Talk:List of common misconceptions/Archive 5

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Dark Side of the Moon

While I understand what the description is saying, it seems too vague to be completely understood. By my understanding, the dark side of the moon is whatever side the sun is not lighting at the time. Thus, a dark side exists...at least, it would certainly be darker than the side the sun is illuminating. I understand that I am taking this extremely literally, but I found it to be oddly written. (204.111.166.31 (talk) 03:25, 19 March 2009 (UTC))

Earthworms

• This page says "An earthworm does not become two worms when cut in half. An earthworm can survive being bisected, but only the front half of the worm (where the mouth is located) can survive, while the other half dries out or starves to death. If one cuts the worm too close to the saddle (the fat pink section where all of the worm's vital organs are located) then the worm may die. ...". This disagrees with Earthworm#Regeneration: when an earthworm is cut in two, ability to regenerate a head and/or a tail at the cut varies with species and where in the worm the cut is. Anthony Appleyard (talk) 22:27, 19 March 2009 (UTC)

There has been no reliable source to show that it is a "common misconception" that a bisected earthworm becomes two worms, so I am removing that item.Edison (talk) 20:16, 28 April 2009 (UTC)

tagging

Have just a bunch in there. The edit summaries are reasonably detailed. In many cases there are just no sources at all, so that's easy. In some cases there are sources that state something is authoratatively X, but do not say it's "commonly perceived" as something else. And a lot of those (like the kosher entry) don't seem to be in fact "common misconceptions." They will at the very least have to be established via reliable sources to be labelled stuff.

I also did a little rewriting on the koran stuff -- it was just factually inaccurate, and it's better now. But it should all probably go because there is considerable controversy even among scholars (lets forget imams and so forth -- controversy gets much worse if we go there) about what the words in the koran actually MEAN. So how can we authoratatively state what Islam does or does not promise or require (by way of refuting an alleged "misconception") when a few hundred years of western scholarship, and the 1,400 year history of Islam itself, haven't definitely sorted out these questions? That's one of the inherent problems with this list. On many of the things here the "truth" is not clearly established.Bali ultimate (talk) 19:57, 20 March 2009 (UTC)

I'm also strongly leaning towards removing all 27 items that are currently flagged as "citation needed." I'll give it some time, though. Bali ultimate (talk) 20:10, 20 March 2009 (UTC)

It's good you tagged every unsourced item, but let's wait til the current AfD situation is resolved before doing anything further. --Armchair info guy (talk) 20:39, 20 March 2009 (UTC)

I haven't come close to tagging every unsourced item. It's just a start. I have just stripped out some patent nonesense about chameleon's exploding if placed on an orange and the like. I think the tagged number is now at about 35. But there's a lot I haven't read yet.Bali ultimate (talk) 21:07, 20 March 2009 (UTC)

• Instead of tagging, why not spend a few seconds Googling? I easily found references for a few tagged items. Dream Focus 10:08, 23 March 2009 (UTC)

Bats

A reliable source will be needed for the assertion that bats are blind is a "common misconception". The existence of the phrase "blind as a bat" does not support this on its own. Anyone who'se watched a nature show knows bats have some vision. I don't presume the majority of people (which i presume the word "common" is refering to in the title of this article) are this stupid. Reliable sources will be needed to back up this assertion.Bali ultimate (talk) 21:29, 20 March 2009 (UTC)

Seasons

This edit [4] reinserts what can charitably be called an unsourced assertion with an edit summary that essentially says "this belongs here." That's not how it works. You will need reliable sourcing establishing this absurdity is a "common misconception." Your opinion that it is is insufficient. (It's my opinoin is that it is not). The way we settle these differences of opinion is with sourcing. So I strongly urge you to revert your own edit. If my efforts to deal with unsourced assertions are thwared, I'll seek out other editors who have not yet engaged with this article who may be likewise interested in making sure we adhere to the sourcing policies that are the only hope of preserving whatever integrity and credibility the project has.Bali ultimate (talk) 21:40, 20 March 2009 (UTC)

Here is an example of bad information on the subject: [5]. This "explanation" implies that the tilt of the earth causes seasons by moving the summer hemisphere closer to the sun, whereas, of course, the northern hemisphere is actually a couple million miles farther from the sun during summer than winter. Of course, the link does not prove that this is a "common misconception" exactly, but it is a prominent website, and I tend to think that we should at least look around for some sources before deleting the entry outright. Rracecarr (talk) 21:52, 20 March 2009 (UTC)

That's not evidence that it's a common misperception (and you're using "Wiki Answers" as a source? not RS) and at any rate this article says the common misperception is that the seasons are caused by being closer to sun in summer "rather than by earth's tiled axis." It gets the first bit right, and maybe it's language is sloppy. But again, it's Wiki Answers, and that doesn't establish much. Perhaps the tile of the list should be changed to "List of misconceptions held by some people." That would bring the sourcing bar down quite substantially. Bali ultimate (talk) 21:58, 20 March 2009 (UTC)

Of course Wiki Answers is not a reliable source. The very reason I quoted it was because it was wrong (and ranked highly in web searches). Let's not intentionally misunderstand each other. And by the way, the language in the Wiki Answers entry ("Because the North is nearer to the heat source, the Sun, than the South part of the earth, the Northern parts gets warmed by the heat of the Sun") is not sloppy, it's flat wrong. I understand that the "commonness" of the misconception needs to be established. However, that does not mean delete the entry. It means tag it, and, if you're not willing to do the work yourself, give others some time to look for sources. Rracecarr (talk) 22:09, 20 March 2009 (UTC)

First off, I’d say most of the sources on this page do not prove that the items are necessarily ‘common misconceptions’; the sources simply disprove the misconceptions. The statement on WikiAnswers proves something—that it is indeed a relatively common misconception, as far as can be possibly judged—and a reliable source can disprove that misconception.—Jchthys 22:30, 20 March 2009 (UTC)

You will need a reliable source saying this is a "common misconception" (or words that amount to the same thing). What you have now is evidence that some contributor to wiki answers is misinformed. That's insufficience (especially when we're talking about something most of us learned in school -- axis, tile, less direct sunlight about covers it).Bali ultimate (talk) 22:42, 20 March 2009 (UTC)

This latest "citation" [6] fails to establish anything other than the basics of axis, tilt, and less direct sunlight. It says nothing about how these basic, well understood facts are in fact "commonly misconceived." Have restored fact tag.Bali ultimate (talk) 15:19, 21 March 2009 (UTC)

I'd like to note that I once got a red X from a science teacher on this very misconception: I replied, "because of axial tilt", she said, "no, it's because the Earth is closer to the sun". So, anecdotally, this is a pretty important misconception. Give it the benefit of the doubt until better sources are found.--Father Goose (talk) 15:37, 21 March 2009 (UTC)

An anecdote involving your ignorant teacher (and how many years ago?) is not RS (I know you know this). Nothing should be in the encyclopedia until it's demonstrably true. As I said somewhere earlier if the list name was "Misconceptsion held by some people" (which is what, in fact, this list currently has) sourcing would be much easier. But "common" implies some large number of folks more or less currently are mistaken about something. That needs to be established in most of these cases, including this one.Bali ultimate (talk) 15:45, 21 March 2009 (UTC)

I’d say that most of the misconceptions on this page have no source saying that they are in fact common misconceptions. I think that’s a hard thing to prove, and not a central point.—Jchthys 16:59, 21 March 2009 (UTC)

You write: "I’d say that most of the misconceptions on this page have no source saying that they are in fact common misconceptions." Ok. I can concede that "some" (very few) of the points on the page have a source for "common misconception." But if i understand this next comment of yours accurately, this is the point at which it becomes impossible for us to find common ground: You write "I think that’s a hard thing to prove, and not a central point." See, to me, determining whether something is or is not a "common misconception" (and the further meta point of whether it's possible to define and determine if ANYTHING is a "common misconception") is the central point for determining: A. Whether something can be included in such a list and, B. (meta) Whether it's appropriate to include such a list at all (i.e. if "common misconception" is not truly categorizable in a limited, specific fashion, then no). Now, i think we can fruitfully argue over points A. and B., but if you think that points A and B are unimportant, we're at an impasse.Bali ultimate (talk) 20:36, 21 March 2009 (UTC)

Sorry for being unclear here. Really, I think that if such a list exists, there need to be clear guidelines about what can be included. Obviously, there needs to be a source proving that the misconception is false; but maybe there wouldn’t need to be a source proving that it is indeed a common misconception, and the community could decide that. I do think there is no harm in keeping the list, so we need to decide about these guidelines. Personally, I think that the season misconception is very common—for example, it occurs both in Latin poetry and in a conversation with my younger brother last week—whereas some other misconceptions that get to stay on the list aren’t.—Jchthys 00:38, 22 March 2009 (UTC)

Maybe it would work to cite two sources: (1) either a reliable source stating that the misconception is relatively common OR a relatively high-profile site or work (WikiAnswers, for instance) that gets the fact wrong, and (2) a reliable source setting the facts straight.—Jchthys 02:16, 22 March 2009 (UTC)

First, don't ever edit my user page again. Second. I don't care what you "personally believe" is common or uncommon. I only care about what is demonstrable via reliable sources, that allow for verification and establish some bar for notability. Your opinion is (just as my opinion is) precisely worthless in these matters. The only accpetable standard is a clear defintion of "common misconception" (hard to see that being reached, but whatever) and then reliable sources outside wikipedia (wiki answers? No. Never. Not RS for about 5 reasons i can think of off the top of my head) that support inclusion via that clear definition. That's it. Otherwise, this is just a blog or myspace (which are free to edit with no rules).Bali ultimate (talk) 02:31, 22 March 2009 (UTC)

I'm not saying that the anecdote about my science teacher is "proof" of the misconception being common -- just that since I've encountered that very misconception in my lifetime, I'm inclined to believe it may be pretty common. As such I am suggesting we give it the benefit of the doubt until someone tracks down sources. If no supporting sources are turned up after careful research, then it should be tossed. It's a question of Wikipedia not being perfect. We toss obvious crap, but there is a benefit to giving other material time to improve. Add a in the interim, or, if you have the time and are a good researcher, do the research yourself.--Father Goose (talk) 03:47, 22 March 2009 (UTC)

What I meant is this: why leave out the seasons misconception until proven worthy, but leave in others?—Jchthys 14:10, 22 March 2009 (UTC)

• I added in the reference to http://www.badastronomy.com/bad/misc/seasons.html which list it as a misconception. Does that not count? It was deleted from the article once again. Discuss this please. Why is that not a suitable reference? See the word "misconception" to the left of the article, that the section it is in? Dream Focus 22:54, 31 March 2009 (UTC)

Bad Astrononomy is a personal blog, so not a reliable source per WP:RS. There is no shortage of published reliable sources on astronomy, so we don't need to use this one. --hippo43 (talk) 23:03, 31 March 2009 (UTC)

http://www.lpi.usra.edu/education/skytellers/seasons/activities/sequences.shtml There is a government educational site that mentions it is a common misconception. Any problems with that one? Dream Focus 23:10, 31 March 2009 (UTC)

Looks good to me. --hippo43 (talk) 23:26, 31 March 2009 (UTC)

Evolution

This reinserted entry is a classic reason so much in this article has to go:

• "The word "theory" in "the theory of evolution" does not imply doubt in mainstream science regarding its validity; the words "theory" and "hypothesis" are not the same in a scientific context (see Evolution as theory and fact). While "theory" in conventional usage tends to denote a "hunch" or conjecture, a scientific theory is a set of principles which, via logical induction, explains the observations in nature. The same inductive inferences can be made to predict observations before they are made. Evolution is a theory in the same sense as the theory of gravity or the theory of relativity."

This just defines "theory" in a scientific sense. Yes many creationists deliberately/ignorantly ignore the precise definition of this word for rhetorical purposes. But this does not make it a "common misconception" (and the entry as stated is problematic -- details of the theory are being changed all the time -- so there is some "doubt" about the full validity and precision of this commonly accepted, by almost all scientists and most educated people, "theory"). Bali ultimate (talk) 20:55, 21 March 2009 (UTC)

I agree that the entry is not phrased in the best possible way. However, as you yourself admit, the "evolution is a theory, not a fact" argument is often used to cast doubt on evolution. I'd say that pretty much means it's a common misconception. The entry needs editing, not deletion. Rracecarr (talk) 21:07, 21 March 2009 (UTC)

I actually believe most of the people who make this argument are playing rhetorical games (that is, they're lying). They know the difference but are seeking to fool what they hope is a gullible audience. Since they have been consistently losing supporters for their position for 50+ years, I see no evidence this is a "common misconception" (by your reasoning, the fact that many crazies believe 9/11 was carried out with fixed explosives by the trilateral commission and the mossad, justifies it's inclusion on this list). In neither case is "common misconception" determined by a reliable source.Bali ultimate (talk) 21:10, 21 March 2009 (UTC)

You are right--nothing in this entry (or pretty much any of the others) establishes the percentage of people who believe the falsehood. That is very hard to do in most cases, and is the main difficulty facing this article. Why can't we just decide what content is appropriate for inclusion on the talk page, as would be done on any other article? If deciding what's common by consensus bugs you, the title could be changed, though I don't have a great suggestion for a new one. Rracecarr (talk) 21:23, 21 March 2009 (UTC)

Now we agree. "Common" is a vague indefinable term, but seems to imply something like "widely held" or "believed by many." Where we disagree is what defines a category that can be listed. I believe such lists should be specifically definable, and possibly completable (i.e. I have no philosphical opposition to "list of rivers" articles -- they have specific inclusion criteria and are completable). (So do most librarians and people that work in business taxonomy and ontologies.) In the interim, we must find sourcing that somehow supports the "common" part of this. "List of misconceptions" is even more unwieldy. For the moment, i think a few entries like ("Napoleon isn't short" can stay -- there are multiple sources discussing this "misconception." My fact tag there is for the innacurate assertion about the "fact" of the history of "petit corporal" In fact, no one knows why that was his nickname, there are 2-3 other theories for it, none proven, and none of that speculation should be mentioned in this article).Bali ultimate (talk) 22:26, 21 March 2009 (UTC)

Normally I would be on your side. It doesn't make sense to have a list unless there's a way to distinguish definitively between items that belong and those that don't. However, I personally really like this list. When I first came to it I learned that a number of things I had believed were wrong. I know you'll say that that is not relevant, but I've seen a number of posts from other users saying essentially the same thing. To take your example, having heard my whole life about small feisty people with "Napoleon complexes", I had assumed he was short. I'm not very likely to have ever ended up at the Napoleon Bonaparte article, and without this list, I would still not know. It is nice to be able read for 15 minutes and correct several lifelong misconceptions. I certainly would be unlikely to do so randomly surfing wikipedia articles on narrowly defined subjects. Screw policy, screw what wikipedia is not, forget all that rigidity. This list is cool. People like it. It should stay.

On a side note, I think the "petit corporal" bit can go, especially if as you say it might not even be true. The fact that he wasn't short is enough--speculation about how the myth arose is not needed. Rracecarr (talk) 23:32, 21 March 2009 (UTC)

Seriously? That is most definitely a common misconception in the US. Many people don't know what "theory" means in a scientific context. Go read Eugenie Scott's book. --Armchair info guy (talk) 01:34, 22 March 2009 (UTC)

"They know the difference but are seeking to fool what they hope is a gullible audience." It is clear that they have a very attentive audience that is willing to believe the distortion as fact -- thus making it a quite common misconception, albeit a deliberately spread one. Nonetheless, its status as a misconception has to be described as such by sources -- as does every entry in this article.--Father Goose (talk) 03:25, 22 March 2009 (UTC)

Father Goose -- do you have a reliable source to support you contention that this is a "common misconeption?" Your and my opinion about "the truth" in this matter is largely irrelevant.Bali ultimate (talk) 03:47, 22 March 2009 (UTC)

I'm not arguing on that basis. What I'm saying is, give it time. Good writing takes time. Good research takes time. This article needs quite a bit of work to bring it up to the standards you are demanding. The standards you are suggesting are appropriate. Insisting that the article meet those standards right this instant is not appropriate.

Ask yourself the question, "what work would be needed to make this article the best it could be?" Then be prepared to a) do the work or b) let others do the work, when the time is available to them. Any parts that are clearly worthless can be tossed right away, which you've been doing -- that's fine. I commend you for your contributions. But please chill out a bit more -- don't relax your standards (don't expect Wikipedia to relax its standards), but don't expect the rest of Wikipedia's editors to bring this article up to them right this instant or else!

If anyone's claiming that this article shouldn't be fully sourced, and all entries fully justified, they're wrong, and you, I, and several other editors here will disregard them. Bit by bit, we can turn this into a quite good article. But, please, holster your defensiveness and impatience, so that we can work on this article at a sane pace, and in a civil environment. Okay? Please.--Father Goose (talk) 04:05, 22 March 2009 (UTC)

Concerns

I've brought up my concerns about the need for reliable sources to establish the inclusion of items on this list here. [7] Bali ultimate (talk) 21:08, 21 March 2009 (UTC)

How long is long enough to ignore sourcing?

