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An astrophysicist reviews the science of "Avatar".

111 points by ilamparithi 17y ago

zackham 17y ago
I'm surprised he didn't question how the link between the characters and the avatars worked. Everything else seemed plausible enough, but I struggled to find an explanation for this. Any thoughts?
- donw 17y ago
  The connections were stable, high-bandwidth, and worked reliably. So, we at least know it wasn't AT&T.
- Nogwater 17y ago
  Exposed (or nearly) nerves for communication. I imagine that they lead to a lobe in the brain that's able to both generate and process mind-to-mind communication. Maybe something like our temporal lobes and Broca's area which handle hearing and language processing. If this type of appendage evolved early enough, then all of the descendants with a common ancestry could maintain a common communication link. This would have had to evolve very early to be shared between both plants and animals, but I suppose it's conceivable if you can imagine plants with a nervous system. Another possibility is that there is a strong mechanism for genetic transfer between different species and kingdoms (maybe very flexible retroviruses or unseen genetic engineering), but then you might expect to see more shared features between plants and animals. The part that I didn't understand why why the Na'vi would always be the "masters" in the link with the other animals (it seemed more peer-to-peer in the link with the trees).
  - anigbrowl 17y ago
    The part that I didn't understand why why the Na'vi would always be the "masters" in the link with the other animals (it seemed more peer-to-peer in the link with the trees). Perhaps because they're best able to hypothesize, in the same way that we train our animals rather than the other way around...although I'm less sure of that when it comes to cats.
    - epochwolf 17y ago
      although I'm less sure of that when it comes to cats. I'm less sure of that when it comes to most humans. Their animals seem to train them, not the other way around.
  - fh 17y ago
    Maybe plants evolved very late on this world, maybe from simple animals that became ever more stationary. Not having to move is an advantage: you can invest more in static defenses (like bark) if you don't have to carry them around. Sea shells are a real life example of something similar. As for the link not being peer-to-peer, it might be as simple as the bigger/more complex nervous system dominating the other one.
    - neilk 17y ago
      That's impossible, at least the way I understand biology. The definition of a plant is that they produce food. An animal produces no food of their own and only takes from others. So plants have to evolve first. You could potentially have motile plants (maybe going directly from free-floating algae to something that swims). But generally, plants are stationary or move passively on Earth because they just don't have the energy. Animals hoover up many times their weight in plants over a year so they can do stuff like intentional motion.
      - billswift 17y ago
        On Earth they co-evolved from different single-celled (protoctist) ancestors.
      - fh 17y ago
        > The definition of a plant is that they produce food. This can't be true: Not all plants are autotrophic, and not all autotrophic organisms are plants.
        neilk 17y ago
        Which plants aren't autotrophic? As for the autotrophic non-plants -- I guess you are referring to algae and some bacteria?
        dalke 17y ago
        Also fungi. I was curious myself and did some searching. Some non-autotrophic plants include the parasitic Cuscuta and Balanophora. There's also semi-parasites like Loranthus and Santalum (sandlewood). See Wikipedia under "Parasitic_plant". The most relevant term is "holoparasitism" and one page says: Holoparasitism has evolved at least six times independently.
- neilk 17y ago
  Also, the link works even in areas which apparently confuse radio waves, like the floaty-mountain parts. Furthermore, there's no way for the army to jam or hijack said signals, or at least, they don't think of doing that. On the other hand, once you have floating mountains, the science has gone out the window.
- gnaritas 17y ago
  Not that it said anything in the movie, but I propose communication via quantum entanglement. It'd explain why the link worked when the radios didn't, there's no real signal to block, and it just sounds fucking cool. Spooky action at a distance is a great plot device for any sci-fi movie and at least partially based on real science.
vyrotek 17y ago
I like to think that their 'network' of knowledge helped them realize they don't need technology and the chaos that comes from it. Or perhaps they have already been where we are and have moved past it realizing there's a better way to live. Edit - Hmm a downvote for an on topic opinion? Would it have been better had I said "Who cares about the details its a freaking movie and you nerds need to get over yourselves?" :)
- donw 17y ago
