothetical planet illustrated. It is not an illustration of the earth looking at the north pole because the direction of rotation of the earth is anticlockwise (looking toward the north pole). 86.144.90.137 (talk) 12:32, 12 September 2012 (UTC)

Opposite? I think that just not all of celestial IPs look to the Earth from Polaris and Ursa Major constellation. Possibly, there are users on Proxima Centauri too – why their PoV should not be represented? Incnis Mrsi (talk) 14:10, 12 September 2012 (UTC)

By convention, the north pole of a planet is the pole where the planet spins anticlockwise. This is true even for Uranus which has a technically retrograde direction of spin in that its north pole is ~6 degrees below the orbital plane (relative to the remaining 7 planets). Also by convention, the earth is generally depicted with the north pole at the top. Even in Australia they don't sell up-side down globes! 86.144.90.137 (talk) 15:25, 12 September 2012 (UTC)

Remaining 7, you said? What about Venus? Incnis Mrsi (talk) 15:35, 12 September 2012 (UTC)

You describe the right way to do it, but see Poles of astronomical bodies. —Tamfang (talk) 18:13, 12 September 2012 (UTC)

Nutation / Wobble/Polar motion

I am a bit concerned about the Nutation article. I wonder if a slight clarification might be added related to the difference between Nutation and Wobble/Polar motion.

The motion of the Earth's rotation axis on the celestial sphere is given by Precession, Nutation PLUS a smaller remainder called the "celestial pole offset". http://www.iers.org/MainDisp.csl?pid=95-93

It is very common to mix up "celestial pole offset" with the geographic motion of the pole on the surface of the earth, known as "Polar Motion" or "wobble".

The IERS monitors both Polar Motion (GPS & VLBI) and the celestial pole offset (VLBI).

Imagine that polaris is exactly at the north celestial pole and we experience 1m of Polar Motion/Wobble. This would mean that:

- My apparent latitude and longitude would change as I view the stars. Polaris would be at a slightly different position in the sky at a fixed location. - Polaris would remain at exactly at the north celestial pole.

Now imagine that polaris is exactly at the north celestial pole and we experience a 1m offset of the celestial pole. This would mean that:

- My apparent latitude and longitude would be unchange as I view the stars. The north rotation pole would be unchanged.

- Polaris would no longer be exactly at the north celestial pole.

132.156.28.88 (talk) 19:54, 6 August 2008 (UTC)

(Left on my talk page [1] but I think that this is best here, as I'm not sure how to answer it. Mike Peel (talk) 16:51, 7 August 2008 (UTC).)

Different kinds of polar motion

This starts to be a real mess. I've tried to get a grip of what different kinds of polar motions we have all together, by doing research here on Wikipedia, and here's what I've got so far:

• True polar wander
• One of the Milankovitch cycles of about 40 000 years
• Several nutations of the Earth, the largest to have a period of about 18 years
• Polar motions, one of those the Chandler wobble with a period of 433 days
• Celestial pole offset, mentioned above

Could the differences between these concepts be clarified? And maybe a summarization of these different kinds of polar motion, could be written in the main article? Mårten Berglund (talk) 23:37, 14 October 2008 (UTC)

Proposed merge of Nutate

The following discussion is closed. Please do not modify it. Subsequent comments should be made in a new section. A summary of the conclusions reached follows.

The result of this discussion was No consensus.

---

I cannot see any reason why the noun and verb should need separate pages. While Nutation is at present primarily about astronomy, other usages, such as in mechanical engineering and botany, presently to be found at Nutate, are equally valid. Globbet (talk) 23:15, 5 June 2010 (UTC)

Please, do it. --Guentherwagner (talk) 20:45, 21 September 2010 (UTC)

 Done - Globbet (talk) 22:57, 20 October 2010 (UTC)

Paradoxically, the nominator himself presented strong arguments against the proposed merger. The main "reason" is that Nutation deals specifically with Earth's nutation (before your contamination, and after my cleanup), surprised? But fortunately it's Wikipedia, mistaken moves may easily be reverted, missing or corrupted content may be resurrected in another form. Incnis Mrsi (talk) 10:36, 28 July 2012 (UTC)

I do not like to be accused of "contaminating" this article, or to be told that my contributions are "mistaken", and especially not by someone employing both sarcasm and a circular argument. Please show more respect. The title of the article is "Nutation", not "Nutation (Earth)", "Nutation (Planetary)", or "Nutation (Astronomy)", but "Nutation". Where is your authority for your conclusion that this article is intended to be solely about planetary nutation? Where is the discussion? How does expanding the article to discuss a variety of applications of the word "Nutation" constitute a contamination of an article entitled "Nutation"? Undoing pending proper discussion. Globbet (talk) 22:07, 28 July 2012 (UTC)

The problem of titles in Wikipedia is separated from articles themselves. If your wish is expanding the article to discuss a variety of applications of the word "Nutation", then Wikipedia is not the best choice. Remember the situation of 2010: there was an article "Nutation" clearly about planetary nutation. You had a possibility to install a hatnote and proceed with article about the engineering notion. You had a possibility to request moving the article "Nutation" to either "Planetary nutation", "Nutation (astronomy)" or "Earth nutation", or just move it yourself, leaving a dab page behind. But what did you choose was a merger, although you definitely should realize that these notions have little in common. What "proper discussion"? Just opinions of two users, where the former went contrary to aforementioned policies and guidelines, as well as the established practice. Guentherwagner provided no substantiation at all. And what do you speaking about respect? I demonstrated my respect, first, by posting to this discussion (BTW even before any actions), and second, by notifying the "Engineering" project, in a hope that experienced users can salvage your content. I had the right just to delete the content I feel is off-topical – it is Wikipedia. Please, if you are willing to continue this dispute, request a third opinion please. Since I consider most of your arguments void, you unlikely have a chance to convince me. Incnis Mrsi (talk) 07:53, 29 July 2012 (UTC)

