zompist bboard

So my conworld has less gravity than earth: I'm not sure, but I figure like 0.5 to 0.6 G and a moderately thicker atmosphere. This means that everything weights less. it means that inertia and drag are comparatively more important than weight. It also means that flying animals can be much larger, and that, for instance, cavalry tactics are much different, since a horse can carry effectively twice the weight and still be able to charge. I imagine trees would be able to grow taller, since circulation is made easier by lower gravity. Most locomotion methods are much easier, so animals can be bigger without paying so much energy for locomotion.

However, gravity is such a base parameter in our world that I can't possibly imagine every consequence a lower gravity might have, especially regarding animals: would animals be taller? less muscular since they don't need to deal with lifting their own weight? somewhere I read that lower gees might produce more slender things, but I dunno, being bigger and having longer limbs creates the problem of flexion and inertia: even without gravity, a heavy thing has momentum, and the longer and less muscular the limbs, the less able it is to take force.

Jumping becomes a much better way of locomotion, but how better? Here's when not paying attention to physics in school, mainly cinematics, is definitely taking its toll... this whole thing is unintuitive to me: If I weighted half what I weight [cause gravity is halved], how far would I be able to jump? twice as high? would I be able to, say, run faster? how do less weight but same inertia conjugate, is what I wonder.

Okay, lemme wrap this up: I know this has been a messy exposition, but the problem might be interesting to some of you. There's two questions here, it seems.

- how would 0.5G affect zoology, as in how would earth animals adapt to lower gravity?
- how would 0.5G affect human biomechanics? as in jumping, running, and stuff.

I guess the underlying question is about low gravity and locomotion. what's up with that? any ideas?

EDIT: as a note, the planet was terraformed around half a million years ago, filled with all kinds of earth animals, save a few things like dogs and wolves and mosquitoes, and introducing pleistocene megafauna and the like. So enough time for a few distinct species to evolve, but most adaptations from these animals to the lower grav are mostly behavioural and anatomical, but minor: say, pretty big eagles, large hares browsing the savanna, something filling the niche of wolves [maybe boars?] and stuff like that. that's why I'm interested in locomotion and the effects on earth animals.

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Articles on Suenu - Amphitrite

How have you got a thicker atmosphere with less gravity? Half the gravity should mean a far thinner atmosphere. Also: how damn small IS this planet?

Horses won't be able to carry twice the weight, because they'll have evolved to be less strong.

Yes, things would be more gracile. And more things would be bipedal.

Among bipedal creatures, jumping is already more efficient on Earth - indeed, for large creatures its TOO efficient (it leads to heat buildup in the groin, which renders the animals sterile - so they either can only do it for short periods (rabbits) or they need to evolve natural radiator systems (kangaroos). But if they do that, jumping is faster, and vastly better over long distances.

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Blog: http://vacuouswastrel.wordpress.com/

But the river tripped on her by and by, lapping
as though her heart was brook: Why, why, why! Weh, O weh
I'se so silly to be flowing but I no canna stay!

Eh? Should we tell that to Venus and Titan? And Titan has even less gravity than this planet here. Of course, it is colder...

The lower gravity would just make the atmosphere thin out slower as you go higher in elevation. I don't have time to mention much else now, though.

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Zain pazitovcor, sio? Sio, tovcor.
You can't read that, right? Yes, it says that.

Why is this a by-product of it being so efficient?

Good point. Perhaps I was being too simplistic there. But surely gravity plays a part in whether there's an atmosphere? It's not a coincidence that earth has an atmosphere, the moon barely has an atmosphere, and most asteroids don't have atmospheres?

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Blog: http://vacuouswastrel.wordpress.com/

But the river tripped on her by and by, lapping
as though her heart was brook: Why, why, why! Weh, O weh
I'se so silly to be flowing but I no canna stay!

