text:
Talk:Four-momentum

A clarification
In the first paragraph is says "The contravariant four-momentum of a particle with relativistic energy E and three-momentum p = (px, py, pz) = γmv... This seems like it is saying p=γmv. Unless I've misunderstood, that is not correct? Jpipersson (talk) 17:36, 15 June 2023 (UTC)

Untitled
You can find some info here: .

Also note that are two conventions: Both are valid and should be appeared in the article. MathKnight 21:54, 16 Mar 2004 (UTC)
 * 1) Take c = 1. In that case x = t,  E = m = P  etc.
 * 2) Keep on classical units of time and space and take x = c*t so c keeps its MKS\CGS value (MKS refrenced on the International System of Units page). I formulated my addition according to that convension.

Excuse me?
In special relativity, four-momentum is a four-vector that replaces classical momentum; the four-momentum of a particle is defined as the particle's mass times the particle's four-velocity.

The highlighted sections mean nothing to the layman. And if you're not a layman and know all about four-momentum, then why did you come here? User:70.25.138.179|70.25.138.179]]

 * I did some major rejiggering of the article -- expanded the intro and divided the rest up into sections. Hopefully I've addressed your concerns about incomprehensibility!  Please comment again if it's still too obscure. HEL 02:56, 5 November 2006 (UTC)

 * You need to read the first sentence of the second ¶ more carefully: "The highlighted sections mean nothing to the layman ". JohndanR (talk) 18:00, 14 October 2020 (UTC)

Merge to momentum
Why is this tag there? Shouldn't the person who put that tag up have discussed their reasoning? Anyway, I disagree. The four-momenum concept is very distinct from momentum, and it needs its own page. Fresheneesz 11:35, 21 May 2006 (UTC)

Sign convention for the metric
Should we comment somewhere that there are two different sign conventions for the metric? This article uses the East Coast / general relativity convention; most particle physics texts these days use the West Coast metric, so that p2 = +m2 (c=1). HEL 18:32, 9 February 2007 (UTC)

What the...?
Anyone want to address the part about "WRONG WRONG WRONG." Not exactly encyclopedia material. —Preceding unsigned comment added by 169.233.41.11 (talk) 02:29, 12 October 2007 (UTC)

Covariance and typography
This article defines 4-momentum as covariant but several other articles (e.g. four-vector and four-force) define it as contravariant. This may confuse some of our readers, so what's the best way to avoid such confusion?

As a separate issue, it would be nice to adopt the convention that 4-vectors are in bold capitals and 3-vectors in bold lowercase. To achieve this we'd need to use a different letter for canonical momentum. Any thoughts?--Dr Greg (talk) 16:49, 3 October 2008 (UTC)

 * Assertion that four-momentum is covariant was introduced in this edit by JRSpriggs (talk, contributions) without giving any reason to do so. --93.136.187.125 (talk) 08:28, 5 December 2009 (UTC)

Coordinate convention
I've modified all the equations to use the convention $$x^0 = ct$$. The version back on 10:37 22 September 2008 correctly used the alternative convention $$x^0 = t$$, but subsequent edits managed to confuse both conventions. The convention I'm using is the same as the four-velocity article and therefore probably less confusing for readers. Someone who's an expert in 4-potentials should check I've modified the relevant equation correctly, as that is outside my area of expertise. --Dr Greg (talk) 12:00, 18 April 2009 (UTC)

équation
Hello, I quote the text "This allows the potential energy from the charged particle in an electrostatic potential and the Lorentz force on the charged particle moving in a magnetic field to be incorporated in a compact way into the Schrödinger equation." Isn't it the Dirac equation instead of schrodinger? — Preceding unsigned comment added by Klinfran (talk • contribs) 00:12, 3 July 2011 (UTC)

Introduction for the novice
I would like to see some background information about this topic for people who don't (or remember) enough math to follow the current text. Kevink707 (talk) —Preceding undated comment added 14:54, 26 September 2011 (UTC).
 * Agreed. A classical encyclopedia entry was never an exercise in explicatory essay-writing to satisfy one's Prof that one understands the term lecture on a topic. JohndanR (talk) 18:06, 14 October 2020 (UTC)

Shouldn't there be another formulation, in Clifford Algebra.
The formulation in Clifford Algebra removes unnecessary complexity (Covariance, contravariance, etc.). CaffeineWitcher (talk) 21:24, 7 December 2022 (UTC)

Covariant 4-momentum metric signature issue
In the Derivation section, just before the second equation, the article reviews the basis changes (from contravariant to covariant) according to the aforementioned metric convention: that the metric signature is (- + + +), or in the article's words, "x0 = −x0, x1 = x1, x2 = x2, x3 = x3 in the present metric convention"; however, it then states the covariant 4-momentum has negated spacelike components, both in the equation $$p_\mu=\left (\frac{E}{c},-\bold{p}\right )$$ and, in agreement, in the clarification following. I believe this statement would actually correspond to the (+ - - -) signature. Considering the product of the contravariant 4-momentum with the covariant 4-momentum shown, $$p^\mu p_\mu=\frac{E^2}{c^2}-|\bold{p}|^2$$, which contradicts the first equation in the Minkowski norm section, which explicitly uses the (- + + +) metric signature.

It doesn't seem this affects anything else in the article, but can someone else verify this? ManOfPretzel (talk) 22:16, 8 April 2023 (UTC)

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/

title: Talk:Four-momentum


text:
Wikipedia talk:Article series/Archive

I wanted the tables to line up with the paragraphs describing them, but I dunno how. If someone can make it happen, that would be scrumptious... Tuf-Kat 22:55, Jan 10, 2004 (UTC)

 * Use a BR clear="all", maybe? Thanks for making this page, Tufkat. I think article series are a great idea, but I think using tables where not absolutely necessary is a really bad idea. We should use this page to consider alternative ways of presenting the links -- Tarquin 23:06, 10 Jan 2004 (UTC)
 * I tend to agree that tables are bad, but they look great for something like this. The best solution is probably to make the table syntax simpler, so that people like me won't be intimidated into doing nothing more than cutting-and-pasting tables from elsewhere... Or maybe make the series table a somehow different section for editing purposes, so that it doesn't show up on the edit window and confuse writers who want to change the text.  A separate edit link could be made to edit the table. Tuf-Kat 23:32, Jan 10, 2004 (UTC)
 * Another thought: depending on how you want to define a "series", the country articles (e.g. Australia) are a series. They have an overview of major subarticles (e.g. History of Australia) with prominent links to the subsubject as below.

==History==

Main article: History of Australia

Stuff happened blah blah convicts and drunkards blah

This is good, but isn't as easily navigable for the user IMHO. Maybe this meta-page should point out that the country articles are undeclared series of a sort. Tuf-Kat 23:32, Jan 10, 2004 (UTC)

How many articles could you have in a series before the tables get really out of hand? Bmills 15:02, 12 Jan 2004 (UTC)

 * Probably 9-10, then it all fits on one screen, with room to see any other tables (like the in the 'this article is part of two series' example). Above that, you need a meta table. Elde 17:53, 12 Jan 2004 (UTC)

Article Series Must Be Chronogical Series?
Just got this message on my talk page: "I disagree with adding a series box to the UC articles. They don't follow any chronological order. The listing at the bottom is more in line with what is done for EU countries." (See UCLA and Belgium for respective examples.) Do series articles have to be about placing things in a chronological order? I believe they can be any group of articles which has a strong reason to be considered as a group. The Culture of the United States series and the music series being a good example. Let's discuss. Among other things, the navigation listing at the bottom is below the fold and therefore hard to find. jengod 01:58, Jan 16, 2004 (UTC)
 * The Jesus series is also not chronological. Both the music series (UK, US) are partially in chronological order, but not entirely.  I think the UC series is a great idea -- it's different from the EU example because Belgium has existed distinct from the EU for most of its history, whereas it would be difficult or impossible to discuss UCLA without at least some understanding of the whole UC system. That should be the purposes of a series, IMHO, that is: to provide an easy way to navigate through articles which could not be studied entirely independently (though of course, each article in the series should be able to stand alone...) Tuf-Kat (P.S. I've made some observations of potential difficulties regarding a Celtic music series at Talk:Celtic music, if anyone is interested)

 * But putting it on top would get in the way of things, especially if WikiProject Universities table is added. When you have various items loosely affiliated, like with the EU, the listing should be relatively out of the way.