  That sounds a bit too much like the 'noble savage', and runs pretty counter-intuitive to the parallels we see back here on Earth. Sentience isn't an 'event'; it's not like some apes woke up one morning a few million years ago, and just somehow knew to make spears and hunt. It happens slowly, starting with the use of naturally occurring tools, like chimpanzees do with sticks, or certain octopi do with coconut shells. Some birds use rocks as tools. Tool use evolves up from there, but if we look at our own species as an example, it probably doesn't ever really stop. The Na'vi are probably more like echoes of human beings at an earlier point in our evolution, with the added property of having an intrinsic physical link to the environment around them. If the ecosystem ties directly into your CNS, you're going to think real hard before engaging in widespread destructive behavior, because you know first-hand how painful the damage is. So things like mining, which gave humans metal, would take the Na'vi longer, because they'd want to find a way to do it that won't cause them a ton of pain. But they'd get there, and since Cameron is talking about sequels, the next installment may very likely show how contact with humans has pushed the Na'vi on to a more rapid path of technological development. And your post really doesn't deserve to be downvoted, so it got a +1 from me. Come on, we're discussing the science fiction in a movie. :)
  - vyrotek 17y ago
    We really could invent a million stories as to how the Na'vi got their 'usb ports'. I mean, without knowing their history they could have been so technologically advanced that they gave themselves and the creatures these things and then their society collapsed. I'm also sure I already read someone's theory about them having been created by a more advanced aliens. Ah, science fiction.
timwiseman 17y ago
This is an excellent article and well worth reading. I would have a couple of nit picks with his nitpicks though, particularly: Since the Na’vi have had the ability to download information and share it in a massive network for long periods of time (evolutionary timescales), they should be way ahead of us in terms of technological development. If the movie ever mentions how long the Na'vi have been around as sentient creatures, I missed it entirely. Even if they would leave the "noble savage" stage much faster than humans did, they certainly would have passed through it and if that happens to be when this movie takes place it is hardly surprising. Also, the type of information that they could pass around in this fashion is never clearly delineated. The Tree of Souls can clearly move everything there is from one mind to another, but it is never shown that this can be done routinely or without price, so it may be less valuable in terms of developing technology than it would seem at first glance.
- shrughes 17y ago
  If the movie ever mentions how long the Na'vi have been around as sentient creatures, I missed it entirely. It did mention that before Jake Sully, there were five Toruk Maktos since the beginning of known history, and the most recent one was Neytiri's grandfather's grandfather. Based on that, we might expect recorded history to only go about twenty (or twenty-four?) generations back.
  - timwiseman 17y ago
    Excellent point. It would tell us more if we knew how long the na'vi lived though.
RyanMcGreal 17y ago
>But even then the odds against evolution producing such similar animals on different planets is astronomical. Convergent evolution? Birds, bats, and flying squirrels; sharks, dolphins and penguins; snakes, worms and legless lizards; and so on.
- timwiseman 17y ago
  I think you have a point. My knowledge of evolution is very basic, but it does not seem too intuitively surprising that a relatively similar planets produce fairly similar life.
- donw 17y ago
  Plus, you've got a lot of similar selective pressures -- O2 atmosphere, around Earth gravity, etc. The only thing that I found odd was that nearly every species except the Pandora primates had two sets of eyes, and everything except for the Na'vi had six legs. But it's passable as a plot device, because a mainstream audience probably wouldn't buy into the story if the Na'vi weren't "human enough"
  - timwiseman 17y ago
    everything except for the Na'vi had six legs. Legs, yes, but if you look at limbs many of the flying creatures had four.
  - Nogwater 17y ago
    It also seemed like most of the other animals had their nostrils on in the shoulder area. (I need to watch it again to confirm.) Why not the Na'vi? Probably because if they looked too alien (four eyes, four arms, no noses), the audience would have a hard time empathizing and seeing them as people.
    - bitwize 17y ago
      Indeed. That is also why the "Fookin' Prawns" of District 9 had similar huge, yellowish, humanlike eyes: give them large compound insect eyes and they become a target of revulsion rather than empathy. Already pretty creepy looking if you ask me.
staticshock 17y ago
So the gas giant in Avatar rotates about 50 times faster than Jupiter. Winds on Jupiter can exceed 100 meters per second, so the winds on Polyphemus would have to exceed 5000 m/s – this is supersonic and clearly implausible. That's odd. I don't think there is substantial proof that winds on Jupiter are caused by planetary rotation. In fact, the atmosphere is part of the same inertial system as the rest of the planet. Here's an article suggesting that the winds are actually generated from within Jupiter's interior: http://www.spacedaily.com/reports/Jupiters_Massive_Winds_Likely_Generated_From_Deep_Inside_Its_Interior.html http://www.spacedaily.com/reports/Jupiters_Massive_Winds_Lik... Additionally, I see no inherent problem in supersonic winds. How does it preclude a foreign planet from being 'plausible'? If there is a problem, I'd like for somebody to help me identify it.
- shrughes 17y ago
  The author mentioned in an update that scene was actually supposed to be a time-lapse.
- chronomex 17y ago
  I know I'm nit-picking, but a rotating planet is not strictly an inertial reference frame. That's why the winds and the oceans circulate on Earth.
a-priori 17y ago
