How do you measure time on a tide locked planet?

[AotrsCommander]

This is both a biomechanical and sociological question.

There is a planet. It orbits around a large star whose goldilocks zone is significantly far from the star that the orbit is measured in thousands of Earth-years¹. The planet is tide-locked². The planet is otherwise the same size and atmospheric content as Earth, but the life that developed is entirely alien.

So. Because the world is tide-locked, there is no day/night cycle and there are no seasons (the orbit cannot be erratic). So you can't measure time by the sun or the stars. In any case, as the plant remains largely habitable by the stabilising feedback of clould cover, the sky isn't always readily visible (and it's often raining). At ground level, there is a continuous stiff breeze coming from the dark side to the light side (again, part of the researched climatic conditons).

So how do you measure time, if you are a plant or a creature or a primitive neolithic tribe?

(Civilisations might make their own measures - I'd have to research into the history of who "invented" hours/minutes/seconds, but the larger question is more fundamental.)

This question arises as I contemplate, as I do on and off, a roleplaying campign game in which the player characters are part of a neolithic tribe, who are forced on a migration by changing geological conditions. As I was thinking about it today about the mechanics of it, I considered "well, you could simplify food to be 1 unit per person per day, maybe half for young children under... five... Wait, hang on. How long is a 'day?' For that matter, how do you measure what's a 'young child?' How long, even, is a guard duty shift going to be...?"

This is a rather metric defining question, the more I think about it.

At the most basic level, how does a plant know when to flower or seed? If it doesn't rely on insect-analgoue pollination, how do plants seed? They can't reliably use wind, since it for the majority only goes in one direction. Rhisomes are one obvious answer, but the other might be as interesting as like the Earth plants which shoot their seeds. But even then - what is the interval? In terrestrial jungles where there are no real seasons, trees of different species fruit at seemingly arbitrary periods, but even there, there is a day/night cycle to work off.

What is an animal's activity cycle going to be like? Again, on Earth, where there are places were day and night are both very long, they do change over. (I'm not even sure how long/when polar creatures sleep during the summer). Logically, one would assume that such creatures to have an functionally cathemerial cycle (i.e. for animals that vare active during both day and night), but even those are subject to the circadian rhythm which is absent here, so what instead defines the period?

For a primitive tribe, how would their society have developed to tell the passage of time? How often do they need to eat, when the basis is not a 24-hour circadian cycle? How do you tell how old someone is (and thus when they reach maturity)? Is there a specialias jon, like a time-keeper in the village whose sole job it is to measure time and how?

This is a very difficult question for me to answer, to the point I'm not even sure where to start looking. Thus, as inspiration (rare these days) has struck me to think about it, I have asked in a few places to see if anyone can offer any suggestions.
Now, in my earlier contemplation of this question, I did make one concession. There is a moon, a relatively late capture. This orbits once every six Earth-days, but though it appears about the same size in the sky as Luna to Earth, it's very small and low mass. (Tides is a difficult question, though it appears to impart about 94% of the acceleration Luna imparts to Earth, due to it's speed. It is assumed to be partly why the planet is not 100% completely tide-locked.) But that's nowhere near fundamental enough for the biology side of the question and aside from potential tides, the moon again won't be readily visible for an easy count even for a civilisation.
I can, of course, elaborate in more detail about the set-up, but I have tried to keep this down to the minimum required boundary conditions, else the question would likely be lost amid the rest of it.
¹There is a long and complicated explanation (in involved a lot of astrophysics maths, among other things) as to the set-up, but I have omitted it here for breivty and relevance to the question at hand.

²Strictly speaking, it's isn't 100%, but the day length is also in thousands of Earth-years at a minimum.

 

[Hornbein]

If they live within reach of the dark side they might be able to see the stars. That makes a unit of a year. A Stonehenge can give you month by observing the appearance of certain stars and measuring their height above the horizon. The week could be determined by the moon.

You can measure hours by water draining, by burning a standard unit, and so forth. You could have a big cistern that takes a week to drain.

How do you tell how old someone is (and thus when they reach maturity)?
If they are like humans they grow a beard or menstruate, become lustful, etc. I live on an island where until recently older people did not know their age. The importance of this is the modern custom of arbitrary ages for retirement, voting, drinking, insurance, etc.

Maybe animals have a sleep cycle, maybe they don't. Not helpful, I know.