Quoting Father Goose from up above: "What I'm saying is, give it time. Good writing takes time. Good research takes time. This article needs quite a bit of work to bring it up to the standards you are demanding.... Insisting that the article meet those standards right this instant is not appropriate." This article has been here for over 5 years. [8]. How much more time should unsourced, largely false information, be allowed to persist, in your opinion? When does an "instant" end?Bali ultimate (talk) 04:29, 22 March 2009 (UTC)

What are you talking about, "largely false"?? Rracecarr (talk) 07:51, 22 March 2009 (UTC)

I wrote a fairly elaborate reply to your questions. But ultimately, the right answers are WP:TIND, WP:IMPERFECT, and {{sofixit}}. If you're really so insistent that this article must be fixed right now, then shut up already and get to work. I and others will help you. This endless jawing is taking our time away from actually doing that work.--Father Goose (talk) 07:57, 22 March 2009 (UTC)

Yes largely false. Most of these things are not by any stretch of the imagination "common misconceptions" (and why are we fighting about this -- they don't have any sources showing that they are, whatever my opinion) so their inclusion here is false, misleading, etc... Furthermore, the whole question of what a common misconception is remains hard to establish. I believe your edit to the lede was helpful "described by multiple reliable sources as widely held by the general populace" but this has set the bar very, very high. The only one on this list i bet you could find multiple reliable sources for (a toilet-reading paper back on a shelf next to "100 Fart Jokes" at the book-store isn't going to cut it) is napoleon wasn't short. The rest of this stuff people don't have beliefs about at all. "During World War II, King Christian X of Denmark did not thwart Nazi attempts to identify Jews by wearing a yellow star himself." Do you think the general populous outside of denmark could even identify King Christian X? of course they can't. As for sofixit, I intend to, but removing unsources material.Bali ultimate (talk) 15:43, 22 March 2009 (UTC)

"Has set the bar very, very high" -- is that a bad thing? I'm pretty sure it's not as high as you think -- though it's certainly higher than it's been so far. Of the handful of entries I've sourced, I have seen that multiple reliable sources do indeed describe the facts in question as widely held misconceptions. One of them, the bit about glass being a liquid, was deleted about a week ago for being slightly contradictory and having imperfect sourcing. As rewritten, it's one of the solidest (pardon the pun) entries on the list -- but if I hadn't been watching the article at the exact moment of its deletion, I wouldn't have known to restore and rewrite it.

Deleting stuff that needs work is counterproductive. If people went through your stuff and deleted anything that was half-finished, you'd tell them to fuck off. It's even more important to not throw out things that are in an imperfect state on Wikipedia, because even if one editor stops working on an article, another will eventually continue with the work, if the article's worth anything at all.

I wouldn't oppose your deleting entries if you made a concerted effort to try to source them first. In fact, that's another thing I'd commend you for, 'cause that's the work that needs to be done. Sources need to be found for every entry on the list. If diligent research turns up nothing to support the claim that a given entry is a "common misconception", then it should be deleted. Like I've pointed out in the past -- and you know it yourself -- deleting things solely on the basis that they're unsourced is not accepted behavior on Wikipedia. So I suggest you stop making empty threats to that effect. I'd especially suggest you not actually follow through on that particular threat. Do do the research if you really want the article to get better.--Father Goose (talk) 03:08, 23 March 2009 (UTC)

As has been noted before, most of the items in this article are brief summaries of facts discussed in other, linked Wikipedia articles. The linked articles contain extensive references, which it is not always necessary to copy here. As with many list articles on Wikipedia, this one serves as an index into other articles. --FOo (talk) 18:26, 22 March 2009 (UTC)

It is never bad to source things. If the items are sourced in other articles, we should copy those sources into this article. Every article on Wikipedia should be able to stand on its own.--Father Goose (talk) 03:08, 23 March 2009 (UTC)

Uncited entries

Moving uncited entries to here. This may get unwieldy and need to be collapsed or moved to a subpage, but being bold to start. Let's either find citations that demonstrate these are common misconceptions or keep them out of mainspace.Bali ultimate (talk) 22:07, 22 March 2009 (UTC)

Please stop moving things here. This is counterproductive. Yes, some need referencing. By moving them here, however, you make that more difficult. Editors must now cut and paste these entries back into the mainspace, figuring out which category they fit in, rather than simply adding references. Further, the references that are in these entries are no longer clickable. Worst of all, some of these entries are perfectly well referenced, both for verifiability and as common misconceptions. By moving things here rather than adding fact tags, you are making the article worse and making extra pointless work for other people, same as plain vandalism. Go find a way to actually contribute. Rracecarr (talk) 18:18, 23 March 2009 (UTC)

I disagree. Do you really think bolding makes your arguments more persuasive? I am contributing by removing unsourced material without prejudice. I understand it's frustrating that establishing something is "commonly misconceived" is so difficult. The burden of providing references is on those wanting to insert people into the encyclopedia, not the other way around when citations do not establish the accuracy of the material.Bali ultimate (talk) 18:21, 23 March 2009 (UTC)

Bolding doesn't make the argument more persuasive, it makes it easier to spot, so that maybe someone who might mistakenly think that what you are doing is helpful or supported by others will be less likely to contribute to the damage. The way to deal with unsourced info is to TAG it. Give people some time to find refs. And certainly stop removing properly referenced material. Rracecarr (talk) 18:29, 23 March 2009 (UTC)

The best way to deal with unsourced info is to actually research and reference it. It's also the hardest way -- it involves doing actual work. But it's ultimately the only way the enyclopedia gets written.--Father Goose (talk) 03:36, 24 March 2009 (UTC)

I would like to suggest, Bali ultimate, that you take a different approach, namely putting two or three undersourced entries up for inspection at a time, and challenging us to perform some collaborative research on them. Ideally, you should join in on that research as well -- so far, you're not doing much more than proving that you know where the 'delete' button is. There is a point at which such behavior becomes disruptive.--Father Goose (talk) 23:45, 23 March 2009 (UTC)

And i reject your suggestion that I "do what you want." I think there's a point at which ignoring good sourcing, as you are doing, becomes disruptive. I have looked into these. You and I disagree. It's my assertion that insisting on original research to support inclusion in a vague, undefined category (common? now? in the past? Does the definition of commonality shift depending on whether it's physics or history as you appear to be arguing below? How is common defined? How recently most of it have been commonly held? Etc...)is an incorrect approach. No sources, no content. It's generally that simple. This thing has been here for years, and without someone like me it would never improve one iota. It woud just bloat, and bloat, and bloat, as it has been doing for a long time.Bali ultimate (talk) 00:38, 24 March 2009 (UTC)

You've looked into these -- as in, you researched them, and found them to be false (or not described as common)? If so, that's fine: that's what we'll ultimately have to do for every entry in the article. But at least one of the entries you removed, about cold-not-causing-colds, was so trivial to source, I get the sense you didn't research it at all.

I would like to see you add sourcing to any part of the article you think is worth keeping. You're not obliged to do so, but I'd like to see it. Research and writing is ultimately the only thing that makes Wikipedia an encyclopedia. If all anyone ever contributed was "deletions", Wikipedia wouldn't exist at all.--Father Goose (talk) 03:25, 24 March 2009 (UTC)

• When floating ice melts, it does not raise the water level (Archimedes' principle). However ice such as glaciers rests on rock, and is held above water: releasing it, or melting raises the level of the water that it is dropped in. The predicted threat of rising sea levels due to global warming is mainly due to the detachment or melting of inland ice, such as that on Greenland and the West Antarctic Ice Sheet in Antarctica, the melting of glaciers, and the thermal expansion of seawater. Melting of sea ice in the Arctic makes a tiny contribution, by lowering the global average salinity (and therefore the density) of seawater.
• The melting of Antarctic ice is not predicted to be the largest cause of rising sea levels in the near future. The partial melting of Antarctic ice is predicted to be only the fourth-largest potential contribution to sea level rise by the year 2100 (−170 to +20 mm), after thermal expansion of the world's oceans (+110 to +430 mm), melting glaciers (+10 to +230 mm), and melting Greenland ice (−20 to +90 mm).

• Koalas are not bears. Koalas belong to the marsupials infraclass of mammals, a separate lineage from the placental mammals of which bears (along with most mammals found outside of Australia and South America, such as rodents, primates, canines, etc.) are members.
• The Platypus is often heralded as the only egg-laying mammal. However, there are four species of Echidna, also of the order Monotremata, which also lay eggs.

• Throughout most traditions, the Bhagavad Gita is not equivalent to the Christian's Bible in level of scriptural authority. It is considered Smriti (that which is remembered) which is a class of scripture lower in rank than Shruti (what is heard), containing the Vedas. The Bhagavad Gita, though, is considered the most popular.
• Hinduism is considered a family of religions and as such has no concept of God universal to all astika sects. Hinduism is thus not strictly polytheistic across all sampradyas (traditions), but can be pantheistic or panentheistic, or be distinctly henotheistic or monotheistic.
• Hindus do not worship "300,000 gods". Someone arranged the various gods that were worshipped in his time in various parts of India, into 30 classes, using a Sanskrit word that means "a class" and also "ten thousand."

• The witch-cult hypothesis -- the notion that medieval witch-hunts were the suppression of an ancient pagan religion which had once been common throughout Europe -- is not considered well-supported by modern anthropologists and historians.
• Paganism is an umbrella term like Christianity - Lutherans, Catholics, and Protestants are all Christians just like Wiccans, Druids, and Shamans are all Pagans.
• Not all witches practice magick (spelled with a 'k' to distinguish it from stage magic). There are forms of witchcraft that are completely philosophical or religious that exclude any magickal practices.
• Plants do not metabolize carbon dioxide (CO₂) directly into oxygen (O₂). Light-dependent reactions capture the energy of light and consume water, producing high-energy molecules and releasing oxygen as a by-product. Light-independent reactions use the high-energy molecules to capture and chemically reduce carbon dioxide, producing carbohydrate precursors and water. See Photosynthesis.
• Christopher Columbus was not the first European to discover North America. The earliest physical evidence of European colonization comes from the Norse: Greenland was settled by Icelanders in 984 CE, and a Norse settlement was established at what is now L'Anse aux Meadows in Newfoundland ca. 1000 CE. Scholars are divided on whether Norse explorer Leif Ericson established the L'Anse aux Meadows settlement.
• The Spaniards did not conquer the Aztecs with a "hundred men and a handful of cannons". Although Cortes only brought with him (approximately) 400 soldiers, 100 sailors, and about 10-20 horses, the conquest of the Aztec was a complicated affair which included thousands of natives who allied themselves to Hernán Cortés and a smallpox outbreak.
• Sarah Palin never claimed to be able to see Russia from her house in Alaska, an attribution to Tina Fey's parody of Governor Palin. She said, in a September 11, 2008 interview with Charlie Gibson: "They're our next-door neighbors, and you can actually see Russia from land here in Alaska, from an island in Alaska." In a September 25, 2008 interview with Katie Couric she added: "It's very important when you consider even national security issues with Russia. As Putin rears his head and comes into the air space of the United States of America, where do they go? It's Alaska. It's just right over the border. It is from Alaska that we send those out to make sure that an eye is being kept on this very powerful nation, Russia, because they are right there, they are right next to our state." Two islands in the Bering Strait called Big Diomede, which sits in Russian territory, and Little Diomede, which is part of the United States are only separated by about two miles and can be seen from one another. The sea between them freezes in the winter.
• The trenches on the Western Front in World War I are often said to have stretched "from the frontier of Switzerland to the English Channel". The trenches reached the coast at the North Sea, not the English Channel. In fact much of the British war effort was a bloody but successful strategy to prevent the Germans reaching the Channel.}}

• In the United States, Police are not required by law to immediately give the Miranda warning when arresting a suspect, and the Miranda warning is not given only to suspects under arrest. Rather, according to the 1966 United States Supreme Court decision in the case of Miranda v. Arizona, a suspect in custody or in a custodial situation must be informed of these rights before being subject to interrogation. If the Miranda warning or similar warning is not read, incriminating statements made by the suspect while in custody are not admissible evidence in court.
• Another misconception is that opponents of official school prayer are largely atheists. Rather, the plaintiffs in many Establishment Clause cases have been members of a minority religion in that area, such as Jews in Engel v. Vitale 370 U.S. 421 (1962) or Catholics in a largely Baptist school district in Santa Fe Independent School Dist. v. Doe 530 U.S. 290 (2000).

• There is no reliable scientific evidence that installing security lighting in outdoor areas actually deters crime; it may actually make crime easier to conceal. For instance, a burglar who is forced to use a flashlight is more easily spotted than one who can see by existing light.
• Passive night vision devices do not actually illuminate an environment, rather enhancing the visibility of light reflecting off surfaces. Image enhancement night vision does not assist visibility in an environment with absolutely no visible light; thermal imaging would be required in this situation.
• The number of megapixels in a digital camera is not a sufficient measure of image quality. The skill of a photographer, the quality of the lens, and the number, size and compression of individual pixels all impact image quality. Most viewers hold contrast, color saturation, and color accuracy to be more important than resolution.
• Card counting in the game of blackjack does not allow the card counter to know specifically what cards are going to be dealt, and it does not guarantee positive returns to the card counter in the short term. Counting cards only allows the player to know that the remaining cards in decks will give the players an edge on the house in the up-coming hands (usually only a few percent), and so allowing the players to maximize the projected (not guaranteed) profits from this edge by betting larger amounts.
• It is a common misconception that the Scottish Tartan has always identified the clan of the wearer. Tartans were more commonly associated with a region, and it is only in modern times that the connection between a pattern and a clan came into being.
• The German crowd witnessing John F. Kennedy's speech in Berlin in 1963 did not mistake Ich bin ein Berliner to mean "I am a jelly doughnut." It is an incorrect American notion that he should have said "Ich bin Berliner" rather than "Ich bin ein Berliner". Different areas of Germany refer to a jelly doughnut as a Berliner.
• During World War II, King Christian X of Denmark did not thwart Nazi attempts to identify Jews by wearing a yellow star himself. Jews in Denmark were never forced to wear the Star of David. The Danish government did help most Jews flee the country before the end of the war.
• Adding salt to water does not make it boil faster; the salt elevates the boiling point of water above the 100 Celsius ( 212 Farenheit ) boiling point of pure water. Furthermore, adding a "pinch" of salt to a pot of water will make little measurable difference. But salt does make the pot of water boil faster through a process called nucleation where the surface of the salt provides a place where bubbles can form.
• Kosher food is not food that has been blessed by a rabbi. It is any food that is not prohibited in the Biblical laws, meets the requirements for slaughter enumerated in the Mishnah (in the case of meat), and is prepared and served in accordance with Jewish law. For kosher certification to be approved, a rabbi or other religious Jew who is well-versed in Jewish law (called a mashgiach) serves as a production supervisor. Jews make individual blessings over the food they eat; there is no blessing said by a rabbi or layman that would make a food kosher.
• Former UK prime minister Tony Blair never said that he remembered sitting behind the goal at St James Park watching Jackie Milburn play for Newcastle United. As Milburn retired from football when Blair was four years old and seating was not introduced until the 1990s it was suggested that he lied about it, in an interview in December 1997 with BBC Radio 5 Live, to boost his working class credentials; however he was misquoted, saying his time as a supporter came just after Milburn.
• UK prime minister Gordon Brown never claimed to be a fan of the Arctic Monkeys nor that he wakes up to them. He did say that if they were playing on the radio it would certainly wake him up.
• Peter Mandelson never mistook mushy peas for guacamole. The mistake was made by a young American researcher working for the then Labour leader Neil Kinnock who mischievously attributed the mistake to his colleague Mandelson.
• Modern spacecraft returning from space do not suffer a communications blackout. While the heated atmosphere in front of the spacecraft prevents direct communication with Earth, and in the early days of the space programs of the world indeed meant that no communication was possible during reentry, systems like the Tracking and Data Relay Satellite System have removed this problem.
• French fries (or French fried potatoes) did not originate in France. The term comes from frying potatoes in the French method (frire, meaning "to deep fry"). French fries were invented in Belgium.
• In the book of Genesis, the serpent in the Garden of Eden is not explicitly identified as being Satan. This is teaching made by later Christians.
• The belief that gunpowder, even though it was a Chinese invention, was first used for war by the Europeans is a misconception. The Chinese used flamethrowers and gunpowder arrows for military purposes from the 900s CE onward.

I found a book which even has a searchable page on Google with the fact mentioned about WW1

WW1 now has a citation I added for it, proving the common misconception. Googling will result in many other cases of that myth, it not just found in one book. I went ahead and deleted the second citation needed, because honestly now, if you don't believe the British trench warfare stopped the Germans from getting to the English Channel in World War 1, you have only to look it up in a damn history book. If someone mentioned that the allies won World War 2, or that the Americans had been the ones to drop a nuclear bomb on the Japanese, then you wouldn't tag it for a reference. Every single sentence ever written does not need a reference. Dream Focus 10:18, 23 March 2009 (UTC)

No, that citation falls far short of proving "common misconception". These days, i doubt most people have any strong sense, accurate or inaccurate, about the extent of the trenches. You or my opinions don't matter; specific reliable (and multiple, in the case of this list according to the criteria) need to demonstrate it's a "Common" misconception. This does not appear to be established yet.

Nope. I read that page. Nothing was said to support that this is a "common misconception." Said something about the front stretching from the channel to switzerland (and didnt' say this was wrong). The front and the trenches are different things. Snipped the entry up above.Bali ultimate (talk) 14:53, 23 March 2009 (UTC)

Are these valid for proof that something is a common misconception?

Are the following valid references to prove something is a common misconception?

• Googling the myth in quotations reveals that thousands of people mentioned it, and thus it is common.
• Sites like http://www.snopes.com/ that disprove common myths, list it.
• The television show Mythbusters disproved it.
• Outdated textbooks that showed the incorrect information to millions of school children every year, for the years they were in use.