First off, I just saw Avatar yesterday and thought it was great. I highly recommend it. Even if you haven't seen it, I don't think this comment will spoil anything for you. I have a few problems with this review, because the author assumes that the Na'vi must follow the same cultural development path as humans. I argue that our path to our current culture didn't start with writing, but with agriculture. Agriculture, and later city-building, is all about destroying nature to build a new environment better suited to our needs. What if, because of the deeply interconnected nature of Pandora, the Na'vi evolved to include the surrounding nature in their in-group? That would imply that, for a Na'vi, morality would apply to a tree as much as another Na'vi. Clearing forests for crops would be tantamount to mass murder. The Na'vi culture is definitely a "Noble savage" stereotype, but note that they have a warrior culture. This implies that they must regularly go to war with other tribes, even if they don't show it in the movie. I also object to citing Steven Pinker's The Blank Slate here. His arguments only apply to human cultures.
- anigbrowl 17y ago
  Moral considerations aside, if life on another planet had evolved with an interconnected signal network then writing or complex artifice might not yield any particular advantage. As for how that could happen to begin with, perhaps a high magnetic flux from the nearby gas giant would favor the development of sensory organs for that medium. Birds are sensitive to the earth's comparatively weak magnetic field (http://www.nature.com/nature/journal/v461/n7268/full/nature08528.html http://www.nature.com/nature/journal/v461/n7268/full/nature0...) and there are several varieties of fish that can generate electricity inside their bodies and use it to communicate (http://www.livescience.com/animals/060602_electric_fish.html http://www.livescience.com/animals/060602_electric_fish.html). That aspect didn't seem far-fetched to me. I was more perplexed by the morphology of some animals - for example I wasn't clear on the benefit of 4 front legs, 4 eyes, and gill-type breathing...but it didn't interfere with my enjoyment of the film, which I'm looking forward to seeing again, probably several times. 'see' being the operative word...people complain about the crudity of the dialog, but the win for me is that you could watch it without knowing a word of English and still 'get' the story - which is far easier said than done.
- jamesbritt 17y ago
zephjc 17y ago
All other things being equal (natural resources and energy), technological progress is directly proportional to a population's size and density (for degree of progress) and its growth delta (for the rate of progress). More specifically, it is the population's ability to transfer existing information and synthesize new information which lends itself to what we recognize technological progress (you have to have the desire to apply such knowledge too, of course). I haven't seen the movie yet, but I'm guessing the Na'vi did not have very large or dense populations. As for their global Gaia network, does the movie explain if it actually transfer chunks of knowledge (memes) or experiential patterns, or is it 'lower level' and works more like sharing emotions?
- timwiseman 17y ago
  All other things being equal (natural resources and energy), technological progress is directly proportional to a population's size and density (for degree of progress) and its growth delta (for the rate of progress). Interesting point. I had never heard it before (I'd be interested if you have a reference that goes into more detail), but it certainly seem like there is a historical correalation and thinking about it you do seem to need at least a minimum population size (enough to allow people to specialize in careers instead of everyone being generalists with food production their prime concern) to develop advanced technology. At least offhand, I am not certain how well that causitive factor holds after that threshold has been reached. And that All other things being equal caveat is likely to be of significant importance here. I am speculating, but I would guess that after the minimum threshold is passed than the amount of value the culture places on education and technology itself will likely swamp out size or growth rates in terms of encouraging technological advance. In other words, after the minimum is reached, you would increase technological development faster by affecting the culture of the people than by increasing the population, and that affect is likely to be so great to mask differences in population size. I haven't seen the movie yet, but I'm guessing the Na'vi did not have very large or dense populations. The total planetary population is never stated but the population for the region the movie focuses on is said to be in the neighborhood of 200,000 very roughly. As for their global Gaia network, does the movie explain if it actually transfer chunks of knowledge (memes) or experiential patterns, or is it 'lower level' and works more like sharing emotions? This is ambiguous. At one point it is shown that at least under certain conditions absolutely everything can be shared and transferred, but that was under exceptional circumstances. How it operates under normal conditions is left quite vague. The movie is well worth seeing if you haven't.
Eliezer 17y ago