 

[AotrsCommander]

The suggestions have been generally "maybe they don't" which on the one hand is a good point, but is raising some difficult mechanical questions, but those are better posed to the places more suited to that. Things like the water clocks I has already conasidered as an obviouis way for a moderatelt advanced society to keep time, but whether it would necessary for a primitive one I'm not sure about. The basic question would be "yes could, but what would the basis for that unit of measure...?"

The moon was, indeed a concession towards having some sort of "week" period.

It has been suggested that perhaps thay perhaps animals don't have a sleep cycle, which is interesting (I'd simply not considered that as a possibility). Somethign for me to consider.

I am wondering now, with the suggestions, perhaps adulthood might be a measure of two factors; size and, as suggested, the onset of "puberty" (or whatever passes for it). The second would be the primary determining factor, but with the proviso that this is not generally assumed until a creature is of a specific size. (Assuming it does not have a very evident juvenile stage, like birds or something. I have not ruled it out; currently, the species in question is not even fully realised yet, all I have is the image that their lower half has a stance like a geranuk standing...)

 

[Vanadium 50]

What's wrong with a wristwatch?

Plenty of earth times do not have astronomical counterparts: the minute, the hour, the week, the time between when you were supposed to change your oil and the time you actually did,

 

[AotrsCommander]

What's wrong with a wristwatch?

Plenty of earth times do not have astronomical counterparts: the minute, the hour, the week, the time between when you were supposed to change your oil and the time you actually did,

But how do you arrive at an "hour" from which to make a wrist watch? Okay, so assuming you make "hour" from, I dunno, "time it takes to burn a stick two arms long" or something like that... How do you get "day" from that? How many "burn-sticks" to a "sky eyeball" (month)?

Pertinently, what is the rate of resource comsumption? If you have a load tribepeople migrating, how much food do you carry and at what rate is it consumed? With a circadian day, you can say "one person requires 1 food unit and 1 water unit per day", but what is the "per" in this instance?

I am trying to avoid arbitatily assigning a "day" period "eats?", at least not without considerable thought. It might be necessary in the end, but dang it if I'm not trying to make an effort to give it as much investigation as possible beforehand.
Edit: TenLongFingers on the speculative evolution reddit suggested the genius idea of using "babyfeedings" as the base unit of time, i.e. the approximate period between when the baby has to be fed (which is your "hour"). Combined with gestation time and weaning (which would be akin "year" or something), it strikes me as much better and elegant solid temporary basis to work from that, like crop growth times or "how long until the meat rots." It makes a great deal of sense, too, for a primitive society still largely in the hunter/gather stages to be focuessed on that, as well. It simply never occurred to me to use that as a metric, but it seems to fit the best of anything suggested so far!

 

[PeroK]

But how do you arrive at an "hour" from which to make a wrist watch? Okay, so assuming you make "hour" from, I dunno, "time it takes to burn a stick two arms long" or something like that... How do you get "day" from that? How many "burn-sticks" to a "sky eyeball" (month)?

It's a good question, but isn't this the point at which you, the writer, are supposed to be creative? What is the purpose of this story if you don't know what you want to say about a species that evolves with no obvious cycles of change in their environment?

Unless you want to explore the concept that they would have a less clear idea of time, then there are bound to be things in their enivornment that they would use. How long crops take to grow, how long certain animals live. There must be some sort of pattern to life.

You also seem to be too queasy to consider something like the female menstruation cycle as an alternative to the month.

 

[Rive]

At the most basic level, how does a plant know when to flower or seed? If it doesn't rely on insect-analgoue pollination, how do plants seed? They can't reliably use wind, since it for the majority only goes in one direction.

With classic gaseous plant hormones are out of the picture, I still have two possible solutions to achieve some kind of synchronicity between plants.

One is, touch. Mimozes and some carnivorous plants are fine examples for that.

Other is: visible light. As I recall some plants are using the amount of yellow light as an indication to pick 'growth mode', since their priorities are different in forests and on open terrain. So it's not exactly absurd idea to have some plants sensitive to the color of their neighbors.

Ps.: one more, but I don't know any existing example for that: hollow, howling 'flowers' could be pretty good tools for the plants to sense each other: transmit and resonate in continuous wind.
But then you have 'windflowers' instead of 'sunflowers'

 

[AotrsCommander]

It's a good question, but isn't this the point at which you, the writer, are supposed to be creative? What is the purpose of this story if you don't know what you want to say about a species that evolves with no obvious cycles of change in their environment?

Unless you want to explore the concept that they would have a less clear idea of time, then there are bound to be things in their enivornment that they would use. How long crops take to grow, how long certain animals live. There must be some sort of pattern to life.

