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?
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.
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).
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.
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.
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.
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.
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.