I'm gonna guess it has something to do with friction, but I'm no expert

The animal burns up energy moving, creating heat as a byproduct; but some of that energy, rather than being dissipated, returns to the body (when the animal lands), again in the form of heat. Theoretically, this energy is all available within the animal's body to use, and indeed some is - it reduces the cost of increasing speed, and in kangaroos it is also used to power breathing - but a lot of it just sits around in the body (particularly the groin) as heat that the animal can't use, and that has to be dissipated somehow. So rabbits, for instance, can only hop for a short distance, even though their hopping is both faster and less energy-intensive than their running.

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Blog: http://vacuouswastrel.wordpress.com/

But the river tripped on her by and by, lapping
as though her heart was brook: Why, why, why! Weh, O weh
I'se so silly to be flowing but I no canna stay!

AIUI, other than in extremely low gravity environments (the Moon, asteroids), gravity and atmospheric pressure have no observed relationship. Theorhetically a lower gravity planet's atmosphere should dissipate over time, but there seem to be other factors involved.



Maybe the radiator need not be quite as efficient if the gonads are located somewhere else? This is an alien world we are talking about.

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George Corley
Producer and Moderating Host, Conlangery Podcast

Oh, sure. And it's not that hard to evolve kangaroo heat dissipation techniques anyway. I'm just saying that it wouldn't be a simple matter of jumping becoming more efficient and hence more popular, since it already outperforms running anyway.

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Blog: http://vacuouswastrel.wordpress.com/

But the river tripped on her by and by, lapping
as though her heart was brook: Why, why, why! Weh, O weh
I'se so silly to be flowing but I no canna stay!

Atmosphere and gravity: venus has a thick atmosphere, and titan does as well. Thing is the closer you're to a sun the faster you're gonna loose atmosphere, but again, venus doesn't have a strong one and it has a mad thick atmosphere. surface pressure is a function of how much gas there is on the system to begin with. there's a lot of ways in which planets gain gas, and a lot more in which they loose it.

Interesting thing, about hopping and heat buildup. so indeed jumping would be more common with things.


nah, most of the life is terrestrial, adapted to the planet, but terrestrial in origin. As for radiating, a thicker atmosphere and a much colder overall climate distribution [temperate along the equator, positively siberian at mid-latitudes] should make it easier. Hop hop hop.



I know this is like the consensus, but I'm not sure its true. On earth, for instance, smaller mammals, which face a much smaller resistence/gravity, aren't very much more gracile than medium-sized things. for a smaller things gravity is les of an issue; ants can get away with having very thin limbs, but elephants don't. However, if you look at very large things that have existed, like dinosaurs, many got away with being very very heavy and still being kinda gracile: take allosaurus or hadrosaurus. Also, consider a gazelle -real thin and gracile- versus, say, an armadillo. Gracility to me seems like more a function of metabolism and the need for quick movement than about the effects of gravity, at the meso level at least [say, from rabbits to allosaurus]

OTOH one could understand gracility like an expensive trait: sure, you can be as gracile as you want, but its gonna cost you in terms of energy, and the less the gravity, the cheaper it is to be gracile. The question is, is gracility an advantageous trait always?.

shit, this is hard!

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Articles on Suenu - Amphitrite

Since your conworld has a thicker atmoshere, I think it'd come down to the ratio of oxygen ( assuming that's what you conspecies breathe) in the planet's atmosphere. If you have a conciderably high ratio of oxygen your lifeforms could afford to have vastly varying levels of gracility or rubustness depending on their niche in the foodchain, that's why the Dinosaurs and Plants of old were so gigantic. Modern life on Earth is smaller due to lower oxygen levels, we can't sustain supersized bodies.

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Tjalehu ge frulehu, tjea ale stjindamihu? Dime sfraiaknanmi.

Economic: -7.33
Social: 0.31

Good points. On Earth we have homonids that run the gambit from spindly H. Sapiens and Gibbons, to stocky H. Neanderthalensis and Gorillas. Niche is far more powerful than adaptation to gravity.

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[quote="Nortaneous"]Is South Africa better off now than it was a few decades ago?[/quote]

AFAIK Neanderthals are still much more gracile than a gorilla. Maybe talking about gigantopithecus? Or A. robustus?

