| Human No More |
05-27-2011 08:26 PM |
My open email to 'Intuitor'
After seeing this page on Avatar: Avatar , I felt the need to reply and address some points. This is my reply:
Quote:
Just in the interest of accuracy, I'd like to point out the mistakes in your article on Avatar. I doubt I will see any changes to it, but I'd like to at least feel I tried - I would be interested in a reply on any points you would still contest though.
Firstly, they're called the Na'vi. Not Navi, or The Navi. Please make an effort with their very name, even if I can understand why many people don't get the other species names.
Basing a timescale of development on history has always been a mistake - I would direct your attention to one of my favourite quotes: "Heavier-than-air flying machines are impossible." — Lord Kelvin, president, Royal Society, 1895. As it is, Avatar is not set in 2056 anyway, but 2154, so I fail to see any problem. As for fuel costs, antimatter is certainly expensive, but remember that antimatter today has never been produced in more than a few single molecules at a time. Obviously that affects the cost, that is like basing a theory on the cost of plutonium in 1942. Storage is an actual valid issue, but heat isn't necessarily a problem as it would be on most spacecraft - you should have noticed, but a significant proportion of the ISV's structure is composed of radiators. The first ISV (that did not use unobtainium as part of its antimatter containment) was three times the size, with the space being cooling systems. While the ISV is nearly a mile long, the majority of it is not a large structure - this is not the Enterprise or whatever. It is a set of cargo and cryo modules being towed on a cable. The majority of it has no massive structures.
Unobtainium itself - the name is not original, certainly, but considering the fact that it was almost certainly discovered and named by physicists, this is easily a joke based on the fact that a compound (no, it is not an element) with such ideal properties was actually discovered. Claiming that unobtainium could be synthesised simply because Pandora can be reached is an example of package-deal fallacy, as well as the simple fact that the majority of naturally occurring compounds found today can no be synthesised either. Not understanding the uses of unobtainium is understandable for someone without knowledge of the background - but it is used for power distribution systems on Earth, transport systems and antimatter containment, so there is certainly at least sufficient demand. The honest fact is though, that even without knowledge of the uses, not only could the basic uses of a high temperature superconductor be reasonably estimated, but it is logical that there is sufficient demand to maintain the production level.
As for shipping machinery to Pandora - the simple fact is that it is not. Almost everything is assembled locally using stereolithography - the main things that are brought from Earth are electronics and other high precision components that can not be manufactured there - not entire vehicles. Infrastructure DOES exist - there is a detailed plan of Hell's Gate here: http://dl.dropbox.com/u/6036637/HABMOD.jpg
Again, the 'use of robots' argument is understandable from someone who has only taken a rudimentary look at the background, and is one I have defeated before. Pandora's magnetic field is stronger then Earth's and renders many complicated electronics unusable (one of the main reasons that the marines' vehicles are primarily from the late 21st century rather than mid 22nd), the atmosphere renders most machinery susceptible to failure and requiring frequent maintenance - which not only requires large numbers of humans, but is the reason that they are used to perform tasks humans can not do, and not ones which they would only be as good as a human for (and more expensive). The 'colony' argument is actually more interesting, but it ignores the fact that the human presence on Pandora is relatively small, the relatively short time they have been there, and the fact that mining operations are mostly using machinery anyway (an example of one of the applications where humans would be impractical directly as mentioned above). Why wait 25-30 years for results when you can get them that year? Considering the fact that if humans coming to Pandora were all a one-way trip, then the ISV's cryo units would be empty on the return journey, so it is not necessarily illogical, only as far as justifying the fuel cost. Considering the fact that the RDA's entire contract relating to space is based on certain provisions (the discussed ones mainly involve military) then child labour seems unlikely - and either way, I don't see the relevance to physics there.
As for the marines' weaponry - the AMP suits do use explosive rounds - an 'angtsik (hammerhead titanothere - 'dinosaur-like beast') is not only covered in natural armour and with a carbon-fibre skeleton, but actually far larger than an elephant and possessing higher kinetic energy - even if killed, it is going to keep going and smash an AMP suit and the marine it contains into a fine paste. The argument of the marines' equipment is another I have heard before - as I mentioned above they are not armed with the weapons available on Earth (primarily electromagnetic based railgun-style weapons) because they are near-useless in Pandora's magnetic field and atmosphere. As it is, their equipment is significantly better than 2009-era ones - the Scorpion, for example (the attack helicopter) is superior to a modern one in every way even in Pandora's atmosphere, which degrades flight characteristics. The question of armour is a simple one - there is nothing that WILL protect against an 8-9 foot bow with over a tonne of draw weight while still being able to move and carry it, and even if it did, the internal injuries would be enough to kill a human, much as people can be injured after a bulletproof vest blocks a shot from a current-day firearm.
A small note about the AMP suits is that they are originally modified from commercial vehicles used for heavy lifting and construction - while they have been used by Earth militaries in some conflicts in areas uninhabitable to humans due to their survivability and sealed cockpit, in those cases then they rely more on sensors, with an armoured cover over the cockpit, which is useless on Pandora due to the the sensor interference and the greatly increased need for visibility. the agility may well be an issue if one was built today, but as you have pointed out elsewhere in your article, it's the future - in this case, it is plausible for a small to moderate improvement, although I will concede that the fight against Quaritch had more human-like movement than the other AMP suits, which was certainly to make it more balanced than it would have otherwise been as a fight. As it is, there is no physical impossibility there.
There are a few theories regarding the Avatar link, but ultimately it is not possible with current technology, but the basic underpinnings are still theoretically possible. The mountains use the Meissner effect - I assume you did not see the rerelease where it was explained in the actual film (rather than background material) what the specific use of unobtainium (room temperature superconductor) is - this does NOT need an extremely large magnetic field such as attracting ferromagnetic objects. Pandora's magnetic field is stronger than Earth's, but not that strong (although I must say I am pleased you did not make the 'normal' misconception there, that the field would kill a human). As for disruption of electronic systems, that is another reason that late 21st century technology is in widespread use rather than mid-22nd, and the design of the aircraft is largely mechanical (although it is said that this technology is also making a comeback on Earth as EMP-based weaponry has fallen into the hands of terrorists there).
Human movement on Pandora is an interesting point - proportionally, the Na'vi are far stronger than humans, and although humans do not visibly bounce when they walk, the effect of 0.8g is far more subtle than most explicitly low gravity worlds - in addition, humans are close on one of the smallest mammals on Pandora. Six legs makes a lot of sense in survival on Pandora - firstly, evolution is not always convergent. Secondly, Pandora has both lower gravity and a significantly denser atmosphere. Six legs allow for far better grip on the ground and more speed and control when running. Most flying creatures have four legs, with the exception of Toruk (Great Leonopteryx), which maintains separate legs with claws, which makes sense for an apex predator, while ikran (banshees) 'sit' on their rear wings when on the ground. Prolemuris (the apelike creatures with the arms that split at the elbow) show adaptation for a treetop environment and presumably spend minimal time on the surface, where a multiple-limb grip on the ground provides its main advantage. It should also be noted that the Na'vi have prehensile toes and an enlarged thumb-like toe with gap, which allows their foot to function much like a hand and increases grip on the ground.
Animals breathing through an operculum actually makes sense - while there is an obvious danger with deep water, they appear able to close, and are presumably able to be cleared with force, while the entire system allows for higher performance breathing during physical activity, as well as improved airflow, particularly in Pandora's denser atmosphere, where less effort is then needed to bring air into the lungs. Again, this seems to be veering more into biology, which is actually more of my specialism than physics, but I am happy to discuss it.
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