Dream Focus 10:23, 23 March 2009 (UTC)

No. That's all original research and none of it provides backing for "common misconception". Thousands of people "mentioned" it on google? Were they wondering if something might be true? Were they doubtful that it was true, but wanted to make sure? Does thousands make something a "common misconception." Etc... Mythbusters or snopes disproving something does not say anything about the commonality of a notion (any more than proving that odd jobs hat doesn't work doesn't suggest that most people believe that it would). Snopes "disproves" many things that only a few people believe. Outdated textbooks are also of no use for "common misconception." Every scientific text book from the 19th century will be wrong on many crucial points. But these "misconceptions" have been changed by research and time; no one holds them NOW. Are we to include every mistaken belief ever once held by humanity? Of course not.Bali ultimate (talk) 13:05, 23 March 2009 (UTC)

By the criteria we've adopted, more than one source should identify something specifically as a common misconception (or words to that effect) for it to belong on this list. It won't be enough to provide sources identifying something as a misconception and a bunch of other sources containing said misconception. If it really is a common misconception, there should be a source available that describes it as exactly that. (And hopefully multiple sources that say as much.) Those sources might include Mythbusters or snopes, but only if they actually describe it as commonly-gotten-wrong -- they investigate a lot of uncommon misconceptions (and truths) as well.--Father Goose (talk) 23:25, 23 March 2009 (UTC)

Unfortunately Google results never count, according to general Wikipedia consensus. This is one of the few cases where I think it would be justified. Snopes.com and Mythbusters seem to be of unusually high quality as far as misconception collecting sources go. I think it shouldn't make a big difference whether they say explicitly that something is a common misconception or not, but that's how it is currently handled. Personally I would accept a bit of original research for establishing this, but think we should only include implausible claims about misconceptions held when they come from a very reliable (e.g. scholarly) source.

I cannot think of a better proof that a misconception is common than its appearance in widely circulated school books. Even if the rules for this page say otherwise, that would be a case for WP:COMMON. --Hans Adler (talk) 22:47, 29 March 2009 (UTC)

Is the chromosome one, the common misconception about humans and aliens breeding together?

I know a lot of people used to say how stupid it was that in science fiction humans and aliens were somehow able to breed together, do to the chromosomes. They'd often mention that the chromosomes of chimpanzees are very close to humans, and yet the two can't breed. Was that where this misconception came from, or was there something else? We know now that any species advance enough to cross solar systems to get here, would surely have holographic video games, cow mutilation equipment(if that fad is still in style among alien pranksters), and of course, a way to alter genes to genetically engineer a hybrid species, most likely to play holographic video games with them(someone alien enough to relate to the games they play, but not 100% pure alien, so they'd have an easier time beating them, of course). Dream Focus 10:38, 23 March 2009 (UTC)

This doesn't seem to address sourcing for "common misconceptoin." Most people probably don't really know what a chromosome is, so i'm having trouble beleiving they have a lot of false beliefs about them based on speculation in science fiction.Bali ultimate (talk) 13:07, 23 March 2009 (UTC)

herbal tea is confirmed by looking at ingredients, isn't it?

• All true teas, including black, green, and white teas, come from the Camellia sinensis plant. Herbal "teas", such as those made from chamomile, peppermint, or rooibos, usually contain no tea.[citation needed]

I don't know what the most popular brands of herbal tea are, but their ingredients are surely found online, and would confirm what they do or do not have in them. Would linking to a commercial site listing the ingredients be an acceptable reference? Dream Focus 10:48, 23 March 2009 (UTC)

No. You need to show that there is a common misconception that herbal 'teas' contain tea. pablo_hablo. 11:02, 23 March 2009 (UTC)

It has the word tea in it, so people would probably be confused. Most would expect something with "tea" in the title, to actually be "tea". Dream Focus 11:36, 23 March 2009 (UTC)

I don't think that you can make any assumption about what "most people" would expect. Ever eaten a hot dog? What percentage of dog did it contain? What about toad in the hole? Including an item on this list is effectively an assertion that the item is a common misconception, and that needs referencing. pablo_hablo. 11:56, 23 March 2009 (UTC)

Then why do we distinguish between "tea" and "herbal tea." Seems clear to me that most people know there's a difference. The inclusion of the tea will require multiple reliable sources calling it a "commonm misconception" or words to that effect.Bali ultimate (talk) 13:09, 23 March 2009 (UTC)

Radiometers and bats

I'll allow the bat to stay (though i think that "some" people mistakenly believe some idiocy doesn't make it common). As the radiometer, there is no establishment in the refs provided at all that it's commonly misunderstood. There is no common understanding, correct or otherwise, about "Crooke's Radiometers." Fewer than 1 people in 100 could identify what it is, let alone the correct physics on how it works. Absent refs establishing that there is a "Common misconception" on the radiometer (and I'm giving wide latitude -- i.e. the bats), i'll remove it againBali ultimate (talk) 18:18, 23 March 2009 (UTC)

Got a ref to support the claim that fewer than 1 in 100 could identify it? Even if you do, if a significant portion of those believe in an incorrect explanation, it's still a common misconception. The ref says: "To understand why these common explanations are wrong..." My Crooke's radiometer, that I got when I was 10, has an incorrect explanation on the box. The referenced article also points out the the Encyclopedia Britannica gets it wrong. Leave it in. Rracecarr (talk) 18:25, 23 March 2009 (UTC)

No i don't. But do you have a ref that supports there are "common misconceptions" about crooke's radiometers? I mentioned my opinion (do you really think it's unlikely that the vast majority of people have never heard of them) as support for the fact that the removal of this unsourced information wasn't frivulous (far different from, say, demanding a cite for "most people think the sky is blue"). Again, neither your nor my opinion matters of course. Nor does the fact that your radiometer received when you were ten had incorrect information on the box (i'm assuming that was long ago, to boot). This is not a list of Scientific beliefs later proven to be incorrect but a list of what is "commonly misconceived" today. I suspect an RFC is our next stop.Bali ultimate (talk) 18:29, 23 March 2009 (UTC)

For the third, time **Y E S** there is a reference for this being a common misconception. It was already there when you hacked the entry, and I finally cut and pasted some text from it above. Rracecarr (talk) 19:06, 23 March 2009 (UTC)

First -- don't say i've "hacked" the article. You're verging into personal attacks. Second, lets break this one down. These two refer to "competing theories" but not "common misconceptions." This one talks about the history of mistaken theories about why it works, up to the current presumed (of course, future research may lead to tweaking the theory again) correct theory. This one says nothing about "common misconceptions." This one from britannica, apparently, , I couldn't get to open. I'll take your word that it outlines a theory that is incorrect. Doesn't sound like it establishes "common misconception" and i'm sure it will be corrected in britanicca as the next update catches up with current science. So, these references all appear useless to me in determining what is or is not a common conception, incorrect or otherwise, about the Crookes radiometer. Reliable sources are not addressing this as provided.Bali ultimate (talk) 19:19, 23 March 2009 (UTC)

The ref I refer to is this one, which you perhaps overlooked. You accusing me of personal attacks is completely laughable, considering your recent edits to your user page. Rracecarr (talk) 19:34, 23 March 2009 (UTC)

No, an explanation why theories from the distant past (and were common at those times) have in fact been demonstrated by modern science to be wrong (and in a paper from 12-13 years ago) does not establish a "common misconception." Is he explaining why theories, in a past less informed age, were wrong? Yes. But once more, that does not establish that this is a common and current misconception (if we don't take current into account, this list could be filed with explanations of why phlogiston was wrong, why the humours theory of illness were wrong, while homeopathic magic in general doesn't work, why you can't make a basilisk out of a pile of rooster dung, etc...).Bali ultimate (talk) 19:38, 23 March 2009 (UTC)

Baez: "To understand why these common explanations are wrong..." Physics Begins with Another M--: "The "myths" [section] clears up misconceptions about physics that occur in everyday language." (The "radiation pressure" explanation is given as "Myth #5" in that section.) Instruments of Science describes the "expanding gas" explanation as "usually given to students today". And the Wolfram Demonstrations site says "A number of other defective explanations, which we will not enumerate here, have been popular through the years."

What this amounts to is multiple reliable sources pointing out that there are several common misconceptions about the Crookes Radiometer. The entry now outlines the two that are specifically singled out by the aforementioned sources as common and wrong. I'm hewing to the rule I suggested about needing multiple sources that identify something as a common misconception. (I hope you will not split hairs and insist on seeing those exact two words.) I'm not slapping on sources and claiming "common misconception" according to some personal notion: I'm sticking to exactly what the sources say.

In addition to the sources that specifically identify various explanations as common misconceptions, I used several sources as references for the "correct" explanations provided -- the Scandurra paper, the description of thermal creep, etc. I also provided a link to the actual Britannica article identified by one of the sources as containing a common misconception. These sources are sources for the correct explanations within the article, serving a different role from the sources that specifically call various explanations common and wrong. Okay? So don't jerk me around. I'm here to help fix this article according to standards I believe we both agree upon. Doing this work is time-consuming, and if I'm going to have you second-guessing and nit-picking everything I do (and I am a very careful writer and researcher when it comes to these things), I'm going to have to ask you to fucking stop. I don't need to be dealing with somebody who's in a judgmental and contrarian state of mind. Work with me to improve this article, or go away.

As I have not researched the bats entry yet, I cannot offer an informed opinion about whether or not it belongs.--Father Goose (talk) 23:08, 23 March 2009 (UTC)

Once again a paper from 12 years ago about misconceptions in the past, when science was less advanced, does not establish a current "common misconception." So you can ask me to "fucking stop" and tell me to "go away" all you want. Your original research and claims are not persuasive to me. I am working to improve this article -- you seek to define my refusal to do what you want as not working to help and call me "contrarian and judgemental." But name calling doesn't make it so. I am in fact demanding iron clad sourcing for rather extraordinary claims (in this instance that anything is "commonly" believed about the physics behind Crookes Radiometers). A discussion of what drives them is well placed in that mechanisms article, as is the evolution of current scientific explanations for what drives them. Absent specific, excellent sourcing that this is a "common misconception" it should go -- and "information" without such sourcing degrades the encyclopedia.Bali ultimate (talk) 23:17, 23 March 2009 (UTC)

And look at this garbage that's just accreted here [9]. Do either of you two agree that an egg can only be balanced on end one day a year is commonly held?Bali ultimate (talk) 23:20, 23 March 2009 (UTC)

I had never heard of that one myself, but snopes seems to indicate that it is somewhat common.Rracecarr (talk) 00:42, 24 March 2009 (UTC)

I've heard it, many times. We still need to improve the sourcing, but I have cause to believe such sourcing will be found.--Father Goose (talk) 03:09, 24 March 2009 (UTC)

Friends of mine who own chickens said they performed that feat last Friday (first day of spring), so yes, it is common (though it still needs sourcing, I suppose).—Jchthys 14:03, 24 March 2009 (UTC)

If I may interject:

Rracecarr and Father Goose have the right idea. A common misconception a dozen years ago is still a common misconception - especially because the people who learned those misconceptions are still around, and haven't been exposed to updates. In this way, a misconception is like a meme; even if current knowledge about how a radiometer works differs from knowledge of a decade ago, people with the older knowledge still spread it around.

This is one of those things that may be transitioning away from the "common" attribute, but right now I'd say it qualifies. ~Amatulić (talk) 23:33, 23 March 2009 (UTC)

It may be not-so-common in the sense that Crookes radiometers are not terribly common in the first place. Nonetheless, I owned one as a kid, and the explanation I received was the incomplete "gas expansion on the black side" one. I am obviously not making the claim that my personal experience is proof of anything. I am however making the claim that -- per the criterion I believe we agreed upon -- multiple sources claim that the "radiation pressure" and "expanding gas" explanations are common (and wrong), meaning the entry passes the threshold of inclusion for this article. I almost get the sense that Bali is arguing that it doesn't belong here because of his personal judgment that Crookes radiometers are some obscure thing. If that's the case, he would be the one engaging in original research. If he were willing to stick to the sources, I think we could end our disagreement over this entry.--Father Goose (talk) 03:09, 24 March 2009 (UTC)

Einstein/God entry

This is a problematic entry. Researching it, from what I can tell, he was neither religious nor an atheist, though that doesn't necessarily make him a deist either. The best we could do is factually describe "what other people think Einstein thought", though that still wouldn't be a factual statement about Einstein's beliefs proper. Probably best to remove it.--Father Goose (talk) 03:53, 24 March 2009 (UTC)

I basically rescued all the entries deleted outright by Pablomismo, because it was clear he made no effort to check on their validity, and I did not want possibly valuable entries to be lost too far back in the history. I decided, subjectively, which entries looked plausible and which looked dubious, and I restored the former (including Einstein) to the article, and moved the latter to talk. I have not researched the Einstein question, and it is quite possible the entry does not belong. I restored everything to avoid throwing the baby out with the bathwater.

This is anecdotal, but I have certainly heard Einstein quotes such as "God does not play dice" used as 'proof' that maybe the most famous scientist ever believed in God, which is at least a misuse of his words, if not a misconception. Rracecarr (talk) 15:02, 24 March 2009 (UTC)

Of course I attempted to check that these were "common misconceptions", and I can't see why you would assume otherwise. I removed them when I was unable to find sources. I stopped when I saw that another user was moving contentious material to the talk page, which struck me as a better way of trimming down the page to some entries which could be shown to be common misconceptions. pablo_hablo. 17:09, 24 March 2009 (UTC)

You either didn't try very hard at all, or you are not very good at finding references, or you are applying an unreasonably high standard. The William Henry Harrison entry, or the Columbus/flat Earth entry are both easy to source, for example. Rracecarr (talk) 18:25, 24 March 2009 (UTC)

Just the normal standard - if it's unreasonably high for this article then so be it. pablo_hablo. 20:23, 24 March 2009 (UTC)

I'm not criticizing the restoration, or even the removal, of any entries in general: I'm just examining this one about Einstein's beliefs. We can't simply say that he did believe in God or that he didn't; the entry makes the cramped claim that he didn't believe in a "personal God" -- but what does that mean, really, and what misconception does it dispel? It isn't precisely a cut-and-dried fact in the first place. His beliefs are the topic of much debate. Therefore, I think it doesn't belong on a "common misconceptions" page. We should limit ourselves to "common misconceptions" where there's an uncontroversially correct explanation.

In light of that, should we retain this entry?--Father Goose (talk) 01:49, 25 March 2009 (UTC)

I don't think so. As you say, Einstein's religious beliefs are debatable, and this together with the fact that there is no common conception about them makes this a spectacularly bad candidate for this list. pablo_hablo. 06:15, 25 March 2009 (UTC)

I don't understand the argument that we can't say he didn't believe in a personal God. Of course, the ultimate source on that is the man himself, and here is a direct quote: "It was, of course, a lie what you read about my religious convictions, a lie which is being systematically repeated. I do not believe in a personal God and I have never denied this but have expressed it clearly." (italics added). As far as I can see, this quote alone establishes the truth of the entry, and even goes part way to establishing it as a common misconception. To be clear, I'm not crazy about the entry myself, but I don't think it's the worst on the list. Rracecarr (talk) 14:10, 25 March 2009 (UTC)

We could say "Einstein did not believe in a personal God", but is that the misconception? We have to find sources that make it clear just what the actual "popular misconception" is about Einstein.--Father Goose (talk) 22:31, 25 March 2009 (UTC)

Dubious

• There is no source given for the claim that gunpowder being a European invention is a common misconception. In Germany it is one of the standard examples (together with porcelain and many other, less standard examples) that are mentioned frequently in connection with the generally accepted wisdom that "most" (possibly a common misconception?) inventions were made in China first. --Hans Adler (talk) 11:10, 24 March 2009 (UTC)

• I can't find a way to tag a statement that is made only implicitly, by saying true things in a context which suggests that anybody doesn't know them. But who, I ask, other than perhaps small children, really believes that chamomile or peppermint infusion contain anything of the tea plant? In German and perhaps some other languages, "tea" has become a generic word for infusions. Perhaps someone has take this as an indication that Germans believe chamomile infusion is tea in the English sense of the word? For roiboos it seems to be only slightly less outrageous. --Hans Adler (talk) 11:20, 24 March 2009 (UTC)

• I don't think "common misconception" comes even close to being a good term for a belief in the bizarre connection between eggs and the first day of spring. --Hans Adler (talk) 11:29, 24 March 2009 (UTC)

• The bit about sparkling wine and teaspoons is reasonable, so I don't want to tag it just because I can't check whether the book it is sourced to bases this on a scientific test or merely on authority. However, I remember reading somewhere that this is actually true in case of a metal spoon which is partially immersed in the wine, because the metal conducts heat and makes the wine reach the fridge temperature earlier. I don't know how plausible that is, and I can't find my source right now, but perhaps somebody is interested in pursuing this. --Hans Adler (talk) 11:46, 24 March 2009 (UTC)

• The bit about mirrors supposedly not inverting left and right is pedantic hair-splitting unworthy of an encyclopedia. --Hans Adler (talk) 11:48, 24 March 2009 (UTC)

• I can see nothing close to a common misconception in the passage about Mount Everest. --Hans Adler (talk) 11:51, 24 March 2009 (UTC)

• In common parlance, "desert" means "dry desert", in the sense of no water being present. Areas covered by ice obviously need not apply. Therefore the Sahara being the largest desert is not a misconception but merely an example of scientific terminology being inconsistent with the plain sense of the words it borrows from normal language. --Hans Adler (talk) 11:55, 24 March 2009 (UTC)

• .tv is, of course, a de facto domain for TV-related websites, so it's hard to see where the supposed misconception comes in. --Hans Adler (talk) 12:04, 24 March 2009 (UTC)

• Toilet waste dumped overboard in an aircraft? Really? Who believes that? --Hans Adler (talk) 12:04, 24 March 2009 (UTC)

Quite a few people actually. I used to work for an airline and it's something people do bring up from time to time. I've also heard it brought up in complaints from people living near airports. To someone in the know, it sounds ridiculous, but that's what this article is for. I've restored the entry. Rpvdk (talk) 14:48, 30 March 2009 (UTC)

These guys are arguing up above that there are "common" beliefs about "crookes radiometers," misconceived or not, and will breach the removal of almost any of this unsourced, original research. It's a thorny problem to be sure. I agree and endorse yoru analysis of the entries you've just summarized.Bali ultimate (talk) 14:38, 24 March 2009 (UTC)

I agree that the Everest entry doesn't correct a misconception. People think it's the tallest mountain, and by the most common definition, it is. It seems more like "people don't realize there are other possible ways to define the height of a mountain" which is not really a misconception. Rracecarr (talk) 15:15, 24 March 2009 (UTC)

Eggs

I removed the following nonsense, and Father Goose added it again:

It is true that you can balance an egg on its end on the vernal equinox (the first day of spring); however, you can also accomplish this delicate feat on any other day.

