User talk:Nike
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[edit] Link on metric time page
Hello Nike,
Quick question: why would a link to an external application that displays a metric time clock be unappropriate content for the metric time page? You removed the link earlier this week.
Many other pages contain links to website containing applications.
Thanks for giving me some background on what you consider to be appropriate content.
- Because the application in question does not relate to the article. Read the article. Metric units of time are the second, kilosecond, millisecond, etc. The metric system specifies time interval, not time of day. Your clock actually displays decimal time of day, not metric time.
- Also, just because someone else does something does not make it right. Read the manual of style. Links are supposed to have information about the subject of the article, not advertise applications which are not even related to the article. Just because you call your clock "metric time" does not make it so. And if it's your web page, then it's a conflict of interest. If you disagree, then you should post in the talk page and get the opinion of others.
- Also, you should always sign your comments. --Nike 20:07, 12 February 2007 (UTC)
[edit] Re: my post in the Talk page on the Julian Day article
This is a reply to your comments on my post, there. I'm sorry, but I'm a newbie here, and I hope this is not out of place here, but I couldn't see any other obvious way of contacting you personally as you suggested I should do if I wanted to know more. You can get in touch with me using the address: xxxxxxxxxx Please do so so that I can email you about this subject. Once we have established contact, could you please remove this email address from this post. I would like to know more, especially about your remark that "Herschel ... was mistaken anyway". Mottelg 09:11, 14 April 2007 (UTC)
One way you could have contacted me would have been to click "E-mail this user", as I just did. Posting on my personal talk page, as you did, is also fine.
This subject has been discussed on the CALNDR-L mailing list, amongst other places. I was first made aware of Herschel's error in a book, but I forget which one. Of course, he was not the first; Gilbert Romme made the same proposal right before he was sentenced to the guillotine during the French Revolution. (see http://prairial.free.fr/calendrier/calendrier.php?lien=discoursromme) The mistake they both made was in thinking that the value of the mean tropical year has anything to do with the Gregorian calendar. If you read Pope Gregory's Inter gravissimas, you will see that the calendar was designed to keep track of the vernal equinox, not the mean tropical year.
The average period between equinoxes is closer to 365.2424, the exact figure depending upon precisely which period is chosen, and is slowly changing over time, which you can calculate yourself, simply by counting the exact number of days between the equinoxes of two years and dividing by the number of years between them. For example:
2000 03 20 07:35:15 UT = JD 2451623.81614
1900 03 21 01:39:08 UT = JD 2415099.56884
(2451623.81614 - 2415099.56884)/100 = 365.242473
2007 03 21 00:07:15 UT = JD 2454180.50503
1957 03 20 21:16:30 UT = JD 2435918.38645
(2454180.50503 - 2435918.38645)/50 = 365.2423716
See also http://www.hermetic.ch/cal_stud/cassidy/err_trop.htm
The actual figure is not 4000 years, but closer to 10000, and by that time the value will be something else that cannot be predicted so far into the future but is currently increasing anyway. Given that the Gregorian calendar is only 425 years old, it should be a very long time before any correction is necessary. Some, including Persian and English astronomers, have proposed a 33-year cycle including 8 leap days, which would be 365.242424 days per year on average. --Nike 19:18, 14 April 2007 (UTC)
>>> click "E-mail this user" <<<
I can't see any such link -- neither here nor where you originally posted your comments. Where is it please?
- In MonoBook, it is in the toolbox on the left side, right under the search box. It may be elsewhere if you are using a different skin. Of course, you have to be looking at someone's user page or talk page. --Nike 11:22, 15 April 2007 (UTC)
Thank you, Nike, for your enlightening remarks. I must bow to your superior knowledge of astronomy. I know that the equinoctial year and tropical year are not the same, by definition and, I suppose, their periods differ slightly (but I don't know why), but I guess I'll have to consult other articles in the Wiki to learn more about the dfifference between them. My gut guess is that precession affects one more than the other (though the tropical year is due to the tilt of the earth's axis of rotation with respect to the plane of its orbit and precession is due to fluctuations in that tilt).
As for the reason for Pope Gregory's calendar reform, I think I can speak with more confidence on this subject. Put simply, he wanted to realign the (northern) Spring equinox with March 20, which was the date of its occurrence around the time of the first council of Nicaea in 325. However, we must examine this in light of the reason behind this goal.
Easter, by decree of that council, had to be celebrated on (or the first Sunday after) the first full moon of Spring -- i.e. the first full moon to occur after the vernal equinox. The trouble is, the council did not specify it that way. Assuming back then that the Julian calendar was reliably aligned with the seasons and would forever remain so (yes, I deliberately use the word seasons), they specified that the full moon in question must be the first one after March 20. The Council of Nicaea was the first ecumenical council of the Christian church and, as such, its decisions came to be regarded as unchangeable. Since he couldn't change the decision, he changed the calendar to realign March 20 with the vernal equinox, and he changed the leap-year rules to ensure that it would always remain so aligned.