 * The word series connotes an order. This order is naturally top-down, and alphabetical order is rather arbitary when speaking of the UCs. The UC campuses cannot be called a "series". They are a grouping. --Jia ng 02:18, 16 Jan 2004 (UTC)

The series for the "Jesus" article is an artificial series (you are telling the reader to read these related articles in a certain order; this order arbitrary). Esp with the location of some of the tables (i.e. near the bottom), it serves no different purpose than a regular "see also" list. I don't see why it was added.

The individual UC campuses are only related by their affiliation with UC, not so much with each other. What would be the relevance of UC Davis for the UCLA article? --Jia ng 02:24, 16 Jan 2004 (UTC)

I'm not trying to be argumentative, just debatative ;) but M-W's fourth definition of series is this: "4 : a succession of volumes or issues published with related subjects or authors, similar format and price, or continuous numbering." For techies, I suspect the connotation of series is numerical order, but for fuzzies, it's like an article series, or a TV series, or a Nancy Drew book series. Techie types get taxotables and tables outlining all the details of every tank ever--let us fuzzie types have a little fun. We could maybe change the name for "article series" tho if someone has something better. jengod 02:27, Jan 16, 2004 (UTC)

P.S. Let us not underestimate "It's pretty" as a reason to include these things. Pretty is important. Seriously. :)  jengod 02:28, Jan 16, 2004 (UTC)

 * The fourth definition still uses the word "succession" (they were published in order). The UCs don't have numbers assigned to them. Under any definition, the box gets too much in the way. Although I find them "pretty" in history articles when we have era articles, they just dont seem right with organizations. Listing them at the bottom is easier to deal with, especially when their relationship among each other is not that vivid. (That is, unlike the history series, we would still be fine if we didn't have either and no link to UC Davis existed at the UCLA article.) --Jia ng 02:35, 16 Jan 2004 (UTC)

 * There's no reason the series table has to be at the top. I think the one at Culture of the United States is near the bottom, because the first half is all about social structure and such, and not the arts (which is the subject of the series).  I agree that the Universities template should be at the top, as it is informative and probably more useful for the reader than a link to Davis, but I don't see what's wrong with putting the series table further down.  Non-chronological series are different from see alsos because they are much more integrally tied together -- UC Davis and UCLA are part of a single system, just like Jewish and Christian perspectives on Jesus are part of an understanding of Jesus.  If I wanted to know everything there is to know about UCLA, I would need to understand its relation to the other parts of the UC system (e.g. school rivalries, which are common when schools are part of one system).  If I wanted to know everything there is to know about Belgium, the European Union is certainly important, and I suppose a bit about other European countries, including other EU countries, but also non-EU Switzerland, for example.  Jiang, you haven't commented on the Culture of the United States series -- do you want to get rid of that one too?  And what about the partially chronological music of the United States?  I do view the word "series" as connoting a chronological order, but I wouldn't be surprised to see that there wasn't one.  Ultimately, what's the harm in placing an easy-to-navigate group of links between the UC campuses?  It doesn't have to be in place of an informative table, and someone looking for information just on UCLA wouldn't be bothered by its existence. Tuf-Kat
 * The succession in the definition above refers to order of publication, which doesn't apply to Wikipedia because articles aren't "published" in chronological order, even when they exist in that way. Tuf-Kat 02:45, Jan 16, 2004 (UTC)
 * So the definition does not apply at all? --Jia ng

 * Their relationship with each other is that they are all part of the University of California system. Jiang, I'm sorry you don't like it, but I believe there is solid enough reason to group them together. Suggested synomyns for series: group, grouping, collection, array, batch, suite, category. Anybody like any of those? jengod 02:46, Jan 16, 2004 (UTC)

I am not against listing them as they were listed before - EU style. That style looks a lot better for this particular purpose. The series table is meant to develop a clear ordering for the reader while grouping a bunch of links horizontally does not. The bottom grouping pops out less - if the relationship with each other is that they are part of the same system, wouldn't a [University of California] link suffice? If this grouping of links could be ommitted without much harm, it is better that it not be the first thing we look at. With the history series, a reader would have to jump out of nowhere if the series table did not exist at Mughal Era (many history era articles lack draw on eras before and after and lack clear definitions).

If you read the articles, you will no particular direct link between UCLA and UCD. None of the schools have rivalries with each other (UCLA is w/ U$C, Berkeley is with Stanfurd). The relationship comes only with a central administration and through history (e.g. Davis was originally the "University Farm" for berkeley's school of agriculture). Discussion of this relationship would all belong in the central UC article. But this said, I am not against listing all the UC campuses, just listing them in the series table for aesthetic and functional reasons.

I don't see anything wrong with partially chronological series (like adding a timeline to a history series), but anything non-chronological has to be a very central theme (the series box is not a simple collection of "see alsos") I removed Warsaw Pact and Tsar from the History of Russia series because they aren't historical periods. I agree that the links for Cuture of the United States are important, and given the number of them, the series box may be something we want to add. But given that the UC links fit at the bottom, why not put them there?--Jia ng 03:00, 16 Jan 2004 (UTC)

 * Maybe the difference is if you see it from the point of someone stumbling onto UCLA vs University of California (subarticle vs parent article) -- UC Davis and UCLA and Berkeley are more relevant than the average see also for the University of California article, even if not for each other. I think the "central administration and history" connection is enough to warrant a series, especially since they are part of a single system.  Since it doesn't look like we are likely to agree any time soon, let's wait awhile and see if anyone else wants to comment.  The issue has the potential of affecting the organization of many articles, and certainly doesn't need to be decided tonight.  Tuf-Kat 03:22, Jan 16, 2004 (UTC)

I agree that the other campuses should be listed. There's no need to argue for that position. I just think my original listing (having them listed at the very bottom under a thick divider vs. having them listed in a series table) looks better and is less obstructive. --Jia ng 03:24, 16 Jan 2004 (UTC)

"University of California grouping" is an unheard of phrase. Why don't I just restore the old formatting? --Jia ng

 * I agree that group is a very poor choice. The old formatting shouldn't be restored because there is no consensus to do so -- at present two out of three people with an expressed opinion like the series, so that should be de facto until more opinions are seen. Tuf-Kat 03:51, Jan 16, 2004 (UTC)

There was no consensus to change it. Majority != consensus. Please elaborate on how the table is better than the original listing. I don't see the point of this. --Jia ng 03:59, 16 Jan 2004 (UTC)

 * There's no consensus on anything to do with article series. I think the table is better because it promotes interlinking between articles that are part of a whole and is by far more attractive than the other format, which stuffs the links at the bottom of the article, below barely relevant see alsos, external links and lists of famous alumni.  I'm not discussing this anymore tonight.  My opinion stands, and we are simply going over the same ground repeatedly.  I am asking you not to revert the articles so that others can compare the format of the campuses and EU countries for themselves without going into the page history and because thus far, most of the people who have expressed an opinion like the table.  I agree that a majority is not consensus -- if you want to revert to prove that two out of three people do not constitute a consensus, go ahead.  I don't engage in edit wars. Tuf-Kat

I will revert half so that it can be properly compared. --Jia ng 06:41, 16 Jan 2004 (UTC)
 * Compare UC Berkeley with UCLA. --Jia ng

 * Dude, revert your heart out. I don't actually care that much, I just thought it looks better. Whatever makes your toes tingle. jengod 08:30, Jan 17, 2004 (UTC)

