The issue is that of how a society measures the more arbitrary lengths of time that make it function. For example, a year makes sense so long as you are on a planet orbiting a star. No problem - one full cycle of the seasons is a year, no need to make up a new word for year. Seasons, particularly as are related to the harvest cycle, also make sense, but in a quasi-modern society (like much of the 20th century), we don't really measure things by "spring, summer, fall, and winter." I suspect those of us on the west coast would have a tough time understanding calendars if we did.

The part that is tripping me up is to come up with a good basis for months, weeks, and hours. (A day is also trivial -- one spin of the planet). Months are a less awful issue, aside from coming up with names. Some of those were fairly arbitrarily decided in the calendar we use today, and I can recreate a history to decide how many there should be and hack together something for their names.

Weeks and hours, however.... I feel a little lost. The week itself was an arbitrary construct by agrarian societies to determine when farmers from distant areas should come to market to sell goods. This is why simple repeating cycles were used (N days, rather than looking at variations in the moon or seasons), from what I understand. We can probably trace the origin of our current seven-day cycle to the Judeo-Christian creation week story. My world is not in any way connected to Earth, so I have no desire to rely on our constructs. However, I also don't want to be different simply for the sake of being different. Should a week be less than 7 or more than 7 days? Is there a good reason for either? Does it seem like a hack if your week has seven days?
... Well, clearly this writer had no imagination... seven days in a week? Why not have the plot happen in New York?...

And then there is the problem of hours. I have no problem calling a somewhat-hour-length time span by the name "hour" (as it beats zigflub, or some other such specfi creation). I don't really have a good idea as to how many of them there should be in a day. "Meet me at the pub at 7" has a meaning in the book... is that way to early to go drinking, or just before midnight?

The society in my book is similar to ours in the sense that people structure their days by a work day (and use hours to do so) rather than by sun-up and sun-down, so it is nearly impossible and definitely unnatural to remove comments about time from their speech patterns.

Anyone know why there are 24 hours in a day? Have any good ideas for why there might be a different number? For the hours/day, I'd rather stay away from "because the gods said so," though a story about the gods, creation or otherwise, might be what I resort to for the number of days in a week.

With respect to the gods, in this book the gods are as real as are our own. That is to say, there are plenty of people who believe with all their souls that He exists and watches over us, but you can't go visit Him at his home and ask Him a question, and He doesn't hold court or send out messengers/news flashes, etc. These aren't Greek gods that talk with/kill/have sex with any humans or animals (though there might be societies that have stories detailing exactly that).

Grant

If you have a world that has an exactly round orbit, with no tilt on the axis, one would use a star to determine the year because otherwise, there would be no other measure of the year.

The month could be divided by another significant number of days. Seven was a holy number.

If twelve is the holy number you use for months of the year, then one divides the day by twelve, then divides the night by twelve, giving you your twenty four hours.

Then Sixty is also a holy number and easy to divide up by one, three, four, five, six, ten, and so on. It is very convenient a number to divide into smaller unites. Then seconds would also use the same holy number.

Where holy numbers are not used, a convenient number of days can be used for the work week. Of course, in some societies, there are no rest days. One works every day of the year.
One must look to see how many days a person can work without a rest, and how many days off in a year becomes a bit silly.
If one has two days off. a five day week is a bit silly. One is off almost as many days as one works. If nine days is the week, that means that there are seven days straight without a break. Anybody who has done that knows it is an effort.
Six days might be good and would fit the holy number thought as six is divisible. Eight days might be OK, just a tiny bit long.

I read one radical historian who said that at one time, there were 360 days in a year and twelve months. Then a world wide disaster hit and five extra days was added to the calendar and the month changed. An extra day was added to the week and that was the day of rest, one would point to in Genesis. It was a brand new day that nothing needed to be done.
He pointed to a number of things around the world, like the south American Native's calendar added five days at the very end, sort of cobbling the days onto it.