OK, my edit summary calling this a "hoax" was misleading. But the two references given do not support the idea that this is a common misconception. One source says it is a "quaint superstitious belief, most often attributed to the Chinese". In other words: People like to claim that somebody, somewhere remote, believes in this. The other source says: "This has to be one of the silliest misconceptions around, and it never seems to die. Every year, without fail, some TV station broadcasts a news segment showing local schoolchildren standing eggs on end on the first day of spring." In other words, the source really claims only that some TV programmes try to spread this myth. There is no evidence that they are successful, and it seems very unlikely.

The extraordinary claim that this is a common misconception requires extraordinary proof, which has not been presented. --Hans Adler (talk) 23:50, 25 March 2009 (UTC)

Done. ("The rage spread across the Western world"; "One reason this myth is so popular".) But please, man, do a bit of research before you remove any more entries. You should be as skeptical of your own state of knowledge as you are toward the entries in this list.--Father Goose (talk) 00:47, 26 March 2009 (UTC)

I wrote this after you told me "C'mon, do some research", and I explained exactly why your sources don't prove what you think they prove. The principle that extraordinary claims require extraordinary proof is fairly well established on Wikipedia. The claim that anyone actually believes that nonsense (as opposed to people claiming it on TV, or writers of silly "popular misconceptions" compilations including it for completeness and entertainment value) surely is extraordinary. --Hans Adler (talk) 00:54, 26 March 2009 (UTC)

It doesn't seem extraordinary to me. Do you really think that the people who make these claims on TV and in books are deliberately lying, or that their viewers aren't fooled? Those would seem to be incompatible beliefs; even if there was a benefit to deliberately lying (increased book sales, say) it would only work if people believed the lie. The egg-balancing claim seems preposterous to you and me because it doesn't make sense that there would be a sudden discrete change in egg-balancing behavior with a duration of one day. But most people don't understand that. Look at the similar claim that the Coriolis force controls the direction water drains in a tub. A guy in Kenya has a rigged demonstration where he walks a few feet across the supposed location of the equator and shows the water draining in opposite directions. Even if you knew nothing about the Coriolis effect you ought to see that it's not going to change discontinuously across some precise dividing line on an object the size of the Earth. Yet Michael Palin was suckered by this, as was anyone at the BBC who vetted his program. Huge numbers of people believe the most ridiculous things. I don't think that's an extraordinary claim. -- BenRG (talk) 14:15, 26 March 2009 (UTC)

Claiming that you believe in the egg nonsense although actually you don't is no different from claiming you hold religious beliefs that you actually don't. This is very widespread behaviour, as you can observe in the large number of nominal Christians who go to church once or twice a year and have their children baptised, although they have only very fuzzy, if any, religious beliefs. It simply doesn't occur to the people in question that you could refer to a misrepresentation about their state of mind on such an irrelevant topic (egg balancing or religion) as "lying". Only when you make it very clear that you are not asking in an entertainment (for eggs) or ceremonial (for religion) context but that you genuinely want to know what they believe will they give you the true answer. But if you merely interview them after a show, or ask them to say the credo in church, they will make sure not to spoil your game. I am sure sociologists and ethnologists already have a rich literature about how such pretended beliefs contribute to a group identity or whatever the purpose they serve. --Hans Adler (talk) 16:20, 29 March 2009 (UTC)

That the egg idiocy is "commonly believed" is not established by these sources and is in fact laughable on its face. The sources just aren't there (the fact that people like to play a pleasant little game once a year is no more evidence of this then a claim that "the belief stepping on a crack will break your mothers back is, in fact, false. Scientific research shows that rates of back-cracking among mothers are the same for both cohorts of crack-steppers, and those who are diligent in enver stepping on cracks).Bali ultimate (talk) 22:42, 29 March 2009 (UTC)

How to mark inclusion of an entry as disputed?

I cannot find a specific template for this. Since entries on this list do not have a heading and most do not state explicitly that what they describe is a common misconception, there is no place to put a "fact" or "dubious" tag. It's very frustrating when removal of obviously bogus information is reverted and you can't even tag it to draw other editors' attention to the problem. --Hans Adler (talk) 00:01, 26 March 2009 (UTC)

If you're questioning that the entry as a whole is a "common misconception" add either {{cn}} or {{dubious}} to the end, and better still, raise your doubts on the talk page. Or research it yourself, and tell us what you found (or didn't find).--Father Goose (talk) 00:55, 26 March 2009 (UTC)

The problem is that these tags are normally used only to tag the statements which they follow. In the case of this list often the statements are OK, but they shouldn't be on the list. You are not addressing this problem. --Hans Adler (talk) 01:55, 26 March 2009 (UTC)

Others have started addressing the problem by adding explicit statements of the type "this is a common misconception" so that they can tag them. This is certainly an option, but it feels a bit strange to add a statement that you feel is wrong merely so that you can tag it. --Hans Adler (talk) 12:37, 27 March 2009 (UTC)

Herbal tea

I removed the following entry, and Father Goose reinstated it:

All true teas, including black, green, and white teas, come from the Camellia sinensis plant. Herbal "teas", such as those made from chamomile, peppermint, or rooibos, usually contain no tea.

Like the entry claiming that the Sahara being the greatest desert is a misconception, this seems to be another instance of the popular misconception that words have a unique meaning, and that subject experts control this meaning. Another example for such a misconception is all the nonsense (not yet on this page) surrounding the natural language word "weight", the word used for it in physics ("mass"), and the different but related concept in physics which unfortunately is called "weight" as well.

Since so many get this wrong, a few people claiming that this is a misconception is not convincing at all. After all, they are obviously wrong. It is a matter of our editorial discretion that we need not and should not repeat incorrect claims merely because they can be sourced.

The following is from the Oxford English Dictionary:

Tea ... 5. Used as a general name for infusions made in the same way as tea (sense 2), usually from the leaves, blossoms, or other parts of plants; mostly used medicinally, sometimes as ordinary drinks.

The first source given for this usage is from 1665/1666.

An encyclopedia article about common misconceptions that perpetuates common misconceptions is a disgrace. --Hans Adler (talk) 00:14, 26 March 2009 (UTC)

In case I wasn't clear enough: There is no evidence that people using the word in this way do anything but abbreviate herbal tea to "tea". If we leave this in without much better evidence for a belief that there are tea leaves in herbal teas, I will feel justified to propose the following entry:

Although human feces are also called "stool", their only relation to chairs is via stool-shaped toilets, which were once popular.

--Hans Adler (talk) 00:48, 26 March 2009 (UTC)

I am obviously not the only who thinks this is silly. See #herbal tea is confirmed by looking at ingredients, isn't it? above. --Hans Adler (talk) 00:58, 26 March 2009 (UTC)

I believe we have agreed that the right way to keep this list focused and factual is to insist that all entries have sources, and even to insist that all entries have multiple sources specifically identifying the "misconception" as "common" (or words to that effect). Insisting on rigorous sourcing is a Good Thing. But it goes both ways -- and this is also a Good Thing: you can't say I believe this is untrue, if you're contradicting what the sources say, any more than you can say I believe this is true without providing sources to back it up. If you can provide sources that themselves claim that something normally held to be a "common misconception" is itself a misconception, then we can shoot the entry down (or maybe even document the misconception-within-a-misconception).--Father Goose (talk) 01:46, 26 March 2009 (UTC)

It's perfectly normal on Wikipedia that we discount sources as unreliable, or as unreliable for a specific purpose, or even for a specific statement. One reason to do so is if the statement for which the source serves is verifiably wrong. In this case the claim that it is a "misconception" (common or not) is contradicted by the Oxford English Dictionary, which is clearly more reliable than random websites of tea enthusiasts and the like. Of course OED doesn't say that the claim that the "misconception" is not one; we need to use our brains to see this. This arguably disqualifies OED as a source for saying that it is not a misconception. But it's still perfectly OK as a strong reason to remove this entry. It's a popular misconception that questionable factoids cannot be removed from a Wikipedia article merely because they are backed by a technically reliable source.

There are thousands of misconceptions that could be on this list; it will never contain all of them. Why are you wikilawyering to keep a questionable one on it? --Hans Adler (talk) 02:06, 26 March 2009 (UTC)

You've deflated the OED argument yourself, so I won't go into that. You are right that just because something is sourced doesn't mean we have to include it on Wikipedia. But once we open the door to "I think this isn't a popular misconception, regardless of what the sources say", we open the door to huge, unresolvable fights over individual entries based on personal taste. And knowing how some people are, it's going to be over almost every. Single. Fucking. Entry. Let's avoid that, please. We've agreed to a pretty stringent objective standard for inclusion. Let's stick to it to inform us both what belongs on the list and what doesn't.

I don't think the list is going to get as bloated as you seem to fear. It's been around for five and a half years and it's still only a bit above 100 entries. It'll probably drop lower still as we cross-examine each entry against the new rigorous sourcing requirement. Positively stupid entries like "chairs are not poop" will never meet the sourcing standard and will not appear on the list. But if it does ever get up to 200 or 300 entries, we'll split it into List of common misconceptions about science, List of common misconceptions about religion, List of common misconceptions about history, and so on.

Letting the sources dictate both what gets removed from and what gets included on this list is the path of least drama for everyone concerned. Okay? Please?--Father Goose (talk) 07:22, 26 March 2009 (UTC)

No, that's not OK because the sources used for this list tend to be sub-standard. How can you argue for including something if it's painfully obvious that it's not even a misconception? "Chamomile infusion is a kind of tea." The only thing that is wrong about this sentence is the claim that "tea" can only mean "tea (OED definition #1)", but never "tea (OED definition #5)". --Hans Adler (talk) 12:35, 26 March 2009 (UTC)

Incidentally, thank you for rewriting and sourcing the "snow words" entry. I'm getting a little ticked off by people who are just here to pass judgment on the article and give it a death by 1000 cuts. I'm encouraged when others pitch in with the work that's needed to actually build it up into a good article.--Father Goose (talk) 07:47, 26 March 2009 (UTC)

I can understand that you are angry about people attacking the list by different means after the AfD failed. I argued for deletion because I think such a list has no place in an encyclopedia. I must and do accept, for the moment, that there was no consensus for deletion (the closing statement "keep" by the admin was clearly wrong IMO). One of my reasons for deleting this list (this one obviously not policy-based) was that it is a cruft-magnet. And this is exactly what I am addressing. The misconceptions about snow words, or "Allah" referring only to the Muslim god, are unquestionably common and worth debunking. But the list loses a lot of its value if such serious entries are mixed with "misconceptions" that are only repeated because of their entertainment value, and others which far from being misconceptions are actually true. We all like to think that others are wrong about something, that's why there are so many sloppy books about popular misconceptions. But an encyclopedia is not the place to be sloppy. If you want that, you should really consider using a different site such as WikiBooks, where fishy misconceptions are much less likely to be deleted. If you start a WikiBook with the collection from this list, you can even get it linked with a nice big template from misconception (and of course from this list, but I am fairly sure it's not going to survive in the long run). --Hans Adler (talk) 12:35, 26 March 2009 (UTC)

I agree that the distinction between "Tea" and "Herbal Tea" is well understood and not commonly misunderstood (after all, they have distinctive names even). That tea is used as a catch-all term for infusions is not a misconception. IT was just readded -- along with an odd claim about sushi [10]; I think the japanese and the asian cultures that have close contact with them, at least, are well aware of the difference.Bali ultimate (talk) 14:24, 26 March 2009 (UTC)

Sushi

I don't know about the tea. But the sushi entry is a common misconception. Did you even do a cursory search? Obviously not. Google "sushi fish misconception". There are THOUSANDS of references. What is your problem?? Rracecarr (talk) 14:26, 26 March 2009 (UTC)

My problem is that if a few people in America or the UK don't speak and fully understand japanese, that is not sufficient to determine "common misconception." NO ONE in japan misunderstands the distinction between the two. And what does sushi mean anyways? -- "Usually raw, but sometimes cooked, fish on top of rice." That the ill-informed generally think of raw fish when thinking of suchi is largely correct.Bali ultimate (talk) 14:30, 26 March 2009 (UTC)

You have just readded tea and sushi rracecarr. That (depending on how you count it) has you at 3rr or perhaps at 4rr (since the first revert was actually to undo the removal of sushi by me, and the removal of tea by someone else. Just letting you know.Bali ultimate (talk) 14:33, 26 March 2009 (UTC)

And rracecar, calling me a vandal [11] is innapropriate and I ask you to desist. Focus on the content, and drop the ad hominems against me (or anyone else who might not agree with you). Bali ultimate (talk) 14:38, 26 March 2009 (UTC)

This is ridiculous. How can you possibly think that because people in Japan know what sushi is, it follows that there can't be a misconception about it in other parts of the world? And I am not at 3rr. 1 edit cannot count as 2 reverts (anyway your claim in that regard is false--it was 1 "undo" reverting an edit by you in which you deleted two entries). Further, 2 consecutive edits that could have been accomplished at once do not count as 2 reverts. And stuff it with the personal attack complaints until you take down the ones on your user page. Rracecarr (talk) 14:41, 26 March 2009 (UTC)

What is the working definition of "common" as applied to "misconceived?" I lived in southeast and north asia for many years. Quite a few people live in that area. I would hazard a guess that very, very few do not understand the difference between sushi and sashimi. I am perfectly willing to accept that some americans, for instance, do not fully understand this difference. I assert 1. that is insufficient to make something "common." 2. A failure to fully grasp the meaning of a word in a foreign tongue, while being in the right ball park, isn't a a misconception.Bali ultimate (talk) 14:53, 26 March 2009 (UTC)

Many Americans, at least, think that if it ain't raw fish, it ain't sushi. That's a misconception. There are plenty of sources on the web describing it as a common misconception. Incidentally, your definition "Usually raw, but sometimes cooked fish on top of rice" is incomplete. There need not be fish at all. Rracecarr (talk) 15:00, 26 March 2009 (UTC)

AFAIK sushi refers to the preparation and type of rice(vinegared), I think for each of the misconceptions we will be able to pick out a subpopulation for whom it is not a common misconception, I can tell you from anecdotal evidence that many Thais have no idea that sushi is not raw fish. Unomi (talk) 05:52, 27 March 2009 (UTC)

• In America, we call raw fish sushi. Do they label things in the stores in this country "sushi" which is anything other than raw fish? Ketchup in America always means tomato ketchup, while the word ketchup in other nations can mean any of a variety of things. Words have different meanings in different nations. Dream Focus 12:28, 27 March 2009 (UTC)

Personally I am not concerned about this entry. Obviously the raw fish is the most interesting feature of sushi for Western people. Therefore a semantic split of the English word "sushi" cbetween the original meaning and the raw fish meaning is an inevitable, natural process. It seems that the raw fish meaning hasn't reached the dictionaries yet, and therefore the entry seems to be correct, albeit slightly pedantic. --Hans Adler (talk) 12:33, 27 March 2009 (UTC)

Mirrors

I removed the following entry from the article, and Father Goose reinstated it:

It is not true that a mirror reverses left and right. It actually inverts front and back. The left and right sides of a person's mirror image seem to be reversed because we are actually accustomed to everyone else's left and right being reversed when they turn around to face us. If, instead of rotating on the spot to face us, people instead flipped over into a handstand, we would see their left and right remain the same, but their top and bottom being reversed from our own. The mirror image faces us without its left and right or top and bottom being reversed in this sense, which is why it is the reverse of what everyone else sees when they look at us. Another way to understand this is the following. The misconception arises because one compares the image in the mirror to an object already 180° rotated around a vertical axis on the plane of the mirror, and then notices a left-right reverse. However, if one takes this (subconscious) rotation also into account, the rotation plus the left-right reverse together actually mean a front-back inversion. (Image a rubber mask being pushed inside-out, as opposed to being turned around.)

My edit summary was: "rm mirror inversion - as the article makes clear, this is merely pedantry, ignoring the fact that left-right inversion is the *normal* way for humans to express orientation inversion". "The article" referred to the first source, which is a psychological article published in a physics journal by a biologist. Father Goose added an off-line source which I cannot check, and which he claims specifically states this is a popular misconception.

The new source may claim this is a popular misconception, but it's obviously not true. Nobody in their right mind thinks that left and right are reversed in a mirror in the literal sense in which it would be a misconception. If I touch a mirror with my right hand, then obviously what I touch is not the mirror image of my left hand. If we say that left and right are reversed, we mean that if the mirror image was a real person, this person would have their heart on the right side of the body.

