Gravity

[Txur’Itan]

The Na'vi were physically very strong as depicted in the film.  Tsu'Tey was literally one hand tossing the Human soldiers in full gear right out the hatch.  Take your average 5'6" grunt, probably 150 lbs avg, with good fitness, and muscle tone that wanders around a bit.  .8 gravity makes that 120 lbs.  Without weight lifting, humans are not likely to one hand toss anything that heavy without harming themselves.  Shoot my niece weighs 40 lbs and I can feel that as pretty darned heavy. I am pretty sure I could one arm toss 40 lbs out a hatch, but still it is not like I'd be able to do that with 100 lbs.

Gravity on Pandora, for the Na'vi at least, is probably incidental when compared to the impact of diet, and the way that they live their lives.

I am inclined to think that with tons of running, climbing, and Jumping everywhere means these guys stay pretty fit.  The the effect of the appropriate food on their bodies is, more resiliency on the muscle fibers, and significantly reduced apoptosis or atrophy.  They may have also learned from Eywa what to eat, and what not to eat, how much and why.

[Unil täftxuyu]

the trees are made of wood, the leaves wouldn't be green if they didn't have chlorophyll which is found in standard earth plant life. The trees likely stayed upright due to their curved structure, giving it a lot more strength than if the wood grains were just facing directly straight up. the undergrowth would also help support the roots of the large trees like hometree, the generally larger trees would greatly support the roots of Hometree.

[shiaru]

the trees are made of wood, the leaves wouldn't be green if they didn't have chlorophyll which is found in standard earth plant life. The trees likely stayed upright due to their curved structure, giving it a lot more strength than if the wood grains were just facing directly straight up. the undergrowth would also help support the roots of the large trees like hometree, the generally larger trees would greatly support the roots of Hometree.

The color of the leaves does denote that they have Chlorophyll but that does not mean that they are made from earth like wood, I explained what I meant in the previous post. The color of the leaves just means that the plants there have adapted to undergo photosynthesis in a similar fashion to those on earth. The trees on Pandora are likely to be made of a derivative of nanofibers similar but not equal to the carbon composite constitution of the Na'vi.

[Toruk Makto]

I think a lot of people are also confusing size with lack of coordination. One thing I pondered was that if the environment on Pandora is made much like a brain with vastly more neurons, then perhaps the biological make up of the Na'vi brain and body also has more neurons than humans. Allowing for more independent reflexes, much like you twitch your eyes or body automatically when something comes at you, it's very possible that there are independent nerve centers to piggy back motor control. Much like very very large dinosaurs equipped with nerve clusters in the lower spine to assist in walking.

And since the unobtainium superconductor is so prevalent on Pandora, perhaps their bodies contain significant amounts of it and have accelerated nervous systems as a result.

[tute nuereime]

Tsu'Tey was literally one hand tossing the Human soldiers in full gear right out the hatch.  Take your average 5'6" grunt, probably 150 lbs avg, with good fitness, and muscle tone that wanders around a bit.  .8 gravity makes that 120 lbs. 

it probably doesn't make much of a difference but you forgot to factor in gear. probably another 10 lbs. in Pandora's gravity.

[Txur’Itan]

Tsu'Tey was literally one hand tossing the Human soldiers in full gear right out the hatch.  Take your average 5'6" grunt, probably 150 lbs avg, with good fitness, and muscle tone that wanders around a bit.  .8 gravity makes that 120 lbs. 

it probably doesn't make much of a difference but you forgot to factor in gear. probably another 10 lbs. in Pandora's gravity.

I did not have an idea how much their gear weighs, materials are a question mark, but I was aware they had it on.  The real life props are made from modified fire arms which may actually be adding 20 Lbs for just the gun and bullets.  Body armor could be 5 - 10 Lbs by itself, grenades maybe 1 Lb. Gill system "Exo Packs".  Don't really know total in pic gear weight. 

In real life, modern combat gear is getting lighter, including the composites that fire arms are made from.  The fictional fire arms, for case-less round machine guns, the possibilities are weight are significantly modified.  10 pounds may be conservative or excessive depending on what the gear is made of, and a negligible increase in that range of 120 to 150 lbs considering the feat of one hand tossing an armed soldier.

