Talk:Calendar
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Do calendars really measure time?
I think a lot of misconceptions about calendars arise from the idea that a calendar measures time, like a clock or like a ruler measures distance.
All known calendars work by naming days (This is the definition in the Nupedia article). As such, a calendar can not measure time more accurately than 1 day. Furthermore, the duration of the day is known to vary in time owing to change in Earth's rotation rate, so is not a good standard in time measurement.
A solar calendar may measure years, by virtue of the fact that its year runs close to the cycle of seasons, but more accurate measurement can be got from an ephemeris.
The year even when measured in SI seconds, varies in duration and so can not be considered a unit of the same time that measured by SI seconds.
That's not a misconception at all--a calendar does indeed measure time just like a clock does, just not very precisely. That doesn't mean it's not a measurement. A measurement simply answers the question "how much"; one can answer precisely or vaguely. If you ask "How much sand in this bucket?", One can measure in "handfuls" just as easily as kilograms, and one is performing essentially the same function. Likewise, "How much time since I was born?" can be answered roughly in years with the help of a calendar, and in fact is a much more useful measurement for most purposes than an exact measurement in seconds: I'm over 1.2 billion seconds old; quick-- can I go into a bar? Run for president? --Lee Daniel Crocker
--- Mr. Crocker is confusing entities (e.g. length) with units (e.g. meter), organizational nomenclature (e.g. kilo-meter), and measuring devices (ruler, laser interferometer). A calendar itself, whether the paper thing on the wall or the rules and conventions used to make them, is NOT an instrument or system of time MEASUREMENT. Chalking up a mark each day is sufficiently similar to a clock (counting regular events) to call that a time measuring device: but that is a simple day count and not a calendar. A calendar is a convention on organizing time, dividing it, or tracking it if you like; but NOT "measuring" it. You might as well call the "minute" a system of time measurement, or a clock, or a calendar: and it is neither of these. So I propose as the initial definition for the article:
"A calendar is a system for organizing periods of time. Calendars generally use the day as the fundamental unit, and give a label (names or numbers) to each day. Days are organized into larger units which usually are repeated in cycles, often based on some natural cycle like month or year. These properties facilitate recording events or periods of history and planning future events."
-- 20011221: Tom Peters
For more discussion on Calendars and Time measurement, you may join the E-mail list CALNDR-L at http://personal.ecu.edu/mccartyr/calndr-l.html
This terminology from the existing article seems less than ideal. "A pragmatic calendar is one that is based on observation; an example is the religious Islamic calendar."
How about calling it "observation based calendar" and get rid of the pragmatic terminology.
"A theoretical calendar is one that is based on a strict set of rules; an example is the Jewish calendar. Such a calendar is also referred to a rule-based or arithmetical calendar."
I thought a "theoretical calendar" was one proposed bu never used.
Let's just move away from those two term and go with Rule based and observation based.
-Paul Hill
I've never seen the term pragmatic calendar used to mean observation-based calendar outside the Nupedia article in which it appears. It may be the author's invention. The terms astronomical and observation-based have been used elsewhere and I have added them to the article.
The same applies to the addition of arithmetical and rule-based for theoretical calendars.
A calendar is not an scheme for "giving names to days and years". What a year is is defined by the calendar...for example, in a lunar calendar a year is something different than in a solar one.
- I didn't write that that line, but actually I can't fault it. The primary purpose of most calendars is indeed to provide names for periods of time. Calendars generally do also define terms of common usage like "month", "week", and "year", and usually give alternate definitions for them that correspond in greater or lesser degree to other usages of those words which are not calendar-based (things like "mean sidereal year" exist independently of any calendar). But the purpose of those definitions is to provide a convenient way to label moments and/or periods of time in the past and future, to make it easier to record history and make long-range plans.
"Provide names to periods of time" that's a bit closer to it...my problem is, a year did not exist until a calendar that defined it did, so a calendar doesn't give a name to a year, creates it. But how do you measure those periods of time? A day is a pretty obvious thing, based on the movement of an astronomical object, the sun. The year is a bit more problematic, and you can only define it observing the constelations in the sky at sunset or sunrise. Thus my attempted definition. If you can do better, please be my guest, but I'm not going to leave that line as it is.
- You could always look at it from the units-of-measurement point of view. Things like "hour", "second", "week", etc. are somewhat arbitrary products of definition, but just as we chose units like "pounds" to be useful for everyday life and commerce (imagine buying food from a grocer if your only units of weight were milligrams or tons), our choice of units for time was not entirely arbitrary. The day was such an obvious thing that it made sense for smaller units to evenly divide it. Likewise the cycle of seasons pre-dated any calendar, so it made sense for calendars to define the "year" unit of time measure in a way that made it convenient for knowing when to plant crops. So I wouldn't call calendars totally "arbitary", but I would say that they defined measurements of time that served the purposes of the prople that created them.
The various astronomical days, months and years really do exist; but the calendrical day and month and year do not. They are creations of the calendar, which approximate the astronomical periods in some ways. But they aren't just inaccurate measurements; to use the astronomical units would be wrong by the calendar. So these units have no existence without the calendar. -- SJK
From VfD
- How to compute calendars - Article rehashes knowledge already available in detail on Gregorian calendar, Julian calendar, and Calendar itself, as well as being very centered on both of those calendars, but not giving details for either. If I have missed something, the missing content should be merged into one of those three and this page deleted; it does not provide additional value. Should the article instead be enhanced to encompass a "how to" guide for every calendar around, a lot of duplication would be neccessary (of the articles for the respective calendars) Eike 03:16, Feb 19, 2004 (UTC)
- Info needs correcting, but merge any useful content with calendar and redirect -- Graham :) 12:01, 19 Feb 2004 (UTC)
- Ditto. Elf 17:14, 19 Feb 2004 (UTC)
- merge and redirect Rossami 04:22, 23 Feb 2004 (UTC)
- If anyone wants to merge How to compute calendars into Calendar, they can access the non-redirected version from here (http://en.wikipedia.org/w/wiki.phtml?title=How_to_compute_calendars&oldid=2515891).
Some reformatting needed?
and additions, especially where it just links to a main article. Lockeownzj00 06:25, 13 Feb 2005 (UTC)
- If you're thinking of placing main article links within the headings, then don't. That is to be avoided according to the Wikipedia:Manual of Style (headings). — Joe Kress 19:01, Feb 13, 2005 (UTC)
"new" calendars
Should we say something about the phenomenon of people trying to build new calendars (such as http://en.wikibooks.org/wiki/Triangular_Earth_Calendar ) ? Is there a name for this, perhaps something like constructed calendar, analogous to constructed language ?
- Some proposed calendars are at calendar reform. — Joe Kress 05:10, 2 Jun 2005 (UTC)