LARGE SPOILERS AHEAD: I liked Avatar, but to me the obvious science fail was the telepathic connection between the Na'vi and the animals. Evolution doesn't work like that! Rattlesnakes do not grow rattles for your benefit! I'm afraid that yon astrophysicist knows rather a bit more about physics than about evolutionary biology if the inter-species universal complex adaptations didn't jump out at him. As for the planetary tree-mind being able to read out human brain networks using its own standardized equipment, who are they kidding? Yes, the whole plot would have worked without it! The central tree could have been providing a vital nutrient without which the local ecosystem would fail, or something that their women needed to reproduce. There's no reason you need telepathy to ride a horse. The final stampede could have been started by one or more heroes, rather than being magic. And the final body-swap wasn't really necessary (just keep using the old equipment), but it could have been an effect of running the interface for a sufficiently long time (the alien brain gets reprogrammed). And then it would have been hard science fiction, which would have made a visually-awesome, okay-plot movie into one of the greatest SF movies of all time. Also, I will accept pretty alien ladies for the sake of plot, but having them cry tears is going too far, and it's not necessary. That really jumped out at me. Avatar was good, but it could have been so much more if they'd spent five minutes thinking about how to get the plot effect they wanted via science instead of magic.
- nvasilak 17y ago
  > I liked Avatar, but to me the obvious science fail was the telepathic connection between the Na'vi and the animals. Evolution doesn't work like that! Rattlesnakes do not grow rattles for your benefit! I'm afraid that yon astrophysicist knows rather a bit more about physics than about evolutionary biology if the inter-species universal complex adaptations didn't jump out at him. You should check this out: http://www.i-sis.org.uk/paris.php http://www.i-sis.org.uk/paris.php The latest science suggests that evolution is less random than we thought, and that unrelated species often swap genetic information. Inter-species universal complex adaptations may be a bit more plausible than we think.
  - hegemonicon 17y ago
    I am not an expert on evolution, but much of this article strikes me as incorrect. The fact that genes are capable of modifying other genes (turning them off/on, splicing in new genes, etc.) doesn't refute the concept of natural selection of random mutations unless you're ALSO positing a new mechanism by which this modification ability can be acquired. I skimmed through and didn't see one, even though he strangely implies that the fact that genes behave in a complex fashion means that organisms aren't coded by them. His (apparent) creationist sympathies and tacit endorsement of the gaia concept leads me to believe he thinks there is some sort of magic at work, which is not a very useful explanation. I'm equally perplexed by his overall point of "genetics is complicated, therefore genetic engineering and capitalism is immoral."
neilk 17y ago
The Na'vi really are little more than noble savages. But they hold out a particular hope that's attractive for technological late-capitalist humans; they feel "connected". In the movie, that metaphor is taken all the way to be a literal connection -- to their communities, to their ancestors, to a spirituality, to their working animals, to the entire ecosystem. I think that's the only way to understand their ponytail USB cables, and the root-mesh information network. It may be amusing to pretend that it's a hard-SF piece and work out the implications, but it's just not. It's a fantasy piece about the longing for connectedness. There is (maybe) a secondary theme of viewing an ecosystem as a giant information exchange. But that wasn't explored well.
- prewett 17y ago
  Just saw the movie, and it was great! I'm not sure the interconnectedness was intended as information transfer, though. They had to communicate with the other tribes by actually going there. It seemed like the network was more like the brain of a planetary organism (eywa). Each individual could access and add to the memories, but was not a communication network. An interesting approach--they truly are "one with the world" in a way other sci-fi (Babylon 5, for example) does inelegantly.
billswift 17y ago
I have no intention of seeing the movie, although I may when it's on DVD if I get sufficiently bored. If you can find a copy see Benford's essay "Reactionary Utopias", originally written as a reaction to Ursula Leguin's anti-industrial screeds masquerading as science fiction.
neilk 17y ago
Another idea about Avatar... maybe this is very loopy, but is it possible that the Na'vi are a metaphor for the internet, and its more democratic culture? Maybe an unconscious one? They live in this world which is literally founded on an information network. People from the default world enter this other world via technology, and by creating avatars which are remotely controlled. There is a power struggle between those who see the communities as something to exploit, and those who see them as something valuable for their own sake.
- endtime 17y ago
  >is it possible that the Na'vi are a metaphor for the internet, and its more democratic culture? The Na'vi culture didn't seem particularly democratic.
roundsquare 17y ago
Since the Na’vi have had the ability to download information and share it in a massive network for long periods of time (evolutionary timescales), they should be way ahead of us in terms of technological development. The information they have access to appears to be someone's entire mind/memories/thoughts/whatever... This would be a HUGE amount of completely unsorted data. Sifting through all of this to find usable information would be very difficult. The comparison to writing and the internet is false. In both cases, data is (to some degree) indexed. Want to build a robot? Search for "how to build a robot" and you have a good place to get started. In fact, they only time they show anyone making direct use of the link (as opposed to a spiritual use) is when they ride animals, which is a link with a single animal.

