Wikipedia:Featured article candidates/Jürgen Ehlers/archive1


 * The following is an archived discussion of a featured article nomination. Please do not modify it. Subsequent comments should be made on the article's talk page or in Wikipedia talk:Featured article candidates. No further edits should be made to this page.

The article was promoted by User:Ian Rose 10:03, 8 June 2013 (UTC).

Jürgen Ehlers

 * Nominator(s): Markus Pössel (talk) 17:42, 14 April 2013 (UTC)

I have worked on this article on and off for some time, and feel it is now ready for FA. It's been through a helpful peer review, and the Guild of Copy Editors have also been kind enough to have a go at it; the GOCE member who took care of it encouragingly commented that the article was "Overall in great shape". It's not an easy subject for two reasons: Ehlers is not in the same league as Einstein, Planck & Co., and that means there are not nearly so many reliable sources about him. I've taken care to exploit all reliable sources I could get my hands on, but a biographical article like this must necessarily be less detailed than for one of the Greats. Secondly, much of Ehlers' work is somewhat technical in nature. I've tried to strike a balance between including sufficient information for the description to be accessible, and keeping the text concise. For both reasons, this article was harder work than my previous FAs, in particular the related general relativity and introduction to general relativity. My reason for picking this topic is that I knew Jürgen Ehlers, and he was a kind colleague from whom I've learned much. Markus Pössel (talk) 17:42, 14 April 2013 (UTC)

Image review - Everything checks out. More to come on the rest of the article. Wadewitz (talk) 23:00, 17 April 2013 (UTC)


 * Support: My concerns were addressed and so I'd like to provide support for FA status. Praemonitus (talk) 23:44, 22 April 2013 (UTC)
 * Comments: I read the article and it seems reasonably well written, but the physics terminology gets pretty dense—at least for me. It should probably have an independent review by an expert. Here are a few observations:

Thank you. Praemonitus (talk) 00:21, 20 April 2013 (UTC)
 * I found this comment in the text: "The first paper, written with Jordan and Kundt, is a treatise on the properties and characteristics&lt;!--properties and characteristics are in some senses, synonyms. what is the intended meaning here?--&gt;": can this be addressed?
 * The meaning of this sentence is somewhat unclear: "It also gives a systematic exposition of the geometric properties of bundles (congruences) of light beams in terms of their expansion (simply put, how the beams converge or diverge), twist and shear (how, apart from growing or shrinking, the cross section is deformed)." Can the intent or context be clarified here?
 * "...shadow produced by a narrow beam of light passing an opaque object": passing, or intersecting?
 * "...the gravitational field inside cannot be static, but must evolve": I'm not clear what this means.
 * What is the "...tt-component of the metric"?
 * It should mention that he had a wife Anita and four children. I thought there should be a little about his parents, but I couldn't find anything.
 * Many thanks for your comments, which I'll address one by one. Generally, it is true that the article has, in part, content that is rather technical - a direct consequence of Ehlers' field of study. I've tried to strike a balance, but I'm of course open to suggestions on where somewhat more detailed explanations would help.
 * "The first paper, written with Jordan and Kundt" - I've changed this to a (hopefully) more accessible sentence.
 * "It also gives a systematic exposition..." - I've put in a somewhat more explicit version.
 * "...shadow produced by a narrow beam of light passing an opaque object": encountering seems best, since part of the beam can intersect, while another part can pass the object.
 * (will address the other comments later) Markus Pössel (talk) 14:28, 20 April 2013 (UTC)
 * Replies to Comments, part 2:
 * "...the gravitational field inside cannot be static, but must evolve" - changed to "change over time", and given the simplest example.
 * So... my completely naive intuition tells me that all of the mass within the event horizon would collapse into the singularity and the internal gravitational field would stabilize based on the boundary conditions. Ehlers' statement is that this cannot happen, but instead the field must be continually evolving in some manner? That's ... strange. Okay, thank you for the example. Praemonitus (talk) 23:44, 22 April 2013 (UTC)
 * "...tt-component of the metric" - added the physical meaning: the rate of ticking of clocks whose spatial coordinates do not change
 * I did add wife and children in the same manner as the obituary you've cited, namely as a statement of whom he left behind. Without a published source on date of marriage and the children's years of birth I see no suitably referenced way to insert that information into the chronological part of the article in an earlier section.
 * Again, thanks for your comments! Markus Pössel (talk) 17:49, 21 April 2013 (UTC)
 * Thank you for addressing my concerns. Good luck with the FAC. Praemonitus (talk) 23:44, 22 April 2013 (UTC)
 * Thank you for your help! Markus Pössel (talk) 10:21, 23 April 2013 (UTC)