If we want to argue on the pedantic level that makes reversal of left and right a misconception, then the claim "It actually inverts front and back." is another misconception. After all, if we are not allowed to rotate our mirror image by 180 degrees before comparing, there is no reason why we should be allowed to shift it so that its centre of gravity coincides with our own. What the mirror really does is a reflection (mathematics). --Hans Adler (talk) 00:30, 26 March 2009 (UTC)

The mirror is back in - it was re-added, i removed (with a mistake in the edit summary; wrote "refraction" when i should have wrote "reflection". Oh, the horror), and it has again been readded. I suppose I'm at my limit for removing unsourced claims. At any rate, i concur with Hans analysis here. It should go.Bali ultimate (talk) 14:40, 26 March 2009 (UTC)

I think the mirror entry, while a little quirky, may belong in the list. People see a left-right inversion because they typically rotate around a vertical axis to turn around (face backward). If people typically rotated about a horizontal axis, somersault-style, to turn around, always keeping, say, their right side to the north, mirrors would seem to invert things top-to-bottom. Thus the common belief that mirrors flip things left-right isn't strictly true. Rracecarr (talk) 15:11, 26 March 2009 (UTC)

No, it does not belong in the list. It's not just that it contains false statements, as I explained above. Someone would have to be exceptionally stupid to believe that a mirror flips left and right in the sense in which it would be false. This is simply a question of how we express a complex idea. If this is a misconception, then surely another misconception is that capitals have voices and can speak ("London announced that..."), and the only reason we can't include it is that nobody called it one. --Hans Adler (talk) 12:17, 27 March 2009 (UTC)

There is no "misconception" here, at all, and it should go.Bali ultimate (talk) 12:31, 27 March 2009 (UTC)

The usual form of this puzzle is the question "why does a mirror reverse left and right rather than top and bottom?" or, to put it another way, "why are reflected images flipped horizontally rather than vertically?" The answer, of course, is that they aren't. Many (even most) people have trouble seeing this, from which I conclude that "mirrors flip horizontally and not vertically" is a common misconception and this item ought to be in the article. Maybe it needs rewording, but there's a real point of confusion to clear up here. -- BenRG (talk) 01:06, 28 March 2009 (UTC)

I agree that there is some confusion here, but it's not on the level where the entry claims it is. If you ask, how can an entire city like London negotiate with another city like Paris, then people will say, it's just a manner of speaking. If you ask, why does a mirror exchange left and right rather than top and bottom, then they will go, waaah!, complicated physics question!, I have no idea, instead of giving the same answer. The problem is that we can't say this, because we don't seem to have the necessary sources to support the correct interpretation. Most sources treat it as a problem of physics, which is exactly the misconception. --Hans Adler (talk) 08:53, 28 March 2009 (UTC)

The general problem here is that low-quality sources are much more likely to say that something is a misconception than high-quality sources. And since it is hard to find out, rather than postulate, whether something really is a common or popular misconception, this particular claim makes it even less likely that the source is good. Therefore this article's criteria have a strong bias towards "reliable sources" of the lowest quality. If an amateur interviewed by a local newspaper talks about a potential "misconception", they are much more likely to call it a [common] misconception than a scholarly article discussing the same topic. Hastily written compilations of "misconceptions" for the mass market make the problem even worse. As a result, we are technically able to reproduce popular misconceptions about "misconceptions", but unable to debunk them.

Here is a good example demonstrating how these pseudo-misconceptions arrive: [12]. It's a typical situation where an amateur who advocates a specific non-standard use of language ("tea" can only refer to products of the tea plant, and "herbal tea" needs scare quotes) is interviewed for edutainment. The format is that of a journalist interviewing an expert, but that's just a game. The non-standard language use serves to mark the distinction between the "expert"'s group (tea enthusiasts) and the rest of the world, but especially the enemy group (herbal tea advocates). An encyclopedia is not the place to take such sources seriously. --Hans Adler (talk) 08:53, 28 March 2009 (UTC)

If you can't provide a reliable source to show that another reliable source is wrong (about the explanation or about its being called a "common misconception"), then the inclusion criteria for this list will not be source-based, but editor-opinion-based, and just about every single idiot in the universe will come by to offer his or her opinion about every single misconception.

This is a horrifying prospect.--Father Goose (talk) 22:06, 28 March 2009 (UTC)

Well, we have a choice between going through all these discussions, even doing that on a page that collects supposedly scientific statements about random fields, with the consequence that for every individual entry only very few, if any, experts watch it. Or simply making false claims. WP:V says: "The threshold for inclusion in Wikipedia is verifiability, not truth." There is a subtle reason for the word "threshold" here, rather than "standard": If we can formally verify something, but we know it's not true, then obviously we must not claim it since that would be lying. See also WP:Editorial discretion. --Hans Adler (talk) 00:00, 29 March 2009 (UTC)

If you're talking about evaluating the merits of one source against another, then sure; if you're talking about evaluating ostensibly reliable sources against nothing more than personal opinion, that's an abandonment of WP:V -- not "editorial discretion". I can't accept the latter, and I doubt the rest of Wikipedia will either.--Father Goose (talk) 16:58, 29 March 2009 (UTC)

It seems you really don't understand WP:V. This policy says what we must not include even if we want to. It does not tell us to include something that we don't want to. (I just double-checked this; I couldn't find a single sentence in WP:V that can be read as an obligation, or even an encouragement, to include something.) "Reliable sources" are full of lies and bullshit (the latter in Harry Frankfurt's technical sense of the word, see On Bullshit). Articles normally focus on a specific field, and editors with knowledge of the field, along with some others, decide what goes into the article and what doesn't. This system obviously breaks down under the special conditions of the present list.

To come back to the topic that started this thread: If you really believe that many people who say that mirrors exchange left and right actually believe that they see the mirror image of their left hand on the right hand side and vice versa, then you have yet to tell us so. --Hans Adler (talk) 22:06, 29 March 2009 (UTC)

I honestly don't know if people believe that or not. People believe such jaw-droppingly stupid things in this world. I know that my belief of what they believe (or ought to believe) isn't worth a hill of beans. There's a difference between my personal view that "obviously it doesn't reverse left and right" and "obviously nobody else could believe that".

I'm prepared to let sources be the authorities on whether "people believe things". And to let the list be a list of "things people have claimed are popular misconceptions". I know not to insist that it be a list of "things that are definitely and quantifiably popular misconceptions". That would force all of us opinionated fucktards here on the talk page to wrangle over the "truth" of each and every entry. I of course include myself in the list of fucktards.

That approach will be perpetually unworkable. I bleed from several orifices at the very prospect of it. What we can do in a factual and consistent manner, however, is to note what several reliable sources have called "common misconceptions", without interjecting any personal opinion as to whether or not those sources are wrong. (If other reliable sources contradict them, then we have to figure out what weight to accord to each source, taking into account the context and overall reliability of each source's statements.)--Father Goose (talk) 21:53, 30 March 2009 (UTC)

Guidelines for this article.

It's obvious that this article will generate continual disagreement if there is no guideline accepted by consensus, with, then the consensus being a matter of dissent and reconsideration. The stronger the consensus on the guideline, the less fruitless discussion there will be.

There was a proposed guideline at Talk:List_of_common_misconceptions/Archive_3#guidelines_for_.22common_misconceptions.22. It should be read and used as a basis. Because I'm in a hurry, I'm not referring to it, but am making some comments myself that would properly be integrated with it.

1. The topic should be notable, which for our purposes can be evidenced by a Wikipedia article that is standing.
2. The misconception and the correction should be covered in the article. Can't get it there, not appropriate here.
3. The misconception should be supported by multiple reliable sources, I'd set a standard of at least three, but two might be adequate. One could be adequate if it is a reliable source asserting that the misconception is common, but I'd still prefer to see a confirmation showing the misconception as actually being held and asserted, which is then a primary source confirming that the misconception isn't just a Straw man.
4. The correction should be supported by:
   1. source of higher quality, or
   2. more recent and more informed source, of equal quality, not contradicted by newer independent sources.

If we can agree on the standards, then specific inclusions become a matter of checking off the list. Whatever agreement is found here should be documented for future editors of this article. --Abd (talk) 15:59, 27 March 2009 (UTC)

On the grounds that notability doesn't limit article content and being supported by the reliable sources required on the third line pretty much proves notability anyway so i think that line is redundant. I think higher quality sources are a definite plus for the article rather than 'did you know' article and tv shows. I think also we have to say strictly no original research. No finding your own misconceptions. etc. --neon white talk 16:56, 27 March 2009 (UTC)

Those criteria sound good to me. I would start by removing any "citation needed" examples. If there is no source given for an example in a list like this, it shouldn't stay in the article waiting for a reference. --hippo43 (talk) 01:55, 28 March 2009 (UTC)

We're actually pretty much going by these standards at this time. As stated in the lead, it's a list of "various ideas described by multiple reliable sources as widely held, but which are false, misleading or otherwise flawed".

I personally have been treating this as "at least two sources that specifically identify something as a 'common misconception', though not necessarily in those exact words". This is more rigorous than "show multiple sources getting this wrong"; that still doesn't necessarily demonstrate that it's a common misconception, or even, for that matter, a misconception.

Unfortunately, people haven't been abiding by this yet. Some editors have tried to remove entries that are sourced, per the above criteria, quite soundly, but that they still contend are "not common misconceptions". A subset of these disputes relate to entries that are more misnomers than misconceptions; I proposed elsewhere that we transfer those ones to List of misnomers, since it's easy to find a dictionary somewhere that treats a technically incorrect name as colloquially correct (such as spiders being insects).

The points you proposed relating to "these misconceptions must be described in other articles on Wikipedia as well" is not the best of ideas, because people can just edit them into those articles, making the requirement toothless. (And it would possibly initiate edit wars across many articles originating from disputes over this one.) External sourcing is the best discriminator for inclusion and exclusion from this list.

While I agree with removing all entries that don't meet the sourcing criteria, I don't support removing all unsourced or undersourced entries immediately -- just the really dubious ones. "Give people time to find sources for plausible information" is a widely held tenet on Wikipedia. We've only adopted the "strict" criteria recently, so it'll take some months before we can properly vet every entry.--Father Goose (talk) 08:16, 28 March 2009 (UTC)

I strongly support removing all unsourced material from this article. This article has been here 5 years, and material can be added IN when it's properly sourced not KEPT in the hopes that sourcing will eventually be found at some point in the indeterminate future. The burden of proof is on inclusion, never the other way around.Bali ultimate (talk) 14:14, 28 March 2009 (UTC)

In that case, you should immediately remove all unsourced facts from the encyclopedia. The community doesn't need to be told yet another time that this is your view -- you're just looking dogmatic at this point. What we need is action! Don't waste another minute!--Father Goose (talk) 21:42, 28 March 2009 (UTC)

Actually, that is totally incorrect (perhaps a common wikipedia misconception ;)) ascording to WP:V policy unsourced info should be removed. Refer to the Jimmy Wales quote at Wikipedia:V#Burden of evidence. I think this is pertinent to this article more than any i've previously dealt with. --neon white talk 08:23, 29 March 2009 (UTC)

Unsourced info should be removed, yes, but not necessarily immediately. In keeping with the principle that Wikipedia is not perfect, unsourced-but-plausible info is generally given some latitude before the aforementioned burden is imposed. No latitude is offered within BLPs, nor to anything that is obvious crap. And the higher the overall quality of the article, the more likely unsourced bits will be removed on sight. But there's not much of an improvement to speak of when an undersourced but decent article is whittled down to a nub, albeit a fully sourced one. Doing that holds up the process of article improvement. The real improvement in such cases comes from adding sources, not reflexively removing unsourced info.--Father Goose (talk) 09:11, 29 March 2009 (UTC)

Removing unsourced information from articles IS article improvement, particularly when sources have not been found for years.Bali ultimate (talk) 14:33, 29 March 2009 (UTC)

Again, that is incorrect, we do not leave info or tag it because we believe it may be correct but when we expect a source to be forthcoming in the near future. --neon white talk 05:53, 31 March 2009 (UTC)

Once again, I challenge you to delete all unsourced information from every Wikipedia article you encounter, forthwith. And if you find that doesn't meet with a positive response, I suggest you take up the issue at Wikipedia talk:Verifiability.--Father Goose (talk) 21:14, 29 March 2009 (UTC)

I'd start with this one article that i'm focused on at the moment (though i of course remove unsourced crap from articles all the time) but know full well that you will stand in the way of removing inappropriate, unsourced information. Edit warring with you won't get me anywhere by myself. Yes, there are many bad articles on Wikipedia. But using this as an argument to not improve this one (by removing unsourced information that doesn't belong here) has to be among the most lame and pathetic arguments i have ever heard for allowing unsourced garbage to remain in an article. If you can't make a better case, consensus will eventually move strongly against you on this one ("I feel it belongs" type arguments don't withstand real scrutiny for long). Believe me.Bali ultimate (talk) 21:26, 29 March 2009 (UTC)

"I feel it doesn't belong (because I say it's not a common misconception even though several sources say it is)" also doesn't withstand scrutiny.

It was my hope to source every entry on this list over the next several months. (And to remove any entry for which I couldn't find sources.) Unfortunately, my attempts to fully source the article have come to a crashing halt as a result of you and others removing entries on the basis of your personal opinions, in defiance of sourcing that supports all factual statements as well as the claim that the entry is a "common misconception".

I can't keep working on it if people are deleting stuff according to personal opinion even after it's been properly researched and sourced. That problem has to be addressed before any kind of constructive work can proceed.--Father Goose (talk) 21:15, 30 March 2009 (UTC)

You can add examples when you find the sources. WP:V policy has absolutely nothing to do with personal opinions. It's community consensus and the only place it cannot be addressed is at the village pump. --neon white talk 05:53, 31 March 2009 (UTC)

Centrifugal force

I have reverted good faith edits by Ozdoc. They were incorrect. Rracecarr (talk) 13:47, 28 March 2009 (UTC)

I don't know if they were correct, but the entry can't stay as it is. Ozdoc rewrote the following entry (with edit summary "actually a real force, in the reference frame of the accelerated object"):

(version before Ozdoc's edit) There is no such thing as centrifugal force, or a force that pushes outward while an object is undergoing circular motion. What many people confuse for centrifugal force is actually just inertia, because the object in motion wants to maintain its velocity and move in as direction tangent to the path of its circular motion. The force people often confuse with centrifugal force is centripetal force, the force required for an object to remain in uniform circular motion. Centrifugal force is one of several so-called pseudo-forces (also known as inertial forces), so named because, unlike real forces, they do not originate in interactions with other bodies situated in the environment of the particle upon which they act.

"There is no such thing" are pretty strong words for a concept that every physics student has to learn (or rather, re-learn, since it should normally be covered in school as well) in their first year. The entire entry looks as if it is intentionally misleading, since while linking to the somewhat related term inertia, it omits the obvious wikilinks centrifugal force, centripetal force, inertial frame of reference and pseudo-force, each of which obviously belongs here, and following any of which one is led immediately to a Wikipedia article that explains why the centrifugal force does in fact exist in a rotating frame of reference. When physicists say the centrifugal force is "not a real force" they don't mean that it doesn't exist in any sense of the word "exist". Otherwise they wouldn't define it, and we wouldn't need the word pseudo-force.

"The force people often confuse with centrifugal force is centripetal force [...]." This is even worse. The "confused" people who believe in the centrifugal force know very well that it is directed away from the centre. The centripetal force is directed towards the centre.

Both wrong statements don't even have supporting citations. (Neither does the rest of the physics in this entry, but at least it seems to be correct.) Ozdoc's use of the words "real force" when referring to a pseudo-force was unfortunate; but the edit summary was correct if you read "real force" as "force that one must take into account in the frame of reference in question in order to get correct results".

Because of some potential subtleties around centrifugal force and reactive centrifugal force I don't feel qualified to correct this entry. See the talk pages of these articles for more further technical information than I can give. Until someone knowledgeable bothers to repair this severely misleading entry I am removing it. --Hans Adler (talk) 15:30, 28 March 2009 (UTC)

This entry should no be here at all. Centrifugal force as it's commonly refered to is not a misunderstanding -- ballet dancers and gymnasts and figure skaters use this concept all the time to control spin, etc... that there is no centrifugal "force" in the specific, physics sense of the word "force" is well explained in the relevant articles hans mentions above, and this is generally not confused by students of physics. That we colloquially speak of a "force that throws things outwards" (or whatever) is not evidence of a misconception.Bali ultimate (talk) 15:51, 28 March 2009 (UTC)

I've seen this "misconception" explained countless times. So, in terms of sources identifying this as a "common misconception", this one's hard to beat. The way I'd choose to phrase it is, "Centrifugal force, per se, is not a real force." Then explain the technicalities the way dozens of sources do. (E.g., [13], [14], [15].)