111 points by ilamparithi 17y ago

I'm surprised he didn't question how the link between the characters and the avatars worked. Everything else seemed plausible enough, but I struggled to find an explanation for this. Any thoughts?

donw 17y ago
The connections were stable, high-bandwidth, and worked reliably. So, we at least know it wasn't AT&T.
Nogwater 17y ago
Exposed (or nearly) nerves for communication. I imagine that they lead to a lobe in the brain that's able to both generate and process mind-to-mind communication. Maybe something like our temporal lobes and Broca's area which handle hearing and language processing. If this type of appendage evolved early enough, then all of the descendants with a common ancestry could maintain a common communication link. This would have had to evolve very early to be shared between both plants and animals, but I suppose it's conceivable if you can imagine plants with a nervous system. Another possibility is that there is a strong mechanism for genetic transfer between different species and kingdoms (maybe very flexible retroviruses or unseen genetic engineering), but then you might expect to see more shared features between plants and animals. The part that I didn't understand why why the Na'vi would always be the "masters" in the link with the other animals (it seemed more peer-to-peer in the link with the trees).
- anigbrowl 17y ago
  The part that I didn't understand why why the Na'vi would always be the "masters" in the link with the other animals (it seemed more peer-to-peer in the link with the trees). Perhaps because they're best able to hypothesize, in the same way that we train our animals rather than the other way around...although I'm less sure of that when it comes to cats.
  - epochwolf 17y ago
    although I'm less sure of that when it comes to cats. I'm less sure of that when it comes to most humans. Their animals seem to train them, not the other way around.
- fh 17y ago
  Maybe plants evolved very late on this world, maybe from simple animals that became ever more stationary. Not having to move is an advantage: you can invest more in static defenses (like bark) if you don't have to carry them around. Sea shells are a real life example of something similar. As for the link not being peer-to-peer, it might be as simple as the bigger/more complex nervous system dominating the other one.
  - neilk 17y ago
    That's impossible, at least the way I understand biology. The definition of a plant is that they produce food. An animal produces no food of their own and only takes from others. So plants have to evolve first. You could potentially have motile plants (maybe going directly from free-floating algae to something that swims). But generally, plants are stationary or move passively on Earth because they just don't have the energy. Animals hoover up many times their weight in plants over a year so they can do stuff like intentional motion.
    - billswift 17y ago
      On Earth they co-evolved from different single-celled (protoctist) ancestors.
    - fh 17y ago
      > The definition of a plant is that they produce food. This can't be true: Not all plants are autotrophic, and not all autotrophic organisms are plants.
      - neilk 17y ago
        Which plants aren't autotrophic? As for the autotrophic non-plants -- I guess you are referring to algae and some bacteria?
        dalke 17y ago
        Also fungi. I was curious myself and did some searching. Some non-autotrophic plants include the parasitic Cuscuta and Balanophora. There's also semi-parasites like Loranthus and Santalum (sandlewood). See Wikipedia under "Parasitic_plant". The most relevant term is "holoparasitism" and one page says: Holoparasitism has evolved at least six times independently.
neilk 17y ago
Also, the link works even in areas which apparently confuse radio waves, like the floaty-mountain parts. Furthermore, there's no way for the army to jam or hijack said signals, or at least, they don't think of doing that. On the other hand, once you have floating mountains, the science has gone out the window.
gnaritas 17y ago
Not that it said anything in the movie, but I propose communication via quantum entanglement. It'd explain why the link worked when the radios didn't, there's no real signal to block, and it just sounds fucking cool. Spooky action at a distance is a great plot device for any sci-fi movie and at least partially based on real science.

vyrotek 17y ago

I like to think that their 'network' of knowledge helped them realize they don't need technology and the chaos that comes from it. Or perhaps they have already been where we are and have moved past it realizing there's a better way to live. Edit - Hmm a downvote for an on topic opinion? Would it have been better had I said "Who cares about the details its a freaking movie and you nerds need to get over yourselves?" :)