 * Support (Note: I peer-reviewed this article.) The article is well-structured, well-written and coherent. The sources are all reputable. I can't speak much to the physics sections, I'm afraid, as they are quite specific. However, the introductory sentences always give a basic idea that I can follow, which I consider essential in articles like these. I'm glad you got to write up your adviser! Wadewitz (talk) 17:44, 23 April 2013 (UTC)
 * Ceranthor Comments
 * he held various lecture- and professorships - Assuming this is a typo?
 * Free of dabs! :)
 * In the winter term of 1955/56, - better as 55-56 I think
 * In 1961, as Jordan's assistant, Ehlers earned his habilitation (qualifying him for a German professorship).  - No need for parentheses, this is fine as prose.
 * He held teaching and research positions at the University of Kiel, Syracuse University and Hamburg University. In 1964, Ehlers again moved to the United States. - These two sentences confuse me. First, you randomly mention a US university. Then you imply that you already stated him moving to the US, but I can't find that being mentioned anywhere.
 *  Ehlers' name had been suggested by Ludwig Biermann, the institute's director at the time. - Obviously Ehler was suggested, not just his name. The name is redundant. "Ehler had"
 * On June 9, 1994, the Society indeed decided to open a Max Planck Institute for Gravitational Physics in Potsdam. - Why the use of indeed? It seems redundant.
 * Ehlers began to look for serviceable ways of characterizing exact solutions invariantly, - Why the italics?


 * Support - Very technical but accessible read.  ceran  thor 22:12, 19 May 2013 (UTC)


 * Many thanks for your comments, and for your support!
 * "lecture- and professorships", for "lectureships and professorships", is not a typo. I've changed it to "various posts as a lecturer and, later, as a professor" which I hope to be more clear.
 * habilitation parentheses removed.
 * 1955/56 changed to 1955-56
 * Kiel, Syracuse and Hamburg are meant to be in sequence, implying that he did move to Syracuse for a position. I've changed this part a little bit; hopefully, I've put matters more clearly in the current version.
 * I've dropped the "name" and now have Biermann recommending Ehlers directly.
 * The "indeed" was meant to link this to the previous sentence - after all, the Society did not decide spontaneously, but in response to the lobbying. But I have no fixed opinion either way, and have removed the "indeed."
 * The italics are for emphasis. The "invariantly" is the important and new thing here. I'm leaving the italics for now; if there's another way of making that emphasis, I'm open to suggestions.
 * Again, thanks for your input! Markus Pössel (talk) 18:06, 20 May 2013 (UTC)
 * All seem fine. Thanks for your speedy fixes!  ceran  thor 19:02, 20 May 2013 (UTC)

Delegate comment -- Hi Markus, been a while since you've been at FAC, yes? Just like to see a source review and spotcheck for accuracy and avoidance of close paraphrasing -- I've left a request at WT:FAC for someone to do that. Cheers, Ian Rose (talk) 16:36, 24 May 2013 (UTC)


 * Yes, it's definitely been a while. World Science Festival, later moved to World Science Festival, 2008 was the last one in late 2008. I don't recall source and image reviews (under that name) from my previous nominations; a more recent custom, I suppose? Is there anything I can and/or am supposed to do facilitate the review and spotcheck (apart from having clearly identified and linked my sources, of course)? Markus Pössel (talk) 18:07, 25 May 2013 (UTC)
 * No, just sit tight -- the fact that most of the refs seem to be online should make spotchecking easier. Cheers, Ian Rose (talk) 23:54, 25 May 2013 (UTC)

