
An astrophysicist reviews the science of "Avatar". - ilamparithi
http://www.aintitcool.com/node/43440
======
a-priori
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.

~~~
jamesbritt
"Agriculture, and later city-building, is all about destroying nature "

 _Destroying_ ? That's some bias there. How about "altering nature".

Humans are part of nature, and changing things around us is natural. Sometimes
it is an act of destruction, but building homes and planting crops hardly fits
that description.

~~~
gnaritas
> Destroying ? That's some bias there. How about "altering nature".

"Altering"? That's some political correctness there. Looking at what we do,
destroying is a far more accurate description.

> Humans are part of nature, and changing things around us is natural.

Using that definition of natural, everything is natural and unnatural has no
meaning at all. Makes communicating a point rather hard. Humans are natural
and since they build cars, cars must be natural as well?

~~~
jamesbritt
"Using that definition of natural, everything is natural and unnatural has no
meaning at all."

No.

"Humans are natural and since they build cars, cars must be natural as well?"

As I said, it's natural for people to build things, so building cars is
natural.

I simply don't adhere to the PC view that if people do it, it must be anti-
nature, unnatural, or bad (though sometimes that happens to be the case).

~~~
gnaritas
I didn't say if people do it it _must_ be anti-nature, only that it usually
is. We generally alter our environment to suite our needs, not to improve it.
I can't think of many instances where our presence has benefited most of the
plants and animals and left them better off then before we arrived; can you?

~~~
epochwolf
_We generally alter our environment to suite our needs, not to improve it._

I don't know about you but I think a house is an improvement over the trees
that were here before. A forest can get pretty cold in winter.

~~~
gnaritas
It's a improvement for you, not for nature or the animals you displaced, which
was exactly my point.

~~~
Alsadius
Who cares about them? That's not snark, I mean it seriously. Humans are
intelligent creatures with desires. Trees are leafy lumps cellulose. They have
no brain, they have no intellect - a tree cannot feel pain or pleasure, joy or
sorrow. Sure, it can live or die, but that life has no moral content. The
natural world is only valuable insofar as it's useful for creatures that
actually are morally relevant - i.e., humans.

That's not saying we should pave the forests - forests are nice, I like having
them around. But it's the human desire to have a forest that's meaningful, not
the forest itself. If humans want houses more, then it's perfectly acceptable
to knock down the trees, turn them into lumber, and build houses with them,
and spit-roast the animals over a wood fire in the backyard for the
housewarming party.

------
Eliezer
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
> 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> 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
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."

------
vyrotek
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?" :)

~~~
blhack
_Or perhaps they have already been where we are and have moved past it
realizing there's a better way to live._

My trek knowlege is pretty poor, but I want to say this is the history of the
Vulcan. They're _extremely_ advanced technologically, but choose to live a
simple life. Unlike the Na'vi, however, they don't shoot animals with
neurotoxin-covered spears, growl at things that make them angry, or try to
fight a war against people with guns using the aforementioned spears.

The Vulcan are one of the most technologically advanced civilizations in The
Federation. If the Na'vi were an advanced race that _chose_ to live simply,
dealing with the Humans wouldn't have been a problem for them.

~~~
gnaritas
> The Vulcan are one of the most technologically advanced civilizations in The
> Federation.

The Vulcans _were_ one of the most technologically advanced civilizations in
the Federation, but not any longer, you haven't been keeping up.

~~~
heresy
Correction, that's only in the parallel universe. :)

~~~
gnaritas
Only if you buy that hypothesis, but I saw it in this universe, so that's the
one it applies to. :) Very creative way to reboot the series without being
constrained by the original though.

------
staticshock
_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_Lik...](http://www.spacedaily.com/reports/Jupiters_Massive_Winds_Likely_Generated_From_Deep_Inside_Its_Interior.html)

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
The author mentioned in an update that scene was actually supposed to be a
time-lapse.

------
timwiseman
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
_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
Excellent point. It would tell us more if we knew how long the na'vi lived
though.

------
neilk
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
>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.

------
zephjc
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
_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.

~~~
billswift
For the population effects see Julian Simon's "The Great Breakthrough and Its
Cause" for the historical analysis. His "Ultimate Resource" talks about the
current and recent historical benefits of population.

------
RyanMcGreal
>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.

~~~
donw
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"

~~~
Nogwater
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
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.

------
zackham
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?

~~~
Nogwater
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).

~~~
fh
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
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.

~~~
fh
> 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
Which plants aren't autotrophic?

As for the autotrophic non-plants -- I guess you are referring to algae and
some bacteria?

~~~
dalke
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.

------
roundsquare
_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.

------
neilk
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
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
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.

