Talk:12-hour clock/Archive 1

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Contents

a.m. A.M. am AM & What about p?

There is an article a.m., but no article p.m. - I was just wondering whether it was necessary to have an a.m. article, when it seems that this one will suffice. If it is deemed necessary, perhaps there should be a p.m. article as well (though I think the first solution might suffice).

Additionally, although I have not yet found a mention in the Wikipedia:Manual_of_Style, I think it might be a worthy effort to begin discussion here concerning whether to use A.M., AM, a.m., or am (Which is what seems to be in use here and is preferred by myself). Should anyone feel that they can add to this please do. User:Moogle 15 Dec 04

There already was a "Post Meridiem" article as well as a "Ante Meridiem" article in addition to the A.M. article. I made the shorter Ante Meridiem a redirect to the A.M. article and made Post Meridiem redirect to a new P.M. article for consistency. I'm not so sure we need either, but I don't have strong feelings about it. As far as A.M., AM, a.m., and am I prefer am with A.M. as a second choice. I think a.m. is just wrong, and AM isn't as typographically pretty as am. Zenyu 18:37, Dec 15, 2004 (UTC)

I thought that the A.M. article was silly the first time I saw it, so I'll merge it and P.M. here. Typographically, I dislike "am" because it's a word, and I also dislike periods (although I don't see how you can claim that they're wrong). Thus I use "AM", although I agree that it's not pretty; that's because it really should be in small caps: "AM". -- Toby Bartels 00:12, 4 Jan 2005 (UTC)

In making my other changes, I edited enough of the article that I decided to put the whole thing in my style (complete with small caps), rather than the previous style. But please don't interpret this as a request to institute a Wikipedia-wide style convention; it's enough that each article be internally consistent (to look good). And I'll hardly be upset if a future rewrite of this article establishes some other style here for a while! ^_^ -- Toby Bartels 02:32, 4 Jan 2005 (UTC)

At some point, a Wikipedia-wide style convention was developed, and is recorded in the Manual of Style. The winners were "a.m." and "p.m.". I have updated this article accordingly.--Srleffler 04:39, 8 April 2006 (UTC)

"especially common in the USA?"

Isn't it more widespread than just the U.S.? I'm pretty sure it's used throughout Canada (except possibly Quebec) as well.

Yes it is widely used in Canada, generally excluding quebec and other French dominated regions such as Northern Ontario

Begging your pardons, but this debate, and the resulting explanation soup of "usage" on the front page of this entry, seems to entirely miss the key point. Which is that the statement "12 PM is not noon" leaves the door wide open for all those less fortunate who will read it and say AHA, so "12 PM is midnight" or so "12 AM is noon" (*tears hair out*). I have visited an optometrist, located in an upscale mall and associated with a national chain, who still proudly displays a sign stating that they are open until 12 AM every Saturday. Yet, they don't understand why they have to keep saying no to Saturday afternoon and evening apointments.

Please have a signature for your messages. Thank You! --Siva1979Talk to me 04:47, 26 April 2006 (UTC)

Reason for use

Can any one explain why certain countries still use the 12-hour clock --AzaToth talk 11:47, 15 November 2005 (UTC)

Because most Americans think that the 24 hour clock is used only in militry settings, for some damned reason or another? Because the vast majourity of my countrymen are ignorant curs? I'm curious too, because most people here are so ****ing ignorant of the outside world, and every one of my teachers wants to hurt me for writings dates as 2005 12 01 or 01 December 2005, et al; and my own family tells me to "Go live in France" when I use the 24 hour clock. 63.146.46.202 05:37, 2 December 2005 (UTC)

It is cultural. 60/5 is 12. 24 is wrong.

Infinitely short periods in time?

"Noon and midnight are only infinitely short points in time, and therefore it is not practical to use any other convention than that which also applies immediately afterwards, when the clock still displays 12:00."

Using this logic, the minute hand would never be able to leave the 12:00 position as anything immediately after would also be 12:00...

The fact that a point has no length has nothing to do with it - the 3am point also has no length but it is definitely am.