Now that I think about it, this is probably one for the misnomers page, since it's another "X is not Y despite it being called Y" entry.--Father Goose (talk) 21:57, 28 March 2009 (UTC)

I think the entry probably has a place in the list. I do not think it was well written. I reverted Ozdoc because the changes made it even worse. His claim that centrifugal force is a result of Newton's third law is completely false (as is Bali's that ballet dancers/gymnasts/skaters use centrifugal force to control spin). There is indeed a common misconception here--it was exemplified in a "science" program I saw on TV recently, to do with tossing pumpkins large distances. One of the machines worked by spinning a pumpkin around and around, faster and faster, on the end of a long arm, and then finally releasing it. In the cartoon explanation, it said that the centrifugal force got bigger and bigger, and caused the pumpkin to fly off when it was released. The animation showed the pumpkin launching in a direction not tangent to the circle it had been following, but perpendicular to it, along a line passing through the center of the circle. This is clearly wrong, and is an illustration of the misconception--people think an outward force will cause an object spinning in a circle to move outward when it is no longer constrained, when really it just continues along a straight path. Rracecarr (talk) 06:51, 29 March 2009 (UTC)

Wow, this type of stupidity didn't even occur to me. Of course if it satisfies the sourcing conditions and someone actually writes a sound explanation, it will make a good entry. --Hans Adler (talk) 15:43, 29 March 2009 (UTC)

Just to clarify my earlier point. When a ballet dancer talks about "centrifugal force" to control spin, it's just a term they use to describe a common phenomena that the body experiences. They think of physics not at all. It's just language the usefully describes a mundane phenomenon, with no thought whatsoever about the physics involved (everyone who has ever spun a weight or something on a string knows it goes in a straight line when the string breaks. Where's the source for common misconception on this one again?)Bali ultimate (talk) 22:32, 29 March 2009 (UTC)

Request for comment on sourcing this list

This rather expansive list has a problem. It is to include only those things that are "common misconceptions." But many items on the list do not have reliable sources that unambigiously describe them as "common misconceptions" (or acceptably similiar language like "widely held false belief" "commonly misunderstood" etc...) Some editors here would like everything that is not well-established as a "common misconception" via reliable sources to be removed (without prejudice to readding if sufficient sources are found). Others argue that the unsourced material should remain, until such a time as sources are found. A review of this talk page will show we're at an impasse on this issue.Bali ultimate (talk) 21:36, 29 March 2009 (UTC)

• There is general consensus that reliable source is required at some level for both misconception and the correction. "Common" is not a precise term, yet it is appropriate here. First of all, the comparison. The source(s) for a correction must be of higher reliability than the source(s) for the misconception, unless we have high-quality reliable source that the misconception is common as well as for the correction. Otherwise we can't call it a "misconception"! My informal standard for this looks at the level of knowledge involved in the source, that's why academic sources, particularly peer-reviewed ones, are superior. Secondly, as to establishing the existence of a misconception, there are sources of low quality that will call something a "common misconception," but this could be a straw man; these exist for various reasons, not the least of which is a writer desperate to fill space. However, it's a start. Ideally, there are reliable sources that do show the misconception (i.e., the author seems to believe the misconception, which isn't surprising if it is a common one, and if there are no such authors anywhere in the universe of marginal publications, I'd have to conclude that nobody worthy of note believes it), and there may be sources of marginal reliability that nevertheless establish that the misconception is common. What sources are adequate for this? There is a diffuse reliable source that nobody mentions, but it is, in fact, our defacto practice, and it is the answer to the rejoinders above about "well, then go and delete everything unsourced in the project." Most of us do not delete stuff that we know is true. I don't. I might tag it, sometimes, sometimes I don't bother, I have better things to waste my time on. In other words, our de-facto consensus is, in fact, a reliable source of a kind, though undocumented. That can't be in a written policy because .... it could be seen as interfering with the very important policy of verifiability, should some Martian read an article here and wonder where to look for verification for what is well-known. And it could be abused; but, note, the problem only arises when there is disagreement. So, here is where editorial judgment comes in. There can be no fixed boundary; however, we can set limits to controversy: i.e., we could set a minimum standard, below which the presumption would be that the alleged misconception is not included. And we can set another level of sourcing at which the misconception is clearly established, the presumption becomes that it is included. And we can develop an efficient procedure by which what is in between these (or is alleged to be an exception) is discussed and vetted for inclusion. In the end, our consensus is the standard, but developing broad consensus for each item is utterly impractical in the long run. I am in favor of relatively strict standards for what we allow to remain on the page, but a welcoming practice that invites discussion and source-searching from editors who drop their favorite misconception on the page without adequate sourcing, and that shows cooperation with this (rather than simple rejection). And, please, do not remove a misconception that is unsourced if you believe, from your own experience, that it is common. On the other hand, don't edit war with someone else who takes it out, based on your own belief and experience, but only revert if consensus has become clear -- and even then don't edit war! --Abd (talk) 00:21, 30 March 2009 (UTC)

• WP:V is perfectly clear on this issue. It applies to all articles and this is no exception. The best way forward is the strip the article down and rebuild. --neon white talk 05:57, 31 March 2009 (UTC)

• I'd say this list suffers the bigger problem of being very ill-defined in scope. "Common misconceptions" is both impractically broad and highly subjective. A complete stub/split/move may be in order. OrangeDog (talk • edits) 01:04, 2 April 2009 (UTC)

• Given the potentially subjective inclusion criteria for this list, and the risk that it becomes effectively OR, I think that every item in this list should have a reliable source documenting that it is indeed a common misconception. The source should not just be offering the opinion that it is a common misconception, but ideally should have some objective measure of how "uncommon" it is. This would most likely have to take the form of a study. Otherwise to be verifiable and NPOV, every entry would have to state something like "it is the opinion of so-and-so that this is a common misconception". I admit that this will require a substantial winnowing of this list; however, it is the only way I can see to yield an article that is fully verifiable. (Full disclosure: I initiated a recent AFD on this article.) Thanks-Locke9k (talk) 05:39, 6 April 2009 (UTC)

• Also, why is this RFC listed in the "Society, sports, law, and sex" RFC section? It seems to me that this article heavily addresses a variety of other topics, such as science and history. Can't it be transcluded into those? If not, its not much of an RFC. Locke9k (talk) 19:16, 7 April 2009 (UTC)
  • In line with my above comment, I have manually transcluded the link to this RFC into other RFC categories whose topics are covered in this article. This should hopefully both get us some more help and make sure that editors with expertise in the wide range of topics covered by this article can contribute to the RFC.Locke9k (talk) 19:23, 7 April 2009 (UTC)
• Link to archived AFD Debate on this article: Wikipedia:Articles_for_deletion/List_of_common_misconceptions_(2nd_nomination). Both the debate and the closure statement make clear that 'being a common misconception' is the unifying subject of this article. Without it, the article would be an indiscriminate collection of information and would have been deleted. Therefore, arguably the most important thing to source for each fact is the contention that it is a 'common misconception'. Locke9k (talk) 22:03, 7 April 2009 (UTC)

• Comment Since it seems we must live with the absurd result of the AfD, anything not clearly verifiable to multiple reliable sources as a 'common misconception' should be excised from the article. Dlabtot (talk) 17:35, 15 April 2009 (UTC)

I'm fine with removing items that aren't cited, but I am concerned about your reference to "multiple reliable sources". I just looked over the AfD and I don't see anything that says we need multiple sources per item. Perhaps I misunderstood you?One source per item should suffice. A Quest For Knowledge (talk) 18:09, 15 April 2009 (UTC)

Otherwise, I believe you'll end up with a list of misconceptions that contradict each other. For example, I think one could find a reliable source that state that it is a common misconception that raising taxes increases government revenue, and another reliable source that states the exact opposite. WP:NPOV tells us that when reliable sources contradict each other, we report what the sources say, but I don't see how that fits into this article. Although, frankly, I should add as a disclaimer, I don't really think "List of..." articles even belong in an encyclopedia.... Dlabtot (talk) 18:20, 15 April 2009 (UTC)

If we have multiple reliable sources that contradict each other, it probably shouldn't be in the article in the first place since it can't be confirmed. But honestly, after searching for sources for about 20 items, not once did I come across a situation where I had a reliable source that contradicted another reliable source. When I say that, remember that I was looking for cites that explictly stated that it was a common misconception (or something similar to that). Once you put in that qualification, the number of possible cites drops dramatically. Not that it could never happen, but I doubt if this will be much of an issue (if at all). If it does indeed happen, then we can address it on a case by case basis. I, for one, would not include information that I could not verify. A Quest For Knowledge (talk) 18:39, 15 April 2009 (UTC)

• Comment Wikipedia is meant to summarise published secondary literature. A number of books deal with popular misconceptions. To take a couple of examples, there are David Deifendorf's Amazing... but False!(ISBN 1402737912) and Lloyd and Mitchinson's The Book of General Ignorance (ISBN 9780307394910, just taking books that have been published in the last few years. It would be amazing if there weren't several more. Hence the outcome of the AfD was the right one: this list belongs on WP. There's a strong overlap between the article as it is currently and the content of these books, so stripping the article down and rebuilding seems an unnecessarily extreme measure. The items need sourcing as popular misconceptions, but inclusion as such in these books would seem to satisfy that requirement: it's not clear why we need to set the bar as high as something "taking the form of a study" (per User:Locke9k above) or multiple sources. MartinPoulter (talk) 18:11, 15 April 2009 (UTC)

• There are plenty of books listing popular misconceptions. The general problem with these is that this is a popular genre and that these books are mainly produced for the mass market, while listing many individual entries each of which would require significant careful research or significant expert knowledge to be done right. Such a book is extremely hard to get right, and most authors do not even seriously try to get it right but simply attempt to list as many "misconceptions" as possible. As a result we have many cases where according to a book (or sometimes a newspaper, for somewhat similar reasons) certain standard dictionary meanings are "misconceptions". This inevitably leads to editors pushing for inclusion of the "misconception" that "tea" can refer to herbal tea, or that "mirrors exchange left and right" (does anyone believe that they see their right hand on the left hand side of the mirror?). As a result we have a list that makes a lot of questionable claims on scholarly subjects, based on sources that get nowhere near our usual standards of referencing for such claims. These are hard to attack because we will hardly ever find a source saying "it is not a popular misconception that...". To make matters worse, since this list is such a hodgepodge, for every single scientific or scholarly claim made in this list the odds are that no editor who is knowledgeable in the relevant subject has the list on their watchlist. --Hans Adler (talk) 19:13, 15 April 2009 (UTC)

"since this list is such a hodgepodge, for every single scientific or scholarly claim made in this list the odds are that no editor who is knowledgeable in the relevant subject has the list on their watchlist" For the short term, I think we should focus on improving the quality of the article. In the long term, we might want to split the page up based on subject area (history, science, politics, sports, etc.). This might help address this issue. A Quest For Knowledge (talk) 20:21, 15 April 2009 (UTC)

This list clearly has the potential to be infinitely long, and yet serve no purpose at all. It needs (MHO of course)to be tackled differently. A better way of dealing with the subject would be to use this article to attempt to define what a common misconception is, and advise contributors that the correction of common misconceptions belongs in the article about the subject of the common misconception (eg the explanation of Napoleon's height in modern units belongs in the article on Napoleon, the discussion on bikes and gyroscopic forces in the article on the bicycle). Contributors could then place here links to articles where a common misconception is debunked, ideally using some standardised format. This would have the advantage that any question of verification that it was indeed a cm would be dealt with by editors of the subject article, as would checking on the response, thereby overcoming the issue raised by A Quest For Knowledge above. --Elen of the Roads (talk) 14:54, 25 April 2009 (UTC)

If it's a list it should be pointing to relevant subsections and not be the present hodge-podge. NBeale (talk) 13:13, 3 May 2009 (UTC)

Water Hose Misconception: Really bad explanation in Physics section. Absurd "misconception"

1. It is not true that a nozzle (or a person's thumb) on the end of a garden hose makes the water squirt farther because the same amount of water gets forced through a smaller opening. The rate of flow of water through the hose is not a set constant; in fact, putting one's thumb over the end of the hose reduces the rate of flow. What is constant is the water pressure at the source. When water is flowing, the pressure decreases the farther from the source one gets due to friction between the water and the pipes it's flowing through. The faster the water moves through the pipe, the greater is the friction that cuts down pressure at the output end. A thumb over the end of the hose decreases the flow rate, causing the friction from the source to decrease, causing the remaining water to have more speed.[87]

I don't have access to the source mentioned, which makes verification and comparison difficult, but this is an awful explanation of what happens. ".... causes the remaining water to have more speed." What's the "remaining water"? It would have to mean the water that issues from the end, but why does it have more "speed"? The explanation actually shows why the water pressure at the end of the hose increases. If there is no restriction at the end, the pressure there approaches zero, and the flow through the pipe will then be determined solely by the friction of the pipe. Yes, as the flow decreases, the friction and therefore the reduction in pressure decreases; if the end is completely blocked, the pressure becomes constant over the whole length of the hose as being the pressure in the water mains. So the water that does come out, from a smaller opening, is under higher pressure, i.e., higher force per unit area. Basic physics: higher force acting on mass, higher acceleration. "It squirts further because it is under higher pressure" is the simplest explanation, and I don't know anyone who actually thinks that the same amount of water is squirted out of a hose when you partially block the opening! Pinhole opening, tiny spray at highest velocity, which can immediately turn into a mist. Very little water. And we all know from experience blocking hoses with our thumbs that the pressure increases the more effectively we block the end. I don't know what to do with this one. Anyone know of any source for the misconception beside that book? Anyone here who believed this before being corrected here or elsewhere? If so, and especially if there is more than one, I'd take that as adequate, personally. --Abd (talk) 01:14, 30 March 2009 (UTC)

There is no common misconception being corrected here; people generally understand how this works. There is no reliable source for this. Yet here it is.Bali ultimate (talk) 01:22, 30 March 2009 (UTC)

I don't think the entry is so bad, although I agree that "causing the remaining water to have more speed" is a very unfortunate phrase. I have a degree in physics, and probably understand the processes affecting pipe flow better than the average person. Before reading this entry, I had never really thought about why water shoots further when you put your thumb over the end of a hose. It is quite possible that if someone had asked me for an explanation, the first thing that would have occurred to me is that the water must speed up going through a constriction. I don't think it's intuitively obvious that the flow rate must decrease in order to make the water squirt farther. Rracecarr (talk) 01:35, 30 March 2009 (UTC)

Actually, what increases is pressure. I usually think of water flow like current flow with electricity, and Ohm's law, I'm sure there is a hydrostatic equivalent. E = I * R, i.e., with the proper units and allowing for the fact that water flow is much more complicated in detail because of turbulence, etc., we have pressure difference = flow rate times resistance, and this is true with any "pipe," i.e., path betweeen two nodes of pressure. By putting our finger over the outlet, we increase the pressure there from zero to a higher value, therefore there is more force against the water. I don't think anyone would have difficulty with the idea that if we increase the water pressure, the water will squirt faster. I agree that it isn't intuitively obvious that the flow rate must decrease in order to make the water squirt farther, because it isn't true. What must happen is for the pressure to increase; decreasing the flow rate is what makes the pressure rise. Again, once just about anyone is led through the thinking, it's easy. Block the opening entirely, you have maximum pressure through the entire length of the hose; it even expands from it, becoming stiffer, etc. I don't think hose "friction" has so much to do with it. Rather, flow is restricted by the faucet, or the size of the pipe coming from the main. If the hose were really, really slippery, would the water flow faster? I rather doubt it. Instead, take the area of the pipe opening from the main; imagine that this is just an opening to the air. How much water would flow through that? If we imagine a big main, pressure loss within the main could be neglected, so we have, quite simply, a problem of how much water will squirt out of a certain size hole if there is a certain pressure. That is the maximum flow rate for the system, forget about the pipes. The pipes, then, I am sure, do slow down the water, some, but not much is my guess, unless they are very long. With the hose open, the flow rate is probably limited mostly by the remaining constriction in the faucet, that being usually a smaller opening than at the end of the hose. Under those conditions, the pressure in the hose, all along its length, is low. What is the pressure at the faucet end of the hose when the hose is open at the other end, compared to the pressure if the end of the hose is closed? I know the answer to the second condition, it is simply the system water pressure. As to the first pressure, it's quite low by comparison. How low would depend on the resistance of the hose, which is small, I expect. The higher the resistance to flow, the higher the pressure in the hose, it would rise from zero at the open end (always), to maximum at the faucet end.

(When we add a constriction, we create a little resistor, the pressure on the hose side will always be higher than on the outside, which is zero (above air pressure, that is).

There could be material for some nice elementary-school or even higher level science projects here, experiments that would demonstrate basic physics. As to the "misconception here," we just saw evidence for it. Someone with a physics degree still fell for the trap. (No personal offence intended, and I fully expect that this editor will follow my argument or could even write it much better. Where did the idea come from that the "water must speed up going through a restriction"? It's tricky. We have testimony here that our physicist might have thought that, at first blush, but that is with no thought at all. The question is whether or not a "common person" would have not only thought that transiently, but even after consideration, and I'm suspecting that not. People have experience with hoses, and it isn't rocket science to consider that blocking the hose must slow the water down, as it does. So why does it squirt? I think that the "common person" -- by which we must now mean someone with no experience with physics -- might simply abandon the question, not conclude that the water "must speed up" as a cause. Speeding up is an effect, not a cause. Why does the water speed up? The answer is in understanding how pressure and flow and resistance are related. Here is a nice little experiment:

Okay, we have this hypothesis, from the item in the article: when water is flowing, the pressure decreases the farther from the source one gets due to friction between the water and the pipes it's flowing through. The faster the water moves through the pipe, the greater is the friction that cuts down pressure at the output end. A thumb over the end of the hose decreases the flow rate, causing the friction from the source to decrease, causing the remaining water to have more speed.

How could we test this? The hypothesis suggests that the pressure decreases uniformly from one end of the hose to the other. Let's make a pressure measuring device by using a nozzle set for fine spray. This nozzle isn't going to remove much water; by collecting the water and measuring how much water we get in a unit of time, we have a direct measure of (relative) pressure. Now, put some tees in the system, one at the faucet end, one in the middle, and one at the far end, the open end, and a nozzle at each, with the nozzles adjusted so that they all spray the same amount of water per unit time at constant pressure. What do we see with no obstruction at the open end? Prediction: very low pressure over the whole hose. Very small pressure at the open end, slightly higher pressure at the faucet end, middle pressure in the middle. If we restrict the open end with the thumb, what do we see? Prediction: almost equal pressure at all three nodes, but much higher. The difference in pressure between the faucet "gauge" and the open end "gauge" decreases. At zero flow, the pressures are all the same, the system water pressure. Pipe "friction" only accounts for the small difference of pressure at high flow rate. No, the cause of the fast squirt is an increase in pressure, but the pipe friction is a minor element, the real place where most of the pressure drop at high flow is created is probably at the faucet. The explanation in our article is actually incorrect and misleading. Is this WP:OR? Maybe, but maybe, at least in Talk, this is absolutely appropriate. I see it as a process of approaching consensus, and nonverifiable source can be a part of that. Whatever works, i.e., if we all agree on it, no problem. Here, though, we see possible hazards of both unsourced text and, possibly, inadequate solidity of sourcing for the "correction." Don't know. Can't verify the source. Having an exact quote would be nice. --Abd (talk) 20:40, 31 March 2009 (UTC)

BTW, the pressure does decrease from one end to the other, probably uniformly (if there are no kinks). It is just that this is only a minor contribution to the pressure change from new restriction at the open end.

I had Richard P. Feynman for freshman and sophomore physics, one of a very small group of people who can say that (it was only done once, so you can figure out when I was there from it). But I didn't learn physics from him, what I learned was how to think. At least a little.... then comes explaining it, which is somewhat harder, it involves communicating with these complex entities which were designed for survival, not for heavily abstract thinking, my guess. --Abd (talk) 20:45, 31 March 2009 (UTC)

You are lucky.Rracecarr (talk) 20:49, 31 March 2009 (UTC)

Trying to simplify this:

Consider a molecule of water. The only reason that it goes further from a constricted nozzle is that its velocity at the point which it leaves the nozzle is higher. So the individual molecules are travelling faster.

