Thescience fiction blockbuster "Avatar" is set on a mysterious alienmoon with out-of-this-world technologies. Its star director, James Cameron, hasnot only directed other science fiction epics like "Aliens, TheAbyss" and the first two "Terminator" films, but was apparentlythe president of his high school science club, a physics major in college andhas an engineer brother who has designed underwater robots.
Sohow much science is there in "Avatar"?
CAUTION:Possible spoilers ahead.
The movieis set on the fictional Pandora, one of the many moons of a fictional Saturn-sizedgas giant, Polyphemus, which is located in the real Alpha Centauri system,which at nearly 4.4 light-years away is the closest star system to Earth.
Whileastronomers have yet to discover moons beyond our solar system, they expectto. And the AlphaCentauri system could be a place worth looking. The larger of the two real, sunlikestars that make up this alien system, Alpha Centauri A, is the fictional Pandora'ssun. In reality, scientists might soon be able to detect habitable moons withthe James Webb Space Telescope and also study their atmospheres for keylife-related gases such as oxygen, and water vapor.
Tropicalrainforests cover most of Pandora's continents, which suggests its motherplanet must be fairly close to its sun to take advantage of its light. A fewyears ago, this might have seemed implausible, but most of the alienplanets scientists have discovered so far are in fact gas giants that areexceedingly close to their stars.
However,life on a gas giant's moon might present a host of challenges. Jupiter's moonsexist within an intense radiation belt of electrons and ions trapped in theplanet's magnetic field, and Saturn's gravitational pull leads to extraordinarytidal effects that may have once ripped apart nascent moons to produce itsrings, and today can drive winds and volcanic eruptions on its moon Titan.
Thedraw that Pandora has for humans is a naturally occurring ore dubbed"unobtanium," an old in-joke in science fiction for materials withphysically impossible qualities. (Technically, since it's a mineral, it mightbetter be called "unobtainite," but that's a pretty nerdy quibble.)Unobtanium is the best superconductor known, and apparently works at roomtemperature. Just as real-world superconductors can float in the presence of amagnetic field, mountains on Pandora apparently loaded with unobtanium canfloat in the powerful magnetic pockets that dot the moon's surface. The filmsshow these magnetic fields can interfere with technology, just as they would inreal life ? although, apparently, not whatever wireless links which allow themain characters to link with their "avatars."
Thedevices that give the film its name are avatars ? artificial bodies the maincharacters operate wirelessly by thought alone. The bodies in question resemblethe native blue-skinned humanoid race, the Na'vi, although they are hybridsthat incorporate the DNA of their operators.
Buildinga body that weaves together human and alien DNA might be far-fetched. Even ifaliens have DNA, humans would probably have more in common with corn oranything else on Earth than with life on Pandora. Still, scientists in reallife are making advance after advance when it comes to brain-computer interfacesto control robot arms and type and speak through machines. Even withoutbrain-computer interfaces, telepresence units are now allowing surgeons toperform life-saving operations from afar.
Thehumans also operate AMP suits, robotic exoskeletons that mimic their drivers'moves and give them incredible strength to handle giant cannons and fightdinosaur-sized aliens. The U.S. Army has been developing exoskeletons for yearsto amplify a soldier's strength using combustion engine-driven hydraulics thatbehave as artificial muscles.
Lifeis often huge on Pandora, with giant dragon-like flying creatures,skyscraper-high trees, and the blue-skinned Na'vi, who grow some 10 feet tall.The gravity on Pandora is said to be lower than on Earth, which probably helpsexplain why everything is so outsized there, as they have less weight draggingthem down.
Mostof the animal life on Pandora is hexapodal ? that is, six-limbed, for threepairs of either arms, legs or wings. One might expect six legs or more to bethe norm on higher gravity worlds, to help them support their weight, buthexapods make up more than half of all known living creatures on Earth ? theinsects ? so widespread hexapody falls within the realm of possibility.
TheNa'vi are tetrapods, or four-limbed just like humans are, which at first makesthem stick out like sore thumbs. Still, there are other tetrapods shown in thefilm ? their flying mounts, the banshees or ikran, possess four wings as theirlimbs. This might intriguingly suggest the Na'vi are more closely related tothese dragon-like animals than any of the land-dwellers shown in the film,although either Na'vi or banshees or both species might in fact come from ahexapodal lineage and merely shed two limbs, just as snakes got rid of theirlegs.
Apparentlyevery living organism on Pandora is bioluminescent,meaning it can produce light. Bioluminescence is also seen on Earth, withfireflies and sea algae, among others. Many of the animals seem to possess twopairs of eyes ? on Earth, insects not only have a pair of compound eyes, but anumber of simple eyes as well.
The'nostrils' of Pandoran animals are often located on their bodies instead oftheir faces, and they often have more than two. This suggests that instead ofcoupling the digestive and respiratory tracts together as humans and othertetrapods do ? which can dangerously lead to choking ? wildlife on Na'vi mayseparate these systems as insects do, which breath through holes dubbed spiracles.
Thebiggest stretch of the imagination when it comes to biology on Pandora mightactually be the Na'vi. Barring their blue skin and tails, they look remarkablyhuman, with four limbs, nostrils on their face, and an upright posture thatmight not be aptly suited for a life spent mostly in the trees. The femaleseven have breasts, even though Cameron admits they aren't placental mammals, andwe're extraordinarily lucky to find them when they are at a comparable level ofintelligence as us ? they might as easily fallen anywhere between animalsbarely capable of language to hyper-advanced cyborgs.
Still,one might forgive a little poetic license in a film that in other waysapparently tried hard to get the science right might.
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