At the end of the day, I'm an engineer more than an anthropoligist, it has to be said. I can identify the problems, but the understanding of culture - especially primitive culture - is simply not something that come naturally. And I don't want to just make stuff up out of the blue without a solid rationale behind it; I want some solid, or at least plausible foundations. If I was willing to just make up stuff out of nothing, I would not have asked for help, at the end of the day.

(I have actually been rater astonished about the amount of responces in the places I've asked, actually, the speculative evolution reddit has been amazingly helpful and volumous in their replies, and it has given me a great deal to think about.)

Case in point:

You also seem to be too queasy to consider something like the female menstruation cycle as an alternative to the month.

Not really; I had literally simply never considered until you mentioned it just now. And it's something would tail into the "babyfeeding" suggestion I mentioned, so I will in fact give this some serious consideration, so thank you for that.

 

[PeroK]

Not really; I had literally simply never considered until you mentioned it just now. And it's something would tail into the "babyfeeding" suggestion I mentioned, so I will in fact give this some serious consideration, so thank you for that.

You can thank the novelist Fay Weldon, from whom I borrowed the idea. It's from the opening of "Down Among the Women":

"Yet here we all are by accident of birth, sprouted breasts and bellies, as cyclical of nature as our timekeeper the moon"

 

[Algr]

Animals and plants react to day and year cycles out of necessity. It gets warm or cold. It gets light or dark. Without those things, there is no need to measure time. Just eat, grow, and do whatever. The need for timekeeping started with "I need to get home before it gets dark, so where is the sun in the sky?" Then it was "Is it time to plant the seeds." On a planet lacking day/night cycles, you have eliminated a major reason for intelligence or complex societies to form. And if they do form, timekeeping will seem strange and difficult for them.

 

[jrmichler]

Three possibilities:

1) Circadian rhythm. It is reasonable for a science fiction author to assume that the inhabitants of this world need regular sleep, and that they will iterate to a regular cycle of sleep and wake. The human cycle time (circadian rhythm) in the absence of light is slightly longer than 24 hours, and is reset daily to 24 hours by light. In the absence of light changes, a different time can easily be justified.

2) Pulse rates in a society of fit adult humans average about 60 beats per minute. When a primitive society advances to some level of civilization (the concept of numbers), the people start to notice things like their pulse. That gives a short time interval.

3) Then the local genius tries to count the number of pulse beats in one sleep wake cycle and invents large numbers. Large numbers are larger than the number of fingers and toes/claws on one person. This is the beginning of math, and thus a possible start of civilization on that planet.

Plus, as mentioned above, even if only occasionally visible, the moon and annual star cycle.

 

[DaveC426913]

Animals and plants react to day and year cycles out of necessity. It gets warm or cold. It gets light or dark. Without those things, there is no need to measure time. Just eat, grow, and do whatever. The need for timekeeping started with "I need to get home before it gets dark, so where is the sun in the sky?" Then it was "Is it time to plant the seeds." On a planet lacking day/night cycles, you have eliminated a major reason for intelligence or complex societies to form. And if they do form, timekeeping will seem strange and difficult for them.

This is worth repeating, and I think should fundamentally inform your thoughts about these alien critters.

You can't start in the middle. You can't start with an analogue of an advanced, complex mammaliesque critter, drop him on a planet with no day-night cycle, spice it up with a few changes, and expect to get sensical results.

Your critters have evolved without day, night or seasons from the time they were from single-celled organisms. They might have evolved eyes but, if they did, they would have a billion years of evolution centred around the particular monotonous light and heat level of your planet. No pupils, no retinal sensitivity-range, etc. They wouldn't have evolved fur or any other temperature-adaptive traits - they'd just be perfectly suited to the constant temp. Also, no specialization for nocturnal vs. diurnal hunting - no circadian rhythm at all. They would not sleep - except like Cetaceans, who sleep with one half of their brain at a time.**

Same thing happens with the planet's entire ecology. Nothing dies off in one season or blooms in another. What does that do to the flora? And the fauna that live off it? If not winter, what does recycle flora and fauna back into the organic resource pool?

But think even bigger...

In the absence of externally changing factors, what will take the place of an evolutionary driver? What advantages could the first multi-cellular organism gain over its competitors that will drive its success?

Here's one idea: the biggest external factor on this planet is the difference between hot and cold regions. To thrive, life will have to push the frontiers of the uninhabitable regions in find food. This suggests that one of the primary drivers of their evolution - even before heat and cold tolerance - will have to be locomotion. Getting to a survivable habitat (and possibly back again) will become a primary driver even in the earliest organisms.

