Talk:General relativity/Archive 10

message: I've been asked to assist with using Harvard reference style. If you wish to do this, here's what you need to know.
* Be careful of stepping on toes. Although parenthetical names are common in the sciences, numbered superscripts are common in the humanities; this is a color/colour kind of choice, and Wikipedia is formally impartial.
* Most of the guidance can be found at WP:CITET, and at .
* In the "References" section, a single template, , handles everything (books, journal articles, web pages, etc.). Most of the fields are the same as  and the like. One important difference is the more detailed handling of author/editor names. Thus Einstein and Gravitation look like this:
*:* 
*:: markup: 
*:*  (See Gravitation (book).)
*:: markup:  (See Gravitation (book).)
* To reference the citation from the text, use one of three templates. Each automatically generates a hypertext link based on the name(s) and date.
*:* Some works on gravitation are so massive they warp spacetime themselves ; yet  presented essential equations with notable brevity. The two ingredients are the curvature tensor and the stress-energy tensor (; ).
*:: markup: Some works on gravitation are so massive they warp spacetime themselves ; yet  presented essential equations with notable brevity. The essential ingredients are the curvature tensor and the stress-energy tensor (; ).
*# For a single work with no author in the text (the most common case), use .
*# For a single work with the author named in the text, use .
*# For multiple works at the same point, use explicit parens and  separated by semicolons.
In my view, footnotes and web pages make a poor user interface combination. Thus I, personally, would never use a footnote for a parenthetical remark; I would either say something in the text proper or say nothing. In kindness to readers, I would attempt to give page numbers for specific items in Gravitation. 
Hope this helps. --KSmrqT 15:46, 16 July 2007 (UTC)
replies: text: Hi KSmrq - many thanks, that helps indeed. For what it's worth, the kind of remark I would like to put into the notes is the kind you find in my current sandbox for this article - explanations of what aspects of the subject being referenced can be found in what form (table etc.) in what reference. --Markus Poessel 18:03, 16 July 2007 (UTC)
thread_title:  Harvard reference style 

message: On Hold.
See draft page at User:Madcoverboy/Sandbox/General relativity for example of merged article. Madcoverboy 18:08, 16 July 2007 (UTC)
thread_title: Merge

message: I have reverted this article back to the last pre-overhaul version.  I keep finding errors and misconceptions in that article which were long gone out of my version.  Overall, I like the idea of moving this article beyond my organization, but I kindly request that this be done with review and consensus.  
To Madcoverboy:  Get with Marcus and decide how this article should look.  I am happy to tighten things back up as needed.
To Marcus:  The outline above looks good to me.  My advice is to settle down and try it out in a sandbox state and see how myself, Madcoverboy, and others like it.
To everyone thinking of doing a rewrite:  Do be advised that when I did my major rewrite of this article, I did it in a sandbox mode, and let others tweak it for a couple of weeks after I announced it.  When the revised article was put into place here, everyone was happy to see it.  This version will be replaced, but it is best if that happens through that same type of process as was used the last time.  --EMS | Talk 14:44, 17 July 2007 (UTC)
replies: text: Hi EMS! A sandbox sounds like a good idea. I guess the first consensus that needs to be reached.is how to proceed.  Speaking for myself, while I will not be able to keep up my current frantic level of Wikipedia activity, I would feel comfortable gently tending to the growth of the "Consequences" and "Astrophysical applications" sections over the next few weeks in my own sandbox, re-using the current text of the "Predictions..." section and adding references as I go.  It would be great if someone else could adopt the current history section, may be take some of the development history used in "Introduction to...", have another look at the history article, spend some comfortable hours with Pais or Stachel, and integrate at least in summary some things from Golden age of general relativity.  Someone else could undertake to merge appropriate chunks of "Relations to other theories" with the "Overview" – I expect that, in the end, we will need to discuss the structure of the "Overview" section as well, but this would be a sensible step that can probably be taken safely before that discussion.  There's work that needs to be done independently of that – find references for each alternative theory listed, convert to new citation style, that sort of thing (do we have consensus on using a separate reference list and, say, Harvnb?  If I'm assuming that prematurely, please tell). I admit that's not as much fun as the other things; if no-one wants to do it (which I can understand), I'll see that I get around to it later.  Once we've grown the different sections in parallel (the changes to "Overview" and "History" might need a sandbox), we'd discuss and realize that each of us would have done everything totally different, and collectively resign from WP after an acrimonious edit war reach some consensus.  I would propose that only then do we tackle the lead.  How does this sound? --Markus Poessel 15:15, 17 July 2007 (UTC)
replies: text:  I am way past being able to keep up a "frantic level" here.  That is why new blood is nice.  One possibiility is to set up a "WIP" (or work in progress) page under this talk page, and use that as the "sandbox".  One thing that has to be decided is what to use as the base for the WIP version:  My structure, Madcoverboy's, or one that you will create from scratch.  Overall, I would like to use your organization, as we can alway go back to Madcoverbnoy's version from history.  Onve a structure is set, and a new version drafted, I advise going through it section by section seeking consesus or at least input.  I for one would hope that a new version could be up within a month or two. --EMS | Talk 15:39, 17 July 2007 (UTC)
replies: text:  WIP sounds like a good idea, then.  Does it come with a box for the main page?  As for the structure, it depends on the consensus.  I like my structure, of course (should quantum gravity get its own section?); I haven't got any structure to offer for the overview (yet - for now, I would recommend the present one).  One month might be a bit optimistic, two months might work.  Feel free to create the WIP; I would then start merging in what I have in my sandbox so far. --Markus Poessel 17:24, 17 July 2007 (UTC)
thread_title:  Reverted back 

