P.S. I am not a physics major holding any degree. This is all merely based on some observations and my general knowledge of science. You have been warned.
So basically, after spending many hours watching the show just marveling over how culturally East Asian/South East Asian/Inuit the show is, I managed to get beyond this to find a very great show. I started to find characters I like, favorite episodes, ect. But then another megaton hit me...
I started to watch the entire show more closely about the art of bending. The history of it, how it works, ect. Then, combined with the Scrolls about how bending works and the Show Bible that proved this postulate...
All of the bending of elements are scientifically sound!
In fact, this is one of the few franchises besides Harry Potter and the Matrix where the fantasy elements are very grounded in reality. Ergo, it does not violate any laws of physics and everything has an easy scientific explanation, unlike such things as Star War's Lightsabers and Repulsortech.
It all starts with that the Show Bible clearly states that there is no "magic" in the world and the only fantasy elements are the creatures, bending and Spirit World. No teleporation, no ki-blasts, no magic flying, ect.
It also continued with the way Firebending is explained by Mike and Brian (which I will get to in a minute) and this whole thing is fuled by one thing: That M. Night has no idea how bending works and is doing it wrong in the movie.
==HOW BENDING WORKS==
There is an old saying in Science:
"You don't see things, you see light bouncing off of things"
Ergo, you don't actually see an object, what you are seeing is a representation of an object vial the light reflecting off it's surface. It's a common thing in science to expect common intuition to only be a half truth, with an ironic and often disturbing meaning behind it.
Well that is when it hit me:
"Characters don't bend elements, they bend forces that create/control said element."
This is why it's called bending. They are not magically conjuring fire, water, wind or earth. Instead they are manipulating a core aspect of that natural force to make the properties of that matter work for their bidding.
It also makes sense when you understand the history of bending. Before the current bending system, people practiced a base form called Energybending. They basically could manipulate some core aspect of the universe (Strings, Quarks, Quantums, Chi, P-Branes or what have you) to directly manipulate the matter of objects. The main use of this was to "hack" each other so they could pass down or remove skills/traits/memories and the like.
The thing about Energybending is that since you are manipulating the direct physic of that property that it's labor extensive and requires a lot of focus. Look at Katara's healing, a possible remnant of such a system where it completely drains her, she can only do so much with it and has to use another form of matter (water) to preform the energy transfer.
So naturally, bending had to evolve.
Two simple things happened:
One, is that the science of their world expanded, allowing them to understand the direct properties around them.
Two, is that because of this, they simply specialized. Instead of slowly wasting energy trying to directly manipulate one form of matter, you could waste less energy simply making minor edits to naturally occurring properties that directly influence matter.
In short, the people of Avatar end up specializing into various manipulation forms and it has served them well for so long that the old techniques of Energybending have been mostly forgotten.
So with that said, lets go into what the benders actually bend.
Bending Property: Atmospheric Pressure.
Explanation: Basically, when Aang is bending he is NOT directly move gasses around. What he is doing is increasing or decreasing the mass of other gasses so that the gasses around them move in the direction he wants.
Note how when he wants an object to move towards him, he does not simply make a "come here" gesture like a telekinetic would, but instead uses a motion simulating suction of space. What Aang is theoretically doing is removing the pressure in front of the object so the object moves forward aka wind pushing from behind.
Similar to Aang moving away objects, his arm waves and kicks remove the pressure outside of the object's range and thus the air rushes in to fill the void and thus...you have Zuko flying into a rock behind him.
Properties: Airbenders are the best in high altitudes because there is lower pressure up there so manipulating pressure is easier to do, and can create massive wind changes and turbulence. It also has less oxygen which would make the Fire Nation hard to attack. Also note the opposite, Aang has a harder time bending Air underwater since the pressure is too great. This will also come to play later in the Firebending Section about Combustion Man.
Bending Property: Electromagnetism
Explanation: Anyone can be a water bender in real life. Here is a trick that I love to show kids who are fans of the show:
Take a comb. Now run it through your hair really fast for about five to ten minutes. Then turn on your sink's water and hold the comb near the water flow but not enough so that they touch.
The water flow will actually BEND towards the comb! CONGRATULATIONS YOU GRADUATED FROM THE SCHOOL OF PAKKU! Why do you ask?
Because what you did was electromagnetically charge the comb by using the friction of the comb through you hair. This is also theoretically how the Water Benders manipulate water. Not by combing their hair, but by creating electromagnetic fields and currents that redirect the electron flow of the atoms in water and thus moving volumes of water. This is further supported that only in the North and South pole water freezes, they do not affect the state of the water but only it's electron flow.
Considering that the Water Tribes learned Water Bending from the moon, which bends water due to electromagnetic gravitational pull of the tides, this is one of the strongest sciences behind any of the bending on the show.