Thanks, Annepin, for the Babyonian steer. According to my Google results the Babylonians may have counted in base 12 because we have three joints on each of four fingers that we can count with the thumb; or they used a base 60 system inspired by geometry, and somehow I prefer this explanation. More at
http://en.wikipedia.org/wiki/Babylonian_mathematics.

Either way, the base for the mathematical system seems to relate to what's easy--either counting on fingers or subdividing a circle using simple tools into equal portions.

The overall cycle of a year is, as you mention, driven by our orbit around the Sun. Subdividing it goes with the equinoxes and the need to know when to sew crops, and when to harvest them. I guess we subdivide further to know, for example, when to start preparing for such activities.

In the early days we told the time with sundials, water clocks and the like, and it was the invention of devices like these that brought in hours of equal length. The time was different in each town, just slightly, with midday depending on exactly when the sun was overhead. There were complicated procedures for adjusting your watch to local 'sun time'. Since a sun-dial is actually only correct at certain times of the year--because the Earth wobbles on its axis--there were more complicated procedures for adjusting the hour as read from the sun-dial into the correct time. (If you don't do that your hours are uneven in length and depend on the time of year, annoying if you're timing the baking of a cake.)

With sun time different at each station on a railway line, timetables had to either be printed in local time for each station, or translated into local time from a table printed using London time. People kept missing the train. Worse, railway engineers would say things like "Switch the points at 10.30 for the train going North", use local time instead of London time, and cause a head-on collision between two trains. This confusion was what made the railways standardise time across the nation--or in America, across just four time zones.

The need for accurate mechanical clocks was driven by navigation of ships at sea. You can navigate north-south according to the stars, but for east-west you need accurate time as well. On land that's not so hard, but at sea the problem was making a pendulum clock that can handle the rocking of the boat--a clock that rocks, if you will. Accurate clocks were invented as a result of a competition organised by the King of England, who tired of ships running aground and losing his treasure. (This was the "longitude problem", more at http://www.nmm.ac.uk/server/show/conWebDoc.355. Scroll down for Harrison's Number 1 Marine Timekeeper, it's beautiful.)

These days navigation still drives a need for ever more accurate clocks, but now for GPS systems. Also, computer networks need accurate clocks to enable them to synchronise data and audit trails.

Methods of time keeping tell much about us, and could be used to weave in detail about an alien race and what matters to them.

I think it was Vernor Vinge who had, on a way-future Earth, a "witching hour," consisting of the longer-than-twenty-four-hours period tacked on as Earth's rotation slowed down. I liked the color it added to the story, as well as the rationale.

quote:

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Maybe because a normal person has 20 fingers?

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Two prominent authors that come to mind that have sucessfully made time true to their worlds so-to-speak are Anne Mc Caffrey and Ursula Le Guin.

I have a difficult time with the endeavor. It is very hard to create a seamless system. Le Guin has tables in the back of her novel, The Left Hand of Darkness (One example I can produce readily)

It seems the most common to play it down. That is to say, I think most writers try not to make it a big deal. I suppose this makes it less confusing on readers.

Another factor to deal with is cicadium rhythm. Our bodies internal clock is very much influenced by evolution. Day and night cycles need to ressemble Earth's in order to suit our needs unless there has been significant alterations in our evolution.

If your world is earthlike, especially in fantasy, it might be best to make it as earthlike as possible, and play it down in a way that is not a big issue unless of course it is integral to the plot. The two mentioned authors had major reasons to clarify time. Le Guin was dealing with intricate breeding cycles of an alien race.

I have seen many sucessful fantasy novels where it wasn't really an issue. Although clearly on another world, time and seasons, never deviated from normal earth measures.

