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The World Calendar is one of the several calendar reforms that have been proposed in the past. This particular calendar has these features:
- The number of days in a month runs in this sequence: 31, 30, 30, 31, 30, 30,… and so on.
- This means every quarter of the year has 31 + 30 + 30 = 91 days, i.e. a whole number of weeks. So the calendar for every quarter is identical. 1 January falls on the same day as 1 April, 1 July, 1 October, and even 1 January next year, and so on.
- Since a year is made of a whole number of quarters, the calendar for every year is also identical. So, you don’t need any tools/algorithms to find the day on which a particular date falls in a year, because every date has a fixed day on which it falls in any year.
- The number of days in such a year is 91 × 4 = 364. This creates a deficit of 1 day in a non-leap year, and 2 days in a leap year. The deficit is solved without disturbing the weekdays, by having an additional day after December 30, called Worldsday, which is not assigned any of the seven days of the week, and is meant to be a holiday worldwide. So, after Sunday, December 30, comes the Worldsday, and then comes Monday, January 1. In leap years, there is an additional day between Sunday, June 30 and Monday, July 1, which is called Leapyear Day, and is not assigned any day of the week. The Worldsday and Leapyear Day are marked W in the calendar below:
How this calendar is better than the current calendar:
- You don’t need any algorithm to find which weekday a particular date fell on in a year. Every date falls on the same weekday every year. It is simple, can be memorized by anyone, and is like a clock.
- Every quarter is of equal length, 13 weeks, thus making accounting and banking data more accurate.
- When the year changes, the calendar does not change. It saves a lot of paper and money every year.
This calendar has religious issues. Fridays have a special significance in Islam. 29 December is a Friday, and you want the next jum’ah prayers to be offered seven days later. But seven days later is a Thursday, because of the intervening Worldsday which is not assigned any weekday. And jum’ah is supposed to be observed on Fridays, not Thursdays. So it disturbs the cycle.
Similar concerns were raised by Jews and Christians, for whom a particular day of the week holds significance (Saturday and Sunday respectively), and the Worldsday disturbs the cycle.
Due to these reasons, this calendar was not adopted despite it being so simple.
(Information compiled from the Wikipedia page:)