The "flow rate" (litres per second, ie total volume of water shipped) will of course initially decrease when the constriction is applied. But the decrease in flow rate does not cause the water to go further.

Abd - does that sum it up? pablo_hablo. 09:04, 14 May 2009 (UTC)

There seems to be a debate going on about the "misconception", below, regarding water in a hose. Unfortunately, the 'correction' is incorrect and also inadequately sourced. There needs to be a reference showing both that the belief is a common misconception and that it is incorrect. There also needs to be a source documenting the correct understanding. Neither of these are present, and this is an excellent example of why good sourcing is so important in this article, as this "correction" is actually creating and spreading a misconception to replace the common view, which is actually mostly correct.

Aside from the fact that it is inadequately sourced, please allow me to explain why the entree is incorrect. First, the statement that "The faster the water moves through the pipe, the greater is the friction that cuts down pressure at the output end" is blatantly wrong. The pressure at the output end is always air pressure. Nothing changes this. Second, the remainder of the explanation is incorrect. It is true that putting your finger over the nozzle of a hose reduces the flow rate, in volume per second, out of the hose. The occurs because your finger effectively narrows the cross-sectional area available for flow at the outlet of the hose. This leads to an increase in "frictional" losses from the water as it flows through the contraction formed by your finger. There are loss factors tabulated and available for a pipe contraction, and if people continue to debate over this I can easily do the math here to show that there is a net increase in losses as a result of the addition of your finger. However, this is simple to see intuitively, as the flow rate scales proportionally to the pressure drop through the hose and inversely to the resistance to flow. The pressure drop is a constant (your finger changes neither the air pressure at the outlet nor the head pressure of the massive reservoir driving flow from your housepipe). Thus the only thing that can reduce flow is an increase in resistance. So, given that the flow rate drops when you add your finger, why does the velocity (in meters per second as opposed to volume per second) of the effluent water increase? Remember that water is essentially incompressible at these pressures, so the volume flow rate of water is a constant down the length of the hose for any given set of conditions. In other words, whatever the flow rate is into the hose from the spigot is also the flow rate out of the nozzle. The velocity of flow (in distance per time) is simply the volume flow rate per time divided by the cross sectional area of flow. When you add your finger, the volume flow rate drops but the cross sectional area of flow drops more. Thus the overall value of this ratio increase and the water leaves the hose at a higher velocity. Thus the so-called 'misconception' is actually almost the correct explanation for the phenomenon. While it is not true that the same amount of water gets forced through a smaller opening, the physical cause of the increase outlet velocity is the fact that the water is getting squeezed through a smaller opening (just a bit less water).

Please do not re-add this entree. It is inadequately sourced, and frankly you are not going to find a reliable source that supports this explanation because no expert in fluid flow would give this incorrect explanation as it is wrong in several elementary respects as I explained above. As a matter of fact, the entry is incorrect. As a matter of Wikipedia policy, given that this claim is contentious you need to adequately source it if you even want to consider re-adding it. The whole point of adequate sourcing is to prevent this sort of error from living in Wikipedia and misinforming people. Thanks-Locke9k (talk) 05:23, 2 May 2009 (UTC)

I undid Ariel's edit simply because it wasn't by a regular editor, it gave a seemingly facile reason for the item being nonsense, and it said "see talk" but a search of this page for the editor's name turned up nothing. Sorry about that. -- BenRG (talk) 10:52, 2 May 2009 (UTC)

No worries. Locke9k (talk) 13:54, 12 May 2009 (UTC)

Rracecarr has once again reverted the removal of this material, without discussion. I have removed it again as it is uncorrect and inadequately referenced, as I describe above. Please respond to the point raised here before any other reinstatement. Locke9k (talk) 13:53, 12 May 2009 (UTC)

It may be that the entry is inadequately referenced, but it is fundamentally correct. I don't have time to explain it exhaustively right now. But I think with a phd in physical oceanography it is not much of a stretch to call myself an expert in fluid flow, disproving your claim that "... no expert in fluid flow would give this incorrect explanation as it is wrong in several elementary respects". Perhaps I will return later to write a rebuttal. Rracecarr (talk) 14:22, 13 May 2009 (UTC)

PhD in physical oceanography? The explanation that was there was well rebutted by a number of users with sufficient physics background. It was incoherent, so I would not brag about the PhD, it will just make you look silly. Why does the water move faster? My explanation: reducing the size of the opening reduces the flow rate. This causes the pressure to rise. (Obvious: with zero flow rate , but an open faucet and clear hose, the pressure everywhere in the hose becomes equal to the pressure in the piping up to the faucet. With a totally open hose, the pressure at the end of the hose goes almost to zero. Given water behind an opening, under pressure, the speed of the water which flows through the opening will increase with the pressure. Higher pressure, faster water spray, but lower overall flow rate. If there is no friction at all in the hose, all this remains true. Friction has nothing to do with the phenomenon. Who wrote your general Physics textbook? Serious question, not a joke or insult.

The explanation of "being squeezed through a smaller opening" as if this is what makes the water squirt faster and further is also incoherent. If the pressure is constant, the water velocity will be constant, if I've got the concept right, no matter how large the hole (more or less, neglecting turbulence, etc.) If there is an opening that water is flowing through, the flow velocity will be proportional to the pressure difference between the two sides of the opening. The faucet has a certain size opening which is presumably smaller than other restrictions in the water system, that is the factor that limits flow. When the flow is low compared to the maximum that the faucet will allow (no hose! open faucet!), the faucet does not reduce pressure much. Put an open hose on this faucet, if the hose is open and not extremely long and uphill, the pressure in the hose is low; most of the pressure drop is across the faucet opening. Start to restrict the flow through the hose, say with a nozzle, the flow drops and the pressure drop across the faucet decreases, so pressure inside the hose rises. With the smallest of openings in the nozzle, the pressure in the hose will approach full system water pressure. At such a low flow rate, though, the maximally fast spray can't maintain a water stream and the spray becomes mist. --Abd (talk) 00:01, 14 May 2009 (UTC)

I didn't write the entry, asshole. I just recognize it as a reasonably well written paragraph pointing out something most people probably never realized--that it is not the flow rate that remains constant, but the pressure at the source. Rracecarr (talk) 00:49, 14 May 2009 (UTC)

I did not imagine, nor did I state, that you wrote the entry. Seems some sensitive nerve has been touched. Be careful; you are an active contributor, you have never been blocked, but your work could be interrupted if you fail to respect WP:NPA. I don't try to get editors blocked for personal attacks on me, but someone else might. If the piece was well written, then please tell me what role friction plays with water pressure, flow rate, and flow velocity? Yes, "source" pressure, more or less, remains constant (big pipes compared with the constriction in the faucet valve). But it's after that fact that the piece becomes incoherent.

Consider this thought experiment. Imagine a pipe with water flowing through it, and a constriction in the middle of the pipe, say the pipe is constricted such that the cross-sectional area is halved in the middle. The flow rate is constant over the whole length of the pipe: the volume of water going through each cross-section of the pipe, per unit time, is the same. That same amount of water, however, is flowing through a narrower pipe at the point of constriction. That is, twice as much water per unit area per unit time is flowing at the constriction. This directly translates to a doubling of the speed of the water. The supposedly mistaken "common misconception" isn't really all that bad. Indeed, the same amount of water is being "forced" through a smaller pipe, so it flows faster. But this explanation doesn't really say why. At the constriction, the water will "squirt" ahead, but the water will then fill the whole pipe after the area of turbulence (where the pipe widens again), and pressure will be (almost) uniform along the pipe except at the transition points. What we see at a point of constriction is a pressure drop; the change in pressure is a force that accelerates the water.

And I really was curious who wrote the physics text you used for basic college-level physics. Quite possibly, I was literally there when it was written. --Abd (talk) 04:33, 14 May 2009 (UTC)

What is the common misconception here?? Most people, I would guess, haven't the slightest idea of the physics behind why this happens. Why is it even being discussed as a common misconception? (I have no idea who is right on the issues of physics). --hippo43 (talk) 05:07, 14 May 2009 (UTC)

[outdent] Locke9's first criticism is that the pressure at the outlet is always atmospheric. Obviously what is meant is the pressure just upstream of the nozzle, or thumb or whatever--the pressure near the end of the hose. The entry could be reworded, if people think it's necessary. The rest of Locke's post is wrong. It is not the frictional losses associated with the thumb that are important. The flow rate does not decrease because of friction. In the completely inviscid case, it would decrease by an even larger factor. Considering the inviscid case is also an easy way to demonstrate that Abd's claim about the unimportance of friction is incorrect. Assuming a given source pressure, for inviscid flow the velocity at the outlet will be the same regardless of the size of the opening--it will be just fast enough to squirt straight up to a height matching the pressure head (thumb will not make it squirt farther). So, here is the deal: friction is NOT the main reason that flow decreases when you apply your thumb; but it IS what causes the pressure drop along the hose, so when you slow the flow with your thumb, reducing the frictional losses in the pipes/hose, the pressure just behind your thumb is greater. If you slow the flow enough to substantially cut frictional losses in the pipes/hose, you squirt to a height approaching the head of pressure at the source.

I will not replace the entry, because it is certainly not sourced as a common misconception. I have replaced it in the past because it irks me to see edits made on the basis of bad physics.

Abd: I apologize for my language. I did not use the FLOP in college, but I have them, and they are fantastic. Rracecarr (talk) 15:46, 14 May 2009 (UTC)

Apology accepted, Rracecarr, and I see, reading above, that I did mention the Feynman lectures before, and that you had acknowledged it. I'd forgotten I'd written that.

On the substance, no, friction is largely irrelevant. This statement is interesting: Assuming a given source pressure, for inviscid flow the velocity at the outlet will be the same regardless of the size of the opening--it will be just fast enough to squirt straight up to a height matching the pressure head (thumb will not make it squirt farther). This is correct, but one might overlook the assumption: Assuming a given source pressure. In this case, "source pressure" refers to the pressure of the water at the thumb, i.e., just on the source side of the restriction that the thumb creates. However, that is not the ordinary case. Ordinarily, as the flow decreases due to an increased restriction (which is simply the reduction of the opening through which the water flows), the pressure increases. The water flows faster (velocity, not flow rate) because of the increase in pressure.

The sensation at the thumb is one of pressure, of "squeezing." And that's accurate, in fact. No squeezing, i.e., no force behind the thumb, no squirting. There is no pressure drop along the hose. Pressure is constant along the hose! The pressure at the faucet end is the same as the pressure at the thumb. (Assuming they are at the same level.) Block the opening completely with your thumb, if you can, the pressure in the hose becomes the system pressure, i.e., the pressure behind the faucet. With a very small opening, that's the pressure that squirts the water out. Allow the flow to increase, the pressure drop at the faucet will increase, being the major site of pressure loss (typically, anyway, normally the pipe supplying the faucet is substantially bigger than the valve opening in the faucet), so the pressure will fall.

What the thumb is doing is increasing the water pressure inside the hose, by reducing the flow rate, causing less pressure to be lost, not from friction, but from the flow constriction at the faucet.

Thought experiment: We have a 50 foot hose, open at the end. With the tap open to a certain position, a certain flow rate will be established. Now we add a few more lengths of hose, all laid out on flat, level ground. What happens to the flow rate? If friction -- i.e., resistance to flow -- is involved, surely there would be more friction, and therefore lower flow rate. What is the pressure profile along the hose? This is my impression and expectation, and this would make a nice science fair project: the pressure in the hose, for its entire length, is very low. The length of the hose does not matter, it does not reduce flow rate. The system pressure drops at the faucet to almost zero in the hose, if the hose end is wide open. My estimation is that pressure in the hose does not start to rise until the end of the hose is constricted to a point where the open cross-sectional area matches that of the faucet opening, and as the opening is reduced below that, the pressure rises toward the system pressure (behind the faucet) until, with zero opening, it is the system pressure. --Abd (talk) 03:03, 15 May 2009 (UTC)

You are mistaken. Adding more hose does reduce the flow rate. Source pressure does not refer to pressure just behind the thumb--it refers to the pressure way back at the water tower, or the large tank with the bladder of compressed air above it. If you open the faucet wide, and there's no nozzle on the hose, the pressure drops fairly steadily to zero along its entire trip, from the source through the plumbing and the hose. More hose = more friction = less flow. You can also get less flow by tightly coiling the hose into a bunch of sharp curves. None of that really matters. The water will flow just fast enough that there's enough friction to bring the pressure to zero at the outlet. Provide a flow constriction, and you reduce the flow, reducing the friction, and so increasing the pressure just behind the constriction from zero to some finite value. Rracecarr (talk) 03:51, 15 May 2009 (UTC)

Yes, adding more hose will reduce the flow rate. But very little; doubling hose length would have, from my experience, no discernible effect on flow rate. How about I try it? Maybe this weekend. Yes, "source pressure" technically refers to an ultimate source, however, the water system in a house, to which a faucet is connected, does not experience a large drop in pressure from turning a single hose faucet on, and so I've been using "source" pressure to refer to the local system pressure. Because the supply to the local system is not unrestricted, local pressure will, in fact, decline with flow rate, but I'm neglecting that. What I'm claiming is that pressure drops occur due to constrictions, for the most part, excepting a very small effect from "friction" and the viscosity of water, which is a kind of friction, and once the flow has been inhibited by a constriction, the pressure beyond that point is not affected significantly by additional constrictions that are not tighter than the earlier one. I don't know why Rracecarr is having such a difficulty here. (If I'm the one having a difficulty, I very much want to know, one gets concerned about errors like this at my age!)

Water does not flow in the hose due to pressure differences along the length, it flows because water is entering the hose at a rate controlled by the faucet, and water is essentially incompressible, so it must flow out the other end of the hose at the same rate. The water entering the hose "pushes" the water out the other end, quite as much as if the water were a solid rod being pushed into the hose at one end and coming out the other.

So, we have an experiment: How much will the flow be reduced if I double the length of hose? If resistance to flow is linear, it could be predicted, perhaps, that half as much water would flow. I'm predicting that the reduction in flow will be low, possibly not even measurable. (There is a small reduction in cross-section at a hose junction, but probably not below that of the restriction in the faucet, and I can make sure that it's that way by using a relatively low flow rate as controlled by the faucet.

But maybe I can short-circuit this. Water is incompressible, for practical purposes. If there is a continuous body of water, the pressure at any level will be constant through the body. (Pressure increases with depth due to the weight of water.) In the example given by Rracecarr, we have a continuous body of water in the hose, assuming no air pockets, and we can insure this by raising the end of the hose slightly and making sure that air has been able to escape from loops. But according to Rracecarr, the pressure declines "fairly steadily to zero along its entire trip." This contradicts the well-known behavior of incompressible liquids, they "conduct" pressure efficiently (at the speed of sound in the liquid, I think.)

So, for starters, I wonder if Rracecarr would predict, using his theory, an approximate level of reduction in flow rate from lengthening the hose (adding a new section of hose). I would make the flow rate low, to make it easier to measure rate more accurately, I.e. I'd want it to take maybe a minute to fill a bucket. How will the flow decrease with additional hose?

Tell me: if pressure is reduced uniformly along the hose, then pressure at the faucet end would be "system pressure," i.e., the pressure behind the faucet. It would also be system pressure (not much elevated) if the flow through the hose is stopped completely. If we open up the hose, how does the pressure change at, say, a tee inserted into the hose at the faucet? From experience, a closed hose will have no effect on pressure at the tee, it will be system pressure or whatever the flow through the faucet allows. However, if the hose is open, pressure at the tee will be very low, not the full pressure predicted by Rracecarr's theory. So: how much would the "head" of water be reduced at the tee by opening up the hose? Obviously, if the two tee openings and their connected hoses are equivalent, then water would flow through both, but what I have in mind is a length of hose connected to the tee to show the head (how high will the water go?) and the other hose is level to the end. I predict that the water will rise only a little, a small percentage of what full pressure would cause. Racecarr's theory leads to a number of contradictions with common experience. Common experience would say that, at the tee, with a hose elevated only a little from the tee, water will squirt out a full pressure when a valve at the end of the hose is shut, and pressure at the tee declines rapidly as that valve is opened, until only a little elevation prevents any water from flowing out the alternate, elevated outlet from the tee.

My claim is equivalent to asserting that the viscosity of water is negligible in the situation described. Freeze the water, or load it down with guar gum, all bets are off.--Abd (talk) 16:14, 15 May 2009 (UTC)

I'm sorry, but you're entirely wrong. Without friction, there is no pressure drop across constrictions. For steady inviscid flow, Bernoulli says that pressure along a streamline is a function of velocity and height only. If pressure drops across, say, a faucet, and the pipe leading to the faucet is the same diameter as the hose connected to it, that pressure drop is due to friction, and friction only. Rracecarr (talk) 18:15, 15 May 2009 (UTC)

Oh, goody! If I'm wrong, I get to learn something. One of the reasons I'm so smart is that I've made a lot of mistakes, it's the fastest way to learn. As long as one pays attention to the facts and to responses. Rracecarr, what do you predict, from your friction theory, will be the result of lengthening the hose by coupling a new section onto it? --Abd (talk) 19:56, 15 May 2009 (UTC)

Part of the confusion here may be the use of the word "friction". Lets talk in technical terms: the issue is transfer of momentum from the fluid to its surroundings (namely, the hose and constriction), where the momentum transfer is in the direction perpendicular to flow. This is probably the closest technical equivalent of what you think of as "friction". The so-called "frictionless" case is the idealized purely inviscid case (which does not exist in nature), in which there is no momentum transfer from the fluid. In this case, no momentum is lost as the fluid flows through an even-diameter pipe.

However, if I understand you correctly Rracecarr, you are incorrect in your statement that there is no pressure drop across a contraction for inviscid flow. Here I provide a mathematical derivation proving that such a pressure drop must in fact occur.