donw 17y ago
That sounds a bit too much like the 'noble savage', and runs pretty counter-intuitive to the parallels we see back here on Earth. Sentience isn't an 'event'; it's not like some apes woke up one morning a few million years ago, and just somehow knew to make spears and hunt. It happens slowly, starting with the use of naturally occurring tools, like chimpanzees do with sticks, or certain octopi do with coconut shells. Some birds use rocks as tools. Tool use evolves up from there, but if we look at our own species as an example, it probably doesn't ever really stop. The Na'vi are probably more like echoes of human beings at an earlier point in our evolution, with the added property of having an intrinsic physical link to the environment around them. If the ecosystem ties directly into your CNS, you're going to think real hard before engaging in widespread destructive behavior, because you know first-hand how painful the damage is. So things like mining, which gave humans metal, would take the Na'vi longer, because they'd want to find a way to do it that won't cause them a ton of pain. But they'd get there, and since Cameron is talking about sequels, the next installment may very likely show how contact with humans has pushed the Na'vi on to a more rapid path of technological development. And your post really doesn't deserve to be downvoted, so it got a +1 from me. Come on, we're discussing the science fiction in a movie. :)
- vyrotek 17y ago
  We really could invent a million stories as to how the Na'vi got their 'usb ports'. I mean, without knowing their history they could have been so technologically advanced that they gave themselves and the creatures these things and then their society collapsed. I'm also sure I already read someone's theory about them having been created by a more advanced aliens. Ah, science fiction.

timwiseman 17y ago

This is an excellent article and well worth reading. I would have a couple of nit picks with his nitpicks though, particularly: Since the Na’vi have had the ability to download information and share it in a massive network for long periods of time (evolutionary timescales), they should be way ahead of us in terms of technological development. If the movie ever mentions how long the Na'vi have been around as sentient creatures, I missed it entirely. Even if they would leave the "noble savage" stage much faster than humans did, they certainly would have passed through it and if that happens to be when this movie takes place it is hardly surprising. Also, the type of information that they could pass around in this fashion is never clearly delineated. The Tree of Souls can clearly move everything there is from one mind to another, but it is never shown that this can be done routinely or without price, so it may be less valuable in terms of developing technology than it would seem at first glance.

shrughes 17y ago
If the movie ever mentions how long the Na'vi have been around as sentient creatures, I missed it entirely. It did mention that before Jake Sully, there were five Toruk Maktos since the beginning of known history, and the most recent one was Neytiri's grandfather's grandfather. Based on that, we might expect recorded history to only go about twenty (or twenty-four?) generations back.
- timwiseman 17y ago
  Excellent point. It would tell us more if we knew how long the na'vi lived though.

RyanMcGreal 17y ago

>But even then the odds against evolution producing such similar animals on different planets is astronomical. Convergent evolution? Birds, bats, and flying squirrels; sharks, dolphins and penguins; snakes, worms and legless lizards; and so on.

timwiseman 17y ago
I think you have a point. My knowledge of evolution is very basic, but it does not seem too intuitively surprising that a relatively similar planets produce fairly similar life.
donw 17y ago
Plus, you've got a lot of similar selective pressures -- O2 atmosphere, around Earth gravity, etc. The only thing that I found odd was that nearly every species except the Pandora primates had two sets of eyes, and everything except for the Na'vi had six legs. But it's passable as a plot device, because a mainstream audience probably wouldn't buy into the story if the Na'vi weren't "human enough"
- timwiseman 17y ago
  everything except for the Na'vi had six legs. Legs, yes, but if you look at limbs many of the flying creatures had four.
- Nogwater 17y ago
  It also seemed like most of the other animals had their nostrils on in the shoulder area. (I need to watch it again to confirm.) Why not the Na'vi? Probably because if they looked too alien (four eyes, four arms, no noses), the audience would have a hard time empathizing and seeing them as people.
  - bitwize 17y ago
    Indeed. That is also why the "Fookin' Prawns" of District 9 had similar huge, yellowish, humanlike eyes: give them large compound insect eyes and they become a target of revulsion rather than empathy. Already pretty creepy looking if you ask me.

staticshock 17y ago

So the gas giant in Avatar rotates about 50 times faster than Jupiter. Winds on Jupiter can exceed 100 meters per second, so the winds on Polyphemus would have to exceed 5000 m/s – this is supersonic and clearly implausible. That's odd. I don't think there is substantial proof that winds on Jupiter are caused by planetary rotation. In fact, the atmosphere is part of the same inertial system as the rest of the planet. Here's an article suggesting that the winds are actually generated from within Jupiter's interior: http://www.spacedaily.com/reports/Jupiters_Massive_Winds_Likely_Generated_From_Deep_Inside_Its_Interior.html http://www.spacedaily.com/reports/Jupiters_Massive_Winds_Lik... Additionally, I see no inherent problem in supersonic winds. How does it preclude a foreign planet from being 'plausible'? If there is a problem, I'd like for somebody to help me identify it.

shrughes 17y ago
The author mentioned in an update that scene was actually supposed to be a time-lapse.
chronomex 17y ago
I know I'm nit-picking, but a rotating planet is not strictly an inertial reference frame. That's why the winds and the oceans circulate on Earth.