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George Corley
Producer and Moderating Host, Conlangery Podcast

Yup. Thicker atmosphere with less nitrogen, a bit more oxygen and like twice the C02, so yeah, supersize 'em.


yeah, that's what I thought. what I'm interested in are the effects lower gravity would have on the behaviour and short-term adaptations of mammals. Again, the world has terrestrial animals. So hopping becomes a better strategy for locomotion, that's real useful, cause it means I get to have things like giant rabbits filling the niche of gazelles, that's nice to know. Also, flying stuff can do better with large sizes, so stuff like giant eagles also work... maybe giant eagles eating giant rabbits xD.

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Articles on Suenu - Amphitrite

How is it so cold with that much CO2?

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George Corley
Producer and Moderating Host, Conlangery Podcast

Colder star.

I just realized... there's another argument against gracility in this planet: Bergmann's rule and Allen's rule: the first states that in colder climates animals tend to grow, the second, that they tend to have relatively shorter limbs. Both these things are responses to the problem of keeping warm: a lower surface-to-volume means you radiate less heat, which is good when its cold. So what, obscene macrofauna?

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Articles on Suenu - Amphitrite

"Obese"? xD

Obscene megafauna is what every SPORE player creates.

Yeah probably. Higher oxygen content and lower gravity will allow for land animals much larger than what occur on Earth.

Another thing -- how do you get to higher oxygen content with colder climates? Are your plants heavily cold-tolerant, or do they just produce more oxygen?

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George Corley
Producer and Moderating Host, Conlangery Podcast

cold-tolerant, plus there's more light. The planet is inside a planetary nebula kinda like the crab nebula, not very far from these massive stars that stirr up the whole interstellar medium there, so even during the night there's a fair amount of light reaching the planet's surface... you can read a book at night only on starlight.

also, macrofauna is awesome! yeah!

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Articles on Suenu - Amphitrite

Torco, FWIW I really want to visit your conplanet!

Contrary to popular belief what you said is a common myth. Carbon dioxide levels were actually higher then they are today. This led to plants growing at insane speeds but sadly they became less nutritious. So in order to get what they needed dinosuars grew larger stomachs and ate stones. But also they needed more air and thus larger lungs. Eventually they reached the size we know of today by being mostly hollow. They were still getting larger with time as levels of carbon dioxide rose. This is from one of my books on paleontology so don't say I am wrong.

Now what I will say now is handwavium matireal this being an alien world. But having lived in Alaska I know that plants do not do well there. The constant sunlight does not give them a chance to rest. They are always working and thus they grow to pitiful sizes while if they were in the lower 48 they would do just fine. You can counter this by say plants only photosythesize a specific spectum that the clouds don't reflect or you can simply have them evolve to handle the light.

Yeah, because, as we all know, books can never be wrong... wait, what? still, the stuff about size makes sense... regarding plants... there's many reasons why plants wouldn't do well there, perhaps more importantly how little sunlight they get, mainly cause it's oblique sunlight, and the cold. Still, isn't there like a LOT of taiga, forests and stuff over there? Still, plants do have circadian rythms, but I'm guessing they would have either evolved or the guys who terraformed the planet adapted them.

yeah, I know, I'm handwaving.


xD awesome. me too!
I think it would be an incredible place,visually... I really should learn to draw/illustrate.

come on, guys, no more awesome tidbits of thought about lower gravity? how about the weight-inertia relationship?
MOAR IDEAS

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Articles on Suenu - Amphitrite

I forgot to mention plants mostly grow after solstace because darkness comes and the plants have been able to mature enough to enjoy it. My sunflowers were proof. They wouldn't grow larger then a foot for two months. After about three hours of darkness were available the reached nine feet in five weeks then died with the snow.

Also that book was recently published backed by five of my teachers and my uncle who is a university professor. It cost me an arm and three toes. I think that it is correct. Besides I saw a similar theory shown on Science channel.