Sources review The sources themselves are impeccable, but checking the citations out out is nightmarish. Citation styles should be simple, and easy for the general reader to follow. I am also surprised by the failure, before this submission, to check that all online links were working. At least half a dozen are not, and I doubt they all went wrong after the submission. Specific problems:
 * General: Multiple sources within single citations tend to be  overcomplicated and difficult to interepret. You should consider splitting these. In some case it might be more appropriate to list alternative sources  as "External links"
 * Some of the sources appear as discursive footnotes, e.g. 9, 27, 31 etc; ref 9 appears to be a general observation rather than a specific citation. This kind of comment should be in a separate listing, as a footnote.
 * A number of the links are not working, or go to inappropriate pages:
 * Ref 3: check the link on "Editor's comment". Is this the intended source? How does it support the cited statement
 * Ref 5: First link returns "not found"
 * Ref 12: Neither of the first two links works (the link to the website, if not used as a source, should appear under "External links").
 * Ref 33: link gives error message
 * Ref 38: first link denies access, requires login
 * Ref 39: link gives address not found
 * Ref 40: second link goes to the wrong page


 * You need to be consistent in providing ISBNs and publisher locations for books
 * Sources 6 and 7 appear to be in German, but are not noted as such.
 * Ref 8: What is the purpose of this CV? Such documents are prepared by the subject, and are not independent reliable sources.
 * Refs 4 and 16 appear to be identical. Use "ref name=" to avoid repetition
 * Ref 13: not properly formatted.
 * Ref 19: both links go to abstracts. You should indicate that the source articles require purchase.
 * Ref 21: Why the "E.g"? Citations should be specific. See also 33
 * Ref 22: first link article requires login or purchase
 * Ref 27: both articles require purchase. This is a recurring problem and I won't mention it again. To be clear: if a source requires purchase or login for access, this needs to be noted.
 * Ref 35: I am confused as to what is being cited here.
 * Ref 41: not properly formatted

I think all these issues need to be addressed before the article is ready for promotion. Brianboulton (talk) 14:18, 27 May 2013 (UTC)


 * Thank you for your thorough check of the citations. I will respond to your points one by one over the next few days. Markus Pössel (talk) 21:38, 27 May 2013 (UTC)


 * Before making specific changes, a few more general issues. For reference, here is a permalink to the current version, in case reference numbers will change later.
 * I would like to keep the additional annotation as per WP:Cite where they tell the reader how the different references act together to support the sentence or pargraph in question (and no, a number of those you cite are not discursive footnotes - they explain the references). I see where having this annotation style, but also list complete references, makes for crowded and thus less easily readable notes. My proposal would be to go the same way I went in general relativity, with Harvard-style references in the notes, and all the references listed in alphabetical order below. That should go a long way of making the notes more readable. It would also solve problems like that of ref. 4 and 16, which contrary to what you wrote are not identical, as one provides a page number, the other doesn't - they could both refer, Harvard-style, to the same article listed in the reference list.
 * I don't see anything in WP:CITE about stating whether or not an article link requires purchase or login, in particular if it is a DOI link. Frankly, I don't think such a policy change would make much sense. The main reference is the printed one in this case, and DOIs are a kind of automatized convenience link. That's the way it sounds in WP:SOURCELINKS, too.
 * Same with listing the language - where is that a requirement, in WP:CITE?
 * I'll see about the uncontroversial issues, such as consistency in ISBNs and so on, now, but for the issues mentioned above, I don't see what's WP:CITE-non-compliant in what I did. Markus Pössel (talk) 08:06, 28 May 2013 (UTC)