I'd like you to take moment to consider your assumptions. Firstly, I think you may have misunderstood the reason for the merge. You seem to assume that I have set out to merge two dissimilar concepts. That was not at all the reason. I merged Nutate and Nutation because it seemed silly to have two articles covering fundamentally the same idea, one using the verb as a title and the other the verbal noun. Secondly, you seem to be assuming that because the article was originally confined to one application of the word "nutation", that it should remain confined to that particular application in perpetuity. It seems to me that if there are other applications of the same word to different examples of fundamentally the same concept, then it is quite legitimate to expand the scope of the article to include those applications. I disagree with your assertion that the concepts have little in common. I would ask you to consider the lead paragraph, and explain how that does not include the concepts added by the merge. In any case, I find astronomical nutation is poorly explained here, the diagram having a clarity the text lacks.

I have seen no policy or guideline that argues against what I did. I am quite happy to see what anyone else may have to say, and to abide by any policy or guideline that clarifies the issue. I repeat, disrespect started with your use of the loaded words 'contamination' and 'mistake', and continues in your telling me my arguments are beneath your contempt. Globbet (talk) 22:04, 29 July 2012 (UTC)

Indeed, Globbet, there was nothing wrong with the way you approached this question. You waited three months before making the move, so it is hardly your fault if only one person commented. And it was two more years before this suddenly became a burning issue. RockMagnetist (talk) 16:18, 6 August 2012 (UTC)

There was nothing procedurally wrong with the way (cf: not any legal thing is a good thing). There was something essentially wrong with the goal, namely, to dump any mention of the word "nutation" into an already established article. Here is not Wiktionary. Incnis Mrsi (talk) 19:52, 6 August 2012 (UTC)

This instance of pushing to Web interface links, which resulted specifically in the removal of a perfectly guidelines-compliant hatnote, reduced my willingness to cooperate to a bare minimum. Oh well… let us install a silly, boring {{split}} ambox and wait for enough experienced users to come in. Incnis Mrsi (talk) 11:34, 5 August 2012 (UTC)

I support either just the "Nutation" article or "Nutation" plus "Nutation (astronomy)" (with Nutation having a brief summary of the astronomy content with a "main article" link). [Update: I abstain, see below.] I disagree with Incnis Mrsi: I think the concepts are all related in that it is talking about the same kind of motion. Planets can exhibit that motion, and machines can exhibit that motion, etc. But it is more-or-less a single concept, which is referred to by a variety of fields. (By the way, we can study the examples of Rotation and Libration for comparison and ideas. Neither is ideal in my opinion.) I do not think a disambiguation page is appropriate or necessary, unless there was something called "nutation" that was not actually referring to this specific kind of motion. --Steve (talk) 14:48, 5 August 2012 (UTC)

Speaking seriously, there is no topic which should be entitled as "Nutation (astronomy)". There is Earth's nutation (or, more generally, planetary nutation) which is relevant also to geodesy and geodynamics. I repeat: Earth's nutation does exist, and it (the single phenomenon) affects Earth-based astronomy, geodesy, geodynamics, and probably even satellites' orbits. What about Steve's analogies: "rotation" is a notoriously well-defined concept in both physics and mathematics, an important case of symmetry. The "nutation" article including mechanical engineering and physiology does not match "rotation". "Libration" is defined as "oscillating motion of orbiting bodies relative to each other" – it is not so precise, but at least intelligent. It is clear that rotation is not a libration (it is not oscillating), and waves in the sea is not a libration too (there is no orbiting body). What is in common, indeed, between
and  ?
The latter is periodic, but the former is not (it is only quasi-periodic). In the latter the axis of rotation is fixed, but in the former it is not. So, there is nothing particularly common in these two complex motions but… the term. And dissimilarity of "Nutation #In physiology" is obvious for any sane person which could make a judgement about physics. Were an article trying to define "this specific kind of motion" exist, it likely would be a WP:SYNTH or WP:OR. So, what solutions are possible but a dab page? Incnis Mrsi (talk) 16:24, 5 August 2012 (UTC)

In the lead of the article Swashplate engine, there is this statement: "The difference is that while a wobble plate nutates, a swash-plate rotates." However, the source cited says nothing about the issue. There are also no citations for any of the mechanical engineering definitions in this article. Perhaps these claims should be verified before we decide what to do with the article. RockMagnetist (talk) 16:12, 6 August 2012 (UTC)

UPDATE: I abstain. I was assuming that "nutation" always meant "a movement of a rotational axis such that the first Euler angle (precession) is constant" as stated in the article, with the possible exception of physiology. But the ensuing conversation has made me very confused, and don't have time or interest to sort it out. So I abstain. --Steve (talk) 23:03, 6 August 2012 (UTC)

Swashplates have two plates, with a bearing between them. One (fixed to the input(sic - assuming a pump, not an engine) shaft) rotates, the other (carrying the pistons) nutates. Andy Dingley (talk) 10:34, 7 August 2012 (UTC)

• Keep article title with hatnote(s), but broaden treatment. The lead states the proper subject of this article pretty well. Nutation is a phenomenon that applies to all kinds of rotating bodies, including gyroscopes, planets, or bullets. One could also add tops and (as someone above suggested) frisbees. The main section should describe the physics, after which applications to the Earth, etc., can be treated. However, the physiological meaning is clearly different since it doesn't involve a rotating body, so that should be a hatnote. The disambiguation page is not needed. RockMagnetist (talk) 18:17, 6 August 2012 (UTC)