I believe that the reason that it doesn't make sense to allocate either am or pm to 12:00 is that it is a point that joins two continuiums, am and pm (similar to two rulers, one red and one blue that are laid end to end). The join point (12:00) is neither am or pm, just like the join point of the two rulers is neither red nor blue. User:24.5.38.74

The point I was trying to make when using the term "infinitely short points in time" could be explained far more precisely, but unfortunately such an explanation would assume that the reader is familiar with the notion of open and closed ends of intervals in mathematics. The explanation could then go like this:
It is customary that the time interval associated with a given time display is closed at the start and open at the end. For example, the fourth hour of the day, during which a U.S.-style digital clock displays 3:MM:SS am, covers the time interval [03:00, 04:00). Likewise, the first minute , during which a U.S.-style digital clock displays 12:00:SS am, covers the time interval [00:00, 00:01), etc. If we accept that convention, then it only makes sense – in the interest of consistency – to also interpret the time intervals denoted by the "am" and "pm" periods as closed at the start and open at the end. In other words, "am" covers the interval [00:00, 12:00) and "pm" covers the interval [12:00, 24:00). Doing it the other way round would lead to the oddity that a clock would have to flip between am and pm an infinitely short time after it flips from 11 to 12.
Such an explanation might appeal more to readers with a good background in mathematics, but I don't know whether we can assume that here. (On the other hand, people come to Wikipedia to broaden their mind, so perhaps it is ok to explain first what open and closed interval ends are?) Markus Kuhn 09:47, 26 April 2006 (UTC)

Neutrality

Does not meantion the advantages of a 12-hour clock. Yes, there are advantages e.g. 60/5=12. (anonymous)

And what exactly is the advantage of that? Sorry, this really is not at all obvious to me. The day still lasts 24 hours, even with the 12-hour notation. The neutral-point-of-view policy does not imply that we must have a section of advantages. Any advantage or disadvantage that we name must be relevant, clearly explained, and well backed by sounds arguments and/or references. In my opinion, the recently added new advantages section falls seriously short of these requirements. Markus Kuhn 12:50, 10 May 2006 (UTC)
It is my personal opinion that the disadvantages outweigh the advantages by far. That does not say there are no advantages. Also aspects perceived as advantages by some people can be relevant to mention. This is common practice in many other articles with contested neutrality. Instead of removing alleged advantages right away, we could try to formulate them more clearly as they are, fact or perceived. −Woodstone 13:14, 10 May 2006 (UTC)
But we do not have to list clearly misleading arguments. In particular the item
  • Some people dislike the idea that midnight has two different notations, depending on whether it is the beginning or end of the day.
is merely a (deliberate?) misunderstanding by the original author. The 24-hour notation – as widely implemented by digital clocks and computers – ranges from 00:00 to 23:59 (or in mathematical interval notation [00:00,24:00[), therefore the notation "00:00" is the unambiguous notation for midnight and the new day starts with the rollover from 23:59:59.999 to 00:00:00.000. The 24:00 notation (mentioned in ISO 8601) exists primarily to remind people about what the exact meaning of 00:00 is if it is used together with a date. As a secondary use, 24:00 may actually be written down at the end of an interval, to avoid having to reference the next day explicitly. The above is a very misleading attempt to misrepresent a clear advantage as a disadvantage. It is neither fair nor based on how the 24-hour notation is used in practice. It should therefore be removed. Markus Kuhn 16:21, 10 May 2006 (UTC)
I see this as a disadvantage of the 24-hour system. (anonymous)
One can only say what is an advantage or a disadvantage in their own mind. Therefore one can't say what is not an advantage or a disadvantage in someone elses mind. The same point can be both an advantage and a disadvantage to different people. Wikipedia should state both sides of the issue and let the reader deside for him/herself, thank you. Zginder 22:16, 11 May 2006 (UTC)
What of the above exactly does the anonymous contributor see as a disadvantage? The lack of ambiguity? You must at least be able to explain your point of view in a coherent way before it can even be considered to remain in an encyclopedia article. Markus Kuhn 10:34, 12 May 2006 (UTC)
First of all, "the anonymous contributor" is me, "Zginder." I get forget to sign in sometimes and today it said I was signed in when I wasn't. Second, I wrote a perfect piece of prose that can't be disagreed with and you disagree with me. Third, if you do not use the 12-hour clock you have no right to tell me how to think in regard to the advantages of it. Fourth, all of the sentences under Criticism and practical problems are statements of fact while when I make the advantages also statements of fact they are changeed to "Some people" a weasel word making them statements of opinion. Fith, I have not changed the Criticism and practical problem, but all anybody else semes to do is to delete or change the Advantages. Sixth, the advantages should always go before the disadvantages; however, someone moved the advantages to after Criticism and practical problems. Zginder 1:46 PM, 13 May 2006 (UTC)

Well, the article now lists several advantages of the am/pm system. I can offer even more. You'll sell a lot more am/pm clocks than 24-hour clocks in the U.S. (To make it clear, that means more profit for the seller!) Also, if you have a Web form to be filled out and one of the fields is the time, and you set it up for the 24-hour format, I guarantee someone will put down 5:00 when they should be putting down 17:00 (Advantage: to avoid mistakes and ambiguity). Yet another is the existence of clock towers. A 24-hour clock on a clock tower would be much more difficult to read and not look as good.