 * This discussion is more important than whether or not this particular series is a good idea. What guideline/rule/policy do you (Jiang) propose? (i.e. what should be added to this meta-page to explain why certain groups are not an appropriate candidate for a series?) Tuf-Kat 02:39, Jan 18, 2004 (UTC)

I don't want the series table to be abused and used as another form for a regular see also list. For there to be a series, most of the articles must have a logical chronological order. The country template (listing "main article:..." under a general topic) is ideal for that situation. Keep links where they belong - not off to the side of the page. --Jiang 06:12, 18 Jan 2004 (UTC)

 * "For there to be a series, most of the articles must have a logical chronological order." I have to say I just don't agree. Articles that have a thematic connection are prime for the article series table. The table series idea basically adds a dimension to Wikipedia--it's an inter-article Table of Contents where before we only had intra-article TOCs. jengod 06:05, Jan 20, 2004 (UTC)

I'd like to chime in here for what it's worth. A chronological connection would be ideal, but probably does not have to be necessary. I think there does have to be a "thematic connection" between the articles though, as you say. However, the UC campuses have no real thematic connection; they're all fairly independent and are simply linked by one, large high-level administration. It's like the 50 U.S. states and the U.S. as a whole or the provinces of Canada versus the whole of Canada. The connection between the individual UC's just isn't that strong, so I think the less prominent formatting at the bottom of the pages is better. This basically amounts to a more elegant form of a list of "see alsos" for all the UC articles. --Minesweeper 03:01, 30 Jan 2004 (UTC)

Article Headers
Per Jiang's changes to Major English dialects pages like American English, another question is:

Should the head section of an article series box say something like: This article is part of the History of the United States series or be reduced to something like History of the United States.

I prefer the former. I just think it looks better. Also, the vast majority of existing series articles have this format. Thoughts? jengod 05:27, Jan 18, 2004 (UTC)

 * No significant opinion, but, on a related note, the English dialects that have articles but aren't part of the "major dialects" series could become a supplemental article a la Music of Washington. For consistency, I prefer the old method, but I don't see either one as being more attractive or useful than the other. Tuf-Kat

I changed it becuase "This article is part of the major English dialects group" sounds very awkward. While the individual articles in the US history series are part of a series, the articles in the dialects box are a listing. They do not make up all the English dialects. "Group" is also not a term used regularly for reading material. You can all a set of documentaries a series or a set of books, but you don't ever see the same used for "group".

Likewise, "the University of California group" makes it seem that "group" is part of the official UC name while we are really talking about a group of articles. --Jiang 06:12, 18 Jan 2004 (UTC)
 * I agree that "group" is very bad. I'm not sure what makes you think that series are being abused to glorify certain see alsos. IIRC, you said you had no problem with Culture of the United States, which isn't chronological in the least, and neither is Jesus, electronic music, European colonization of the Americas or heavy metal music. I think series work well to help guide a user around to various articles that are part of a broader subject.  It improves the cohesion of the encyclopedia, and promotes a grander view of making groups of articles more complete and more in sync with each other.  I agree that they are particularly useful in chronological series, but I don't see why they should be limited to that. Tuf-Kat

I do have a problem with the "Jesus series". Even if it is to be kept, it ought to be renamed to something different. Views of Jesus? The heavy metal music series is acceptable if it includes all types of heavy metal. Does the culture of the US series encompass all components of American culture? If not, then the series is a bad idea - it implies something that is not true. --Jiang 17:47, 21 Jan 2004 (UTC)

 * Perhaps all of the above is true, but I think the article series train is already its own momentum now, as does much with Wikipedia, and people are gonna do what they feel is best for the articles they edit. I think the best we can do is try to keep the article series a clean and well-lit place. If you don't like the series thing as a rule, perhaps a whole other paradigm needs to be cooked up. As it is, I like my assertion from before that the article series is basically an inter-article TOC to supplement intra-article TOCs. jengod 03:11, Jan 23, 2004 (UTC)

 * That is what a category system is supposed to do. I in fact very much so dislike the whole article series idea and wish I would have opposed it earlier - most of those dam boxes contain no useful content that pertain to the article itself. All they really do is push real content (such as images and tables of data about the subject) down while only being useful for navigation. A much smarter way to do that is have a list on a parent topic, such as biology, and link the word biology somewhere in the lead section (usually as the second word: "In biology, ... "). Or better yet, make the subject area part of a WikiProject and have a more limited set of navigational aids (see carbon and Battle of Lützen (1632)). I think footers are much less harmful and think that many of these series boxes should be converted into them. --mav 07:55, 15 Mar 2004 (UTC)

 * Except that a category system tends to become a tree, at best a simple one, at worst a complex crosslinked and exception filled one. Unless every article contains uplinks and downlinks, you cannot traverse the tree, and you end up with endless sterile 'list of articles about mollycoddling' pages.  (And on those pages you still end up with the need for up, down, and cross links.)

 * Of course the boxes contain no useful content, because they are meta-data, not content. When you are organizing something as simple as a Star Trek episode guide, or an E.R. fansite, simple methods of categorization and navigation suffice.  When dealing with something as complex as the material here at the 'pedia, that is no longer true.  T

 * The problem with simple links, as you propose, is that they all bear the same near zero weight. A trivial link appears on the page identically to an important link. Elde 09:37, 15 Mar 2004 (UTC)

 * Actually, a proper category system would be more complex than a tree, because an article can belong to two categories, neither of which is a subcategory of the other. This is one of the main flaws in this idea: people are trying to force articles that are linked in all sorts of complex ways into arbitrary one-dimensional sequences. The reason why the material here is interconnected in complex ways is because subjects in real life are interconnected in complex ways. Making up series and saying, "This is the way it all fits together," is a gross oversimplification and thorougly un-NPOV. Organising links within NPOV text is the best way of organising them, because it doesn't promote editorial opinions on the way subjects are linked. -- Oliver P. 01:33, 16 Mar 2004 (UTC)

 * Organising links within NPOV text is the best way of organising them, because it doesn't promote editorial opinions on the way subjects are linked. Any method of organizing links is inherently POV.  Once can choose to make or leave out a link utterly without fetters.  Elde 08:55, 16 Mar 2004 (UTC)

 * And mixing metadata with content is really bad database design. Thanks for giving me another reason to dislike these boxes. There is still the very important issue that these boxes push real content down on the page. Also, a well-designed category system could be used to create these boxes in the sidebar that already exists on every page. Not too hard to code a "series:Foo" metadata tag. Again, footers would be a better compromise until we get a category system. --mav

 * If we were designing a database, that would be a valuable point. But we aren't.  We are building an encyclopedia, that is filling in a database.  I doubt that there is such a thing as a really well designed category system, Yahoo! has been at it for years, and their system is an absolute horror of redundancy and cross-links.  I've worked off and on designing category systems, and even for topics much simpler than what the 'pedia plans to cover, such rendundancies and cross links are impossible to avoid.  I agree, the boxes should be relegated to somewhere other than the top of the page however.Elde 08:55, 16 Mar 2004 (UTC)

Advice wanted
I'm toying with the notion, If we ever reach the position where the server improves enough to take it on, of creating a Poetry series. This would be a bit different from the history-based series idea because relationships between the various pages would be looser and because there are a lot of pages. Does anyone think this is workable? Bmills 13:52, 19 Jan 2004 (UTC)
 * Might be good -- would the articles in the series be poems/poets/genres/something else? All of the above? What would the table look like? Tuf-Kat 18:00, Jan 19, 2004 (UTC)
 * That would be great. What topics did you want to include? jengod 03:50, Jan 20, 2004 (UTC)

I was planning to use the Poetry page as the base page and add, at least, national poetries and poetic movements and groups. These should provide enough links out to individual poets and poems, I hope. I'm a bit intimidated by the table and it clearly will not go in chronological order. What do you both think? Bmills 12:58, 20 Jan 2004 (UTC)
 * Sounds like an awfully long table, but it might work... Can't hurt to try. Tuf-Kat 19:21, Jan 20, 2004 (UTC)