  Okay, let us accept that gyroscopes, planets, bullets and even frisbees exhibit some specific type of motion RockMagnetist calls a nutation. Yet another time the same question: what in common is between such gyroscope–planet–bullet nutation and the motion of a swashplate? If there is not any, then the article has to be decontaminated (see my point above). Next, consider the question of the dab page. There are at least three distinct meanings (gyroscope–planet–bullet, sacrum, plants) which are not disputed. There are also sources (from Globbet) which indicate that the word "nutation" is used in mechanical engineering, apparently in a sense different from gyroscope–planet–bullet nutation. So, the disambiguation page is needed. Incnis Mrsi (talk) 19:52, 6 August 2012 (UTC)

One point at a time. This type of motion is not what "Rock Magnetist calls a nutation". They are what Feynman and Goldstein call a nutation, as you can confirm with the references I added to the article. Feynman applies it to a gyroscope and Goldstein to a top and to the Earth. I'm sure I can find several more, although you can hardly get more authoritative than that. That, and its applications, should be the subject of an article called "Nutation". RockMagnetist (talk) 20:05, 6 August 2012 (UTC)

As for the mechanical engineering meanings, I haven't seen a source for any of that yet (see also my earlier comment about swashplates). It's hard to judge whether they are the same or different without adequate information. If there are indeed more than two distinct meanings for nutation, I might change my vote - although a hatnote may still be appropriate (see Disambiguation page or hatnotes?). RockMagnetist (talk) 20:13, 6 August 2012 (UTC)

What about http://www.engineersedge.com/instrumentation/nutating_disk_displacment_meter.htm ? It is a link from the "article" which started this topic. Incnis Mrsi (talk) 20:51, 6 August 2012 (UTC)

I'm not sure. Possibly it could be considered an example of forced nutation. RockMagnetist (talk) 23:29, 6 August 2012 (UTC)

Perhaps that motion of a wobble plate can be considered as a degenerate case of precession, but it is definitely not a nutation (either forced or voluntary), according to Euler angles arguments. But the source does exist (although with the word "nutating"), eh? Incnis Mrsi (talk) 05:43, 7 August 2012 (UTC)

• The issue of multiple uses of nutation for different, but sometimes related, things is similar to that of precession. Perhaps that set of articles can act as a template. -AndrewDressel (talk) 23:08, 6 August 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.

Maximum nutation (angle on celestial sphere)?

What's the maximum angle of the Earth's nutation? The nutated axis is shifted how many arc seconds from its mean position? That info ought to be here somewhere.

Seems like it should be 10+ seconds-- but can that maximum occur at any time in the 18.6-year cycle? If it can, nutation in longitude would sometimes exceed 23 arc seconds-- which it never does? Tim Zukas (talk) 23:05, 5 August 2011 (UTC)

Did I mess up the Malayan characters?

I had to edit this article from the top, to add a new section ("Physiology"), and my computer displayed the following as word-salad:

ml:അക്ഷഭ്രംശം

Would someone with the proper character sets be so kind as to check the article's history and, if need be, replace these characters? Thanks! Jonah Winters (talk) 16:31, 12 October 2011 (UTC)

Fate of the article

Surprisingly, I found that not all experienced users share my (and RockMagnetist (talk · contribs)'s) point that the motion of 2010 was a mistake and resulted in a confusion (to which I refer as an article contamination). So, independently of the history of this question, the fate of the article must be determined to avoid further mergist–splittist confrontation (BTW I am not generally a splittist, I consistently oppose only to mergers-because-of-the-same-word). There are following possibilities:

1. Preserve additions made by Globbet (talk · contribs) and Jonah22 (talk · contribs) and encourage such links as Andy Dingley (talk · contribs) made (possibly, through a redirect such as nutation (engineering)).
2. Trim these additions and leave only references to such meaning (so, Andy Dingley's "correction" should be reverted or, at least, altered).
3. Radically cleanse the article along the lines of [2], essentially restoring the situation of early 2010, but with RockMagnetist's recent additions and reasonable generalizations.

Of course, I support the variant 3, myself. Opinions? Incnis Mrsi (talk) 10:04, 7 August 2012 (UTC)

Please state clearly, for the benefit of those like myself who haven't been part of the previous argument, why this article on nutation (under that name, no disambiguation) should apparently not include engineering uses of the term. There are many of these, with plentiful sourcing. Andy Dingley (talk) 10:29, 7 August 2012 (UTC)

You are really sorry for getting to the party late ☺   Please, read the discussion above, the same discussion which are mentioned in the edit you reverted. Incnis Mrsi (talk) 10:40, 7 August 2012 (UTC)

There is a section above discussing a merger from nutate. As described there, that's fixing up a content split that has spanned the noun and verb forms of the same word. I see no problem with that.

Why are you claiming that engineering uses of nutation should be excluded from nutation? That's nothing to do with a grammatical merge. Andy Dingley (talk) 11:09, 7 August 2012 (UTC)

I just claim that "engineering use(s) of nutation" is not the same as the topic of an article established for several years. There was, and there an article about the nutation by Feynman, Goldstein and RockMagnetist. There was no and there is no article about the nutation by Globbet and Andy Dingley. Moreover: there is no "nutation (astronomy)". There is an important phenomenon of Earth's nutation which claims the plurality (if not majority) of uses of the word. It is not astronomy, it is actually mechanics. So, even if the engineering appeared, the majority of inbound links leads to "the old" nutation, as one can easily observe. So, moving such article to the unqualified "nutation" title is not the possibility. Conclusion: either the "nutation" article will persist as an unintelligible mess, or engineers will link something different from nutation if not happy with my recent addition to wikt:nutate. Incnis Mrsi (talk) 12:15, 7 August 2012 (UTC)