message: The "Relationships" section has been split, with the first two subsectionsbeing relegated to Physical theories modified by general relativity, and the remaining ones on the GR-QM relationship and alternate theories being made into sections in this article.  The GR-QM relationsjip text has been removed from Physical theories modified by general relativity, and a link to that article added to the "Mathematics of general relativity" subsection as a "See Aslo" subheading.  Hopefully that resolves this issue. --EMS | Talk 17:50, 18 July 2007 (UTC)
replies: text: Great, that's a big step forward.  Thanks! --Markus Poessel 19:03, 18 July 2007 (UTC)
replies: text: Do we still set-up the "work in progress" sandbox, though?  Or should all work be done on the main page itself?  It might be OK just to do the restructuring there; some of the new sections would be a bit thin to start with, but that should soon improve... Just waiting for the word (although I'll not be able to devote more than half my wikitime to this as long as the FAC review/the re-writing for Introduction to general relativity is still going on); -- Markus Poessel 19:08, 18 July 2007 (UTC)
replies: text:  IMO this is a quality article and we should avoid "damaging" it as best we can.  Incremental changes can and should be done in the article itself, but a major reconstruction needs to be prototyped and developed off to the side until there is a consensus in favor or letting it replace the existing article.  Right now my focus is on integrating those part of the work of Madcoverboy which are a net asset into the existing article.  That certainly will be an improvement, but your work may be able to take things a good bit further.  WP:BOLD reads "Be bold, but don't be reckless", and IMO the only thing reckless ahout Madcoverboy's version was his replacing the existing article with it before it was properly discussed and tweaked by the community.  So I call on you to set up the WIP page and start fleshing it out.  Let's see what develops, and how it can best be used. --EMS | Talk 22:12, 18 July 2007 (UTC)
replies: text: OK, I have created the WIP page. I have no idea how to properly advertise its existence on the main page, or on this talk page - add some kind of box at the top of the page, I suppose?  I'd appreciate pointers here. --Markus Poessel 08:14, 19 July 2007 (UTC)
replies: text:  One thing that you need is a "WIP_talk" subpage for discussion of the WIP subpage, and a banner in the WIP version pointing people to that talk page.  I strongly advise segregating the WIP talk and the (live) article talk.  (Do note that improvement of the real article can and should continue even with the rewrite in progress.) --EMS | Talk 20:29, 19 July 2007 (UTC)
thread_title:  The dispositions of the "Relationships ..." section 