a-priori 17y ago

First off, I just saw Avatar yesterday and thought it was great. I highly recommend it. Even if you haven't seen it, I don't think this comment will spoil anything for you. I have a few problems with this review, because the author assumes that the Na'vi must follow the same cultural development path as humans. I argue that our path to our current culture didn't start with writing, but with agriculture. Agriculture, and later city-building, is all about destroying nature to build a new environment better suited to our needs. What if, because of the deeply interconnected nature of Pandora, the Na'vi evolved to include the surrounding nature in their in-group? That would imply that, for a Na'vi, morality would apply to a tree as much as another Na'vi. Clearing forests for crops would be tantamount to mass murder. The Na'vi culture is definitely a "Noble savage" stereotype, but note that they have a warrior culture. This implies that they must regularly go to war with other tribes, even if they don't show it in the movie. I also object to citing Steven Pinker's The Blank Slate here. His arguments only apply to human cultures.

anigbrowl 17y ago
Moral considerations aside, if life on another planet had evolved with an interconnected signal network then writing or complex artifice might not yield any particular advantage. As for how that could happen to begin with, perhaps a high magnetic flux from the nearby gas giant would favor the development of sensory organs for that medium. Birds are sensitive to the earth's comparatively weak magnetic field (http://www.nature.com/nature/journal/v461/n7268/full/nature08528.html http://www.nature.com/nature/journal/v461/n7268/full/nature0...) and there are several varieties of fish that can generate electricity inside their bodies and use it to communicate (http://www.livescience.com/animals/060602_electric_fish.html http://www.livescience.com/animals/060602_electric_fish.html). That aspect didn't seem far-fetched to me. I was more perplexed by the morphology of some animals - for example I wasn't clear on the benefit of 4 front legs, 4 eyes, and gill-type breathing...but it didn't interfere with my enjoyment of the film, which I'm looking forward to seeing again, probably several times. 'see' being the operative word...people complain about the crudity of the dialog, but the win for me is that you could watch it without knowing a word of English and still 'get' the story - which is far easier said than done.
jamesbritt 17y ago

zephjc 17y ago

All other things being equal (natural resources and energy), technological progress is directly proportional to a population's size and density (for degree of progress) and its growth delta (for the rate of progress). More specifically, it is the population's ability to transfer existing information and synthesize new information which lends itself to what we recognize technological progress (you have to have the desire to apply such knowledge too, of course). I haven't seen the movie yet, but I'm guessing the Na'vi did not have very large or dense populations. As for their global Gaia network, does the movie explain if it actually transfer chunks of knowledge (memes) or experiential patterns, or is it 'lower level' and works more like sharing emotions?

timwiseman 17y ago
All other things being equal (natural resources and energy), technological progress is directly proportional to a population's size and density (for degree of progress) and its growth delta (for the rate of progress). Interesting point. I had never heard it before (I'd be interested if you have a reference that goes into more detail), but it certainly seem like there is a historical correalation and thinking about it you do seem to need at least a minimum population size (enough to allow people to specialize in careers instead of everyone being generalists with food production their prime concern) to develop advanced technology. At least offhand, I am not certain how well that causitive factor holds after that threshold has been reached. And that All other things being equal caveat is likely to be of significant importance here. I am speculating, but I would guess that after the minimum threshold is passed than the amount of value the culture places on education and technology itself will likely swamp out size or growth rates in terms of encouraging technological advance. In other words, after the minimum is reached, you would increase technological development faster by affecting the culture of the people than by increasing the population, and that affect is likely to be so great to mask differences in population size. I haven't seen the movie yet, but I'm guessing the Na'vi did not have very large or dense populations. The total planetary population is never stated but the population for the region the movie focuses on is said to be in the neighborhood of 200,000 very roughly. As for their global Gaia network, does the movie explain if it actually transfer chunks of knowledge (memes) or experiential patterns, or is it 'lower level' and works more like sharing emotions? This is ambiguous. At one point it is shown that at least under certain conditions absolutely everything can be shared and transferred, but that was under exceptional circumstances. How it operates under normal conditions is left quite vague. The movie is well worth seeing if you haven't.