I don't see it being necessarily unintelligible, or a mess. I think it is taking an unrealistically narrow view to conclude that nutation in planets is the one true meaning of the word. There are various more-or-less similar motions, all sharing an element of nodding, and all called nutation. That is the real world situation, and like the real world, it may be considered by some to be unfortunately rather untidy. Tant pis. I do not think that Wikipedia is improved by creating a different article for each subtle nuance of difference in the kinematics of these motions. That only one type of nutation was originally described in the article seems to me a very poor reason for resisting improvement by expansion to cover a wider, but still fully relevant, scope. Individually none of the examples warrants more than a few paragraphs of explanation, and for readers to be sent hither and yon to find a particular example, or to assimilate a general picture, seems to me to be a waste of their time, as compared to single article that covers both the loose general idea and all the variations. It still would not be a large or complicated article. Nobody has yet come up with guidelines that suggest this is wrongheaded. Indeed, if I were in the mood, I think I could make an argument that hiving off the various manifestations of nutation into different articles would itself be a sort of WP:OR. Fortunately, I am not. Globbet (talk) 17:30, 8 August 2012 (UTC)

Globbet, I think that the creation of new articles is an unfortunate side issue that was introduced. The current disambiguation page takes care of all the meanings without any new articles. It addresses your original concern (having two pages called "Nutate" and "Nutation", which I agree was silly), while also addressing the concerns of some of the other contributors to this discussion. As I say below, I don't have strong feelings about the inclusion of other meanings in this article, but if they remain someone will have to find citations for them and clearly explain their relation to the physics definition. RockMagnetist (talk) 17:52, 8 August 2012 (UTC)

Why unfortunate? It is the goal of Wikipedia, to make articles on topics not yet covered, just that. And not converting existing articles to a semantic mess like Wiktionary articles, I repeat. Incnis Mrsi (talk) 18:28, 8 August 2012 (UTC)

It's unfortunate only because it is a separate issue and makes agreement more difficult. RockMagnetist (talk) 18:30, 8 August 2012 (UTC)

Sorry, I did not notice Globbet's WP:OR argument in time. An original research it is, these various manifestations of the stuff into different articles… The WP:No original research policy strongly prohibits such researches in article bodies, titles, as well as original synthesis. Does the policy prohibits original analysis? It is the thing I make here for years. Incnis Mrsi (talk) 06:48, 9 August 2012 (UTC)

Andy, I don't doubt that there are plenty of sources on the engineering uses of "nutation", but so far there aren't any in Wikipedia articles. I'd appreciate it if you could add some, because I don't know much about the engineering uses. RockMagnetist (talk) 17:12, 7 August 2012 (UTC)

I'm here because of disk wheels (actually wobbly-web wheel) and their stiffness to resist nutation. Other, more obvious, examples are nutating disk water meters (probably the reason most engineers first learned the word "nutating"). Nutating engines (i.e. swashplates) are a regular occurrence in kookscience (their real problems became evident in the 1930s and haven't gone away since), but they have respectable sources investigating them too. Helicopters obviously have their similar mechanism. Nutating motions are also a fairly obscure vibration problem in whirling shafts. The rest is the usual research for cites. Andy Dingley (talk) 21:46, 7 August 2012 (UTC)

I don't think the history of the article should weigh too heavily in this discussion. So far this article has failed to develop the general physics of nutation, and there has been an overemphasis on the planetary application. I am also not particularly worried about "contamination". A section entitled "Other uses of the term" with the biological and engineering uses would do no harm if the main subject was adequately developed. However, I think the current disambiguation page is good. So I support using the {{otheruses}} template and moving the other meanings to more appropriate articles.

I want to emphasize that this issue is not very important. Someone could do far more good to the article by adding the basic physics. RockMagnetist (talk) 16:54, 7 August 2012 (UTC)

My above vote is based on the assumption that the physics meaning is the dominant one. I think it is, but plenty of alternatives show up among the top hits in a Google search. So I would also be fine with "Nutation" being the disambiguation page and this page being renamed "Nutation (physics)". RockMagnetist (talk) 17:04, 7 August 2012 (UTC)

Heated debates like this one are unpleasant for everyone, and there is the danger that the antagonists will get locked into opposing viewpoints and refuse to budge. That would result in more profitless debate. I would like to push for a compromise: Rename this article Nutation (physics) and move Nutation (disambiguation) to Nutation. I think that addresses the main concerns of everyone. It focuses the subject of this article while giving equal weight to other definitions of nutation. RockMagnetist (talk) 18:11, 8 August 2012 (UTC)

It is an option, but, except for changing incoming links, it is technically the case 3, a radical decontamination. I hinted twice that article titles are the separate question, but they did not hear me, nor your calls to present more sources, and replied mostly with inconstructive flamebursts. WikiProject Engineering also did not help us. So, where is Nutation (engineering) after a week of flamewar? There is no yet. Incnis Mrsi (talk) 18:28, 8 August 2012 (UTC)

I, for one, wanted to get this issue resolved before adding anything else that might not be deemed acceptable. Can you tell me what I have written that is unconstructive or inflammatory (at my talk page), please? In the meantime, here for example, is a link to a NASA paper (see the PDF link for the actual paper). Globbet (talk) 00:25, 9 August 2012 (UTC)

To search here(subscription required)? It is not convenient for WP, but if you found some document of a special importance, could you upload it there? Incnis Mrsi (talk) 06:48, 9 August 2012 (UTC)

Yes, it is similar to option 3, not restoring any old version but just removing the two sections that cover other meanings (or moving the content to other articles). Let's not worry about who is right. Let's just come to an agreement. I take it that you would be o.k. with this option if the other editors agree? RockMagnetist (talk) 18:33, 8 August 2012 (UTC)