I've made a start, and done something a bit different by linking to article headings to help keep the table under control for now. Bmills 15:49, 21 Jan 2004 (UTC) And a groups and movements series as another way of controlling size. Bmills 16:41, 21 Jan 2004 (UTC)

 * See my comments about the content of the series at Talk:Poetry. In addition, the title of the article where the table is (in the table) should be de-linked, bolded, and have gray background (which the poetry series does not). Let's keep all the formatting consistent. There is also no need to split "This is part of the poetry series" into 2 lines when one line would not cause extra horizontal expansion. --Jiang 17:42, 21 Jan 2004 (UTC)

 * B, my impression is that the Poetry groups and movements series "works" but that the Poetry series is all over the map and becomes the glorified "see also" situation that Jiang feared. Maybe the Poetry domain needs either more time to grow or a smaller ambition footprint? Also, Jiang, I'm going to add: "In addition, the title of the article where the table is (in the table) should be de-linked, bolded, and have gray background (which the poetry series does not)." to the main page as one of the initial guidelines that (I hope) every can/has agree(d) on. jengod 09:09, Jan 22, 2004 (UTC)

 * My only complaint is with the title. National Poetries just doesn't sound right at all.  Poetries by nation is better, but only marginally.  I encountered the same problem when I made List of cultural and regional genres of music, and never came to a solution.  Maybe there isn't one. Tuf-Kat 22:27, Jan 22, 2004 (UTC)

"National poetries" simply links to poetry. Then we have "poetry" listed in the middle of the table. Having two links to the same place in one table is just plain confusing. And why at the middle and not the top? Why at all? Shouldint the series contain articles of the same specificity? The general topic belongs on top.

When making such a "series", one should anticipate all the items that should be included. It is fine to leave red links in the table. But if we were to do this for the poetry "series" (by adding all the countries in the world), we would have an entire column of red links, likely significantly longer than the article itself. I think the "National poetries" series as it is, is a net loss. --Jiang 00:26, 23 Jan 2004 (UTC)

I'm liking the National Poetries series myself. In fact, I suggest you go for broke and switch the Poetry of the United States link to U.S. Poetry so that it matches with Irish poetry, Slovak poetry, etc, schemes. This should evolve nicely. I eventually see it splitting into something like a group of series: European poetry, Ancient poetry, Asian poetry, etc. jengod 03:15, Jan 23, 2004 (UTC)

Msg for article series
It would nice if there was a way to use a msg to create the boxes for articles series. The main problem is probably that the usual model highlights the present article, something the probably can't be done with. -- User:Docu

 * There is now an ability to use {{msg: for series in which the self-link to current article is bolded, but not linked. It used for the History of Sweden although the table formatting is not consistent with the formatting addressed here, and I created one for Electronic music, using the format designated here.  Should we have a standard name, like series_ e.g. series_electronic_music, rather than use the name of the top-level article?  --Lexor|Talk 09:37, 19 Feb 2004 (UTC)
 * I like the Electronic music series format better than the Swedish one, which just looks weird. I don't think having a standardized title for the mediawiki message will be that useful, since these are not likely to be used that often after their original introduction.  It would be nice if they were intuitively titled, butthat would probably be more trouble than it's worth.

 * For the top article, I write "This article is an overview of the history of Sweden". I think this is better than "is at the top" or "is the parent article of" and the other variations people have used.  Does anybody agree that this should be standard? Should there even be a standard?Tuf-Kat 18:01, Feb 19, 2004 (UTC)

 * I agree that "an overview" is a better than "at the top", I think we should start making at least some guidelines and recommendations towards a standard. We have gone through the phase of collecting current practise, I think it's a good idea to codify it a little before it gets too balkanized.   I will put messages on the pages that use the "Swedish"-style Seriesbox (we should probably have a name for it), with a link to this page, and start the discussion. --Lexor|Talk 09:52, 20 Feb 2004 (UTC)

At this point I think that some form of standardization has a bigger value than the actual styles proposed. Styles, layout and coloring does not generally harmonize anywhere on Wikipeda and I think that this will need to be adressed "globally" at some point, plauseably by css classes or similar. At present I think that the grayish header on the proposals makes the table seem dull rather than sober. -- Mic 11:35, Feb 22, 2004 (UTC)

Examples below:

{{electronic_music_top}} Parent article series box:

{{Electronic dance music-footer}} Daughter article series box:

{{History_of_Sweden}} Other example:

Style sheet definition for article series tables
The box on Lists_of_people looks better on some browsers than others. If there was a way, it would be nice to define a default in the style sheet that would work for most. -- User:Docu

Hybrid Infobox/Seriesbox
I have created a hybrid Infobox and article series box at User:TUF-KAT/Fun with tables to improve navigation among the major topics in Greek mythology. Tuf-Kat 20:56, Feb 9, 2004 (UTC)

MediaWiki HOW-TO Page
For those of us who don't yet know how MediaWiki msgs work, is there a how-to page? jengod 18:30, Feb 19, 2004 (UTC)
 * Not really, but there is MediaWiki namespace. The important part for this discussion is the "custom messages".  You can create a custom message, just like any other article in a namespace, by typing MediaWiki:NAME.  Put the text you want there.  To place the text in an article, type  .  This will display the text in the article, but the source code will continue to read  .  Any changes made to the message in the MediaWiki namespace will be displayed anywhere the message is placed.  You can also type , and that will be replaced with the message itself -- this method allows it to be changed at the article edit window, and does not reflect any changes made to the message in the MediaWiki namespace.  The latest wrinkle is that any self-links in the Wikipedia, such as this one are changed into bold text automatically.  This way, the same mediawiki message could be used for all of the articles in a series, and the computer will automatically bold the entry for the article in question instead of creating a self-link.  Hope this helps... Tuf-Kat 19:39, Feb 19, 2004 (UTC)

Standard for seriesbox
A number of recent article series boxes (I propose seriesbox as a shorthand, in analogy to infobox) which use the MediaWiki namespace, tend to use a format which looks more like a table of contents box (right), and less like the original article series boxes (left).

My preference is for the style #1, over style #2, because:
 * 1) It takes up less real-estate and is less obtrusive since it uses smaller text for the intro article, and uses a bit less space between the text and the box.
 * 2) It is less likely to be confused with a table of contents for the article (different background color and style).
 * 3) It is more common wikipedia-wide for article seriesbox than the more recent style.

I think it would be useful to codify this as a loose guideline/standard, before these start proliferating too much. --Lexor|Talk 10:20, 20 Feb 2004 (UTC)

Style Poll
I still prefer the color and style of #2 above the others (which are all the same in style/color). Make #2 the size of the others and that's where I'd vote. - UtherSRG 01:27, 21 Feb 2004 (UTC)
 * In favor of style #1:
 * Lexor|Talk 10:20, 20 Feb 2004 (UTC)
 * Tuf-Kat
 * Jiang
 * In favor of style #2
 * Dori | Talk 14:25, Feb 20, 2004 (UTC) It looks much better IMO.
 * No preference/mix
 * UtherSRGI like the thinness of #1, but the color of #2.
 * I added a style #3, perhaps this would work as a compromise. --Lexor|Talk 22:54, 20 Feb 2004 (UTC)
 * In favor of style #3
 * In favor of style #4
 * Jengod (changed vote)
 * Tuf-Kat
 * Ryan_Cable

 * Style #2 uses the same background color as the table of contents (TOC), because it actually uses id=toc from the CSS stylesheet. I think that seriesbox should be a different color to that of the TOC to ensure that it isn't mistaken as a TOC.  If you could suggest an alternative color scheme that is more to your liking but isn't identical to the TOC color scheme, that would be good. --Lexor|Talk 04:26, 21 Feb 2004 (UTC)

 * Agreed. I prefer the others over style 2. --Jiang

Text Poll

 * Call the top article "the parent article of the XXX series"
 * Call the top article "an overview of the XXX series"
 * Tuf-Kat, Jengod, Lexor|Talk, Jiang
 * "This article is part of the XXX series"
 * UtherSRG - Look at Same-sex marriage for why the other options don't work as well. (They all work, this works better, IMO). Scratch that. It's because I prefer using wiki msgs for this, and differentiating between parent articles and children articles makes that not possible for the parent article. Let's say someone develops an article for Same-sex marriage in Fushal (kudos if you know where that is). The link would have to be added twice, once to the parent's list, once to the child list. The better solution has one message that works for both the parent and child articles.
 * UtherSRG - Look at Same-sex marriage for why the other options don't work as well. (They all work, this works better, IMO). Scratch that. It's because I prefer using wiki msgs for this, and differentiating between parent articles and children articles makes that not possible for the parent article. Let's say someone develops an article for Same-sex marriage in Fushal (kudos if you know where that is). The link would have to be added twice, once to the parent's list, once to the child list. The better solution has one message that works for both the parent and child articles.