 * I think "nightmarish" was rather harsh a word, but I readily admit that splitting into Notes and References makes that part of the article much more readable than before, and I am somewhat embarrassed to find that so many of the links I thought would be stable did, in the meantime, break. This is what I did to fix things:
 * I moved all articles and books into a separate reference section, using Harvard notation to refer to them from the (newly rechristened) Notes section, reducing redundancy in the process
 * All books that have ISBNs (not all do) should now have them listed. Publisher locations are, consistently, not.
 * Ref 3: The editor's note is indeed the intended source. It's a 5 page essay which accompanies a re-publication of the original article, putting the article into perspective and describing the historical context.
 * I fixed all the broken links.
 * Ref 8: The only purpose of the CV is to confirm that Ashtekar was a guest at the Max Planck Institut für Physik und Astrophysik on various dates. Since this is non-controversial information, I would like to leave this in as a reference.
 * Ref 13: Changed this to the AEI obituary, which is now properly linked as a reference, including the authors (that is, the institute directors)
 * About "e.g." - in the case of 24, for instance, I am using one specific cosmology book as source for a statement that can be found in every cosmology book. "E.g." signals the reader that this is not a canonical, let alone the canonical reference for this statement. For someone not familiar with the subject, that is important information, and the reference would lose if I left it out.
 * Going through your list, my conclusion is that, in combination with my previous reply, I have now addressed all the concerns you raised. Thanks again for your attention to detail. Markus Pössel (talk) 15:36, 28 May 2013 (UTC)


 * You certainly have improved the layout of citations and references. I have not rechecked all the links and will take your word for it that they are now all working. On the question of language and subscription tags, WP:CITE is a guideline, not holy writ. It has long been a convention at FAC that these tags be used, as a guide to the reader, and I strongly advise that they are added here (I see GermanJoe makes much the same point, below). The only other thing I have objection to is the CV. Items in a CV don't confirm or authenticate anything; it is the principle of using such dubious sources that is in question, rather than this particular case where the information is non-controversial. If there is no other source that confirms Ashtekar's presence, I suggest you leave this detail out. Otherwise, no further issues on sources. Brianboulton (talk) 12:32, 1 June 2013 (UTC)


 * Thanks for your additional comments!
 * I've removed the CVs, and am now relying on the blog article by Breuer who mentions who was a guest in the Ehlers group at the time in question.
 * As far as I can see, GermanJoe has indeed added missing language tags; I have no problem with those. But I think subscription tags really are a bad idea. Whether or not the DOI leads to a subscriber-only article is a function of time - a number of journals have a "moving wall" policy for when an article will become freely available, so a number of subscription tags will become outdated over time. Adding subscription tags without any automatization in place creates additional work for WP editors without adding important extra information. Also, in an age of e-prints, having the DOI-linked version of the article subscription only doesn't necessarily mean that there is no non-subscription way of accessing the article content. Also, what counts as "subscription required"? Does a free registration that lets you look at three items without paying for a subscription (such as for JSTOR) count? That would surely depend on whether or not whoever is looking at the article has already used up his or her free quota. To sum up, I think a "subscription required" tag doesn't do justice to the various situations we could be dealing with, and seeing that all the details about access (as well as, usually, an abstract) are just one click away, it doesn't add sufficient information to be worth the trouble - and I feel the same about adding a "purchase required" to listings of books; something I note that you are not advocating either, but which I think is perfectly analogous case. So, just as GermanJoe did, I would like to leave that particular tag out of the Jürgen Ehlers article.
 * Having fixed the Ashtekar CV problem, and given arguments why I do not think the subscription tags are necessary or useful (and while WP:CITE is a guideline, as you write, it is a guideline that Featured article criteria sets out for those bringing articles to FAC to follow - so these tags are definitely not required), I believe I have now addressed all your comments. Markus Pössel (talk) 15:55, 1 June 2013 (UTC)
 * Subscription tags are a warning to the reader that he/she won't necessarily get access to the source article. I have JSTOR access, so I know, when I see a subscription tag on one of these, that I can access it. But there are lots of paywalls that I can't penetrate without a subscription, and I like to know in advance when this is the case. In the past I have been disappointed to find, having clicked on the link, that I cannot read the article without paying some exorbitant fee; it's no comfort to know that maybe, in a few years, the article will become freely accessible. That is my position; I don't, however, see this as a sufficient issue to withhold the article's promotion if there are no other issues outstanding, and will leave it to the delegates. Brianboulton (talk) 07:30, 2 June 2013 (UTC)