Why would anyone wish to add to an article when the inevitable result would be a torrent of abuse? Andy Dingley (talk) 19:14, 8 August 2012 (UTC)

Can't anyone answer my question with a simple yes or no? RockMagnetist (talk) 19:22, 8 August 2012 (UTC)

OK. No. I am sorry, but I disagree. The engineering usage is as much physics as the one applied to astronomy. I see no point in the disambiguation article because I think the whole lot belongs in one place. Globbet (talk) 00:25, 9 August 2012 (UTC)

Read Euler rotations, please. Maybe, you will realize at last, that "your" nutation is orthogonal to þ^e olde goode nutation. @RockMagnetist, I would approve moving of þ^e olde goode nutation only after Nutation (engineering) appeared. Maybe, even as a redirect, but not to any place within þ^e olde goode article. In general, the variant 1 is the only possibility which I consider degrading. These are different complex motions, period. Incnis Mrsi (talk) 06:48, 9 August 2012 (UTC)

I'm afraid I don't really understand your complaint against engineering. From this last comment, I think you mean that "engineering" uses of the term nutation are not "true" nutation, but are "merely" precession instead? There are two issues with that: firstly that this narrow definition of nutation is largely unsourced, or at least uncited inline in either article, so that it's hard to verify that this is an accepted definition from RS, or just one that has arisen on WP.

Secondly, the engineering uses include both precession and nutation, even by the narrow definitions here. Not all do, all the time, but plenty do. Most swashplate engines and pumps involve precession, but the helicopter control aspect is nutation. The rigidity issue for disk wheels involves both. Andy Dingley (talk) 11:46, 9 August 2012 (UTC)

As the problematical sentence from the wobbly-web wheel article states,

“ It is flexible for axial loads, perpendicular to the disk plane and also for nutating, wobble of the axle at an angle to the main axis. ”

Is this your "rigidity issue for disk wheels"? It is the engineering nutation in frames of reference of both the disk and the axle. It may look like þ^e olde goode nutation in the car's frame of reference, but this depends on how exactly these parts move, and has little relevance to disk wheel's mechanical properties. Incnis Mrsi (talk) 12:24, 9 August 2012 (UTC)

Yes. The problem motions (which neither a simple disk wheel nor a coned disk wheel resist) are both precession and nutation. Resisting them depends a lot upon the wheel's properties, particularly how its shape varies from that of the simple disk. Andy Dingley (talk) 13:12, 9 August 2012 (UTC)

Look at all this effort going into talking about the article. Perhaps we could devote some effort to improving the article itself? Correct me if I'm wrong, but my impression is that not one of us have contributed any content.

I have a new proposal: Shelve the whole debate until we have more, better sourced, material on the different meanings. Without that, the arguments will continue going in circles. Let's add material and try not to revert each others' edits. RockMagnetist (talk) 16:16, 9 August 2012 (UTC)

Edit warring et al from user:Incnis Mrsi

Apologies for getting to the party late...

Incnis Mrsi seems to be busy soapboxing this article to exclude engineering topics. This has extended to searching linked articles and changing their inbound wls from nutation to wikt:nutate. Apparently this is done because "it's precession and not nutation" [3], in which case why use a Wiktionary link that's still about nutation, rather than precession?

I also note some clear PAs against Globbet, throwing terms like "contamination" around. They're now stretching that into trolling other editor's talk pages and article creation histories, see [[4].

What's going on? If this article is to split into nutation (astronomy) and nutation (engineering) then that's fine, but this sort of behaviour just isn't acceptable. Andy Dingley (talk) 10:16, 7 August 2012 (UTC)

I am not so insulted with "edit warring" and even "soapboxing", but you, Andy Dingley, will certainly account for breaches of WP: Assume good faith such as "trolling". Incnis Mrsi (talk) 10:32, 7 August 2012 (UTC)

Trolling: [5]

Following another editor's (who you have no previous overlap with) contribs history and then throwing in a bizarre and dubious curveball. Trolling. Andy Dingley (talk) 10:37, 7 August 2012 (UTC)

You are just engaged in an OR in an article's title, and reject well-known punctuational guidelines. You cannot substantiate your ownership intentions, so resort to name-calling and pushing to "undo" button. Incnis Mrsi (talk) 10:46, 7 August 2012 (UTC)

Ownership? I didn't create the name. It was listed at requested articles, under precisely that name, for at least two years before I created the stub.

Having the word "Museum" in the title of an article about a museum isn't "punctuation". Why did you remove it?

Why did you even go near that article, if it wasn't just from trolling another editor who had the temerity to challenge your soapboxing on another article? Andy Dingley (talk) 11:06, 7 August 2012 (UTC)

Yet another violation of the AGF principle. The conduct of Andy Dingley is not only flame-provoking, it is detrimental for the spirit of this collaborative project. Stop searching for trolls and other malevolent persons, concentrate on your point. Incnis Mrsi (talk) 12:15, 7 August 2012 (UTC)

Why don't you move this debate to a user talk page? RockMagnetist (talk) 17:08, 7 August 2012 (UTC)

Merger proposal

I just discovered that there is an article on Free nutation with nothing more than a dictionary definition. Seems pointless. I propose merging it with Nutation. If the material on free nutation grows enough, it could always be split off again. RockMagnetist (talk) 18:14, 9 August 2012 (UTC)

Nothing to merge. First, a material object cannot be a sphere. It may be a ball, though (it is a very common confusion among English-speakers). Second, these are the inertia tensor, as well as mechanical properties, which do matter, not the form. Just redirect and forget. Incnis Mrsi (talk) 19:09, 9 August 2012 (UTC)

I agree with your proposed action. Globbet (talk) 23:28, 9 August 2012 (UTC)