[tute nuereime]

10 pounds may be conservative or excessive depending on what the gear is made of, and a negligible increase in that range of 120 to 150 lbs considering the feat of one hand tossing an armed soldier.

i was just using 10 pounds as an easy to use number.

[Txur’Itan]

10 pounds may be conservative or excessive depending on what the gear is made of, and a negligible increase in that range of 120 to 150 lbs considering the feat of one hand tossing an armed soldier.

i was just using 10 pounds as an easy to use number.

I like easy... 

[Beduino]

About the trees, like the Hometree. They can be made of wood, but a harder type of wood. Like in earth we have diferent types of wood. Some are strong, some are weak. And maybe the unobtanium has it's place making the wood harder, since the biggest concentration of it is just lieing under the Hometree.
At my point of view, there is no need of it to be sometihng near a nanofiber or sorta.

You guys are trying to find a reasonable explanation for things in Pandora with Earth rules and caracteristics, wich does not need to happen, since it's not Earth

[Eywal ngaru teing oeti]

I find all of this interesting. Some of the stuff is correct, but you guys are forgetting to take into account that every tree on Pandora is connected and that there is Unobtainum in the soil, so that could account for how big and strong the trees are. It could also be that Eywa wanted the plants and animals like that.

[Motxokxen]

About the trees, like the Hometree. They can be made of wood, but a harder type of wood. Like in earth we have diferent types of wood. Some are strong, some are weak. And maybe the unobtanium has it's place making the wood harder, since the biggest concentration of it is just lieing under the Hometree.
At my point of view, there is no need of it to be sometihng near a nanofiber or sorta.

You guys are trying to find a reasonable explanation for things in Pandora with Earth rules and caracteristics, wich does not need to happen, since it's not Earth

i recon that unobtanium is actually a by product of trees, since the home tree always seems to be on top of them

[Sadrice]

What I do like, very much, is that Jake Sully atrophied at an alarming rate - much less than one would expect, in three months of inactivity. This was to the good.

His legs weren't atrophied because of the gravity, it was because he's a parapalegic.  He hasn't used those muscles since he was injured.

I've been wondering about the trees as well so far the only conclusion i can come up with it that they are not made of wood. And by wood I mean cellulose fibers and lignin. I think they are rather derivative of nanofibers perhaps similar but not equal to the bone structure of the Na'vi. This would enable it to grow larger than anything on earth and be able to support itself since its total weight is not the same as it would be if it was our kind of wood.

They could well be made of anything.  Remember that the colonel said that the Na'vi have naturally occurring arbon fiber in their bones, perhaps that adaptation was developed way back in the prokaryotic or early eukaryotic, so it could be found throughout all the major taxa.

Anyways, the main limit to height in earth trees is the ability to use transpiration to draw water up the xylem to the top of the tree, witch sets a hard limit on tree height to just under 400 feet.  The lesser gravity would lengthen this, but not nearly enough to account for the bigger trees, much less hometree.  Perhaps Pandoran plants have developed better ways to lift water up out of the roots?  Maybe even some sort of active transport or pumping?  A big tree has an immense amount of spare energy from photosynthesis, which might be productively channelled to water transport.

One thing I pondered was that if the environment on Pandora is made much like a brain with vastly more neurons, then perhaps the biological make up of the Na'vi brain and body also has more neurons than humans. Allowing for more independent reflexes, much like you twitch your eyes or body automatically when something comes at you, it's very possible that there are independent nerve centres to piggy back motor control. Much like very very large dinosaurs equipped with nerve clusters in the lower spine to assist in walking.