Now, what does a billion years of evolution on top of that early start do to the divergence between Terrestrial life and life on OneFace?
**Or would they evolve to have sleep/wake-mates? Like, rather than sexual partners, they might evolve to have a social bond - or even a physical connection with partner or partners that has the opposite sleep cycle. A OneFacer "animal" is really the conglomeration of two subunit-critters, each of which have a sleep cycle that is out-phase with its mate.

Intelligent evolution really took off with the mutation of the three subunit animal - allowing them to sleep longer and have more than one mind awake at a time, leading not only to complex and abstract thought - but the early invention of internal and then external language.

 

[AotrsCommander]

Your critters have evolved without day, night or seasons from the time they were from single-celled organisms. They might have evolved eyes but, if they did, they would have a billion years of evolution centred around the particular monotonous light and heat level of your planet. No pupils, no retinal sensitivity-range, etc. They wouldn't have evolved fur or any other temperature-adaptive traits - they'd just be perfectly suited to the constant temp.

Other points noted, but you've lost me here.

The light levels are not monotonous, nor is the temperature. At a given point on the globe, yes, the light level is FIXED (well, aside from breaks in the cloud cover because weather still happens), and caves and rifts and firests), but that's not the same, since it you move anywhere, it does change.

Also, wait... Did I mentioned this on this thread... No, no I did not. Sorry, the sheer amount of responses to this today on all four places has been staggering. Far beyond anything I normally expect.)

Right, let me back up a second then.

To whit: the central (nay initial defining) concept about this world is that every so often (and a semi-random interval), the star dims.

(With help from this forum, several years ago, this was hased out to be one idea is based on RCB variable stars, which change in brightness - not much change in the IR specturm, mostly just visible - but turned up to 11.

Note that to do this, I fully admit to having had to hand-wave the length of the life of the star and the effectiveness[1] of the dimming period being extended. I can and will try to ground in physics as much as possible, but sometimes, you do have to plaster over with some handwavium.)

So you have a world where civilisations develop and sometimes get quite far, and then are plunged into a literal dark age when the sun dims, leading to extinctions... Until the next time. But the periods are long enough that the successive lot generally doesn't even know it happened, basically. (Funnily enough, when nothign changes for a very long time, every tends to get fracked up when it changes rapidly.)

(Meaning a campaign world full of Stuff To Explore...)

Some of the inspiration from this comes from an old Doctor Who episode (3rd or 4th Doctor, I think?) wherein the Doctor and co visit a planet appearing to be suffering from a Horrible Mutant Plague, but it turns out their planet has a stupid long eccentric orbit or something, and every so [however long], the climate changes and their biology adapts and they, like, change into crab people or something for the harsher "winter" conditions. I.e., the biology (and that of the planet) is geared up for the change, but the civilisation ISN'T, queue panic.

So. Aside from the fact the light and temperature levels change if you go towards or away from the dark/night side, occasionally the flora and fauna have to deal with what is, essentially, a seasonal change. (The intelligent creatures generally get taken by surprise by this, because it happens as intervals longer than their civilisations.) So I can still see a good reason for vision to have evolved to terrestrial levels.

However, and this is the other point, the end-point for this exercise is something is not just a written narrative, but has to stand up to being, like, used and played. With that by necessity of having to be, like, played on, I have to split some difference between making aliens and making something that isn't so completely alien that it makes it impractical to play. (I would find it very difficult to decribe a world to players in terms of, like, electrosense or something, for instance.)

(Furs and feathers would more likely be things found on thinsg in colder climates, certainly; but the world still has continental drift and such, so while migration is... Probably? Unlikely, the flora and fauna is not going to have been locked into its own isolated climatic kingdoms since it evolved.)
[1]The true cause is currently unknown, but could be either: a) natural magic or other paranatural phenomena or b) Sufficiently Advanced technology/magic/paranatural phenomena.

 

[BillTre]

Interesting response @DaveC426913! I like that kind of thinking.

I can image some ways things in a monotonous environment could produce changes over time:

• Cycles in populations, like predator prey cycles
• Things like breeding synchronization (which pheromone communications could underlie). These behaviors overwhelm predator population's ability to eat new prey by producing a huge simultaneous appearance of lots of prey. The predator can only eat a fraction of the population, but due to its irregular appearance the predator populations can not, in the long run, be built up to eat a larger fraction of the prey.
• Continuing evolution: Although a constant environment would be expected to to be well adapted to by any organism. However, improvements in internal biochemical efficiency may continue (probably at a decreasing rate over time).

