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It is a fraction of the lunar month…about 1/4.2. That’s hardly a nice clean division of the lunar month. You’d be a heck of a lot closer with 5 weeks of 6 days

It is a fraction of the lunar month…about 1/4.2. That’s hardly a nice clean division of the lunar month. You’d be a heck of a lot closer with 5 weeks of 6 days each!

Torwald 5y ago
It's related to the lunar phases, not a purely mathmatical division.
- rhn_mk1 5y ago
  But lunar phases... are a mathematical division? 1/4?
  - QuercusMax 5y ago
    New moon and full moon are real things you can see, not an arbitrary mathematical division. And then the first / third quarter is just halfway between. Results in about 7 days per lunar quarter.
    - tshaddox 5y ago
      But it's really not even close to "about 7 days per lunar quarter," at least not close enough that using the calendar can tell you anything useful about when future new moons will be. Even if you're just looking ahead 4 weeks you'll already miss the new moon by a day and a half!
    - rhn_mk1 5y ago
      We can see the result of (not arbitrary, but) precise mathematical divisions. "Halfway between" is a mathematical division. I must be missing something huge here.
CapitalistCartr 5y ago
Have 4 seven-day weeks, with an extra "holiday" every month for the new (or full) Moon consisting of alternating one and two days. Average month: 29.5 days.
- bsedlm 5y ago
  that'd be super cool. one or two days off every month! (in addition to weekends)!
  - gumby 5y ago
    In the pre-computer days it would make things like computing interest harder. In Rome, interest and rent were mostly computed by the month, and the days inserted to keep the calendar aligned were deliberately between years to make these calculations easy to do (no interest or rent was due, and they could not be used as start or stop days of contractual relationships). Using a pencil influenced other modern things too, like the Dow indexes and GDP.
- anonporridge 5y ago
  Or just a 13 month calendar of 28 days each, plus a floating "year day" and "leap day" that aren't a part of any week or given any week day designation. https://en.wikipedia.org/wiki/International_Fixed_Calendar https://en.wikipedia.org/wiki/International_Fixed_Calendar
anonporridge 5y ago
Powers of 2 tend to be superior for more factors. Four weeks means we can easily reason about halves and quarters of months. Five weeks means we can only easily reason about fifths of months. For a similar reason, it might have been better if humanity had settled on a base 12 number system rather than base 10. We can only easily halve 10 while we can easily halve, third, and quarter 12. More factors means it's more intuitive to reason about common fractions of things. Earlier civilizations did use base 12, and we still have elements of that history in common use, like the special names for eleven and twelve in the English language and our 12 hour clocks. A common theory for the prevalence of myths about 6 fingered foreigners in the Bible is that these other cultures used base 12 numbers, and the only way people using base 10 could understand that was to assume that they must have 6 fingers to count with. Interestingly, you can actually use your fingers to count to 12, using the 3 segments on each of your 4 fingers rather than the 5 whole fingers.
- tshaddox 5y ago
  > Powers of 2 tend to be superior for more factors. Four weeks means we can easily reason about halves and quarters of months. Five weeks means we can only easily reason about fifths of months. Sure, but the nice 4 week period is not actually anywhere close to a lunar month, so the "groupings of 4 weeks" part makes sense because 4 is a nice number, but the "7 days to a week because 4 of them will add up to a lunar month" thing is just not even close. We're not talking about something like leap seconds where the drift is slow relative to a human lifespan. 28 days is a whole day and a half shorter than a lunar month.

It is a fraction of the lunar month…about 1/4.2. That’s hardly a nice clean division of the lunar month. You’d be a heck of a lot closer with 5 weeks of 6 days each!

Torwald 5y ago

It's related to the lunar phases, not a purely mathmatical division.

rhn_mk1 5y ago
But lunar phases... are a mathematical division? 1/4?
- QuercusMax 5y ago
  New moon and full moon are real things you can see, not an arbitrary mathematical division. And then the first / third quarter is just halfway between. Results in about 7 days per lunar quarter.
  - tshaddox 5y ago
    But it's really not even close to "about 7 days per lunar quarter," at least not close enough that using the calendar can tell you anything useful about when future new moons will be. Even if you're just looking ahead 4 weeks you'll already miss the new moon by a day and a half!
  - rhn_mk1 5y ago
    We can see the result of (not arbitrary, but) precise mathematical divisions. "Halfway between" is a mathematical division. I must be missing something huge here.

CapitalistCartr 5y ago

Have 4 seven-day weeks, with an extra "holiday" every month for the new (or full) Moon consisting of alternating one and two days. Average month: 29.5 days.

bsedlm 5y ago
that'd be super cool. one or two days off every month! (in addition to weekends)!
- gumby 5y ago
  In the pre-computer days it would make things like computing interest harder. In Rome, interest and rent were mostly computed by the month, and the days inserted to keep the calendar aligned were deliberately between years to make these calculations easy to do (no interest or rent was due, and they could not be used as start or stop days of contractual relationships). Using a pencil influenced other modern things too, like the Dow indexes and GDP.
anonporridge 5y ago
Or just a 13 month calendar of 28 days each, plus a floating "year day" and "leap day" that aren't a part of any week or given any week day designation. https://en.wikipedia.org/wiki/International_Fixed_Calendar https://en.wikipedia.org/wiki/International_Fixed_Calendar

anonporridge 5y ago

Powers of 2 tend to be superior for more factors. Four weeks means we can easily reason about halves and quarters of months. Five weeks means we can only easily reason about fifths of months. For a similar reason, it might have been better if humanity had settled on a base 12 number system rather than base 10. We can only easily halve 10 while we can easily halve, third, and quarter 12. More factors means it's more intuitive to reason about common fractions of things. Earlier civilizations did use base 12, and we still have elements of that history in common use, like the special names for eleven and twelve in the English language and our 12 hour clocks. A common theory for the prevalence of myths about 6 fingered foreigners in the Bible is that these other cultures used base 12 numbers, and the only way people using base 10 could understand that was to assume that they must have 6 fingers to count with. Interestingly, you can actually use your fingers to count to 12, using the 3 segments on each of your 4 fingers rather than the 5 whole fingers.

tshaddox 5y ago
> Powers of 2 tend to be superior for more factors. Four weeks means we can easily reason about halves and quarters of months. Five weeks means we can only easily reason about fifths of months. Sure, but the nice 4 week period is not actually anywhere close to a lunar month, so the "groupings of 4 weeks" part makes sense because 4 is a nice number, but the "7 days to a week because 4 of them will add up to a lunar month" thing is just not even close. We're not talking about something like leap seconds where the drift is slow relative to a human lifespan. 28 days is a whole day and a half shorter than a lunar month.