Still, I greatly prefer the 24-hour format on computers, especially for file dates. I find the use of am/pm times in a list of files extremely awkward and ugly. [Alan E. Feldman 2006/07/02 16:15 UTC]

What is wrong with these statements?

  • The 24-hour clock does not say what day midnight belongs to (to take this to completion one cannot say two days instead one must say two days and two midnight. There are 365.2424 days and midnights in a year. etc.) by saying midnight is 12:00 a.m. the 12-hour clock assigns midnight to the day which is beginning.
  • In using the 12-hour clock one can state which of two events, one in the morning and one in the evening, without a time. (e.g. "The a.m. meeting or the p.m. meeting?" "The a.m.") In these situations the time is known to all. The 24-hour clock doesn't have any way to do that without saying early morning, morning, dawn, forenoon, noon, afternoon, dusk, evening, night, or midnight with are vague, some longer to say, and can change with season.

Zginder 4:20 p.m., 20 July 2006 (UTC)

For the first bullet, the 24-hour clock very precisely states what day midnight belongs to. It is the boundary between two days: the end of one day and the beginning of the next day. In order to avoid confusion about what is meant by midnight on July 20, 2006 one can say 2006-07-20 00:00 for midnight at the beginning of the day and 2006-07-20 24:00 for the one at the end. Every midnight is shared between two days.
For the second bullet, how would saying the morning(afternoon) meeting be any less clear than the a.m.(p.m.) meeting?
Woodstone 17:51, 20 July 2006 (UTC)
For the second, a.m./p.m. are more encompassing than any other terms in English. All others (Except for noon and midnight) can change times throughout the year. Zginder 11:48 p.m., 20 July 2006 (UTC)
Do you also think people have trouble knowing when to say good morning/afternoon/evening/night? I hear people saying that correctly all the time. I never heard anyone wishing me good a.m. or p.m. −Woodstone 22:21, 20 July 2006 (UTC)
That's not the point. What if you have some thing at 5:00 a.m. and 7:00 p.m. Whether it is light or not depends on the season. That is the point. They are also shorter and people do say "good, what is it now afternoon or evening." Zginder 1:03 p.m., 21 July 2006 (UTC)
I completely do not understand what you're at. Why is it important if it's dark or light? Is it dark during a.m. and light during p.m.? In your example almost any answer would be clear: morning or night would be at 05:00, afternoon or evening would be at 17:00. Are you implying that people often ask you ; "is it a.m. or p.m.?" I never heard that and there is no need for it. And is saying "a.m." really shorter than "morning"? —The preceding unsigned comment was added by Woodstone (talkcontribs).
If it is dark at 7:00 p.m. it is night; however, if it is light it is the evening, therefore if it is an event that happens at 7:00 p.m. every day or every week one can not say evening or night when reffering to all happening of the events. One must state a time. One more thing you wrote that 7:00 p.m. is 17:00 if you think this how can you be editing this article. Also, I think that in the article the 12-hour clock we should use the 12-hour clock. Zginder 8:17 p.m., 21 July 2006 (EDT)
Saying "a.m." isn't shorter, but writing it is. -- 65.68.75.155 04:59, 28 July 2006 (UTC)

Sumerians and half open intervals

Moved from the article:

  • Some people claim that changing the notation if the clock destroys cultural identity and abominates the language, because the day begins with midnight and ends right before midnight. In other words, it is customary that the time interval associated with a given time display is closed at the start and open at the end. If we accept that convention, then it only makes sense – in the interest of consistency – to also interpret the time intervals denoted by the period of a day as closed at the start and open at the end. In other words, "day" covers the interval [12:00 AM, 12:00 AM).
  • The Sumerians had a sexagesimal or base-60 numbering system. So that explains why there are 60 seconds in a minute and 60 minutes in an hour.. Now look at degrees, notice how 40°12'13" is 40 degrees, 12 minutes, 13 seconds... There are 360 degrees in a full orbit, or 60*60/6. Let's try dividing 60 by 5, we get 12... Why 5? well 60 can be factored these primes 2,3,5 any multiple of them makes a nice simple divisor, so 2,3,5,6,10,12,15,18,30 are your basic options, of those the only ones that make sense here are 3, 5, 6. Why they chose 5 not 3 or 6 I can't tell you, maybe they just thought 15 or 18 hours were still excessive, and 10 too few? Maybe 12 was better because it could be divided twice in half? Note, 24 is not in the list 2,3,5,6,10,12,15,18,30. This is a problim with clocks with analog dials.