The last is probably the weakest of argument.
They all are properties of populations where dynamics can arise.

 

[Algr]

If your planet is so far from its star, how did it become tidally locked? That usually happens with red dwarfs. (Which are also known to be of variable brightness.)

Some of the inspiration from this comes from an old Doctor Who episode (3rd or 4th Doctor, I think?) wherein the Doctor and co visit a planet appearing to be suffering from a Horrible Mutant Plague, but it turns out their planet has a stupid long eccentric orbit

The Mutants, Third Doctor, 1972.

 

[Vanadium 50]

You define the "hour" as 20x the time to cook a 3-minute egg.

 

[DaveC426913]

The light levels are not monotonous, nor is the temperature. At a given point on the globe, yes, the light level is FIXED (well, aside from breaks in the cloud cover because weather still happens), and caves and rifts and firests), but that's not the same, since if you move anywhere, it does change.

Yes. IF you move.

But why would you?

On Earth, all species must contend with widely fluctuating light levels and temperatures because those are entirely uncontrollable environmental factors - those things will change daily (or monthly). Earth critter must have adaptations or they'd starve / get eaten every time the sun goes down/comes up.

But on oneFace, why would species bother moving from the ideal habitat they're suited to? Why would those who evolve in the temperate zone bother venturing into hostile cold/hot territory, especially where other endemic critters are better suited? They would be at an advantage if they just stayed put (in the same way a Cheetah is best suited to dry arid flats and would lose to tigers if the ventured into the jungle).

Now, that is not to say they wouldn't get there eventually, driven by survival pressures - but that change is on the scale of many generations (as each gen pushes the boundaries of the frontier), not on the scale of individuals.

You might have, say, a species of feloids that have adapted to the night side, and you might have a species of feloids that have adapted to the day side, but there is no environmental pressure for the same feloid species to have both day adaptation and might adaptations simultaneously. That would be just too expensive.

 

[russ_watters]

But how do you arrive at an "hour" from which to make a wrist watch? Okay, so assuming you make "hour" from, I dunno, "time it takes to burn a stick two arms long" or something like that... How do you get "day" from that? How many "burn-sticks" to a "sky eyeball" (month)?

You need to decide why they want to measure time to begin with and measure that. Is it sleep cycle? Interval between meals? Hunts? Harvests? Lifespans? Make that a base unit and then sub-divide.

 

[AotrsCommander]

If your planet is so far from its star, how did it become tidally locked? That usually happens with red dwarfs. (Which are also known to be of variable brightness.)

From the gentleman I spoke to on this forum when I designed thre system (in 2014).

The thing is, the amount of angular momentum a planetary body ends up with after most of the protoplanetary debris had been cleared during the formation of the system can be almost anything, especially for smaller bodies(i.e., not gas giants). So you could conceivably have a planet that never really had much of angular momentum to shed, so it eventually did get tidally locked to the distant star, especially if given a lot of time.

The Mutants, Third Doctor, 1972.

That sounds about right.

Yes. IF you move.

But why would you?

On Earth, all species must contend with widely fluctuating light levels and temperatures because those are entirely uncontrollable environmental factors - those things will change daily (or monthly). Earth critter must have adaptations or they'd starve / get eaten every time the sun goes down/comes up.

But on oneFace, why would species bother moving from the ideal habitat they're suited to? Why would those who evolve in the temperate zone bother venturing into hostile cold/hot territory, especially where other endemic critters are better suited? They would be at an advantage if they just stayed put (in the same way a Cheetah is best suited to dry arid flats and would lose to tigers if the ventured into the jungle).

Now, that is not to say they wouldn't get there eventually, driven by survival pressures - but that change is on the scale of many generations (as each gen pushes the boundaries of the frontier), not on the scale of individuals.

You might have, say, a species of feloids that have adapted to the night side, and you might have a species of feloids that have adapted to the day side, but there is no environmental pressure for the same feloid species to have both day adaptation and might adaptations simultaneously. That would be just too expensive.

I'm sorry, I don't buy this arguement. Jungles exist as a largely steady environment and they are among the most diverse and competative environments. Deep sea thermophiles might command their environments largely, but that's because they ARE extremeophiles, and their environment is likewise not 100% static because the gushers open and close.

