Talk:Conversion of units/Archive 2006

Light Year?

Is there an official definition of a light-year anywhere? Whoever supplied the figure listed here apparantly used a Julian year. Is it really officially defined as such, or is it not a formally-defined unit?

I don’t know how official that value is, but it is in accordance to the main article: light year. Christoph Päper 18:42, 6 March 2006 (UTC)

Exact/Defined Formatting

I think splitting the "Relation to SI Units" columns into "Definition" and "SI Equivilency" or something to that effect would make the mess of numbers much clearer. I can do this if there is no objection. Prometheus235 18:58, 16 Jun 2005 (UTC)

Kudos to User:Crissov for doing the def. column. I tried to polish up the length table to make it more intuitive between exact, defined, and approx. quantites, here's the first bit of it:

Key:

• () Repeated digits, e.g. 1/11 = 0.09(09)
• Bold Exact quantities

Length, l

Name of unit	Symbol	Definition	SI equivalent
metre (SI base unit)	m	co × (1/299 792 458) s	1 m
inch	in, "		2.54×10-2 m
fermi, femtometre	fm	10-15 m	10-15 m
x unit; siegbahn	xu		1.0021×10-13 m
stigma, picometre	pm	10-12 m	10-12 m
Bohr radius; atomic unit of length	a0, b; au	α/(4πR∞)	5.291 772 083×10-11 ± 19×10-20 m
ångström	Å	10-10 m	10-10 m
micrometre, micron	µ, µm	10-6 m	10-6 m
twip	twp	1/1440 in	1.763 (8)×10-5 m
mil; thou	mil	10-3 in	2.54×10-5 m
mickey		1/200 in	1.27×10-4 m
point (ATA)	pt	0.013837 in	3.514 598×10-4 m
point (PostScript)	pt	1/72 in	3.52(7)×10-4 m
point (metric)	pt	3/8 mm	3.75×10-4 m
point (Didot; European)	pt	1/72 French royal inch	3.759 715×10-4 m

I more or less removed superfluous digits, converted it all to meters w/ sci. notation, filled in definitions, etc. I'd like some feedback before I go and do everything. -- Prometheus235 21:04, 20 Jun 2005 (UTC)

I prefer engineer style, x·10^3·n, but scientific style should be fine. I also prefer · over ×, but × seems to be more common in English usage. Equals sign etc. have an advantage when copying to plain text. Christoph Päper 21:54, 20 Jun 2005 (UTC)

I'd actually prefer the ˙ and eng notation (for some quantities), but × seems to be more prevelant in WP. I'm trying to move away from all the equals, approx, equivalent to signs because they are generally confusing, as far as copying into plaintext it doesn't seems that important, most users would probably only be interested in one of the quantities so wouldn't mind a missing sign. I'd also like to sort the units differently, so users wouldn't have to sift through the dozens of obscure units to find a more common one, however I'm not exactly sure how. -- Prometheus235 23:20, 20 Jun 2005 (UTC)

Planck time

Hey, according to this table, a Planck time is defined as: rt(Gh/c^5), where h is a Planck constant. According to the page, it is rt(Gh-bar/c^5), where h-bar is a reduced Planck constant, h/2π. I'm assuming the second one is correct, so I'll change it to that. However, I don't know how to make an hbar without using math tags, which screw up the table. Now the only way I can show that the h is a Dirac's constant, not a Planck constant, is by making the h link to Dirac's constant, which redirects to... Planck's constant. Quite annoying. If anyone can make an hbar that works here, it'd be appreciated. --Dyss 2 July 2005 21:12 (UTC)

Thanks for all your incredible work here. I have, however, noticed a discrepancy in the measure of Planck time. On this table it is equated with SI units as: 1.351 211 818×10^-43 s.

However, on a related wiki page, [1], the measure is: 5.391 x 10^-44. [--207.30.168.9 23:26, 8 November 2005 (UTC) - Karl Kaiser]

Link to "sign"

In the table "Angle", I have removed the link on the word "sign", because it pointed to an article about positive and negative numbers. Couldn't find an appropriate page to link it to. Iggle 07:21, 29 March 2006 (UTC)

Candela, Lumen and Lux

An anon asked on the article page about these units. The El Reyko 20:35, 6 April 2006 (UTC)

templates

I made some templates for conversion, see {{fahrenheit}}, {{inch}} and {{fluid ounce}}. _→AzaToth 21:04, 13 April 2006 (UTC)

Radiation?

I was looking up fatal doses of radiation the other day, and it occured to me that there are several different kinds of ways to measure radiation. Off the top of my head I can think of rems, rads, grays, and roentgens. Should a section be made to include in this article?

