Time Keeping for Aliens

[Ray McCarthy]

Not a problem.

• Ships use the universal co-ordinated time of their homeworld. (as do aircraft, ships, spacestations and spacecraft today, they keep GMT/UTC)*.
• Ships use the calendar of their homeworld.
• Each homeworld uses their own time & calendar system to suit the day length (rotation), seasons (elipical and/or tilt) and star orbit length of "year".
• Date/time conversion between homeworlds is trivial for computers (I have programs for my fictitious worlds and ones exist for Mars etc).

[* Long ago ships kept the calendar and time of their home country. Before railways resulted in a National Time, many people used local solar noon as local 1200 hours.]

 

[Mad Alice]

A second is the relative time of a single human heart beat while the heart is at rest.
The Babylonians noticed that the stars change of position nightly worked out to 1/360 of the Sky's rotation.

Coincidence? Geometry and Physiology (ancient, Egypt, general, Sumeria) - History -U.S. and World, studying past, wars, presidents, language, economy - City-Data Forum

This is an idea of how the heart beat can be used with technology for measured rhythms.
The triple heartbeat of time lords in doctor who gives you an example of how aliens might present this.
Biological and Technological Time in Katharine Hawthorne’s "ClockWork"

This is a treatise of ancient medicine that describes the Indian and Chinese measurements based on the pulse.

http://www.hindawi.com/journals/crp/2011/164832/
Again, these different perceptions could help you develope an alien timekeeping technology.

 

[JC Kang]

Love this thread!

I think the original poster has the right idea to look back and think what influenced our own time keeping systems. Stuff like orbital periods of the planet and its moons are pretty obvious, as well as phalanges and life cycles to keep time. Of course some other considerations might be how the aliens perceive their surroundings-- what if they are blind? what if they don't have phalanges at all? Is there some food they rely on that grows in life cycles?

 

[Ray McCarthy]

The Babylonians noticed that the stars change of position nightly worked out to 1/360 of the Sky's rotation.

Except it isn't. It's close to 1/365.25, which they certainly eventually figured out. I think they liked 360 as a rounder number as it's 6 x 60 and 60 divides by 1, 2, 3, 4, 5 or 6. As well as 12 or 10. Counting to 10 or 12 on hands was very common. Newgrange in Ireland is staggeringly probably over 4500 years old and would allowed folk to count that the year was slightly longer than 365 (after four years the alignment would be a day late). The Ancient Babylonians and later Chinese were also excellent astronomers.

The 360 as an approximation of days in the year, according to Georges Ifrah, is only one of several competing and unproven theories. According to him, no-one knows where the 360 comes from.

Pulse rate is irrelevant unless you already have a measure of time and a number system. A minute of time now is quite different from Sumerian and Babylonian minutes of time.

Phalanges (aka finger and toe bones), claws, tails, limbs and tentacles etc are indeed obvious and likely bases for numbers, though here that has given rise to 5, 10, 12, 20 and possibly others as it depends on if joints / knuckles are counted and how it's done. So for realistic aliens you can easily have several historic number systems and one dominant one. One imagination failure in almost ALL TV/Cinema and many SF is that Alien worlds often seem to have a single homogeneous culture /ethnicity now and in the past. To me that's lazy and unrealistic. So I put different languages (or dialects) and ethnic groups (or vestiges of them) on different regions, esp. continents and often skin colouration related to background region of an ethnic group (near Arctic, temperate, tropics, equatorial might give rise to four main variations of appearance, as might plains people vs jungle (Africa has very tall and very short ethnic groups). Humans in reality vary from 4ft (maybe less than 1.2m) to 7ft (certainly over 2m). Perhaps some aliens might vary in height even more.

Also some African tribes (Batutsi?) commonly have 5 fingers and thumb. Aliens might have variable polydactyly by ethnic group and maybe two common number bases. (It occurs commonly in cats).


When you build something that is only illuminated at a specific time on the Winter solstice, then a year later you know how many days long a year is.
Virtually every planet has an axial tilt and a slightly elliptical orbit. Which ever of those has a larger effect will decide the seasons. Tilt causes seasons to be marked outside tropics. A more Elliptical orbit and little tilt means seasons change even at equator. If the tilt is more significant (probably common), then seasons change little between the tropics and most outside the tropics, more so as you are closer to the poles.

Solstice means "sun standing still". This only appears to happen due to axial tilt, twice a year. It's more obvious on the short day of winter than longer day of summer, so "time keeping" observatories of the ancients were built for the winter solstice.

 

[Denise Tanaka]

Gosh... I was intrigued by the thread title and thought I could jump in with a comment but as usual, I am late to the party. Wow! Such a wealth of information!

Well, I was going to say that a good place to start is asking WHY you need a calendar system? Why do the characters in your book need to know what day it is at all? For agricultural societies, it is critical to know when to plant seeds, how to track the growth of crops, how to predict the weather patterns of seasons, etc. For commerce and trade, whether by sea-faring cultures or star travelers, it is critical to know when to launch off into the great beyond. Fishermen watch the migration of species. Renaissance explorers watch for the right season to sail and they navigated by the constellations. Star travelers will need to watch for the orbits of planets, and what not. Communication across vast distances is also important, like Ray said.