Same here. Maschen (talk) 10:28, 16 August 2012 (UTC)

Given the triviality of the merge - I just did it now. Maschen (talk) 10:36, 16 August 2012 (UTC)

Thanks. Having allowed a week for responses, I had forgotten about it! RockMagnetist (talk) 16:18, 16 August 2012 (UTC)

I reverted it; you created a redirect to an article that does not include the term. One of the most annoying things on Wikipedia from a reader's perspective, enter a search term, get redirected to an article that doesn't use that term. -68.107.137.178 (talk) 10:36, 8 May 2013 (UTC)

Although I agree that it is annoying, please don't undo consensus changes without discussion. The proper solution is to mention free nutation in this article. Apparently the merge wasn't done correctly. RockMagnetist (talk) 16:35, 8 May 2013 (UTC)

I have added the definition of free nutation to the lead. RockMagnetist (talk) 16:40, 8 May 2013 (UTC)

Actually, the consensus was to delete any mention of free nutation and just redirect the page titled free nutation to this article without adding any information about free nutation to this article; which, since the definition appeared to be wrong, might have been a good idea; however, having a redirect to nothing here, was useless. And, nutation is used differently from free nutation, and free nutation is still not developed in this article, which is itself, disorganized and fails to offer a general understanding of what nutation is, much less free nutation, and where it is used in the introduction. But, I am used to this, "Get away from my article! we already decided how to fix it based on faulty evidence and without doing what we said we were doing and without knowing what we did" Wikipedia syndrome. I was okay with writing an article on free nutation, but, since nobody wants a definition of free nutation, whatever. -68.107.137.178 (talk) 16:56, 8 May 2013 (UTC)

If you don't make it clear what you are trying to do, how can you expect to get cooperation? If you want to write an article, and not just restore a dictionary definition, I'm all for it. However, it might be better to improve this article first (I agree that it needs plenty of work). RockMagnetist (talk) 17:08, 8 May 2013 (UTC)

It's not as if anyone here is clear; we have a disagreement about an incorrect definition that got turned into a merge that was just a redirect to an article that doesn't mention the topic. What's clear about that? What I did was an improvement, and since it is hard to figure out what was done here (not what you think was done, by the way), there's a limited amount of conversation I can have without spending an extensive amount of time trying to figure out what the consensus really was. I am not the least interested in nutation, only free nutation. -68.107.137.178 (talk) 17:44, 8 May 2013 (UTC)

I don't think you have read the above consensus correctly, but does it really matter? There is now exactly as much information on free nutation in this article as there was in your last non-direct version of Free nutation. Even if there were a separate article on free nutation, this article should include a summary of it. So why not start by adding a section on free nutation in this article? Then, if it grows long enough, split it. No one would object to that. RockMagnetist (talk) 18:03, 8 May 2013 (UTC)

Split (Sacrum)

I think the section on Physiology should remain here because there needs to be a note that it is a different concept, and that is all there is here. Does anyone have any objections to me removing the tag? Op47 (talk) 19:13, 9 February 2013 (UTC)

Removing what? The Nutation #Physiology is a part of an entire problem. Possibly, this section has some relevance to Nutation (engineering), but not to the rest of "article". Incnis Mrsi (talk) 22:16, 9 February 2013 (UTC)

Correction

I think the formula for kinetic energy T in Rigid body dynamics got an extra term. Should be just T =... + \frac{1}{2}I_3\left(\dot{\psi})^2, no \dot{\phi}\cos\theta\right)^2. — Preceding unsigned comment added by David Gurarie (talk • contribs) 06:09, 24 August 2013 (UTC)

Split

I have been looking at this article for over a year now and failing to make any sense of what is going on. Looking at the history of Nutation (disambiguation), the penny finally dropped. Nutate was moved to Nutation (disambiguation). Then an attempt was made to restrict the article Nutation to the Physics and Astronomy terms. So the proposed hierarchy is:

Nutation -- Physics and Astronomy only

Nutation (disambiguation)

Nutation (engineering)

Sacrum#Articulations

etc.

Well now I can see why we aren't getting anywhere. Even speaking as a physicist, I do not see why the physics use of the term should take priority over the other uses of the term. A more equitable solution would be:

Nutation -- was Nutation (disambiguation)

Nutation (physics) -- was this article

Nutation (engineering)

Sacrum#Articulations

etc.

Given the length this tag has been up, I am going to open and RfC to try and get a resolution. I will give 3 options i.e. the 2 above and the 3rd to leave the article merged. I trust that we can move forward with whatever decision is made.— Preceding unsigned comment added by op47 (talk • contribs) 19:13, 9 February 2013‎

RfC: Do we split this article? and if so how?

The following discussion 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.

---

Do we split the article or leave it merged.— Preceding unsigned comment added by Op47 (talk • contribs) 18:50, 21 December 2013‎

This survey, as originally constructed by Op47 (talk · contribs), does not transcribe properly to the RfC page. The options below were originally separate sections:

1. This article takes priority

Nutation -- Physics and Astronomy only

Nutation (disambiguation)

Nutation (engineering)

Sacrum#Articulations

etc.

2. Disambiguation page takes priority

Nutation -- was Nutation (disambiguation)

Nutation (physics) -- was this article

Nutation (engineering)

Sacrum#Articulations

etc.

3. Leave the article merged

RockMagnetist (talk) 18:27, 26 December 2013 (UTC)

Survey

Please only vote in the survey section and use the section "threaded discussion" for any discussion that may be required.