Our number of reflexes really doesn't have that much to do with how many neurons we have in comparison to them, it's more an issue of what they're developed to do.  Humans are descended from arboreal apes, but we left the trees long ago, and though we still retain some of those adaptations, like flexible shoulders, allowing to reach back and above us and swing from branches, we are really adapted to the plains of africa  We're cursorial hunters, who can outrun a gazelle, so long as we just keep running after the same one long enough.  The Na'vi are actively arboreal, like Earth monkeys or orangutans, and they aren't really any more agile than them, just very good at climbing trees and getting through them.  That is why their chest muscles look so odd to a human.  They have different musculature, giving them strength to adduct at the shoulder, so they can do stuff like climb the fines to the mountains to get ikran so much faster than any human ever could, but not much faster than a gibbon.

Also, regarding the independent nerve centres, or second brains in the hips, that's not actually true.  It was first postulated because the channel for the spinal cord widens dramatically in the hip are of some dinosaurs, especially big ornithischians like Stegasaurus and the saurapods, letting it perhaps accommodate a big spinal ganglion, but really, this is kind of a stupid idea.  Birds, which are, after all, basically modern dinosaurs (though descended from saurischians, not ornithischians) also have a big hollowing in their spinal canal, do not have a second brain.  Instead, they have something called the Glycogen Body, an organ of somewhat mysterious purpose, that is full of cells that store glycogen, a complex carbohydrate storage molecule stockpiled by your liver and muscles.  There's some speculation that the glycogen body stores energy to be released to fuel the nervous system in times of stress.

In short, biology: it's a bit more complicated than that.

-Summer Glau

[Reronsem Si]

Our number of reflexes really doesn't have that much to do with how many neurons we have in comparison to them, it's more an issue of what they're developed to do.  Humans are descended from arboreal apes, but we left the trees long ago, and though we still retain some of those adaptations, like flexible shoulders, allowing to reach back and above us and swing from branches, we are really adapted to the plains of africa  We're cursorial hunters, who can outrun a gazelle, so long as we just keep running after the same one long enough.  The Na'vi are actively arboreal, like Earth monkeys or orangutans, and they aren't really any more agile than them, just very good at climbing trees and getting through them.  That is why their chest muscles look so odd to a human.  They have different musculature, giving them strength to adduct at the shoulder, so they can do stuff like climb the fines to the mountains to get ikran so much faster than any human ever could, but not much faster than a gibbon.

Also, regarding the independent nerve centres, or second brains in the hips, that's not actually true.  It was first postulated because the channel for the spinal cord widens dramatically in the hip are of some dinosaurs, especially big ornithischians like Stegasaurus and the saurapods, letting it perhaps accommodate a big spinal ganglion, but really, this is kind of a stupid idea.  Birds, which are, after all, basically modern dinosaurs (though descended from saurischians, not ornithischians) also have a big hollowing in their spinal canal, do not have a second brain.  Instead, they have something called the Glycogen Body, an organ of somewhat mysterious purpose, that is full of cells that store glycogen, a complex carbohydrate storage molecule stockpiled by your liver and muscles.  There's some speculation that the glycogen body stores energy to be released to fuel the nervous system in times of stress.

Don't ruin my dream! In reality though, I would agree with you. Have to understand that not many of us are biologist or scientist for that matter, just fan boys/girls who are thinking well outside the box when sometimes the answer lies within the box.

[Tanhì Tireafya'o]

Well, I think the reason humans walk so earth-like is because of the cryo-sleep? Their muscles have weakened after five and a half years of sleep. I only wonder why they could walk at all then, even after the message: You've been in cryo-sleep for five.somewhat years. You will be weak, You will be hungry. (Except for Jake Sully, he can't walk at all.)

According to the Activists Survival Guide Pandora is 4.4 lightyears away from earth. According to google's calculator the speed of light is 299 792 458 m/s and a year has 31 556 926 seconds. So that would make Pandora have a distance of 299 792 458 * (31 556 926 *4.4) = 4,162632501484208e+16 = 41.626.325.014.842.080 metres away. Or: about 42 thousand billiard metres away from Earth. That's quite far.
They've been a bit longer that 5 years in cryo sleep, so their average speed would've been: 41 626 325 014 842 080 / (31 556 926 * 5) = 263 817 363,04000003042121403079628 m/s. Or: 73 282 601 Kilometres per second. That's fast.