Borders
Is it my screen or am I the only one to use the Cologne Blue-skin? Either designs have large black borders (similar to.. ) which are anything but pretty. If you use boarders, I'd prefer that they have the style "border-collapse: collapse;". -- User:Docu

 * BTW I had tried to edit the standard one at Lists_of_incumbents, but without much success. The result looks different depending on skin and browser. -- User:Docu

Discussion on meta on generic CSS classes
Some discussion arising on IRC has resulted in some discussion on the meta wiki which might lead to support for global CSS styles, see: Generic_css_classes_for_content. --Lexor|Talk

title: Wikipedia talk:Article series/Archive


text: User talk:64.26.167.209

title: User talk:64.26.167.209


text:
Autostereogram

An autostereogram is a two-dimensional (2D) image that can create the optical illusion of a three-dimensional (3D) scene. Autostereograms use only one image to accomplish the effect while normal stereograms require two. The 3D scene in an autostereogram is often unrecognizable until it is viewed properly, unlike typical stereograms. Viewing any kind of stereogram properly may cause the viewer to experience vergence-accommodation conflict.

The optical illusion of an autostereogram is one of depth perception and involves stereopsis: depth perception arising from the different perspective each eye has of a three-dimensional scene, called binocular parallax.

Individuals with disordered binocular vision and who cannot perceive depth may require a wiggle stereogram to achieve a similar effect.

The simplest type of autostereogram consists of a horizontally repeating pattern, with small changes throughout, that looks like wallpaper. When viewed with proper vergence, the repeating patterns appear to float above or below the background. The well-known Magic Eye books feature another type of autostereogram called a random-dot autostereogram, similar to the first example, above. In this type of autostereogram, every pixel in the image is computed from a pattern strip and a depth map. A hidden 3D scene emerges when the image is viewed with the correct vergence.

Unlike normal stereograms, autostereograms do not require the use of a stereoscope. A stereoscope presents 2D images of the same object from slightly different angles to the left eye and the right eye, allowing the viewer to reconstruct the original object via binocular disparity. When viewed with the proper vergence, an autostereogram does the same, the binocular disparity existing in adjacent parts of the repeating 2D patterns.

There are two ways an autostereogram can be viewed: wall-eyed and cross-eyed. Most autostereograms (including those in this article) are designed to be viewed in only one way, which is usually wall-eyed. Wall-eyed viewing requires that the two eyes adopt a relatively parallel angle, while cross-eyed viewing requires a relatively convergent angle. An image designed for wall-eyed viewing if viewed correctly will appear to pop out of the background, whereas if viewed cross-eyed it will instead appear as a cut-out behind the background and may be difficult to bring entirely into focus.

History
In 1593, Giambattista della Porta viewed one page of a book with one eye and another page with the other eye. He was able to read one of the pages, the other being invisible, and switch "the visual virtue" to read the other page, the first becoming invisible. This is an early example of dissociating vergence from accommodation—a necessary ability for seeing autostereograms. However, Porta saw competition between images viewed by the two eyes, binocular rivalry.

It was not until 1838 that the Charles Wheatstone published an example of cooperation between the images in the two eyes: stereopsis (binocular depth perception). He explained that the depth arose from differences in the horizontal positions of the images in the two eyes. He supported his explanation by showing flat, two-dimensional pictures with such horizontal differences, stereograms, separately to the left and right eyes through a stereoscope he invented based on mirrors. From such pairs of flat images, people experienced the illusion of depth.

In 1844, David Brewster discovered the "wallpaper effect". He noticed that when he stared at repeated patterns in wallpapers while varying his vergence, he could see them either behind the wall (with wall-eyed vergence) or in front of the wall (with cross-eyed vergence). This is the basis of wallpaper-style autostereograms.

In 1939 Boris Kompaneysky published the first random-dot stereogram containing a hand-drawn image of the face of Venus, intended to be viewed with a device.

In 1959, Bela Julesz, vision scientist, psychologist, and MacArthur Fellow, invented random dot stereograms while working at Bell Laboratories on recognizing camouflaged objects from aerial pictures taken by spy planes. At the time, many vision scientists assumed that stereopsis required prior analysis of visible contours of images in each eye, but Julesz showed it occurs with images with no such visible contours in each of the eyes. The contours of the depth object become visible only after stereopsis had processed the differences in the horizontal positions of dots in the two eyes' images.

Japanese designer Masayuki Ito, following Julesz, created a single image stereogram in 1970 and Swiss painter Alfons Schilling created a handmade single-image stereogram in 1974, after creating more than one viewer and meeting with Julesz. Having experience with stereo imaging in holography, lenticular photography, and vectography, he developed a random-dot method based on closely spaced vertical lines in parallax.

In 1979, Christopher Tyler of Smith-Kettlewell Institute, a student of Julesz and a visual psychophysicist, combined the theories behind single-image wallpaper stereograms and random-dot stereograms (the work of Julesz and Schilling) to create the first black-and-white random-dot autostereogram with the assistance of computer programmer Maureen Clarke using Apple II and BASIC. Stork and Rocca published the first scholarly paper and provided software for generating random-dot stereograms. This type of autostereogram allows a person to see 3D shapes from a single 2D image without the aid of optical equipment. In 1991 computer programmer Tom Baccei and artist Cheri Smith created the first color random-dot autostereograms, later marketed as Magic Eye.

A computer procedure that extracts back the hidden geometry out of an autostereogram image was described by Ron Kimmel. In addition to classical stereo it adds smoothness as an important assumption in the surface reconstruction.

In the late '90s many children's magazines featured autostereograms. Even gaming magazines like Nintendo Power had a section specifically made for these illusions. Since then several books were published with Magic Eye Beyond 3D: Improve Your Vision being one key publication that placed this intriguing illusion into the mainstream.

Simple wallpaper
Stereopsis, or stereo vision, is the visual blending of two similar but not identical images into one, with resulting visual perception of solidity and depth. In the human brain, stereopsis results from complex mechanisms that form a three-dimensional impression by matching each point (or set of points) in one eye's view with the equivalent point (or set of points) in the other eye's view. Using binocular disparity, the brain derives the points' positions in the otherwise inscrutable z-axis (depth).

When the brain is presented with a repeating pattern like wallpaper, it has difficulty matching the two eyes' views accurately. By looking at a horizontally repeating pattern, but converging the two eyes at a point behind the pattern, it is possible to trick the brain into matching one element of the pattern, as seen by the left eye, with another (similar looking) element, beside the first, as seen by the right eye. With the typical wall-eyed viewing, this gives the illusion of a plane bearing the same pattern but located behind the real wall. The distance at which this plane lies behind the wall depends only on the spacing between identical elements.

Autostereograms use this dependence of depth on spacing to create three-dimensional images. If, over some area of the picture, the pattern is repeated at smaller distances, that area will appear closer than the background plane. If the distance of repeats is longer over some area, then that area will appear more distant (like a hole in the plane).

