Why seven day weeks?

Very large parts of the world, economy, businesses, cultures and religions evolved with the seven-day week for literally thousands of years. Changing to a different calendar system is already a massive undertaking. Attempting to change the typical length of the week cycle is pretty much impossible.

Most of our day to day lives are typically closely linked to the week cycle. Which days you go to work or school and which days you don’t. Even if you are working different shifts, you are probably thinking about your shifts in terms of the week cycle. For example if the next shift is a weekend shift or not. Chances are most of the things you do multiple times per month on a schedule, are scheduled with respect to the week cycle. Very rarely is something scheduled to always be on the 4^th of a month; it’s typically something like “every Monday”, “every 1^st Wednesday of the month”, or “every 2^nd Friday”, etc.

This is also the reason why calendars where the typical week length is not seven will never be adopted, because the schedules are so different that those calendars couldn’t be used in parallel with the Gregorian Calendar.

Breaking the week cycle

So why does SAC13 break the week cycle, then, if it’s so important? Because every alternative would result in a worse calendar for most people. The alternative would either not have a fixed layout, which is so important that it is the only thing all calendar proposals agree on. Or not have a solar calendar, and intentionally allow calendar drift. To my knowledge, nobody seriously suggested that yet. Or to use leap weeks, which come with a whole lot of other issues like high year length variability, sometimes a different number of months, or vastly different month lengths like in the Symmetry454 calendar where some months are 28 days and some are 35 days.

Why do we even need weekdays?

We need weekdays because the currently established calendar system is not one calendar, but actually two. The Gregorian Calendar, which defines months, their length, and leap year rule, and a technically completely separate “calendar” that existed long before the Gregorian Calendar: A repeating cycle of seven-day weeks. Those weeks actually don’t have anything to do with the Gregorian Calendar itself, they are just overlaid on top of it. This is also why it’s not easily possible to determine the weekday for a given date (if you are not into mental gymnastics).

Our day to day lives happen with respect to the week cycle and long term things are planned with the Gregorian Calendar. That’s why we need Weekday names, because if I’d just write “16^th April 2017”, would you know if it was on a weekend or not? Chances are, you have no idea. It was a Wednesday, but that additional information was only needed because the Gregorian Calendar and the week cycle are two different systems used in parallel.

No names vs new names

The reason SAC13 doesn’t use the traditional weekday names (Monday, Tuesday, etc.) is that it uses sync days to synchronize the calendar and to fix its weekdays. This causes SAC13’s weeks to drift against the strict seven day week cycle used with the Gregorian Calendar. If SAC13 used the same names, days would have (most of time) different weekdays in SAC13 and the Gregorian Calendar. A Tuesday in SAC13 might be a Sunday in the Gregorian Calendar. There are only two solutions to that: either using new weekday names or dropping them entirely.

The problem with coming up with new weekday names is that it’s hard to find something most people like, is translatable into many languages and doesn’t favor a specific culture, region or language. I thought about it a lot and came to the conclusion to just refer to them descriptively, like “3^rd Weekday”, “Weekday Three”, or “D3”.

As mentioned in the Introduction, it’s pretty simple to determine the day of the week in SAC13 for any day. Simply find the previous multiple of seven and take the difference. For example, for the 24^th, find the last multiple of seven (21^st), take the difference (3), so it’s the 3^rd day of the week, “Weekday Three” or “D3”.

This isn’t possible in the Gregorian Calendar; that’s why weekday names are pretty helpful there.

The point I wanted to make is, that in the Gregorian Calendar a date doesn’t tell you if it’s a business day or weekend (unless you very good at some mental gymnastics). With SAC13 you don’t need that. You don’t even need a date. The year doesn’t matter, the month doesn’t matter, just the day of the month. It couldn’t be any easier.