I really do not see why the story about Sumerian number systems represents an advantage. If you want to include that story it might perhaps better fit in a "background" or "history" section. Anyway it should be rewritten, as it is rather conversationally formulated, not encyclopedic. And it should be Substantiated with sources, as it looks like original research, which is not accepted in wikipedia.

Similarly, I do not see how the story about half-open intervals presents an advantage. It sounds like a very specific (even personal), not general interpretation of what a clock time is meant to mean.

Woodstone 07:49, 10 May 2006 (UTC)

I agree, but right now it just says "Some people claim that changing the notation of the clock to 24-hours destroys cultural values and identity and abominates the language," which is bewildering. I think we should remove that too. 132.236.113.119 07:03, 9 July 2006 (UTC)

It was removed several times and reverted by others. Anyway it starts by saying "Some people claim ...", so it's not untrue and doesn't really harm (the strength of expression exposes its silliness). −Woodstone 10:36, 9 July 2006 (UTC)

Consistency between 12-hour clock and 24-hour clock

Can we ensure that there is consistency between 12-hour clock and 24-hour clock? The issues are almost identical but the articles are inconsistent.

Perhaps we should have a single article. bobblewik 07:27, 15 May 2006 (UTC)

Use by country

We now have a "Use by country" section in both the 12-hour clock and 24-hour clock pages, which will lead to redundancies and inconsistencies. How about moving this entire section into a new separate article Date and time notation by country, were contributors interested in giving a detailed account on the related conventions have all the space they need? Markus Kuhn 13:10, 15 May 2006 (UTC)

I concer. —The preceding unsigned comment was added by 68.239.157.115 (talk • contribs).

In the "History and usage" section, I suggest United Kingdom be moved from "It is the dominant form of time written and spoken in" to "It is commonly used alongside the 24-hour clock in". In speach the 12 hour clock is almost exclusively used, and shop opening times are, for example "open 9 to 5, Monday to Saturday". But in timetables (bus, train, plane), airport and railway station departure boards, any technical document and many official documents the 24 hour clock is used to remove ambiguity.

Translations of a.m. and p.m.

They both come from Latin and are "ante meridiem" and "post meridiem" in Latin. We all agree on that, right? Now "ante" means "before" and "post" means "after," right? Now for meridiem, which is a Latin idiom literally meaning "the middle day" (see wikitionary under meridies). Meridiem is transliterated into English as meridian. (I don't want to see someone change this back to meridem which not an English word and if you think it is find it in a dictionary.) Now Woodstone thinks that "midday" is the best translation; however, this word has a connotation of the middle part of the day and not a point in time. The middle of the day is a little better but can still have that connotation. Forenoon and Afternoon both have a connotation of the day light time before and after noon. So, I suggest using "before noon" and "after noon"(two words) to express the meanings of these phases even tho "noon" can also mean the middle part of the day, and "after noon" can be confused with "afternoon." Zginder 2:10 PM, 10 June 2006 (UTC)

Maybe we could say (ante meridiem(a.m., Latin for before the middle point of the day.) Zginder 2:15 PM, 10 June 2006 (UTC)

Midday is both a literal and a correct translation. Also in Latin the word "meridies" is both used to stand for the moment of noon and for the afternoon (and also "south"). There is also a Latin word meridianus, which is the adjective form, leading to the English "meridian". Translations as "the middle of the day" are just as correct, since Latin does not have articles. In my view giving a whole list of hardly different translations is only confusing. I have no objection against adding "before/after noon" as (the most idiomatic) translation. −Woodstone 16:22, 10 June 2006 (UTC)
I don't think we should have that many translations either but it keeps being changed and we need to decide what should be there. Zginder 11:39 PM, 10 June 2006 (UTC)

OK, if we accept before/after noon as the correct translation, then it is still a problem. What exactly does one mean by noon? Back when am and pm originated, people used Local Solar Time. In that scenario, noon is the middle of the day (between sunrise and sunset) and is exactly when the sun crosses the meridian which is then the same as "12:00 noon". But with our current time system you'd have to be at one of a finite set of longitudes which vary with date for 12:00 noon to be the instant when the sun crosses the meridian because of the existence of time zones, the equation of time, and such. So with our current timekeeping system, noon is not defined precisely enough to apply the literal translation argument. Our noon is not the same as their noon. So what's the point of all this fuss over a literal translation when we are mixing different "noons" from different eras? No one uses arguments like this for anything else, including AD and BC! Why do some insist on making an exception for am and pm? Alan E. Feldman 2006-12-15 18:11 UTC.