However, in linking Easter to the equinox, the council's aim was to ensure that Easter would always be celebrated in the first lunation of Spring. Prior to 325, the date of Easter had been linked to its antecedent, the Jewish festival of Passover. (The Last Supper was a Passover "seder" (ritual meal) that Jesus was conducting with his disciples, and the "Paschal lamb" was originally a real lamb that was traditionally eaten at the Passover seder. Hence the connection between the two.) The council's decision was not intended to change when Easter occurred (well, actually one purpose of the new rule was to ensure that Easter would never coincide exactly with the beginning of Passover, so a slight change was intended), but the main motivation was to sever the dependency on Passover and establish independent rules for the new church for fixing the date of Easter.
Nevertheless, despite the desire to create independent rules, in one sense a certain dependency on Passover was still retained. The rules were intended to preserve a property that Easter shared with Passover, namely: the requirement that the festival must always be celebrated in the Spring season (more particularly, on or near the first full moon of Spring). So, when you get right down to it, the main criterion of accuracy for the Christian calendar is how well it remains synchronised with the SEASONS. Whether, for THAT PURPOSE, it is preferrable that its year should more accurately approximate the TROPICAL or EQUINOCTIAL year, I cannot say authoritatively at the moment, but clearly, the equinox is of interest (at least to the church) only insofar as it serves to herald the change of season from winter to spring.
Since the same requirement is true of Passover, it is also of interest to the Jewish calendar how well a predominantly solar calendar like the Gregorian remains reliably synchronised with the seasons.
I am creating an electronic Jewish / Gregorian / Julian calendar to investigate correlations between them over a long time (many millennia), both proleptically and into the very distant future. (Not with commercial intent, but as an academic tool.) I am aware of the fact that the astronomical values are slowly changing over time and that we cannot predict how accurate the Gregorian calendar will be thousands of years hence, but it is of interest nonetheless to create such a tool based on present knowledge at least. I would like to make the Gregorian calendar optionally (at the user's discretion) "Herschel-Compliant". Hence my interest in adapting the JDN to date formulae to enable those conversions to work with such a calendar.
Nike, do you understand those formulae well enough to advise what changes this would require to the formulae given in the Julian Day article? Also, can you say whether a "Herschel-compliant" Gregorian calendar would (on present knowledge) be more accurately or less accurately synchronised with the SEASONS than our present Gregorian calendar? Mottelg 10:24, 15 April 2007 (UTC)
- I don't claim a "superior knowledge". I just happen to know a little about this one issue, so I do not need a lecture on the subject. I would not rely on Wikipedia as a primary source for this sort of information, or for anything else, for that matter. I would start with some of Simon Cassidy's articles and algorithms at http://www.hermetic.ch/cal_stud/cassidy/ where he talks about the differences between each of the seasonal years and the problem with using the mean tropical year. I strongly suggest subscribing to CALNDR-L. There are people on that list who are very knowledgeable about calendar issues and writing calendar software, and I'm sure you'll get answers to your questions there. And, of course, read the basics from Dee, Newcomb, Meeus, etc. --Nike 11:22, 15 April 2007 (UTC)
[edit] hi
you said that Swatch Internet Time had nothing to do with Metric time, but if you go on the Metric time page, even at first glance (i havnt even bothered looking any further) the simple mention of 'Ke' shows a link to Swatch Internet Time, as the 'beat' is a metric devision further of the already metric 'ke'. thanks Pollypenhouse (talk) 15:17, 23 December 2007 (UTC)
- You admit that you have not read the metric time article, which is obvious, as it does not say what you claim. It clearly states that Swatch's Internet Time is in no way metric. The metric system is a coordinated system of units in which multiple and submultiple units are formed by adding specific prefixes. Although some have tried to extend Swatch with "centibeats", etc., these are not actually part of Swatch's Internet Time. Beats are no more metric than any other non-metric unit. Just because there are 1000 beats in a day does not mean anything. 1000 beats is simply a day, not a kilobeat. Likewise, there is nothing metric about ke. That is, in fact, the Chinese term for a quarter-hour, which historically was used for 1/100 day, but there are no prefixes used with it, either, and it has nothing to do with Swatch or the metric system. There has only ever been one unit of time used with the metric system, and that is the second, with common`metric submultiples including millisecond, microsecond and nanosecond. You are confusing metric with decimal. Even though the metric system is decimal, not everything decimal is metric. The metric system is defined by a number of international treaties and by the BIPM. They do not include Swatch. Swatch, itself, never described its time as being metric. --Nike (talk) 19:11, 23 December 2007 (UTC)