• Support option 1, I think this option is best; if somebody can demonstrate that the engineering and physics definitions are of equal precedence, I would be willing to change my vote. Of course, a hatnote would be needed at the top of this article. StringTheory11 (t • c) 05:38, 26 December 2013 (UTC)
• Support option 1. One article one topic, so the physiology and engineering articles should not be in this one, and I believe that the physics and astronomy meaning satisfies WP:PRIMARYTOPIC. —David Eppstein (talk) 18:13, 26 December 2013 (UTC)
• I don't have strong feelings but this article (nutation) should not be a DAB page. This main article should describe the physics, leaving related topics to other articles. In short I support option 1. M∧Ŝc²ħεИ_τlk 11:30, 28 December 2013 (UTC)
• Good move. This is my opinion. In short, anything except 3. Incnis Mrsi (talk) 18:41, 28 December 2013 (UTC)

  Andy asks why do I think so. He claims that “the engineering uses include both precession and nutation”. Maybe it’s true, but such things as nutating disc engines and nutating disc flow meters definitely rely on precession (first and third Euler angle changes), not on “our” nutation (second and third Euler angles). Even if some instances of “their” nutation include both first and second Euler angles, it obviously needs a clarification outside þ^e olde goode article on nutation. There is a separate article now. Make it better. Incnis Mrsi (talk) 19:45, 28 December 2013 (UTC)

• Option 2. Granting that option 3 makes no sense, as it stands this situation makes no sense either, being based apparently on the idea that some or other sub-topic might have "precedence" over another. The overall use of the term is what should have precedence, so that if a reader does not know what some nut case named any of half a dozen topic articles, his first try should either show up unambiguously in the list, or if not, the disambiguation should show up first. Not only does the current situation fail to assist the run-of-the-mill reader, it doesn't even favour the "precedence" of physics or astronomy for anyone who just enters "Nutation". I went and entered "Nutation" to see what happened, and got: 1 Nutation (that could mean anything or nothing in particular) and 2-5 Nutation in plants, anatomy, disambiguation and engineering. The logical option should be that if the user enters just Nutation, the list appearing would show "physics & astronomy" (or if preferred those two in two articles; might be a good idea) and if he can't decide on his favourite flavour, then plain vanilla takes him to disambiguation. If he does know, then his choice is visibly present for immediate selection. Surely preference for the option that leads to the fewest dud choices is elementary info theory? And surely this requires that where any disambiguation article is useful, it should be the most generally (parsimoniously) titled? And this would apply irrespective of "precedence", supporting a minimal tree search in any case? JonRichfield (talk) 12:13, 30 December 2013 (UTC)
• option 1, nutation is a kind of motion, motion is physics, main topic is physics. Also, as much as I see the other uses are about specific-thing doing nutation(-like) movement. Neither other option would hurt either: disambig first would work fine enough, and the engineering stuff is not (yet) so large that it couldn't stay nerged until expansion. - Nabla (talk) 02:53, 19 January 2014 (UTC) (coming from wp:frs)

  Could you clarify what do you support? The current arrangement, Globbet–Jonah22 arrangement, or something intermediate with Andy Dingley’s stuff inside but biology outside? Incnis Mrsi (talk) 08:55, 19 January 2014 (UTC)

  @Incnis Mrsi: There isn't any "Andy Dingley's stuff" - he hasn't contributed any content. The main differences between those two versions are that the sections on mechanical engineering (mostly due to Globbet (talk · contribs)) and physiology (mostly written by Jonah22 (talk · contribs)) have been removed, while I have added the section on rigid body dynamics. I hope you're not seriously suggesting that anyone would want the rigid body dynamics removed. RockMagnetist (talk) 22:10, 19 January 2014 (UTC)

  "option 1" is unambiguously defined on the question - and I already clarified my general idea (physics here). - Nabla (talk) 22:54, 24 January 2014 (UTC)

Threaded discussion

Two points that came up in an earlier discussion:

1. The article on precession covers multiple definitions in one article. Because precession and nutation are closely related, it would be nice to have a consistent approach for the articles (whatever that approach turns out to be).
2. There was disagreement on whether there were any reliable sources for a clear alternative definition of nutation in engineering. RockMagnetist (talk) 18:50, 26 December 2013 (UTC)

Do you think it would be prudent to notify all contributors to the initial discussion above (of course notifying participants on all sides)? StringTheory11 (t • c) 19:14, 26 December 2013 (UTC)

@StringTheory11: probably - although some of them may be tired of this discussion. RockMagnetist (talk) 03:58, 27 December 2013 (UTC)

Alright, pinging @Globbet:, @Guentherwagner:, @Incnis Mrsi:, @Sbyrnes321:, @Andy Dingley:, @AndrewDressel:, and @Maschen:. Please don't turn this into a crapfest.... StringTheory11 (t • c) 00:59, 28 December 2013 (UTC)

(Personal attack removed)

Andy, I quite understand. I would have sorted this article out long ago if I could see any form of concensus through all the nastiness that is going on. Can we all please remember that all that is required is to put a vote on the survey above, and allow others to have theirs. Remember, you are not more correct by screaming at us. Op47 (talk) 16:43, 28 December 2013 (UTC)

Why not to say simply you are not correct? Or, even better, why should anyone comment hatred outbursts at all? Incnis Mrsi (talk) 18:41, 28 December 2013 (UTC)

But I'd be more correct, if I ignored all other editors and edited the articles how I wanted them despite? I'm accused of "personal attacks" and blanked for linking to Incnis Mrsi's own disruptive edits, but it's OK to call me a cunt and no one bats an eyelid? Andy Dingley (talk) 18:48, 28 December 2013 (UTC)

It turns out that the insults on Andy's talk page were from sockpuppets of a blocked user, Europefan (talk · contribs), and had nothing to do with this discussion. RockMagnetist (talk) 04:24, 31 December 2013 (UTC)

• Note: Incnis Mrsi (talk · contribs) has created the page Nutation (engineering). RockMagnetist (talk) 17:19, 28 December 2013 (UTC)

Below comment moved to threaded discussion from survey section

@JonRichfield:, I can't reproduce your experiment. When I enter "Nutation" in the Wikipedia search bar, I get this article. You seemed to end up on a disambiguation page, but one with different content than any version of the disambiguation page in the last year or more. RockMagnetist (talk) 18:55, 30 December 2013 (UTC)

@RockMagnetist: it seems JonRichfield meant a google search.

