Here in the United States, except for most of Arizona and Hawaii, we’ve gone into Daylight Saving Time, when we shift our clocks forward an hour so we can take advantage of more sunlight in the evenings after work. You know what DST is, because while the whole world doesn’t use it, probably 95% of this blog’s traffic comes from countries that do. However, DST is not universally applied internationally. The US and the UK shift a few weeks apart, and Australia observes DST opposite the rest of the world due to flipped seasons. It also picks different dates. This video explains the history of DST and how things just don’t line up all that smoothly, and even the odd DST observing and non-observing enclaves within Native territories in Arizona:
So last week we here on the east coast of the United States were 16 hours behind Sydney, Australia, now we’re 15, and in another few weeks it’ll be just 14. And just when it looked like we were catching up to the Aussies, it’ll all reverse and go back to 16 hours in a few short months.
Alright, so what’s my vague justification for talking about DST under the auspices of World Building? It brings up an important question when it comes to non-earth worlds: What time is it? How granular is time? In a less advanced civilization there may be just four broad times: morning, midday, evening, and night. If you’re not trying to plan specific and detailed events, that’s all you really need, and it’s more about our perception of time than actual hours. “Morning” changes by hours a year, to when it starts, when it ends, and how long it is, thanks to lengthening and shortening of a day and by ones latitude.
A more advanced society requires more advanced time keeping. Broad subdivisions of time independent of the rising and setting of the sun come first. We call these hours on earth, and arbitrarily divide a day into 24 of them. There are 24 because the Egyptians liked to use base 12, and split the equinox day into equal halves, twelve portions of daylight, twelve portions of darkness. Why 12 when we have 10 fingers? Because they counted knuckles, not digits. It’s handily a mathematically significant number because there are more factors of 12 than 10, but it’s largely arbitrary due to one culture’s affinity for a number and later cultures’ affinity for that culture.
Once a society becomes more advanced, it needs more granular time. This won’t necessarily lead straight to minutes, but could be quarters of the longer time blocks, or perhaps eighths. Even modern society we tend to use only halves and less frequently quarters for most of our daily activities. Sixty minutes on earth come from old methods of hand counting from cultures that lacked calculators and needed ways of tallying numbers larger than ten using the digits on their hands. It’s the old 12 knuckles on one hand, multiplied by 2, 3, 4, or 5 on the other. Thumbs need not apply. We further divide things into seconds, again with 60 per minute. After that, time becomes decimal, belying the fact that smaller units of times than seconds weren’t really necessary until after the scientific revolution. Thus we end up with milliseconds and picoseconds.
There are some who suggest that all of time should be decimalized the way subdivisions of seconds are. A day would be 10 hours of 100 minutes of 100 seconds, which the length of each being determined by taking the period of revolution of the earth and dividing by the correct number. While there’s a certain logic to this decimalization, there is so much cultural momentum to overcome that decimal time will likely never be more than just a novelty. We see this here in the United States as various movements fail to convert the country from imperial to metric measurements.
We further complicated time of day with time zones, designed so that noon in each part of the world roughly represents the midpoint between sunrise and sunset, but rarely actually does. There is some push to eliminate those just as there is a push for the decimalization of time. This is more successful as there are already organizations, such as major world navies, who see the benefit of referring to an exact moment of time by the same numerical representation wherever you are in the world. Thus 0300 Zulu is 0300 Zulu whether a ship is in the Atlantic, Pacific, or Indian oceans. It’s handy for any organization attempting to synchronize around the planet, or even beyond it, something that wasn’t necessary or possible until very recently.
So let’s pretend we’re world building time on the earth. The day was divided into 12 units (and the night an additional 12) because 12 was a culturally significant number for an early culture, in no small part because it represented the number of segments on the fingers of one hand. Hours and seconds were divided five times farther because early cultures would use this counting-to-twelve method on one hand, then use the fingers on the other hand for the multipliers 2x through 5x. Subdividions of seconds are the only units of time that are decimalized because they are only useful to scientists who prefer decimalization because it makes math easier. These divisions have nothing to do with when the sun rises or sets, and even arbitrarily shift by an hour at a time. The earth itself is divided into 24 major time zones (we won’t even start with the minor half and quarter hour zones) one per hour of the day for offset, though these are slowly going away in favor of a universal time. And this is all before we’ve put down our first settlement on a planet that rotates at a different rate than earth, which will further complicate things.
So we’re back to the original question. What time is it? It’s a complex question that will deal with the history of your planet and culture, cultural norms, scientific advancement, and ultimately may cause debate and confusion on a planet shrunk by high speed communication.
And this is without even asking two far more complicated, but legitimate, world building questions: What day is today? And when is lunch?