My point is, think of the problem that your characters need to solve. Don't just arbitrarily make up an ingenious mathematical calendar and impose it down onto them.

 

[J5V]

My short answer would be: it depends on a readily-accessible reference for time.

For many years, we've seen midday, we've seen a full moon.

Within a couple of generations, some might argue that we'll be on decimalized time (or noon = 0.5), or SI-based time. That accessibility would include how computable it is from the environment, so technology might be good enough for everyone in human-explored space to use UTC with its "YYYY-MMM-DD hh:mm:ss.n +(h) -(c-shift)" indefinitely.

To think about this for aliens, or to be genuinely 'universal', you have to disregard anything that is Geocentric (year/season/day), or human-centric (second), including an arbitrary zero value (compare Kelvin with Celcius).

So 'ticks' might relate to the oscillations in a specific atom, or some other physical process. Perhaps 'ticks since the universe was believed to have been formed' will prevail, with an agreed near-history value.

 

[TitaniumTi]

What if the aliens' time-keeping was determined by their circadian rhythm? If they were crepuscular - awake at dawn and dusk - then the daily cycle might naturally be divided into four parts, and those four parts might be further subdivided.

If there was strong physiological control over wake-sleep cycles, the question "how long does the journey take?" might be replaced by "can we get there before sleep-time?"

 

[JC Kang]

What if the aliens' time-keeping was determined by their circadian rhythm? If they were crepuscular - awake at dawn and dusk - then the daily cycle might naturally be divided into four parts, and those four parts might be further subdivided.

Right, but their circadian rhythm would probably be based on stuff going on the the observable astrophysics scale.

 

[JC Kang]

Which is to say, they evolved based on what happens on their planet-- the amount of sunlight, the gravity from any moons, etc. So would they pay attention to their circadian rhythm, or on the length of the day? Hah, it's too early in the morning so I can't articulate what I'm trying to say....

 

[james lanfear]

I don't think that our way of measuring time has necessarily stopped evolving, either. It may well change in the future. Imagine a time when a civilisation, ours or alien, has extended it's population out into the near reaches of it's system. With so much of the population living on new worlds & moons, in space ships, in/on orbiting habitats, etc. The old measure of time would become less & less relevant.
Also, a space-faring capability might well indicate an equal level of bio-engineering tech. Bodies may well be adapted (& improved upon) to new bio-rhythms to suit these new environments. So, the biological 'clock' of the old system might be discounted.
Politics & influence would have a big bearing on choice, too.
Traditionalists clinging to the old ways, technological societies constantly embracing the new & more practical ideas.

 

[Mirannan]

Trinary numbers are, I believe, used in some computing applications; the hardware uses charges or magnetism -1, 0, +1. So this might influence the situation.

A multi-planetary society might use local times based on planetary rotations and revolutions, with a universal time scale based on fundamentals such as Planck length, time and mass. Of course for practical uses, large multiples of these might be used. Or perhaps based on the basic numbers attached to the hydrogen atom; its mass and the frequency and wavelength of what we call 21cm radiation.

 

[Piousflea84]

Any form of timekeeping used by an alien civilization will almost certainly, like our own, be highly irregular and not particularly logical. Why is February only 28 days and July+August are both 31 days? Because some emperor said so. Humans have repeatedly tried to make our (Gregorian) calendar more logical, but it's highly improbable that we will ever abolish our old calendar. Even if we colonized Mars and the Asteroid Belt, our Earth-based holidays, popular culture, commercial culture, and business transactions are all based on a calendar system designed by medieval monks.

An alien culture would have its own unique quirks, many of them sociocultural rather than astronomical. Their calendar would very likely be informed by their biology... we humans have longstanding superstitions about the moon and the menstrual cycle because they are both approximately 28 days. An alien planet may or may not have a Luna-sized moon. Some people believe that an Earth/Luna type system is very rare as it requires a collision between two rocky planets... other people believe that a Luna-sized Moon may be required for the evolution of complex land-dwelling life-forms (because of tides, ocean chemistry, coastal erosion, etc). None of that is scientifically proven.

On a planet with one sun and no satellites (such as Venus), timekeeping would have to go by the sun and stars. One would think that would encourage very simple calendars as there's no need to reconcile a "month" cycle with a "year" cycle. But I would actually think the opposite... the moonless month would not be tied to any natural phenomenon so it could be defined by an entirely political process. Any primitive king or religious leader could change the length of the month, or of a specific month, on a whim. Their "month-like" cycle may be completely irregular and culturally/socially determined.

On a planet with a close-binary system (such as Tatooine) the suns would orbit each other fairly quickly, ranging from days to a small number of weeks. The period of the sun would very likely be used as a "week-like" cycle, and a "month" would be defined as a whole number multiple of bi-solar cycles.