 * Since the tag issue is more general than this FAC discussion, I've started a discussion here on the WP:CITE talk page. Markus Pössel (talk) 16:27, 1 June 2013 (UTC)

Spotcheck - OK (see comments) In the interest of transparency, i focused mostly on German and less technical texts. Checks showed no problems with close paraphrasing or obvious inaccuracies. The article is written as summary and seems to cover all notable, important aspects of its topic. I see no reason to doubt the finer scientific details, as the article had an extensive PR with a lot of constructive, knowledgable feedback. GermanJoe (talk) 09:54, 30 May 2013 (UTC)
 * ref 5 (Huisken 2009), career data appears accurate, no close paraphrasing (simple facts listed) - OK
 * ref 8 (Ashtekar) - OK, but i'd suggest to add a source for the other guests aswell (if possible). It may be common knowledge for topic experts, but where was that information retrieved from?
 * ref 14 (Schücking 2000) - OK.
 * ref 24 (Liddle 2003) - OK.
 * ref 31 (Schutz 1996) - OK.
 * ref 33 and 12 (Braun 2008, in German) - OK
 * ref 35 (Breuer, in German) - OK
 * ref 36 (biennial report, in German) - OK
 * ref 40 (awards), the different awards are covered by several sources (in German). - OK
 * Language and subscription tags are useful convenience tools for the reader to navigate through the references (they might even be required, but i am too lazy to check). I fixed some broken harv links and added a few tags. GermanJoe (talk) 09:54, 30 May 2013 (UTC)
 * Many thanks for the spotcheck! As for ref 8, I've now added the Breuer 2008 text as a reference, which mentions the various Munich department members and guests. I've also added two more online CVs for corroboration; for the other persons listed, no such CVs appear to exist. (I guess once you've got tenure, the motivation to put your CV online is drastically reduced.) And no, it's not common knowledge apart from those who actually were part of that group, so it was definitely useful to point out this omission. Markus Pössel (talk) 17:58, 31 May 2013 (UTC)
 * Updated the only minor point, thanks. GermanJoe (talk) 18:11, 31 May 2013 (UTC)


 * Support. (having stumbled here from my FAC nomination). I've made some minor formatting changes, but that was all really. Other than that, the article is quite well done and meticulously referenced. Just wanted to say it's so nice to see a strong quality improvement project on an article related to science. Thanks very much for the quality improvement efforts, to all involved. &mdash; Cirt (talk) 00:20, 4 June 2013 (UTC)


 * Thanks for the formatting fixes, for the support and for your kind words! Markus Pössel (talk) 06:54, 4 June 2013 (UTC)

Delegate comments (2)
 * First of all, tks Brian and Joe for source review/spotcheck, and of course all the other reviewers for their efforts.
 * Markus, I'd usually expect each paragraph to end with a citation -- this isn't the case with the second para of Ehlers group.
 * There are a few duplicate links -- some may be justified if the gap between hem is sufficient but pls review in any case. This script helps locate them. Cheers, Ian Rose (talk) 13:15, 7 June 2013 (UTC)


 * Thanks for your comments!
 * Ehlers group: What used to be citation 22 covered both the second and third paragraph; it's possible this was a single, longish paragraph which was split during copy-editing without the citation being adjusted. I've split the citation accordingly.
 * Thanks for the pointer to the script; I've removed one of the duplicate links; the remaining five should, in my opinion, be left in - each is not very close to its duplicate, and each involves a term that is important in that particular context, and that readers might want to click to understand better that particular paragraph.
 * Markus Pössel (talk) 17:03, 7 June 2013 (UTC)
 * That's fine, tks. Cheers, Ian Rose (talk) 02:11, 8 June 2013 (UTC)

Ian Rose (talk) 02:44, 8 June 2013 (UTC)
 * The above discussion is preserved as an archive. Please do not modify it. No further edits should be made to this page.