Andorlaine would be no different. Nothing about the set up make Weather Not Happen. Continental drift still happens. Volcanicity still happens. Erosion happens (if anything, faster). Mass extinctions will still have happened. The temperature will still fluctuate - granted probably more on a level like those in the jungles, but it's not a series of static little pocket enviroments that have evolved in isolation for billions of years just because the planet doesn't have a day/night cycle.

I mean, you ask why would life would want to move? I mean, that's... Fundamentally asking a question that make no sense to me, since the (unachiveable) end-goal of life is to reproduce and spread the species. That goes against everything I've ever read about the natural world. Sure, different biomes are a thing on Earth where species don't migrate, but why would there NOT be a "grey wolf" equivalent that spans huge swaths of the global environement? Let's assume that things initially developed the way you said, with creatures only evolving to see in their explict lighting environment (and ignore the dimming periods). The first creature that evolves a way to utilise different lighting conditions would have an immediate huge competative advantage, because it can expand its territory to other biomes.

Yes, specialist species will definitely exist, likely more on Andorlaine because, as you say, the environments are more static. But this absolutely does not mean that generalists (the real winners of the evolutionary race anyway) not to evolve.

(I mean, and this is also leaving aside there are other forms of eyesight than the vertebrate eyeball, the insect eye being an immediately obvious one.

Actually, come to that, the world has had a cameo already in something else I did, and a group of travellers briefly explored a tiny corner, and one of the few species they ran into (it was on the dark side) had eyespots and didn't even appear to use vision as it's primary sense. But the magical floaty cnidarian/comb jelly creature is not a good candidiate for a player character species.)

Your comment about it being "too expensive" to have both day and night adaptions also makes me scratch my head, because modern animals have no problems literally doing that. (Even before the fact that anything on the light side will have to have developed some level of dealing with changing light conditions, because, as noted, every few thousand years, it gets darker for a few hundred years. So they would have had to develop or at least retain those traits anyway, even if they are recessive.)

Now, stuff on the dark side? I'll grant you, seem to me to be likely to be much more extremophile and in environments that don't alter as much (also obviously, dimming doesn't really happen when it's always dark), so yes, over there, there is likely to be different species that have lost (or at least have become recessive) traits like vision, like cave dwellers or something. (Though again, if continetal drift eventually takes them to the light side, they'd be going extinct.)

Stuff on the substellar point are going to be extremophiles only, because the temperature around there will be just too hot for conventinal life anyway (boiling point of water and such, the close you get to the substeller point), so those, yes, are likely to stay largely unchanged; but that's such a hostile environment that its not a viable habitat for thing BUT those creatures.

 

[DaveC426913]

I mean, you ask why would life would want to move? I mean, that's... Fundamentally asking a question that make no sense to me, since the (unachiveable) end-goal of life is to reproduce and spread the species.

Yes. But that's on the scale of generations, not on the scale of individuals.

Yes, specialist species will definitely exist, likely more on Andorlaine because, as you say, the environments are more static. But this absolutely does not mean that generalists (the real winners of the evolutionary race anyway) not to evolve.

Generalists have the advantage during tumultuous times. The specialists are the default success in a static environment.

Your comment about it being "too expensive" to have both day and night adaptions also makes me scratch my head, because modern animals have no problems literally doing that. (Even before the fact that anything on the light side will have to have developed some level of dealing with changing light conditions,

You haven't been reading my explanations. Modern Terrestrial animals have to be flexible; their environment literally changes every 12 hours.

because, as noted, every few thousand years, it gets darker for a few hundred years. So they would have had to develop or at least retain those traits anyway, even if they are recessive.)

OK. I thought we were blue-skying this world. I did not realize you've already fixed your back story and premise. And it sounds like you're determined to make them a lot like terrestrials.

I will recuse myself.

 

[hmmm27]

Wouldn't the dark side end up with *all* the water ?

Timewise, maybe they don't bother developing a sense of time, considering it in much the same way as early humans would the vertical dimension : it's "up" and that's pretty much it.

 

[Office_Shredder]

Wouldn't the dark side end up with *all* the water ?

Water still flows to the lowest point in a connected system, so this isn't obvious to me. Maybe there would be an evaporation -> rain cycle that would cause consistent erosion in a way that makes this true?

@AotrsCommander the random dimming reminds me of the three body problem series, where chaotic orbit around multiple stars causes life to evolve to just instantly hibernate when conditions get too extreme.

 

[hmmm27]

Water still flows to the lowest point in a connected system, so this isn't obvious to me.

Water does ; ice, not so much. Tide-locked planet. Maybe deep underground oceans.