On a planet with far-binary suns (such as Alpha Centauri) the suns would have a decades-to-centuries orbit. This could be used as the alien equivalent of the Mayan tun or the Chinese sexagenary cycle. Because this cycle would not synchronize with the planetary orbit ('year'), the multi-decade-cycle would occasionally experience "leap years". This would almost certainly have some religious or superstitious significance, as it would only happen once every several centuries.

On an Earth-like moon orbiting a Jovian or Supra-Jovian gas giant (such as Endor or Yavin), there are a vast number of complications. Any gas giant with enough satellite material to build an Earth-sized world would have a huge number of smaller moons, ring systems and ring bodies. From the standpoint of a primitive alien ("Ewok") living on the Earth-sized moon, each of the smaller moons would have its own unique orbital patterns. Orbital resonances would encourage 2:3, 3:4, 4:6 correspondences between orbital periods. Many "Endormoons" would therefore follow a predictable path that is some multiple of Endor's own orbital cycle. Further-out "Endormoons" would follow non-resonant and therefore unpredictable orbits. All of the Endormoons would appear significantly smaller than Earth's moon as the orbital spacing around a gas giant is much larger than Earth-Luna spacing... and their size would change dramatically as they went around their orbits.

It is likely that the Ewoks would come up with complicated mythological explanations for what moon represents what god/ess and why they follow or don't follow a predictable pattern. The more predictable moons could be used as the basis for a "monthly" calendar.

An "Endor" orbiting a supraJovian giant would likely be tidally locked due to the latter's high gravity. Therefore, one side of Endor would always face the gas giant while the other side never sees the gas giant. The day/night cycle on Endor would sync up with the waxing/waning cycle of its giant planet. In addition, an Ewok tribe from the anti-planetary side of Endor might have no idea that the planet even exists, other than vague legends. If an explorer from such a tribe were to venture into a land where the giant plant is visible, they would be absolutely floored - which may be interpreted as some kind of spiritual or religious epiphany.

An "Endor" would likely experience severe tidal heating and volcanic activity due to the motion of the other gas giant moons. The frequency of volcanic events would correlate with lunar conjunctions... which could be observed from Endor's surface as an unusually large and bright moon in between "Endor" and its gas giant. (the alignment may not be exact if the moons have some orbital tilt) A primitive Ewok culture would almost certainly interpret this as some kind of conflict between the Gods; it would have its own holiday and probably involve sacrificing large humanoids to a neurotic metal-skinned being.

 

[Vertigo]

The use of 12 months is almost certainly due to it's divisibility rather than stars (I suspect the astrological signs were 'designed' to fit the number not the other way around). The same is true of 60 seconds to the minute, 60 minutes to the hour, 12 hours in half a day, 360 degrees, 16 ounces to the pound. All these numbers are easily divisible; the one really sad thing about our numbering system is that we have been landed with such an inconvenient number base just because of the number of digits on our hands (and feet). Life (and mathematics) would be so much easier if we used a base twelve or sixteen (although we might have been slower to develop the equivalents of 'decimals' - 0.5 as opposed to 1/2). I think it's unlikely an alien would base their time system on any physical atomic type properties because, just as with us, their timing system will have been long established before they were capable of discovering such things.

I would think aliens would likely have exactly the same issues. The numbering system would probably have a base determined by number of digits but they would probably also use easily divisible numbers whenever there is a need for subdivision such as time and weights. The beauty of 12 is that we can halve, quarter and third it (and it's multiples) which, I suspect, is probably why it is treated as a sacred number in so many contexts.

 

[Mirannan]

The use of 12 months is almost certainly due to it's divisibility rather than stars (I suspect the astrological signs were 'designed' to fit the number not the other way around). The same is true of 60 seconds to the minute, 60 minutes to the hour, 12 hours in half a day, 360 degrees, 16 ounces to the pound. All these numbers are easily divisible; the one really sad thing about our numbering system is that we have been landed with such an inconvenient number base just because of the number of digits on our hands (and feet). Life (and mathematics) would be so much easier if we used a base twelve or sixteen (although we might have been slower to develop the equivalents of 'decimals' - 0.5 as opposed to 1/2). I think it's unlikely an alien would base their time system on any physical atomic type properties because, just as with us, their timing system will have been long established before they were capable of discovering such things.

I would think aliens would likely have exactly the same issues. The numbering system would probably have a base determined by number of digits but they would probably also use easily divisible numbers whenever there is a need for subdivision such as time and weights. The beauty of 12 is that we can halve, quarter and third it (and it's multiples) which, I suspect, is probably why it is treated as a sacred number in so many contexts.

I think you are almost certain to be right. For one thing, there is a sign missing from the astrological zodiac. Ophiuchus straddles the zodiac; considerably more of the zodiac is in that constellation than in Scorpio for example. Another point is that the size of the astrological signs (in terms of time over the year) are equal and the actual size of said signs on the ecliptic are wildly different from each other. And the third point is that we are now in the age of Aquarius - which means that the signs used by astrologers are two months out from the facts in the first place, even allowing for the missing sign and the unequal sizes.

Regarding time systems; I agree, except that a multi-planetary civilisation would have to have an agreed time standard - which might well be a completely new one for political reasons.