Consider an inviscid, incompressible fluid. Since it is incompressible, the flow rate of this fluid through a hose of constant diameter must be a constant as a function of position along the pipe, in order to satisfy conservation of mass. Let the index 1 indicate variables before a contraction and the index 2 indicate variables after the contraction. The flow rates are then given by $F_{1}=V_{1}A_{1}$ and $F_{2}=V_{2}A_{2}$ where A represents cross-sectional area of flow, F represents volumetric flowrate, and V represents velocity.

Now, as per the above statement, $F_{1}=F_{2}$. Thus $V_{1}A_{1}=V_{2}A_{2}$. Rearranging, ${\frac {V_{1}}{V_{2}}}={\frac {A_{2}}{A_{1}}}$. Thus if $A_{2}>A_{1}$, as is the case for a contraction, then the velocity after the contraction is less than the velocity before the contraction. Lets now consider how this fits into Bernoulli's principle, which you keep mentioning. Bernoulli's equation is: ${\tfrac {1}{2}}\,\rho \,v^{2}\,+\,\rho \,g\,z\,+\,p\,=\,{\text{constant}}\,$. Now lets say the hose is laying on the ground, in which case z=0. Then we are left with${\tfrac {1}{2}}\,\rho \,v^{2}\,+\,p\,=\,{\text{constant}}\,$. Now, from the above, v increases across the contraction for an inviscid fluid. Thus in order to satisfy Bernoulli's equation p must drop across the contraction. Thus, even for inviscid flow, there is a pressure drop across a contraction. Locke9k (talk) 21:34, 15 May 2009 (UTC)

I withdraw my earlier objection to inclusion of the misconception (although I stand by my analysis of inviscid pressure drop across a contract above). Now that I actually do the math it would appear that the essence of the original was correct, although possibly with some rewording. This can be shown by a simple energy balance. The kinetic energy of the effluent water must be equal to the potential energy of the head of water driving it, minus frictional losses:

${\frac {1}{2}}\rho v_{0}^{2}=\rho gh-l_{f}$

where $l_{f}$ is frictional losses and $gh$ is the head of pressure. Rearranging this gives: $v_{0}=(2(gh-{\tfrac {l}{\rho }}))^{1/2}$. Thus for a constant pressure head, the only way the outlet velocity can increase is with a decrease in losses. It thus follows that if putting your thumb over the outlet to the hose increases the outlet velocity, it must be decreasing the net frictional losses.

My apologies for my incorrect analysis above. It was based on intuitive thinking that really only applies for constant flow-rate driven flow rather than constant pressure driven flow. Its a good example of why even for an expert it can be important to do the math for a new problem before talking rather than relying purely on intuition.

Commensurate with this analysis, I'll strike through my incorrect statements above. I'll also work on finding some better referencing so we can add this one back in in a better form. If its such a common misconception that it can fool people knowledgeable in fluid flow then it probably belongs in the article.Locke9k (talk) 22:06, 15 May 2009 (UTC)

This discussion is far beyond my ability to understand it. I don't know if this helps or hurts, but I raised the question on the Science Reference Desk but I got lost in the math.[16] A Quest For Knowledge (talk) 22:21, 15 May 2009 (UTC)

The gist of it is that I originally trusted my intuition in criticizing this entree, which turned out to be incorrect. Unfortunately overconfidence in intuition can be one of the pitfalls of being fairly expert in a subject but not having encountered a specific problem before. I have above shown mathematically in a rigorous way that the entree and Rracecarr's defense of it are essentially correct, although it needed some minor corrections. The outstanding question now is whether it is adequately sourced as being a misconception and as being corrected, or whether it can be adequately sourced. Locke9k (talk) 22:27, 15 May 2009 (UTC)

We are, unfortunately, conducting original research here; I don't mind a level of that, but, in this case, much of the original research above is incorrect or, at least, confused or confusing. I responded further in a post to User talk:Rracecarr#"Friction" with water?. One point out of it:

The net flow (say, so many gallons per minute) is the same all along the hose. However, through a constriction, to get the same flow, the speed (say, feet per second) must increase to compensate.

By the Bernoulli principle, if the velocity is constant, as it is along an unconstricted length of hose, the pressure must also be constant. So the pressure does not decline along the hose, as Rracecarr claimed; rather, with an open hose, or with any constriction at the end, the pressure along the hose is constant; the changes in pressure only take place at places of constriction, where pressure decreases as speed increases. If the hose is open at the end, the pressure in the hose is essentially zero, assuming the hose is level, and it is zero all the way back to the faucet.

(Because water is not perfectly free of viscosity, this isn't absolutely true, but for practical purposes, it is.)

While it is true that, when we constrict the output of a hose, as with a thumb, the pressure increases, when we look at the steady state with a given outlet size, the water is not flowing faster in the hose itself, indeed, it is flowing slower. But then it is quite reasonable to understand what is happening at the outlet is that this same flow (i.e., the same as is flowing into the hose and as is flowing out of it) is "squeezed" through a smaller opening, and therefore must travel faster. Thus the supposed "popular conception" is not wrong, though it is incomplete, it does not address the reduction in flow rate and increase in pressure inside the hose which goes together with the increase in speed at the hose opening. The increase in pressure is caused by the water being "squeezed" through a smaller opening!

The increase in pressure can also be understood as being caused by a lessening of the pressure drop across the faucet feeding the hose (mostly), due to decreased flow. The flow does not decrease from "friction," not with an inviscid liquid like water, but from pure reduction in the channel size with a constant pressure. Rracecarr was correct that with constant pressure behind an opening, the speed of water leaving the opening does not vary with opening size. But the total flow rate varies directly with the pressure and the size of the opening, and the flow rate affects the pressure loss at the faucet, and the resulting increase in pressure can approach the full system pressure as the flow approaches zero. I'm still not satisfied with this explanation.

When I put my thumb over the end of the hose, I can feel the squeezing, in fact. It really does feel like I've got an incompressible liquid, as I do, and, in fact, if there were no water source, no water pressure, and under certain conditions, I could get the water to squirt about as far with the same thumb pressure. Because the system would be losing water, I'd have to have the squeezing be arranged to be able to move, but it's not a bad way to think about this, that the thumb is squeezing water out of the hose or "squeezing it through a smaller opening." The thumb pressure increases the water pressure at the same time as it reduces the opening size. (The water pressure cannot exceed the pressure applied by the thumb!)

Bottom line: the article was incorrect, friction is not the explanation at all. --Abd (talk) 23:33, 15 May 2009 (UTC)

Let me see if I can explain the above math in intuitive terms. I'll start by mentioning that the viscosity and thus frictional losses of water are non-negligible. A key way of seeing this is to note that it is much harder to push an equal flowrate through a small tube than a large one. This will come up again later in the explanation. There are many other ways to show this, but suffice it so say that if you go to the WP page on Bernoulli's principle it points out that "Bernoulli's equation is not applicable where there are viscous forces."

So with that aside, lets see if we can understand intuitively what the equations say. Essentially, the above energy balance equation says that the kinetic energy of the outlet fluid must be equal to the pressure-related potential energy at the reservoir driving flow, minus any energy lost to friction. Neither potential or kinetic energy are a function of hose diameter, so regardless of the specifics of the intervening pipe, in the absence of friction at a fixed inlet pressure the water will always exit the hose the same speed! No property of the hose such as diameter, bends, or constrictions will affect this. So we have established that the velocity at the outlet is fixed. As you pointed out, the flow rate must be constant along the hose. So since the velocity at the outlet is fixed, the diameter at the outlet sets the flow rate all along the hose!

So what does this mean practically? Lets imagine a hose with a nozzle at the end with flow being driven by some fixed pressure from a large reservoir. This is exactly the situation we are imagining. However, for an inviscid fluid, if we leave the size of the nozzle outlet the same but change the diameter of the hose it is attached to, the flow rate of fluid will stay the same! Now lets add friction. First remember that with friction added the outlet velocity will be lower than it would be in the inviscid case due to frictional energy losses. Also remember that I mentioned that the resistance to flow decreases as the hose diameter increases. So if we mentally fix the size of the nozzle outlet and vary the size of the hose, the resistance to flow will drop as the pipe gets larger and the outlet velocity will increase and approach the inviscid case. Now flip this around. If we make the nozzle outlet smaller and smaller for a fixed hose size, we are making the hose relatively larger compared to the nozzle and accomplishing the same effect. So essentially by making the nozzle smaller we are dropping the rate of flow, dropping the resistance in the rest of the hose by making it relatively larger compared to the flow rate, and thus increasing the outlet velocity based on the energy balance I described above. Thus the explanation is correct: by constricting flow more we are reducing the flow rate relative to the size in the rest of the hose, the reducing frictional losses and increasing the velocity. We are not pushing the same amount of water through a smaller hole: the mechanism of action is in fact by dropping the flow rate and thus the resistance.

Hopefully this gives you a more intuitive view of what is happening than the above math. As far as your claim of OR goes, I don't think it really is. These equations are long long established and certainly within the main body of science. There was a reference on the entree, and I will try to find that book and check it out. I'll also see if I can find other reference; I suspect they are out there. Locke9k (talk) 02:11, 16 May 2009 (UTC)

To correct a possible misunderstanding, the application of those equations to the situation falls within OR. The math may have been correctly applied to frictional losses -- I have not checked it -- but did not deal with the case that frictional losses are low, which is what I'm claiming. In other words, the increase in pressure at the outlet by introducing a constriction there will occur even if frictional losses are negligible. Neither editor arguing for friction here has ventured to make predictions about the result of the addition of extra hose experiment. The flow out of a faucet is limited by the faucet setting, which amounts to the size of the opening allowed for water to flow through, under the case that there are no prior restrictions back to the ultimate source of pressure that approach it in tightness. When we add hose to the faucet, the hose, if open at the end, does not, I claim, significantly change the flow, no matter how long it is. It could be a hundred miles long, as long as it is level; water will flow through it at a pressure that approaches zero. Significant viscosity would change this. If the hose is full of water, without significant constrictions, the pressure everywhere in the hose will be the same (at steady state). Locke assumes significant resistance to water flow in the hose. That is contrary to my experience, but my intention is still to test it by measuring flow as affected by the addition of hose length, a very simple experiment. Because the assumption of frictional loss is intimately woven into Locke9k's discussion, I won't answer in detail easy assertion, but only this:

... since the velocity at the outlet is fixed, the diameter at the outlet sets the flow rate all along the hose!

That is not true in the general case. With an open hose, the flow rate is set by the faucet. What is said here is true only when the outlet is smaller, i.e., more restrictive, than the opening in the faucet. The pressure in the hose does not begin to rise significantly until the outlet opening has been reduced so that it becomes the significant blockage to flow. Until then the pressure in the hose will be close to zero (zero with an ideal inviscid liquid).

Consider it this way: suppose the faucet is set to allow a slow rate of flow. The hose will not resist this rate of flow; with a level hose, the water will simply flow at very low pressure through the hose. The hose will, in fact, if completely level, not fill with water, the water flows by gravity at each point. (i.e., the pressure does vary in the hose, but only by gravity across the vertical inside dimension of the hose; at a given height, the pressure along the hose is constant.) (With a very long hose "frictional resistance" to flow may indeed cause the hose to fill at the faucet end.) (Imagine that the faucet is just dripping. With an open hose, the water will still flow, at the drip rate, to the end of the hose, where it will drip out. Behind that drip, at the faucet, is high pressure, so if the hose should be constricted at the end, say it is allowed to fill by raising the end slightly, which allows the air to escape as the hose fills with water, and then the end is fully blocked with a thumb, the pressure will increase to the system pressure and the water will "try" to squirt out (because the hose is elastic, generally, there is at this point a certain "stored pressure" in the hose, released by contraction of the hose; if not for that, the squirt would be extremely brief). The pressure drop, originally entirely at the faucet, is now at the outlet, because the thumb has restricted flow below what the faucet allows. Again, anyone who has tried to patch a pipe leak knows how it may be difficult to stop with tape wrapped around a pipe, unless the leak is so small that other factors take over. Basically, the tape must be tight enough to resist the full system pressure applied at a small point.

We can cut to the chase, by this common-sense analysis: Imagine a hose with a constriction in the middle. Water is flowing through the hose. The speed of the water is a constant along parts of the hose with invariant cross-section. The flow rate is constant along the hose. Since the same water is flowing through a smaller diameter hose, at the constriction, the velocity must increase there to keep the overall flow rate constant. After the constriction, the velocity drops back to the original value. The simple explanation of the velocity increase at the constriction is that the same amount of water is being squeezed through a smaller opening is actually reasonable; however, when the opening is constricted to a point that the hose no longer accommodates the normal flow from the faucet, the pressure as the water enters this tighter constriction begins to rise, as the pressure drop at the faucet is reduced -- which drop is not caused by friction unless the opening is very small -- and this pressure increase adds to the force behind the squirt. The whole phenomenon, one with which we are, nearly all of us, familiar, requires no friction for explanation, and my prediction is that experiment will show that frictional effects are negligible. I was hoping that describing the experiment would be enough; instead, apparently, one or more editors got lost in the math. --Abd (talk) 14:42, 18 May 2009 (UTC)

It appears that you did not fully follow my derivation above. In fact, I did not assume the presence of friction - I started with the inviscid ("frictionless") case and worked from there. Actually, the derivation above relies upon no approximations of any kind. I have simply written down the equation for conservation of energy in this system, which is a law of nature. There's no getting around it, and your statement that they 'haven't been applied to the low friction case' simply isn't true. Conservation of energy always applies provided that you are not in a relativistic / nuclear situation.

As far as your experiment goes, if you made the hose sufficiently long, you would find that it affected the flow rate. Doubling the length is simply probably not enough to make a noticable difference, since as you pointed out most of the resistance is from the valve in the faucet. If you look at the overall resistance in the line, the vast majority of the resistance is from the faucet and only a very small percentage is from the hose. Thus doubling the hose length is really only very slightly increasing the overall resistance. This is particularly true when the flow rate is set low, which means the valve is almost closed and is offering very large resistance.

As far as your OR statement goes, I agree that it would be best to have this clearly stated outright in a reliable source. There actually was one source offered in the entree, and I am planning to check that out as soon as I can - it may turn out to be an adequate source. Otherwise, I will look for other sources. Locke9k (talk) 23:23, 27 May 2009 (UTC)

What actually happens?

Above, friction was repeatedly proposed as an explanation for the commonly-observed increase in pressure when flow is reduced in a hose, i.e., that when the flow rate decreases, loss of pressure due to friction was reduced. It was claimed that pressure in a hose that is open at the end is reduced from source pressure (pressure at the faucet in this case) to zero at the end. To test the hypothesis that frictional loss of pressure was proportional to flow rate, I conceived of a thought experiment: measure the flow rate through a hose that is one length (25 feet), then measure the flow rate when no other parameters are changed except that the hose is doubled in length by coupling an additional hose section. I claimed that the flow rate would not change, whereas if frictional losses would reduce the pressure to zero at a given flow rate over the length of the original hose, there would then be no pressure for the additional length of hose; but this argument would apply to any length of hose as the original and therefore the pressure would be zero over any length of hose. The thought experiment wasn't adequate, apparently, to convince those arguing for friction with complex equations. So, yesterday morning, needing to use a hose on a lawn, I tested the idea. I connected a 25 foot length of hose to a faucet and adjusted the faucet to what seemed to be roughly half of full force. I measured the time to fill a bucket that was approximately 5 gallon capacity, it was 101 seconds. I then coupled an additional 25 feet of hose on, and measured the fill time. It was 100 seconds, which is within time measurement error. (In addition, when I was filling the bucket the first time, for part of the fill, about half, I had the hose end elevated by the bucket height, which would slightly slow the fill rate because of gravity differential; for the remainder of the time and for the second run, the hose end was kept at the bottom of the bucket.)

Adding length of hose does not significantly reduce the flow rate and therefore friction with the hose is a negligible effect.

My prediction is that the hose could be made any length and that flow rate would not be reduced, that the only restriction on flow is that produced by a constriction in the line, which is not a frictional effect, but simply a reflection of the fact that flow of a non-viscous liquid through an opening is proportional to source pressure and the cross-sectional area of the opening (if turbulence can be neglected), and that water, on this scale, behaves non-viscously. Hence a flow through an open hose is generally determined by the faucet setting, if this is the tightest constriction in the line. Putting the thumb over the end of the hose moves the tightest constriction to the end of the hose, shifting the point of pressure loss to that location, the pressure loss at the faucet moves toward zero. Communication of pressure through a full hose, if we neglect the elasticity of the hose, moves at the speed of sound in the water, so pressure increases immediately at the hose end, causing the squirting seen. I was unable to stop the flow at the end with my thumb, getting myself quite wet through trying; I could not assert full system pressure with my thumb, which is what would have been required.

(There is also obviously some pressure, possibly transient, involved in coupling a new length of hose, at the junction with the old hose, because that, as well, squirted water as I added the hose. I had to add it "live, " with water flowing, because I didn't want to change the faucet setting. I really did get quite soaked. I do not pretend to understand this phenomenon.)

This is, of course, original research, and is useful only for background, and as an object lesson. What is above as analysis of the situation, by editors apparently competent with math and basic physics, is also original research, and, though asserted with great confidence, was dead wrong. Likewise the original source cited in the article for the frictional explanation, though published, was wrong. We should be careful about unconfirmed original research, no matter where published, and not assert it as definitive, which was the error made in our entry on this matter.

This is of application to my current major Wikipedia project, Cold fusion. Theory should always be subservient to getting wet. Those with science backgrounds are especially invited to watch Cold fusion, where there is apparent collision between long-established theory, widespread rejection of experimental results and interpretations twenty years ago, to the point that cold fusion came to be considered an example of pseudoscience, and ongoing peer-reviewed publication of positive results, anomalous under accepted theory, and coverage of this in other reliable sources. --Abd (talk) 13:07, 24 May 2009 (UTC)