Discuss links here

Editors regularly clean out undiscussed links from this article. Please discuss here if you want a link not to be cleaned out regularly. (You can help!)

I start this section because I fully agree with the recent cleanup edit. This article is not a Web directory to online converters. If there are specific reasons to include particular links, please provide them here first. Femto 17:54, 29 May 2006 (UTC)

Hi, I posted the following link: http://publicliterature.org/tools/unit_conversion/

It helped me do a college project very well. It's got units from many fields. Please consider it as a regular link.—The preceding unsigned comment was added by 69.140.31.81 (talk • contribs) .

Should be avoided as an external link (WP:EL). All I got is a page with code for Google ads and a Shockwave Flash application that I won't run on my system. Generally, I don't think this article can benefit from external conversion services. Femto 11:50, 9 June 2006 (UTC)

I just removed a bunch of these from individual unit articles like kilometre. I though maybe one such link might belong on this page, if any, but I think I agree with you. —johndburger 19:16, 9 June 2006 (UTC)

I put in Unicalc Live web calculator doing units conversion by dimensional analysis as this is a powerful and easy to use tool I use all the time. Your mileage may vary. Jim Bowery 19:02, 3 July 2006 (UTC)

Please read Wikipedia:External links, and then explain why this link belongs here. In what way does the calculator add to a reader's understanding of the topic, over and above the article and the other external links? It may be a great site, it may be in the same topic area as the article, but that does not mean it is a good external link. —johndburger 02:38, 4 July 2006 (UTC)

"Sites that contain neutral and accurate material not already in the article. Ideally this content should be integrated into the Wikipedia article, then the link would remain as a reference, but in some cases this is not possible for copyright reasons or because 'the site has a level of detail which is inappropriate for the Wikipedia article. Sites with other meaningful, relevant content that is not suitable for inclusion in an article, such as textbooks." Jim Bowery 20:03, 4 July 2006 (UTC)

Where does the "content" come in here? Femto 11:37, 7 July 2006 (UTC)

That was my (perhaps too subtle) point—there is little, if any, actual content on that site at all, unless you count "60 kph = 100215 furlonghs/fortnight" and the like. So it seems to me it's completely ineligible as an external link, at least for this article. —johndburger 01:50, 8 July 2006 (UTC)

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I believe http://www.unitconversion.org should be featured in the external links section since it is the only site to support correct conversions between units - besides it is ads free. —The preceding unsigned comment was added by 195.131.172.165 (talk • contribs) .

Hm, I'm prompted to install a demo version right there, not what I'd call completely ads free... As soon as the first external conversion service link gets allowed, there'll follow a rat tail of spamlinks which someone feels at least as worthy of inclusion. The history of this section shows that everybody has their own favorite. It's a purely subjective decision, and WP's external links are not a popularity-based Web directory. We can't add all, so there is none. A solution could be to include one link only, to an open Web directory on these conversion tools, as suggested by WP:EL. Femto 11:37, 7 July 2006 (UTC)

you are completely off here - the site offers all the converters for FREE. it is unmatched with any others in the list - just dig futher. the _site_ is ad free

its very handy and way forward of any others online javascript converters

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I would like to add a link to http://www.converzions.com

converZions is an extensive unit conversion site that can answer conversion related question such as: 'How many kilograms are in ten pounds?' I believe it will be a useful resource for the readers of this article. Please approve. —The preceding unsigned comment was added by 67.80.55.108 (talk • contribs) .

Rather not, see my reasonings above. Femto 12:55, 28 July 2006 (UTC)

Javascript Converter

Do we want to make a javascript unit converter part of wikipedia? --RobBrisbane 00:45, 13 June 2006 (UTC)

all the numbers you get after performing calculations on a calculator or with pencil and paper are not meaningful.

What does this mean? Is it - a) not all the numbers you get are meaningful, or b) all the numbers you get are meaningless.

TharkunColl 23:04, 13 June 2006 (UTC)

Logically it literally means (b) but obviously the author would have intended (a) so it needs fixing. Then, on the other hand, "All that glisters is not gold". Jimp 00:25, 17 May 2007 (UTC)

Reference section added

A change was made today, redefining a line from 1/12 to 1/16 inch. I changed it back, and added a reference section so we can show where we obtained information on the more obscure units. I used Harvard style references rather than the usual <ref> tags because the raised reference numbers caused by <ref> tags could be mistaken for exponents in this context. --Gerry Ashton 01:46, 13 August 2006 (UTC)

Zentner

An editor using the IP address 87.160.227.58 claims a Zentner is 50 kg rather than 100 kg. I have reverted this change because no citation was provided to prove the claim. --Gerry Ashton 19:18, 14 October 2006 (UTC)

The second hit googling zentner is this. Looks like there are at least two meanings. -- Bpmullins 19:58, 14 October 2006 (UTC)

Thanks for adding that to the table, Garry. I'd have done it, but I wasn't sure of how to format it and hadn't had a chance to fiddle around.

