Talk:Epoch

I would prefer to name this article something like "epoch (computers)" to clearly differentiate it from things like epoch (astronomy). That is, astronomy epochs are dates that are used as a reference point, so it's not necessarily clear from this article title that the article doesn't discuss astronomy. --Interiot 18:27, 6 December 2005 (UTC)

The top of the page points to the epoch article for disambiguation. JFG 10:07, 2 January 2006 (UTC)

Now that you added a nice astronomy summary in here too, this disambig pointer can go away, along with the wiktionary pointer which was hidden behind "reference date". I have also simplified the epoch page to make it clearer (and added this wiktionary link where it belongs), tell me what you think. JFG 00:12, 4 January 2006 (UTC)

Yeah, it's definitely better than it was, but it still feels a bit lopsided since the chronology and astronomy sections are basically pointers to more substantial articles and computers isn't. Perhaps eventually computers will get its own article, and this article will have a a couple paragraphs of summary on each topic to tie everything together nicely (the alternatives being to revert to a simple disambig page (which isn't preferable because these topics really do have strong connections), or for it to become increasingly lopsided over time). --Interiot 00:33, 4 January 2006 (UTC)

IMHO astronomy can remain a small summary here because the term used by astronomers is just epoch, not epoch date, which is why I listed it separately in the epoch disambig. However I'm not a native English speaker so please correct me if I'm wrong.

As Ike9898 noted, the concept of an epoch date is very similar in chronology and computing: defining an origin of time, instant 0 (or 1). In contrast, the astronomical epoch is a slightly different idea: picking a particular instant as a photograph of the Universe from which celestial positions at other instants can be computed.

As for the computer section being longer than the chronology section, it's just because I happen to know more about computers (and the original stub started with this meaning) -- I sure hope that people will expand the human side of the concept. JFG 01:54, 4 January 2006 (UTC)

Ultimately though, there's only a couple of uses of the word "epoch" that use them as instants in time as a reference point for other measurements, as compared to epoch as a large span of time. And each use has its wrinkles and competing reference points. That's why I think astronomy goes here.

Somebody just improved the epoch page by explicitly classifying uses of the term to define moments in time vs periods of time. This ambiguity in the English language must have been the root of confusion about this term. Now "epoch date" can be seen as a specialized term for the "moment in time" acception of the "epoch" word, and it's clearer. -- JFG 14:33, 5 January 2006 (UTC)

No no, I didn't mean to imply that the computing section was remotely bad, it's quite good IMHO. I just think that at some point, it will be forced to split off as its own article, at which point people will ask why the current article can't just be merged with epoch, as they'll both be disambig-ish at that point. I was arguing that they shouldn't be merged down the road, because this article serves to note the tie-ins between human chronology / computers / astronomy more than simple one-liners could, and that's a good thing.

As for "epoch" versus "epoch date", I'm not sure that "epoch date" is necessarily the perfect term. These google searches show that "epoch date" is rarely used: --Interiot 02:40, 4 January 2006 (UTC)

	epoch	epoch date
Excel	303,000	230
Unix	428,000	535
GPS	363,000	506
astronomy	637,000	1,090
J2000.0	76,000	448
Gregorian	88,000	170

Well, maybe we could move this article to Epoch (date), Epoch (instant in time), or something like that. What say you? ike9898 16:15, 5 January 2006 (UTC)

(added more to the table that makes the case even stronger) Yeah, it should probably be changed to Epoch (x). Maybe Epoch (reference point) would work? Or (instant in time) could work. Anybody else have any thoughts? --Interiot 17:11, 5 January 2006 (UTC)

These Googlefights look quite compelling, but I think they are misleading. Through recent refactoring, we have noticed that the English word epoch has the dominant meaning of a period and the secondary meaning of an instant. Consequently we have clearly separated those meanings on the epoch page and we have refined the epoch date page to encompass all the nuances of the epoch as an instant concept. The Google results for "epoch" include all meanings of the word, whereas "epoch date" narrows results radically to pages (such as this Wikipedia entry) that need to explicitly make the difference between the two main meanings of epoch. Therefore I vote to leave both pages as they are. In addition, just renaming "epoch date" to "epoch (date)" would seem less elegant to me. If we decide to change the name because "epoch date" is indeed rarely used, I would prefer "Epoch (reference date)". -- JFG 02:16, 6 January 2006 (UTC)

Epoch (reference time)? Epoch (time reference)? ike9898 18:30, 5 January 2006 (UTC)

Mac and Unix Epoch Clarification

The Unix-epoch should be clarified. The article says that the Unix epoch date is Jan. 1 1970, but 1904 on Macs. Is Mac OS X's epoch date 1970 because of its Unix base, or is 1904 like pre-OS X Macs? 68.174.116.251 05:56, 1 January 2006 (UTC)

Done, along with more clarifications, rewrite and fact-checking. JFG 05:41, 2 January 2006 (UTC)

Expanding the Chronology section

Thanks Ike9898 for expanding the chronology section. I suggest expanding it further in NPOV spirit by adding the list of epoch dates for significant calendars in present use, which are currently hidden towards the end of the Common era article as Other calendars currently in use. What do you think? JFG 10:07, 2 January 2006 (UTC)

Sure, maybe one more example would be helpful. There are many examples in calendar era. The problem that I have with the current article is that it seems to imply that epoch date means something different in human chronology vs. computing. As far as I can tell it is exactly the same concept. I think that there should be a general definition, before the two sections. The sections can talk about examples and details in each area. Ike9898

Totally agree, it is indeed the same concept, but it was not clearly stated until we started working on those pages; don't they look good now? ;-) JFG 00:12, 4 January 2006 (UTC)