message: I have noticed that at least three users (editors who use this talk page) have their own personal versions of this article (in a sandbox or other user page). And I have seen the intention expressed above to develop these separately and then substitute them for the existing version. I strenuously object to these plans. This multifurcation (Wikipedia:Content forking) will cause edit wars. It will cause wasted effort as people have to make the same changes over and over again because they were not included into someone's version which then replaced the whole article.
If you want to make a change, please make it in the one and only version, i.e. here. Pay due regard to integrating it with the recent changes made by others. Do your changes gradually, so that others can review and approve each stage before you continue to the next stage. JRSpriggs 02:52, 18 July 2007 (UTC)
replies: text: I only advocated the multi-sandbox approach for parts of the article - namely: agree on the structure, parcel out the work, and then (possibly) develop the sections separately in separate sandboxes.  Anyway, the currently favoured solution would be to have one "Work in Progress" page (construction site) on this talk page, and of all contributors editing there.  I think that's better than editing the article directly, since the re-structuring we are about to do is likely to leave some things dangling.  Either have a WOP, or we need to place a big "We apologize for the inconvenience, but there is major construction work going on". --Markus Poessel 06:48, 18 July 2007 (UTC)
replies: text:  My view is that this is an embarrassment of riches and needs to somehow be coordinated and managed.  I agree that minor changes can and should be done on the article itself, but as I note above a major restructuring must be done off to the side.  My feeling is that people can play in their sandboxes but in the end we need to either integrate the most useful parts of which version into this article or iron out the differences in a WIP (work in progress) subpage of this discussion page.  (Wikipedia forwna on developmental versions being present in the article space.) --EMS | Talk 22:17, 18 July 2007 (UTC)
thread_title:  Only one version 

message: The under construction template is looking huge and ugly at the top! We must remember that many of the readers who will come to the article will come only to read and not to write. They would be put off by such a huge banner advertising that this article is undergoing major work. That is a message for editors, not for readers. I suggest we place it in talk or replace it with something more discreet. Loom91 12:25, 20 July 2007 (UTC)
replies: text: Thanks for insulting my very first template Loom, I will certainly change or remove it if the other editors agree.--Cronholm144 12:32, 20 July 2007 (UTC)
replies: text: Come on, you can't take that personally! I'm sorry if I offended you, but in Wikipedia we are always criticising each others works. If all those were taken as personal insults the situation would become impossible. I'm merely pointing out that such a large template will distract readers and give them the impression that the article is not meant to be ready for reading yet. Loom91 13:00, 20 July 2007 (UTC)
replies: text: The ALL CAPS kinda stung, but let's see what other think.--Cronholm144 13:31, 20 July 2007 (UTC)
replies: text: I always advice new users of the internet to be weary of the Caps Lock. Looks like I fell victim to this old age trap, though I used Shift, not Caps Lock (is that considered a mitigating circumstance?). I apologize. Loom91 13:49, 20 July 2007 (UTC)
thread_title:  The template is unsightly! 

message: The following sentence appears in the introduction: "The first success of general relativity was in explaining the anomalous perihelion precession of Mercury."  Perihelion, precession and Mercury are all wikilinked but do not link to the explanation of the anomalous perihelion precession of Mercury which is described further down in the article.  While the rest of the items in the introduction are clear or link to explanatory articles, this sentence requires a knowledge of the subject to be understood.  Would it not be better to link "anomalous perihelion precession of Mercury" to the explanation later in the article?  --CloudSurfer 08:08, 22 July 2007 (UTC)
thread_title:  Anomalous perihelion precession of Mercury 