I think the anon editor was correct that the Zentner is always 50 kg - see the discussion here. Cheers -- Bpmullins 21:13, 14 October 2006 (UTC)

That discussion appears to have come from the British Weights and Measures Association, an anti-metric advocacy group, so that just isn't a reliable source and I give it no weight. --Gerry Ashton 22:00, 14 October 2006 (UTC)

Okay, I see your point there. However, 'zent' seems cognate to 'cent'=100, and as a traditional measure it wouldn't have meant 100 kg. Or so it looks to me. I'll continue digging... -- Bpmullins 15:29, 15 October 2006 (UTC)

I hope you noticed the footnote indicating that the 100 kg meaning comes from the Swiss Federal Office for Metrology website. I have no way to know whether it might have meant 100 Swiss pounds before it meant 100 kg, and I have no way to know whether the Swiss actually pay any attention to their Office for Metrology. The only thing I'm sure of is I'll never use the Zentner, and if anyone sends me a document using it, I'll reject the document and demand it be rewritten in SI units. --Gerry Ashton 16:55, 15 October 2006 (UTC)

Like the English hundredweight (and similar quintal/centner) the German Zentner used to mean one hundred pounds (Pfund), but just like the English one that didn't always mean 100, but for example in 19th-century Prussia it was 110 Pfund. With the metrication during Napoleonic occupation and the process of German unification until 1871 some traditional units had been given round metric values and, most importantly, these were the same nation-wide. This included most prominently the Pfund of 500 g, which made the Zentner 50 kg without a change in its base definition of 100 Pfund. (Other examples are the Scheffel (German bushel) of 50 l and the Morgen (German acre) of 25 a.) Austria(-Hungary) was finally not part of the new German Empire and so maybe the differing definition of 100 kg evolved. Switzerland (like perhaps some Southern states like Baden) already had the French quintal of 100 kg and Zentner is actually just the German word for that, so they went with this deciton value, which was called Doppelzentner (i.e. "double centner") in the North. Some sources list Meterzentner, which is just an optional distinguishing term like "short hundredweight", "metric ton" or "Neu-Scheffel". The articles quintal and de:Zentner provide most or all of this information. There's a myriad of "metric" units like this one, should they all be included, recognising that most of them are outdated and merely colloquial today? Christoph Päper 12:07, 18 October 2006 (UTC)

Thanks for the information. With such a complicated history, a unit like this won't fit comfortably in tabular format. Maybe we should just provide a link to the relevant articles? -- Bpmullins 16:24, 18 October 2006 (UTC)

When this series of edits began, the Zentner article was totally unsourced. It is somewhat better now, although still weak on sources. Still, I think the best solution is to not give a value in the table and instead provide some kind of link or note, along the lines of "Definitions vary, seek clarification from source." --Gerry Ashton 18:04, 18 October 2006 (UTC)

I emailed the author of the source in Bpmullins' first post to this discussion and here is his reply to me:

The zentner is the German "hundredweight"; it originally meant 100 pfund but usually means 100 kg today. The same considerations apply to other European hundredweight measures such as the quintal. This is a particular egregious example of a common problem: any table of equivalents of units is time dependent, because definitions of units change over time. If you're building a table of current equivalents, then 100 kg is a zentner. If you're more interested in early 20th century units, then it's 50 kg, and if you're interested in 19th century units its 100 (or maybe 110) pfund.

Russ Rowlett

University of North Carolina

Chapel Hill NC USA

So, basically in order to define it, you would have to qualify what time period the zentner is from—19th century, early 20th century, or present.—MJCdetroit 15:12, 19 October 2006 (UTC)

I’m sorry, but Mr. Rowlett’s information is erroneous. The Zentner is still considered 50 kg in most if not all parts of Germany. (The notion of a 100-kg definition had been repeatedly removed from the article in the German WP, probably because people thought that part had to be wrong, because they never heard of this definition that differs from their experience. Austrian and Swiss users are minorities.) This is also the only federal definition there ever has been. There are, however, increasingly more people not familiar with the unit at all, who might assume it to be 100 kg. I don’t know much about comparable processes in other European countries.

He is of course right in pointing out that units may have their definitions changed over time, and be it just for higher precision. Christoph Päper 21:04, 21 October 2006 (UTC)