People who have never been able to perceive 3D shapes hidden within an autostereogram find it hard to understand remarks such as, "the 3D image will just pop out of the background, after you stare at the picture long enough", or "the 3D objects will just emerge from the background". It helps to illustrate how 3D images "emerge" from the background from a second viewer's perspective. If the virtual 3D objects reconstructed by the autostereogram viewer's brain were real objects, a second viewer observing the scene from the side would see these objects floating in the air above the background image.

The 3D effects in the example autostereogram are created by repeating the tiger rider icons every 140 pixels on the background plane, the shark rider icons every 130 pixels on the second plane, and the tiger icons every 120 pixels on the highest plane. The closer a set of icons are packed horizontally, the higher they are lifted from the background plane. This repeat distance is referred to as the depth or z-axis value of a particular pattern in the autostereogram. The depth value is also known as Z-buffer value.

The brain is capable of almost instantly matching hundreds of patterns repeated at different intervals in order to recreate correct depth information for each pattern. An autostereogram may contain some 50 tigers of varying size, repeated at different intervals against a complex, repeated background. Yet, despite the apparent chaotic arrangement of patterns, the brain is able to place every tiger icon at its proper depth.

Depth maps
Autostereograms where patterns in a particular row are repeated horizontally with the same spacing can be read either cross-eyed or wall-eyed. In such autostereograms, both types of reading will produce similar depth interpretation, with the exception that the cross-eyed reading reverses the depth (images that once popped out are now pushed in).

However, icons in a row do not need to be arranged at identical intervals. An autostereogram with varying intervals between icons across a row presents these icons at different depth planes to the viewer. The depth for each icon is computed from the distance between it and its neighbor at the left. These types of autostereograms are designed to be read in only one way, either cross-eyed or wall-eyed. All autostereograms in this article are encoded for wall-eyed viewing, unless specifically marked otherwise. An autostereogram encoded for wall-eyed viewing will produce inverse patterns when viewed cross-eyed, and vice versa.

The wall-eyed depth map example autostereogram to the right encodes 3 planes across the x-axis. The background plane is on the left side of the picture. The highest plane is shown on the right side of the picture. There is a narrow middle plane in the middle of the x-axis. Starting with a background plane where icons are spaced at 140 pixels, one can raise a particular icon by shifting it a certain number of pixels to the left. For instance, the middle plane is created by shifting an icon 10 pixels to the left, effectively creating a spacing consisting of 130 pixels. The brain does not rely on intelligible icons which represent objects or concepts. In this autostereogram, patterns become smaller and smaller down the y-axis, until they look like random dots. The brain is still able to match these random dot patterns.

The distance relationship between any pixel and its counterpart in the equivalent pattern to the left can be expressed in a depth map. A depth map is simply a grayscale image which represents the distance between a pixel and its left counterpart using a grayscale value between black and white. By convention, the closer the distance is, the brighter the color becomes.

Using this convention, a grayscale depth map for the example autostereogram can be created with black, gray and white representing shifts of 0 pixels, 10 pixels and 20 pixels, respectively as shown in the greyscale example autostereogram. A depth map is the key to creation of random-dot autostereograms.

Random-dot
A computer program can take a depth map and an accompanying pattern image to produce an autostereogram. The program tiles the pattern image horizontally to cover an area whose size is identical to the depth map. Conceptually, at every pixel in the output image, the program looks up the grayscale value of the equivalent pixel in the depth map image, and uses this value to determine the amount of horizontal shift required for the pixel.

One way to accomplish this is to make the program scan every line in the output image pixel-by-pixel from left to right. It seeds the first series of pixels in a row from the pattern image. Then it consults the depth map to retrieve appropriate shift values for subsequent pixels. For every pixel, it subtracts the shift from the width of the pattern image to arrive at a repeat interval. It uses this repeat interval to look up the color of the counterpart pixel to the left and uses its color as the new pixel's own color.

Unlike the simple depth planes created by simple wallpaper autostereograms, subtle changes in spacing specified by the depth map can create the illusion of smooth gradients in distance. This is possible because the grayscale depth map allows individual pixels to be placed on one of 2n depth planes, where n is the number of bits used by each pixel in the depth map. In practice, the total number of depth planes is determined by the number of pixels used for the width of the pattern image. Each grayscale value must be translated into pixel space in order to shift pixels in the final autostereogram. As a result, the number of depth planes must be smaller than the pattern width.

The fine-tuned gradient requires a pattern image more complex than standard repeating-pattern wallpaper, so typically a pattern consisting of repeated random dots is used. When the autostereogram is viewed with proper viewing technique, a hidden 3D scene emerges. Autostereograms of this form are known as Random Dot Autostereograms.

Smooth gradients can also be achieved with an intelligible pattern, assuming that the pattern is complex enough and does not have big, horizontal, monotonic patches. A big area painted with monotonic color without change in hue and brightness does not lend itself to pixel shifting, as the result of the horizontal shift is identical to the original patch. The following depth map of a shark with smooth gradient produces a perfectly readable autostereogram, even though the 2D image contains small monotonic areas; the brain is able to recognize these small gaps and fill in the blanks (illusory contours). While intelligible, repeated patterns are used instead of random dots, this type of autostereogram is still known by many as a Random Dot Autostereogram, because it is created using the same process.

Animated
When a series of autostereograms are shown one after another, in the same way moving pictures are shown, the brain perceives an animated autostereogram. If all autostereograms in the animation are produced using the same background pattern, it is often possible to see faint outlines of parts of the moving 3D object in the 2D autostereogram image without wall-eyed viewing; the constantly shifting pixels of the moving object can be clearly distinguished from the static background plane. To eliminate this side effect, animated autostereograms often use shifting background in order to disguise the moving parts.

When a regular repeating pattern is viewed on a CRT monitor as if it were a wallpaper autostereogram, it is usually possible to see depth ripples. This can also be seen in the background to a static, random-dot autostereogram. These are caused by the sideways shifts in the image due to small changes in the deflection sensitivity (linearity) of the line scan, which then become interpreted as depth. This effect is especially apparent at the left hand edge of the screen where the scan speed is still settling after the flyback phase. On a TFT LCD, which functions differently, this does not occur and the effect is not present. Higher quality CRT displays also have better linearity and exhibit less or none of this effect.

Mechanisms for viewing
Much advice exists about seeing the intended three-dimensional image in an autostereogram. While some people may quickly see the 3D image in an autostereogram with little effort, others must learn to train their eyes to decouple eye convergence from lens focusing.

Not every person can see the 3D illusion in autostereograms. Because autostereograms are constructed based on stereo vision, persons with a variety of visual impairments, even those affecting only one eye, are unable to see the three-dimensional images.

People with amblyopia (also known as lazy eye) are unable to see the three-dimensional images. Children with poor or dysfunctional eyesight during a critical period in childhood may grow up stereoblind, as their brains are not stimulated by stereo images during the critical period. If such a vision problem is not corrected in early childhood, the damage becomes permanent and the adult will never be able to see autostereograms. It is estimated that some 1 percent to 5 percent of the population is affected by amblyopia.

3D perception
Depth perception results from many monocular and binocular visual clues. For objects relatively close to the eyes, binocular vision plays an important role in depth perception. Binocular vision allows the brain to create a single Cyclopean image and to attach a depth level to each point in it.

The brain uses coordinate shift (also known as parallax) of matched objects to identify depth of these objects. The depth level of each point in the combined image can be represented by a grayscale pixel on a 2D image, for the benefit of the reader. The closer a point appears to the brain, the brighter it is painted. Thus, the way the brain perceives depth using binocular vision can be captured by a depth map (Cyclopean image) painted based on coordinate shift.

The eye operates like a photographic camera. It has an adjustable iris which can open (or close) to allow more (or less) light to enter the eye. As with any camera except pinhole cameras, it needs to focus light rays entering through the iris (aperture in a camera) so that they focus on a single point on the retina in order to produce a sharp image. The eye achieves this goal by adjusting a lens behind the cornea to refract light appropriately.