Weird sentence

It is more efficient to split a series up in to two parts. For example we do not have different names for negative numbers; we use the − sign.

I don't understand this sentence, and the use of "we" is problematic. What do negative numbers have to do with time notation? Could someone who knows what the argument is supposed to be rephrase it, and write in a way that doesn't show that the author uses the 12-hour clock? Thanks, PruneauT 12:38, 16 June 2006 (UTC)

Since no one seems to answer, i've deleted the sentence. PruneauT 00:29, 20 June 2006 (UTC)

Zginder put it back in. I think the argument is goofy. It is not "more efficient" to split any arbitrary linear sequence into two parts. "More efficient" by what measure? Presentation size? No. Internal numeric representation (say in binary bits or BCD (binary coded decimal))? No. I've removed it but we'll see if it comes back. tbird20d. (sorry, editing as anonymous).

More efficient in human brain power, easier to examine and logic. Zginder 12:46 PM (PDT) 2006 June 21.

Australia - Double negative

"It is unlikely that Australia will never migrate to 24-hour notation." What did the author intend to say? I assume it was "...will ever...", but I've nothing to back it up.

I copied it from 24-hour clock and I was confused by it. Copied question over there. Zginder 13:29, 27 July 2006 (UTC)

Manual of Style

Regular editors of this article may be interested in some proposed changes to the use of am/pm/noon etc. in the Manual of Style (WP:DATE), relying in part on this article. See Wikipedia talk:Manual of Style (dates and numbers)#Imporvement about guidelines in Time. — Joe Kress 16:28, 8 August 2006 (UTC)

Weird statement

"the day starts at 12 midnight instead of 6 a.m. when the sun comes up." The sun doesn't (always) come up at 6 a.m. Why is this here? - anomynous passer-by

Removed content

I removed two paragraphs from the article.

  • From the section Advantages over the 24-hour clock: because this sentence doesn't show an advantage of 12-hour clock over 24-hour clock. Maybe it fits better in another part of the article but it's a claim that would need some citing.

Some people claim that changing the notation of the clock destroys cultural identity and abominates the language.

  • From the section Pronunciation: because the paragraph is about the pronounciation of 24-hour times. I'm including this in here: 24-hour clock.

Military circles use the 24-hour clock exclusively and would typically pronounce times ending in :00 minutes as the hour followed by "hundred" with an optional "hours". For instance, 16:00 would be pronounced "sixteen hundred" or "sixteen hundred hours".

--Bisco 00:06, 1 October 2006 (UTC)

Typography - half hours

From the Typography section:

hence 5:30 is half past 5 or merely half five

Is this correct? I thought 5:30 would be half six.--Bisco 00:11, 1 October 2006 (UTC)

I happened to notice this older remark when inserting mine below. Yes, it is correct. In English "half five" is short for "half past five". There is no expression "half to five" that could be shortened to it (unlike in German). −Woodstone 14:14, 15 October 2006 (UTC)

Chiming 24 times?

Does anyone know of a clock chiming up to 24 times? It is mentioned in the article, but I doubt if any exist. −Woodstone 14:10, 15 October 2006 (UTC)

It was certainly common centuries ago - see striking clock for a quote about a famous example from 14th century. But I very much doubt whether you'd find a similar clock that still does it today, and even in Italy they changed most of their clocks to conventional striking ages ago. Cormullion 15:16, 15 October 2006 (UTC)

XXIIII

I am just wondering whether anyone knows anything about this, I am not sure, that being said, I believe it should be XXIV to conform with roman numeral system, however I have an old grandpa clock that has four inscribed as IIII not IV so does anyone know if its a common thing to have that in clock? 4, 14, 24 on clocks might be commonly stated on clocks as IIII, XIIII, XXIIII 86.108.117.175 23:18, 27 October 2006 (UTC)

IIII and related Roman numerals are discussed at Roman numerals#IIII or IV?. — Joe Kress 05:31, 30 October 2006 (UTC)
Conformity and consistency are a bit of a modern concern - I don't think it was much of an issue in a world where every country and sometimes every state or city had its own conventions and units. As for 24, here are some examples of numbering schemes for the varying numerals (4, 9, 14, 19, 24):
  • Florence, Venice Rialto, Venice St Marks, Padua, Clusone: IIII ... VIIII ... XIIII ... XVIIII ... XXIIII
  • Cremona: IV IX XIV XIX XXIV
  • Mantua: IIII IX XIIII XIX XXIIII
  • Shepherd clock Greenwich: IIII IX XIV XIX 0 (;-))
so with this set of data, the 'I's have it, just... Cormullion 14:22, 31 October 2006 (UTC)