@JonRichfield: You say the main article should be about the principle use of the term - how much more is the term used in physics and astronomy compared to engineering, biology, or other places? Probably the same extent, one may argue. Still, the reader can get to the DAB page from the top of this physics page with option 1, so there isn't exactly any loss of continuity. M∧Ŝc²ħεИ_τlk 23:52, 30 December 2013 (UTC)

@JonRichfield:, just FYI, there would definitely be a hatnote at the top of the article that links not only to Nutation (disambiguation), but also directly to Nutation (engineering) if option 1 is chosen. StringTheory11 (t • c) 04:15, 31 December 2013 (UTC)

<phew!> Hold on folks. First: go to a convenient WP page. Find the search box (near the top right-hand in my software). The box shows a little magnifying glass. Type in Nutation. Do not click nor press enter. A drop-down list appears with Nutation at the top, and beneath it four (VARIOUSLY formatted <blech>) article names that begin with Nutation. For good measure they are followed by: "Containing Nutation" in case the list does not include the one you know you want. You then guess which one you want in the despairing hope that the top one might deal with Phys & Astro... (In these circles it no doubt is unnecessary to specify WHICH Astro...?) Anyway, Nuttin' up my sleeve, no google. Have I ever...? Naaah! (continued on next rock...) JonRichfield (talk) 14:01, 31 December 2013 (UTC)

@Maschen: You say: "You say the main article should be about the principle use of the term..." I say nothing of the type, unless you can point me at where I said anything so ridiculous. I used expressions such as "...overall use of the term..." and "...the most generally (parsimoniously) titled..." What is so difficult about that? You surely are familiar with the principles and implications of branch-and-bound tree searching? And of the advantages of promoting its implementation so as to eliminate as much as possible as early as possible on each probe? By typing in nutation with the articles all suitably named (and assuming (harmlessly from my point of view) that each article is properly and helpfully named, for example "Nutation (Physics)" "Nutation (Astronomy)" (Or if you prefer "Nutation (Astronomy and Physics and Applied Maths)") one invariably gets a single, convenient, unambiguous result with one click, no matter which option you wanted, often before you have finished typing, and in no way slower or requiring more clicks or keystrokes than if you had happened to know in advance that the one you wanted was not qualified. Why make life harder for astronomers just so that you can force botanists to suffer? And while we are at it, will someone please rename the botanical article to "Nutation (Botany)" or something equally rational and uniform with the other names? The only name that could be rationally abbreviated is "Nutation (Disambiguation)" (And don't get me started on the half-witted nature of the standards for constructing disambiguation pages. Haven't I suffered enough?) JonRichfield (talk) 14:01, 31 December 2013 (UTC)

@StringTheory11: Oh and I forgot to add: being pathologically anal retentive, and regarding as I do, hatnotes and links as sacred and to be used wherever appropriate (nearly wherever possible FTM) I am all in favour of their lavish use, especially in such cases as this, where certain of the concepts are common to all articles. This is independent of the rest of the discussion, I should say. Cheers. Jon JonRichfield (talk) 14:01, 31 December 2013 (UTC)

@JonRichfield: You raise some good points. I like the idea of renaming Nutation in plants to Nutation (botany), so (on the assumption it is not controversial) I have renamed it. Your main concern is a broad one and clearly applies to many articles, so this may not be the place to solve it. In essence, you're calling for a change in the PRIMARYTOPIC guideline. This may not be a simple issue, as there are a lot of ways to access a page. For example, I typed in "Nutation" and hit return without paying attention to the completions, so PRIMARYTOPIC worked well for me. Until the policy changes, I recommend we follow it. RockMagnetist (talk) 17:49, 31 December 2013 (UTC)

@RockMagnetist: Gramercy sir! Renaming Nutation in plants made sense, and retaining it as a redir made even more sense. I still disagree with the primarytopic thing, but of course that is not a show-stopper, so I'll quit while I'm ahead! Cheers, JonRichfield (talk) 18:34, 31 December 2013 (UTC)

Analogies with precession

RockMagnetist (talk · contribs) called for consistent approach for the articles. IMHO we now moving towards it.

• Precession is a WP:CONCEPTDAB (one said: covers multiple definitions) about several types of “rotation superposed with another rotation”. Namely:
  • Axial precession;
  • Nodal precession (similar thing, but for an orbital motion);
  • Apsidal precession (two “rotations” in the same plane: an elliptic Keplerian orbit rotates itself).

  Note that each of three types has its own article.

• Nutation has to be an article about changes in the axis of rotation that are not another rotation. There aren’t so many flavours of nutation, so n + 1 articles are not needed.
• All other types of rotational motion should require more articles, or be merged with appropriate context articles and be navigable from dab pages.

In short: the precession article does not appear to be such a mess. Incnis Mrsi (talk) 10:09, 29 December 2013 (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.

Do the North and South Poles move from their geographical position ?

Just for people like me, as a reasonably scientific person with a moderate grasp of physics, please would someone add information to clarify whether this planetary nutation is causing the North and South Poles to regularly move from their geographical position, or do they not actually have a totally fixed position ? Many thanks for your help ! Darkman101 (talk) 21:00, 21 November 2024 (UTC)

See polar motion. —Tamfang (talk) 05:52, 22 November 2024 (UTC)