When a person stares at an object, the two eyeballs rotate sideways to point to the object, so that the object appears at the center of the image formed on each eye's retina. In order to look at a nearby object, the two eyeballs rotate towards each other so that their eyesight can converge on the object. This is referred to as cross-eyed viewing. To see a faraway object, the two eyeballs diverge to become almost parallel to each other. This is known as wall-eyed viewing, where the convergence angle is much smaller than that in cross-eyed viewing.

Stereo-vision based on parallax allows the brain to calculate depths of objects relative to the point of convergence. It is the convergence angle that gives the brain the absolute reference depth value for the point of convergence from which absolute depths of all other objects can be inferred.

Simulated 3D perception
The eyes normally focus and converge at the same distance in a process known as accommodative convergence. That is, when looking at a faraway object, the brain automatically flattens the lenses and rotates the two eyeballs for wall-eyed viewing. It is possible to train the brain to decouple these two operations. This decoupling has no useful purpose in everyday life, because it prevents the brain from interpreting objects in a coherent manner. To see a human-made picture such as an autostereogram where patterns are repeated horizontally, however, decoupling of focusing from convergence is crucial.

By focusing the lenses on a nearby autostereogram where patterns are repeated and by converging the eyeballs at a distant point behind the autostereogram image, one can trick the brain into seeing 3D images. If the patterns received by the two eyes are similar enough, the brain will consider these two patterns a match and treat them as coming from the same imaginary object. This type of visualization is known as wall-eyed viewing, because the eyeballs adopt a wall-eyed convergence on a distant plane, even though the autostereogram image is actually closer to the eyes. Because the two eyeballs converge on a plane farther away, the perceived location of the imaginary object is behind the autostereogram. The imaginary object also appears bigger than the patterns on the autostereogram because of foreshortening.

The following autostereogram shows three rows of repeated patterns. Each pattern is repeated at a different interval to place it on a different depth plane. The two non-repeating lines can be used to verify correct wall-eyed viewing. When the autostereogram is correctly interpreted by the brain using wall-eyed viewing, and one stares at the dolphin in the middle of the visual field, the brain should see two sets of flickering lines, as a result of binocular rivalry.

While there are six dolphin patterns in the autostereogram, the brain should see seven "apparent" dolphins on the plane of the autostereogram. This is a side effect of the pairing of similar patterns by the brain. There are five pairs of dolphin patterns in this image. This allows the brain to create five apparent dolphins. The leftmost pattern and the rightmost pattern by themselves have no partner, but the brain tries to assimilate these two patterns onto the established depth plane of adjacent dolphins despite binocular rivalry. As a result, there are seven apparent dolphins, with the leftmost and the rightmost ones appearing with a slight flicker, not dissimilar to the two sets of flickering lines observed when one stares at the 4th apparent dolphin.

Because of foreshortening, the difference in convergence needed to see repeated patterns on different planes causes the brain to attribute different sizes to patterns with identical 2D sizes. In the autostereogram of three rows of cubes, while all cubes have the same physical 2D dimensions, the ones on the top row appear bigger, because they are perceived as farther away than the cubes on the second and third rows.

Viewing techniques

If one has two eyes, fairly healthy eyesight, and no neurological conditions which prevent the perception of depth, then one is capable of learning to see the images within autostereograms. "Like learning to ride a bicycle or to swim, some pick it up immediately, while others have a harder time."

As with a photographic camera, it is easier to make the eye focus on an object when there is intense ambient light. With intense lighting, the eye can constrict the pupil, yet allow enough light to reach the retina. The more the eye resembles a pinhole camera, the less it depends on focusing through the lens. In other words, the degree of decoupling between focusing and convergence needed to visualize an autostereogram is reduced. This places less strain on the brain. Therefore, it may be easier for first-time autostereogram viewers to "see" their first 3D images if they attempt this feat with bright lighting.

Vergence control is important in being able to see 3D images. Thus it may help to concentrate on converging/diverging the two eyes to shift images that reach the two eyes, instead of trying to see a clear, focused image. Although the lens adjusts reflexively in order to produce clear, focused images, voluntary control over this process is possible. The viewer alternates instead between converging and diverging the two eyes, in the process seeing "double images" typically seen when one is drunk or otherwise intoxicated. Eventually the brain will successfully match a pair of patterns reported by the two eyes and lock onto this particular degree of convergence. The brain will also adjust eye lenses to get a clear image of the matched pair. Once this is done, the images around the matched patterns quickly become clear as the brain matches additional patterns using roughly the same degree of convergence.

When one moves one's attention from one depth plane to another (for instance, from the top row of the chessboard to the bottom row), the two eyes need to adjust their convergence to match the new repeating interval of patterns. If the level of change in convergence is too high during this shift, sometimes the brain can lose the hard-earned decoupling between focusing and convergence. For a first-time viewer, therefore, it may be easier to see the autostereogram, if the two eyes rehearse the convergence exercise on an autostereogram where the depth of patterns across a particular row remains constant.

In a random dot autostereogram, the 3D image is usually shown in the middle of the autostereogram against a background depth plane (see the shark autostereogram). It may help to establish proper convergence first by staring at either the top or the bottom of the autostereogram, where patterns are usually repeated at a constant interval. Once the brain locks onto the background depth plane, it has a reference convergence degree from which it can then match patterns at different depth levels in the middle of the image.

The majority of autostereograms, including those in this article, are designed for divergent (wall-eyed) viewing. One way to help the brain concentrate on divergence instead of focusing is to hold the picture in front of the face, with the nose touching the picture. With the picture so close to their eyes, most people cannot focus on the picture. The brain may give up trying to move eye muscles in order to get a clear picture. If one slowly pulls back the picture away from the face, while refraining from focusing or rotating eyes, at some point the brain will lock onto a pair of patterns when the distance between them matches the current convergence degree of the two eyeballs.

Another way is to stare at an object behind the picture in an attempt to establish proper divergence, while keeping part of the eyesight fixed on the picture to convince the brain to focus on the picture. A modified method has the viewer focus on their reflection on a reflective surface of the picture, which the brain perceives as being located twice as far away as the picture itself. This may help persuade the brain to adopt the required divergence while focusing on the nearby picture. Those who wear eyeglasses with so-called "progressive" lenses, in which the focal length gradually changes so as to ease the viewing of close objects using the lower part of the lens, may find that viewing a stereogram is easier if the glasses are pushed up a little so that the stereogram is viewed through a part of the lens optimized for images that are closer than the actual distance to the stereogram. When the eyes are made divergent by looking (or pretending to look) at a far-away object, the overcorrection from viewing the stereogram through the "wrong" part of the lens can bring the stereogram into focus without needing to overcome the tendency to focus on the far-away object while attempting to focus on the stereogram.

For crossed-eyed autostereograms, a different approach needs to be taken. The viewer may hold one finger between their eyes and move it slowly towards the picture, maintaining focus on the finger at all times, until they are correctly focused on the spot that will allow them to view the illusion.

Stereoblindness, however, is not known to permit the usages of any of these techniques, especially for persons in whom it may be, or is, permanent.

Terminology

 * Stereogram and autostereogram
 * Stereogram was originally used to describe as a pair of 2D images used in stereoscope to present a 3D image to viewers. The "auto" in autostereogram describes an image that does not require a stereoscope. The term stereogram is now often used interchangeably with autostereogram. Dr. Christopher Tyler, inventor of the autostereogram, consistently refers to single image stereograms as autostereograms to distinguish them from other forms of stereograms.

 * Random dot stereogram (RDS)
 * Random dot stereogram, describes a pair of 2D images containing random dots which, when viewed with a stereoscope, produced a 3D image. The term is now often used interchangeably with random dot autostereogram.

 * Single image stereogram (SIS)
 * Single image stereogram (SIS). SIS differs from earlier stereograms in its use of a single 2D image instead of a stereo pair and is viewed without a device. Thus, the term is often used as a synonym of autostereogram. When the single 2D image is viewed with proper eye convergence, it causes the brain to fuse different patterns perceived by the two eyes into a virtual 3D image without, hidden within the 2D image, the aid of any optical equipment. SIS images are created using a repeating pattern. Programs for their creation include Mathematica.