 

[Drakkith]

Without an external source of timekeeping upon which to rely, I expect that evolution would develop a reliable bio-chemical 'clock' early on during the development of complex life on the planet. It would seem to be a very powerful tool for survival and reproduction, as individual organisms could sync up with others for things like seeding, mass movement, or whatever.

 

[AotrsCommander]

My apologies: I have had to do Actual Work, and thus have not had time to look over everything in the last couple of days.The replies from the various places I posted this have ranged from "life would have no cycles at all" to "some sort of circiadian cycle would develop" and "creatures wouldn't ever sleep" to "intelligent creatues have to sleep to remove toxic build-up of neuro chemicals in the brains."

So what I am largely getting is that is there is very likely no right answer.

I am leaning towards:

"Deepbreath" => approx two seconds and short measure (estimated from timed deliverate inhale/exhale)

"Babyfeeding" => modal period between feeding times for newborn babies (to be researched/estimated if possible from human babies maybe later, if I can claw back any time to do so)

and then possibly "weaning" (modal time to solid food) and possibly "gestation;" possibly even, as suggested above, a menstrucal cycle.

I have considered and discarded artifical means of timing (like crops/burning sticks) etc. as too variable (and the village is primarily a fishing village - AND crops assumes that the tribe are not obligate carnivores, which is not a given at this point.) While water clocks are again, an obvious one for more advanced civilisations, a neolithic tribe feels unliekly to have developed them.In addition, there is a reasonable arguement that the players will have to develop/improve their method of timekeeping as part of their oddessey as the tribe is forced to migrate.

However, as the one running the game, I will of course need some base level of time-marking to track resource usages (and stuff like how long Things Last) within the game; poison frequency, for example. A combat round being three deepbreaths and a minute 30 deepbreaths should be quite sufficient for at least the combat timings; "babyfeedings" will probably work in some increment for food resource comsumption intervals. Sleep and rest intervals are, as I say, apparently whatever I choose to do, since there appears to be no real concensus.

I will likely be using some of each answer; the tribe and other intelligent species (or at least some of them) might need a period of rest - as of this morning, I'm actually considering that effecticely trance (vis a vis Tolkien elves, dreaming with their eyes open) might be a neat approach and would make sense in context. Meanwhile, lower lifeforms might not need that cycle and be able to rest their brains in stages if they need to at all.Note that, however, the aforementioned is merely nominal; having had all the reponses, I do need to go away and have a proper think about it (something to do on my weekly walks) before I write up anything concrete.

OK. I thought we were blue-skying this world. I did not realize you've already fixed your back story and premise. And it sounds like you're determined to make them a lot like terrestrials.

I will recuse myself.

Fair enough; but likewise, in fairness, even in the OP I said this was for a roleplaying campaign world, and further it was predicated by a tribe being forced to migrate. I never said this was 100% an exercise in speculative evolution, the biomechanical question was only part of it.

(I started thinking about the project and doing some of the initial work as far back as 2014, so yes, the high concept stuff (and the astrophysics to the best of my abilities) have long been set, else I would not have even been here to ask. I just did not want to bury the actual question under a ton of explanation/exposition like I usually do when starting these sorts of threads. And, having NOT done that this time, I had an unexpected cornacopia of responses where I expected (maybe) one or two. Coincidence? I don't know but I suspect not.)

But even if I generally agreed with your reasoning (which I don't, but that doesn't really matter), that means that, all other concerns aside, it HAS to be capable of being played by actual human players and doing all the things a [fantasy] campaign world does. That puts a practical limit on what you can attempt to do verses creating a speculative evolution exercise, because it has to be USED.

(Used and comprehended by people - long-term, since when I do these things, the intention is they will be used for decades - who are not sad enough to spend months doing astrophysics calculations to make a sporting attempt at science rather than just going "the sun magically goes dark sometimes and Bad Creatures Come Out." (Which was the very highest-level concept from which my initial questions eight years ago came: "but is it possible to do that with as much real astrophysics as possible?"))

 

[hmmm27]

You've a 6 day lunar cycle, so there's your timekeeper : certainly good enough for neolithic civilization. Twelve is a universally decent number so there's a natural'ish division.

Why the fascination with timekeeping ? we did well enough with just "sun up" "sun down" and "noon" (and seasons) for tens of thousands of years.

Using sunwards as a north "pole" and the light/dark terminator as "equator", moisture-based civilization would probably tend to crowd around just north of the equator : there'd be a sub-equatorial ring of tens-of-kilometre's high ice mountains in the darkness : the source of all water from either plain runoff, or pressurized underground "springs".