I'd never really given much thought to the fact that 12 is a superior number (divisors add up to greater than the number)... which does make it convenient. I always saw that as a good reason for a system of measurement or money and never really thought about time. I'm a little wary though, of having things be identical to our systems because... it breaks the lack of reality, I think. If a world is familiar, and yet fantastical (because of magic and a different social structure), it seems to me that pulling things exactly out of our own world leads people to believe that there is a connection between Earth and the world in the story (which I never intend to have), or else it brings you out of the fantasy and makes you aware of the writing. It seems almost like coming across a fast-food burger store.

The effect, I think, would be as if you were a writer that came up with a new name for everything b/c it is in some alien language. Shoes are mggxzz, pants are bulgiizzax, cars are tilmukka, and so on. Suppose then that you somehow managed to find readers who were okay with all this. Imagine how jarring it would be then, when a character fastens his bulgiizzax with a "belt."

The Mayan and Babylonian examples are great examples of alternative systems of time and measurement definitely worth looking into.

Reinventing the origins of the smallest things that we use without a second thought today are some of the most frustrating and interesting parts of worldbuilding to me -- thanks for all the feedback.

Another time keeping mechanism was "watches" (mentioned in the new testament) I forget how they line up with our clock, but presumably they corresponded with the changing of the guard.

http://www.britannica.com/clockworks/t_candle.html

http://en.wikipedia.org/wiki/Candle_clocks

Interesting stuff.

Once everybody agrees to the figures, it becomes easy to work with.

Of course, instead of using week, month, year, one could use eight day, forty day, four hundred day, instead. One would get a description of the time periods and it would not require a new set of words.
One might use BELLS rather than hours, and just decide how many bells are used in a day. One might only use the bells during daylight hours. Also the day might start at noon rather than sun-up. so the start of the day is always the same.

For me, it would be akin to stopping and saying "wait a minute, why do all of these people on another world speak English?!"

There is always a line, imo, where it's not a matter of making your world unique; it's a matter of translating to the reader. We pretend that these fantasy worlds speak our language or we couldn't read the dialogue. I also believe this often applies to distances as well. If the main character thinks "what's that I hear in the woods, it's about 50 grlumfs away..." that doesn't tell us anything, unless we know how to translate a grlumf into feet, meters, or something we're familiar with. Most of the time, the extra effort pulls us out of the story, rather than making the story seem more believable. I believe the same is true even more so with time. The vast majority of humankind uses seconds, minutes, hours. It's the way we think about time. So unless you have an extremely important reason that your world needs a different time system, I say stick with seconds/minutes/hours/days.

At the same time, I would argue that the number of hours per day, the number of days per month (if there even is a "month") or days per year are somewhat different scenarios. The day and year of a planet are defined by the geometry of the solar system. More so in science fiction than fantasy, I would be somewhat suspect of people on a planet that just happens to have identical 24 hour days and 365 (well.. and a quarter) day years. At the same time, again unless it really matters, there's no reason to bring these issues to attention in any novel. Just because 20 year old John Smith lives on a planet with 483 day years, doesn't mean there can't be some "standard year" by which people age themselves.

On the wider subject, time is very important to my WIP and it's been really fun to play with. In my world, time operates at 1/6 the speed of Earth and the sun-up sun-down time is only 1/12th of the total day (I won't bore you with why). And, most of the inhabitants are only active during the day. So it led to an interesting realization for me that the nocturnal inhabitants were active for TONS of hours (132 to be exact) without the others, leading to some interesting plot ideas!

Ben Franklyn invented the concept of Daylight savings time. His idea, though, was to be done during the winter. Candles were expensive.
What he proposed is that the people come to work an hour early, and use candles for the fixed morning hours. The would leave work while it was still daylight so they would burn their own candles for the night.

Edited to add that the store chain, Seven Eleven, got its name because it was the first store that was open from seven in the morning to eleven at night, when towns would close down completely at five in the afternoon.
competition caused other establishments to extend their hours, to have more shifts. Now, Seven Eleven is open twenty four hours a day because of the changes they forced to happen.