message: All the banners at the top of this talk page frightened me a little bit, so I figured I'd better check in here before making a change.
In the section, "Mathematical framework", we have the following:
Local Lorentz Invariance requires that the manifolds described in GR be 4-dimensional and Lorentzian instead of Riemannian.
Then in the next section on "Geometry":
Due to the expectation that spacetime is curved, Riemannian geometry (a type of non-Euclidean geometry) must be used.
So my recommendation is to change the latter to say:
Due to the expectation that spacetime is curved, non-Euclidean geometry must be used.
Am I missing something dumb?  Please tell me if I am so I don't embarrass myself.  :)  VectorPosse 08:05, 15 August 2007 (UTC)
replies: text: It depends on what you mean by "Riemannian geometry". Some people define it in a way that requires the signature of the metric to be all pluses and some do not. The geometry of space-time according to GTR is Riemannian in the broader sense, but not in the narrower sense. To the more picky, it is pseudo-Riemannian, i.e. Lorentzian. JRSpriggs 21:01, 15 August 2007 (UTC)
replies: text: Fair enough.  I don't know about physics conventions, but I agree with you that in differential geometry, a metric that isn't required to be positive definite would have to be called something other than Riemannian.  In any case, this article should be edited in some manner so it doesn't appear to be contradictory (even if one interpretation is unambiguous).  VectorPosse 21:21, 15 August 2007 (UTC)
thread_title:  Recommended change 

message: By earlier consensus, the "Predictions" section is to be replaced by a more general section "Consequences of Einstein's Theory" (which encompasses the predictions relevant for the classical tests, but also more mathematical developments) and a section about "Astrophysical applications".  I've been working on the replacement for the last few weeks, and it's now reached a stage where everything is more or less there, though in need of some polishing – I've tried to make sure that all major current GR research topics are mentioned, and that everything is properly referenced, but I haven't done much re-reading and re-editing of the resulting text.  Anyway, the result can be found on the  sandbox page Talk:General_relativity/WIP; I would think what's there is in a suitably advanced state to be moved to the main page right away, unless a consensus emerges that we should discuss it while it remains on the WIP page. --Markus Poessel 18:28, 30 August 2007 (UTC)
replies: text: OK, since more than a week has passed without any objections, I've now moved the two sections in question, plus their references, to the main article. --Markus Poessel 08:19, 9 September 2007 (UTC)
thread_title:  Replacing "Predictions" with "Consequences..." and "Astrophysical applications" 

message: To Markus Poessel: You said "... there's a discontinuity between exterior and interior Schwarzschild, ... what is a very real break between the interior and exterior region. ...". Actually, there is no discontinuity or singularity at the event horizon — it is just a typical region of spacetime. There is a problem with the Schwarzschild coordinates on that hyper-surface, but there are other coordinate systems which behave nicely there including Kruskal-Szekeres coordinates. JRSpriggs 01:31, 15 September 2007 (UTC)
replies: text: Everything you say is correct. But remember that we were talking about Schwarzschild coordinates. My point was that, when writing down the metric in the usual form (as you did) and talking about exterior/interior, you're automatically talking about two different coordinate patches.  As these are two different patches, it makes no sense to argue that, by continuity, t, which is a time coordinate in the exterior, should be called a time coordinate in the interior, as well. Markus Poessel 06:54, 15 September 2007 (UTC)
replies: text: OK. By the way, the Schwarzschild metric is only an approximation to the metric of a physical black hole (even aside from quantum mechanical issues). There is no "white hole" in the past of a large star which explodes and leaves behind a black hole. Material falls into the black hole making it larger. And, if the universe lasts long enough, the black hole will evaporate due to Hawking radiation which means that it will eventually shrink and may not have an event horizon after all. JRSpriggs 02:07, 16 September 2007 (UTC)
replies: text:  Yep.  In fact, I'd been thinking that a Penrose diagram for a realistic (non-eternal) black hole might make a nice illustration for either the horizon or singularity section (without the Hawking radiation bit, though).  Perhaps we should explicitly mention maximally extended solutions, too. --Markus Poessel 13:41, 16 September 2007 (UTC)
thread_title: Discontinuity at event horizon?

message: I have concluded that my putting the gravitational waves section after the orbital decay subsection is causing more trouble than that ordering is worth.  So I have moved the gravitational waves section up to be above the orbital effects section.  (I figured that I had to be the one to do this since Marcus wants to respect my decisions regarding this article.) --EMS | Talk 04:36, 23 September 2007 (UTC)
replies: text: OK, that looks like a good compromise. --Markus Poessel 06:44, 23 September 2007 (UTC)
thread_title:  An adjustment to the restructuring