Migratory patterns would probably be food-based : run out of food, walk latitudinally until you hit a crop planted by the tribe in front a couple months ago, stick around, plant crops, move on.

Probably wars between clockwise and counterclockwise tribes, since those f*ckers just ate your next meal.

 

[DaveC426913]

That last bit's very clever.

 

[Drakkith]

I have considered and discarded artifical means of timing (like crops/burning sticks) etc. as too variable (and the village is primarily a fishing village - AND crops assumes that the tribe are not obligate carnivores, which is not a given at this point.) While water clocks are again, an obvious one for more advanced civilisations, a neolithic tribe feels unliekly to have developed them.

The real problem with water clocks, hourglasses, etc, is not just that they are variable, but that you don't have a universal means to 'calibrate' them since there is no day/night cycle or other repetitive cycle. At least here on Earth we all have a roughly 24 hour reference to use that doesn't change except on the timescale of millions of years.

This also applies to biological clocks. I can imagine one village making fun of the next village over because they 'sleep' 1.2x as often. Or perhaps each bloodline has a slightly different internal clock. Perhaps the family that can stay 'awake' the longest is viewed as having exceptionally good blood and vice versa.

Oh the fictional possibilities are endless!!

 

[hmmm27]

That last bit's very clever.

Well, that's what that Star Trek episode was all about.

 

[Strato Incendus]

Ps.: one more, but I don't know any existing example for that: hollow, howling 'flowers' could be pretty good tools for the plants to sense each other: transmit and resonate in continuous wind.
But then you have 'windflowers' instead of 'sunflowers'

I was wondering to what extend tidally locked planets would even experience winds — and if so, of what sort (strength, direction etc.)?

With no rotation, no different levels of heat from the sun hitting any given point on the surface, I struggle to imagine in what ways the star could even influence the weather on the planet — aside from different levels in intensity of the star’s own activity, and the planet’s changing distance to the star during its orbit around it.

Note that most tidally locked planets should be rocky planets around red dwarf stars, not around big stars of the type you described. Meaning, the habitable zone is so close to the star that the planet’s orbit would only take a few (say, 5 to 11) days to complete once.

If there are winds in at least two directions, temperatures in one given location on the surface could then be influenced by whether the wind is currently coming from the day side (warm) or night side (cold). This could “simulate” a day-and-night shift, if not in terms of light exposure, then at least in terms of temperature.

I chimed in here because I have a tidally locked planet in my story, too — so I’m facing the same problems.

 

[Vanadium 50]

The real problem with water clocks, hourglasses, etc, is not just that they are variable, but that you don't have a universal means to 'calibrate' the

Problem for whom?

Long before we had a fixed number of krypton wavelengths we had meters. Even today you can go to Greenwich England and compare your meter (or possibly yard) to two ticks a meter apart.

So, post-industrial, your standard of time is WWV. number , Pre-industrial, you read it off a table of lenths of the seconds pendula.

Having clocks with microsecond accuracy is a new development, and surprisingly not a requirement for life or civilization. Watch some old TV shows and you'll hear "My watch was a few minutes slow (or fast)." They survived.

And didn't rush out with a sextant to shoot some stars to figure out what tijme it was.

 

[DaveC426913]

Having clocks with microsecond accuracy is a new development...

Wow, what's that like?

I throw a little party on days when two clocks in my house are within ten minutes of each other.

 

[Nik_2213]

A caution about female cycles: several of my wife's friends had to go to boarding school as teens while their parents were 'out of country'. IIRC, was mentioned that, disconcertingly, and apparently driven by pheromones, their cycles soon phase-locked with the swiftest 'cycler' in group during the Autumn term, stayed 'synchronised' until the following Summer. A large proportion of group would be simultaneously laid low with severe 'monthly' cramps etc.

Consequence for time estimation is that different extended-family groups might have a 'cycle' that differed by a day or two, significant off-sets soon accumulating.
Additional issues due stress from excess activity or reduced nutrition modulating cycles...

 

[Strato Incendus]

Yeah, I've been wondering about that, too, and to what extent it would occur to all young women on the same spaceship.

I guess it depends on the size of the spaceship, how much time who spends with whom during the day, to what extent pheromones "in the air" cause this, and if the ventilation system (which needs to be able to "recycle" the air somehow anyway) is capable of mitigating that.

 

[Hornbein]

Mercury is basically tidally locked but nevertheless the part facing the sun changes. It's because the orbit is elliptical.