Eliezer 17y ago

LARGE SPOILERS AHEAD: I liked Avatar, but to me the obvious science fail was the telepathic connection between the Na'vi and the animals. Evolution doesn't work like that! Rattlesnakes do not grow rattles for your benefit! I'm afraid that yon astrophysicist knows rather a bit more about physics than about evolutionary biology if the inter-species universal complex adaptations didn't jump out at him. As for the planetary tree-mind being able to read out human brain networks using its own standardized equipment, who are they kidding? Yes, the whole plot would have worked without it! The central tree could have been providing a vital nutrient without which the local ecosystem would fail, or something that their women needed to reproduce. There's no reason you need telepathy to ride a horse. The final stampede could have been started by one or more heroes, rather than being magic. And the final body-swap wasn't really necessary (just keep using the old equipment), but it could have been an effect of running the interface for a sufficiently long time (the alien brain gets reprogrammed). And then it would have been hard science fiction, which would have made a visually-awesome, okay-plot movie into one of the greatest SF movies of all time. Also, I will accept pretty alien ladies for the sake of plot, but having them cry tears is going too far, and it's not necessary. That really jumped out at me. Avatar was good, but it could have been so much more if they'd spent five minutes thinking about how to get the plot effect they wanted via science instead of magic.

nvasilak 17y ago
> I liked Avatar, but to me the obvious science fail was the telepathic connection between the Na'vi and the animals. Evolution doesn't work like that! Rattlesnakes do not grow rattles for your benefit! I'm afraid that yon astrophysicist knows rather a bit more about physics than about evolutionary biology if the inter-species universal complex adaptations didn't jump out at him. You should check this out: http://www.i-sis.org.uk/paris.php http://www.i-sis.org.uk/paris.php The latest science suggests that evolution is less random than we thought, and that unrelated species often swap genetic information. Inter-species universal complex adaptations may be a bit more plausible than we think.
- hegemonicon 17y ago
  I am not an expert on evolution, but much of this article strikes me as incorrect. The fact that genes are capable of modifying other genes (turning them off/on, splicing in new genes, etc.) doesn't refute the concept of natural selection of random mutations unless you're ALSO positing a new mechanism by which this modification ability can be acquired. I skimmed through and didn't see one, even though he strangely implies that the fact that genes behave in a complex fashion means that organisms aren't coded by them. His (apparent) creationist sympathies and tacit endorsement of the gaia concept leads me to believe he thinks there is some sort of magic at work, which is not a very useful explanation. I'm equally perplexed by his overall point of "genetics is complicated, therefore genetic engineering and capitalism is immoral."

neilk 17y ago

The Na'vi really are little more than noble savages. But they hold out a particular hope that's attractive for technological late-capitalist humans; they feel "connected". In the movie, that metaphor is taken all the way to be a literal connection -- to their communities, to their ancestors, to a spirituality, to their working animals, to the entire ecosystem. I think that's the only way to understand their ponytail USB cables, and the root-mesh information network. It may be amusing to pretend that it's a hard-SF piece and work out the implications, but it's just not. It's a fantasy piece about the longing for connectedness. There is (maybe) a secondary theme of viewing an ecosystem as a giant information exchange. But that wasn't explored well.

prewett 17y ago
Just saw the movie, and it was great! I'm not sure the interconnectedness was intended as information transfer, though. They had to communicate with the other tribes by actually going there. It seemed like the network was more like the brain of a planetary organism (eywa). Each individual could access and add to the memories, but was not a communication network. An interesting approach--they truly are "one with the world" in a way other sci-fi (Babylon 5, for example) does inelegantly.

billswift 17y ago

I have no intention of seeing the movie, although I may when it's on DVD if I get sufficiently bored. If you can find a copy see Benford's essay "Reactionary Utopias", originally written as a reaction to Ursula Leguin's anti-industrial screeds masquerading as science fiction.

neilk 17y ago

Another idea about Avatar... maybe this is very loopy, but is it possible that the Na'vi are a metaphor for the internet, and its more democratic culture? Maybe an unconscious one? They live in this world which is literally founded on an information network. People from the default world enter this other world via technology, and by creating avatars which are remotely controlled. There is a power struggle between those who see the communities as something to exploit, and those who see them as something valuable for their own sake.

endtime 17y ago
>is it possible that the Na'vi are a metaphor for the internet, and its more democratic culture? The Na'vi culture didn't seem particularly democratic.

roundsquare 17y ago

Since the Na’vi have had the ability to download information and share it in a massive network for long periods of time (evolutionary timescales), they should be way ahead of us in terms of technological development. The information they have access to appears to be someone's entire mind/memories/thoughts/whatever... This would be a HUGE amount of completely unsorted data. Sifting through all of this to find usable information would be very difficult. The comparison to writing and the internet is false. In both cases, data is (to some degree) indexed. Want to build a robot? Search for "how to build a robot" and you have a good place to get started. In fact, they only time they show anyone making direct use of the link (as opposed to a spiritual use) is when they ride animals, which is a link with a single animal.