 * Random dot autostereogram/hidden image stereogram
 * Is also known as single image random dot stereogram (SIRDS). This term also refers to autostereograms where the hidden 3D image is created using a random pattern of dots within one image, shaped by a depth map within a dedicated stereogram rendering program.

 * Wallpaper autostereogram/object array stereogram/texture offset stereogram
 * Wallpaper autostereogram is a single 2D image where recognizable patterns are repeated at various intervals to raise or lower each pattern's perceived 3D location in relation to the display surface. Despite the repetition, these are a type of single image autostereogram.

 * Single image random text stereogram (SIRTS)
 * A single image random text ASCII stereogram is an alternative to SIRDS using random ASCII text instead of dots to produce a 3D form of ASCII art.

 * Map textured stereogram
 * In a map textured stereogram, "a fitted texture is mapped onto the depth image and repeated a number of times" resulting in a pattern where the resulting 3D image is often partially or fully visible before viewing.

title: Autostereogram


text:
Bloomsbury Theatre

The Bloomsbury Theatre is a theatre on Gordon Street, Bloomsbury, in the London Borough of Camden, owned by University College London. The Theatre has a seating capacity of 541 and offers a professional programme of innovative music, drama, comedy and dance all year round as well as providing a space for student-led productions.

Funded by a UGC grant and a considerable private donation, the theatre was opened in 1968 as the Collegiate Theatre, and was renamed the Bloomsbury Theatre in 1982. Between 2001 and 2008, the theatre was known as The UCL Bloomsbury, to emphasise links with UCL, who use it for student productions 12 weeks a year. The Bloomsbury Theatre recently returned to the logo designed by cartoonist Gerald Scarfe which it had used for nearly twenty years until 2001. The main theatre was closed for building works in 2015 and reopened in February 2019.

The theatre building also provides access to the UCL Union Fitness Centre and Clubs and Societies Centre on the 2nd, 3rd and 4th floors. The basement also holds one of the three University Shops. A UCL Union-run café is on the Ground Floor. Access to the Main UCL Wilkins Building (Octagon Building) and the UCL Refectory is possible through the theatre building.

Amongst the many other artists who have performed at the theatre are; UCL alumnus Ricky Gervais has performed two of his standup shows in the theatre, where they were also filmed for release on DVD and was the venue for Crusader Norman Housley come-back lecture series: Contesting the Crusades, which he developed into a popular history book.

In July 1982, the Bloomsbury Theatre premiered the English language performance of Pirandello's Liola by Internationalist Theatre directed by UCL alumnus Fabio Perselli who also did the translation.

From 2001, the theatre provided a residency for the New London Orchestra and hosted Robin Ince's "Nine Lessons and Carols for Godless People" for several years.

May 2006 Paul Simon performed a concert which was recorded for the BBC Radio 2

January 2008 Adele performed her first solo concert which included a full performance of her debut album 19 which went to No.1 in the UK charts in the same week.

Christopher Nolan and Emma Thomas meet whilst being members of UCL Film Society and cite the Bloomsbury theatre as being key to developing their directing and producer careers.

title: Bloomsbury Theatre


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Faslane (bay)

Faslane (Gaelic: Am Fas Leathann) on Gare Loch is the name of a bay near the village of Garelochhead, and is now the main part of HM Naval Base Clyde in Argyll and Bute, Scotland, as well as being a Defence Logistics Organisation port, operated in dual site organisation with Great Harbour, Greenock, by Serco Denholm.

Faslane is currently home to the United Kingdom's Trident SSBN submarines

There is also Faslane Peace Camp outside the base, protesting since 1982 against the nuclear missiles and submarines there.

History
The immediate area was sparsely populated until a naval base was constructed during World War II, though Garelochhead was already a thriving village served by Clyde steamers and a railway station. A shipbreakers operated at Faslane until the mid-1980s, when its site was taken over for expansion of the naval base.

title: Faslane (bay)


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Talk:Ulster Scots dialect

Orthography?
I came to this article (again) from a comment on the article Ä about how a-diaeresis is being used in some new orthographies of Ulster Scots, but there's very little information about orthography like one might find in other articles about languages or dialects. It would be good if someone who knows more about it could expand this article further in that regard. — OwenBlacker (Talk) 13:29, 24 October 2015 (UTC)
 * I would also like to see some information about orthography. As a speaker of (Scottish) Scots I find the orthography quite difficult to parse sometimes and most of it seems to have no historical context. SaoiDunNeachdain (talk) 15:23, 25 April 2021 (UTC)

Total lack of linguistic information
This article contains a hell of a lot of information about the status of Ulster Scots, about how many (or few) people speak it, about its revival movement and whether the language they cultivate has the right to be called 'Scots'. But there is nothing about the language itself. Imo, the core of every article about a linguistic variety should be about its properties. How is it different from Lowlands Scots? How is it related to the various Lowlands (sub)dialects? Are there any internal differences, and if yes, to what extent? Was the dialect influenced by Ulster Irish, and to what extent? I expect to find the answers to questions like these in an article about Ulster Scots, especially when it's so long. Steinbach (talk) 11:41, 24 July 2020 (UTC)
 * I would really appreciate a reply. Steinbach (talk) 08:44, 21 August 2020 (UTC)

Neutrality issues
The "new orthographies" section seems to consist entirely of attacks on the language CiphriusKane (talk) 07:04, 8 July 2021 (UTC)
 * The source ye used is SquareSpace, a website building site. This to me makes it unreliable as it's akin to WordPress. When I tried visiting the source, it just gave me a blank page. Also ye removed the NPOV tag CiphriusKane (talk) 05:51, 9 July 2021 (UTC)
 * This would be better approached by requesting further citation ; removal requires discussion.

BBX118 10:16, 9 July 2021 (UTC)
 * Given how ye were the one who added it and keeps insisting on adding it, surely adding it should require addition? I believe that's what WP:BRD says. And stop removing the NPOV tag please CiphriusKane (talk) 10:20, 9 July 2021 (UTC)
 * I haven't removed the tag. The information has been listed for a while; we'll need discussion if you feel it's not pertinent. The fact the dialect is distinct from Scots in that it is partially constructed is important to mention.

BBX118 10:54, 9 July 2021 (UTC)
 * I'm finding the constructed claim to be rather contentious. Had an Ulster Scots speaker mention that they think calling it "constructed" is a political point rather than factual statement, so having a blog as the source feels really inappropriate to me.  Also, I'd advise ye double check yer edits, because ye removed the NPOV tag that I added twice though ye probably missed that. EDIT Why do ye think it's a conlang?  Dialects tend to be distinct.  I'm pretty sure ye'll find that northern and southern German dialects differ greatly, and Australian English has its own unique aspects, so are they conlangs as well? CiphriusKane (talk) 17:01, 9 July 2021 (UTC)

Unclehot (talk) 08:12, 8 August 2021 (UTC)
 * could we remove the NPOV I don't see how dismissing a source that is unreliable and me and other users can't actually see is not neutral.

Unclehot (talk) 06:40, 9 August 2021 (UTC)
 * I have reverted the edit of BBX118 as it's unreliable and is not working for other users. I believe I pinged the wrong person on this talk page when asking about removing the NPOV. Would you believe it to be appropriate to remove the NPOV now? I don't really believe that the article has any neutrality issues but if it does we could work on resolving them. I feel like leaving the NPOV up for so long creates distrust in the article.

Formatting: quotation and excerpts
1. The section of the "new orthographies" that starts with "It is certainly" and ends with "counter-intuitive and false" should have quotation marks around it since the text is a quotation.

2. It is not clear to me why the excerpts under "sample texts" by Barney Maglone and Robert Huddleston should have spacing between lines. The excerpt by Hugh Porter doesn't.

ICE77 (talk) 16:53, 5 July 2022 (UTC)

title: Talk:Ulster Scots dialect