Lightning Redirection: It also is why I was not surprised that in the second season, Iroh's method of redirection of lightning was based on him studying the methods of water bending. Since Water Bending movements and philosophy is about controlling electric currents and fields, it makes sense that redirecting a high voltage electric current could only be possible by using Water Bending techniques.
Bending Property: Atomic Structure and Mass
Explanation: Earthbenders rearrange the electrons in Atoms so that their structure changes. They seem to only do this to solid structures, but theoretically a master Earth bender could use this to change a property's element. Also, no wonder a scientist would be an Earth Kingdom native since they would also be potential master alchemists.
When one bends earth, they never bend earth into odd shaped structures. All structures that earth benders build on the show are structures that would be natural to said property. Rocks come out in slabs and chunks, not into perfectly round circles or trapezoids. Hell even when Toph sandbends (sandbending has a special note since sand can be manipulated by electrostatic properties and thus why it's also part waterbending movements) the map of Ba Sing Se, all the buildings and statues are rough geometric outlines instead of highly detailed smooth figures.
Metal Bending: Metal is a refined element. When you refine basic elements into a compound (NOT A MIXTURE) you get this unnatural property. Earthbenders seem to only be able to bend base solid elements so when they become refined compounds, the Earthbender cannot "lock" onto the individual elements and thus cannot bend the material. Hence why it's no surprise that Toph can metal bend because of the unrefined particles inherited in refined compounds and ironically, ULTRA SOUND is how one detects unrefined particles in a solid compound.
This also explains why Earth Benders NEED to be directly connected to the element they are manipulating and, much like how Gekkos can manipulate electrons in atoms to stick onto flat surfaces, Earthbenders can adhere to walls.
Bending Property: Thermodynamics
Firebenders manipulate Thermodynamics. They can basically transfer heat from one source to another. The way a firebender creates fire is by drawing and/or magnifying their local heat source to high temperatures. This can be their own body heat (which will exhaust them) or from external heat sources like other people's body temperature, atmospheric temperature, the sun, comets, ect.
By super-heating the air around them, it rapidly oxidizes the other air particles (mainly nitrogen, methane and other compounds) and uses the surrounding oxygen as a fuel source. This is very different than "Pyrokinesis" which is what M. Night and fans claim...who are very wrong. Pyrokinesis would mean that the Firebenders can literally conjure fire when ever they please. They would not be affected by water, temperature or low oxygen/air pressure and thus they would not have to use a passing low orbiting comet as a large heat source to overpower the Air Nomads. In fact, if they were Pyrokinetic, they would be virtually unstoppable compared to the rest of the bending arts and would violate all the physics rules that are in said arts.
This is proof because a pyrokinetic would be able to keep fire in a sustained environment without worry of the fire dissipating/snuffing out and would be able to form it into various shapes ala Voldemort in the Order of the Phoenix movie. They would also be totally immune to any kind of burning (aka no Zuko's scar) and would directly produce it from their bodies. If you watch the show, fire has a air of separation between the bender and the user, because the fire is created externally from the user's self. The fire, unless it hits an object also dissipates once it reaches a certain distance just like real fire does in air. Meaning they simply create fire naturally rather than directly manipulating the element.
This explains many things. For one thing, it explains why Firebenders can heat up objects without creating flame such as when Iroh burns the Earth Mercenary with his shackle...he was simply transferring one heat source (body temperature/air) to the metal shackle and since most metals are perfect heat conductors they burn very easily. This also explains why their weaknesses is lack of heat sources (Eclipses/Night/Rain/ect) and also why the Boiling Rock's prison's Freeze Chambers are so damaging to Fire Benders. They remove all the available heat sources and thus they cannot bend any thermal around them.
Lightning Generation: While the exact nature of how lightning created is unknown, what is known is that it involves either super heating or super cooling of the air, something a thermal energy manipulator like a Fire Bender can do. It also involves water vapor and it involves ionization of air particles. The theory is that Firebenders can either super heat or super cool (maybe both, very rapidly) the air around them to ionize the air around them, thus forming an electric current. The current then can be aimed by directing the electromagnetic flow to the target depending via the one with the most positive charge.
Combustion Man: His abilities are based on that he can superheat air to such an degree that no other firebender has reached. He also seem to only be able to do this at one specific concentrated location in space as oppose to a wide area. He simply super heats air particles so much that he causes them to expand rapidly creating his infamous explosions. Such a high level of expansion means that even someone as powerful as Aang cannot create air pressure strong enough to deflect it and thus Aang can only doge it. Maybe in the Avatar state he could, who knows!
The point is not only to show how much thought was put into the bending (consciously or subconsciously who knows) but also how M. Night is simply getting it wrong. With this kind of logic layout, all his statements about bending and in particular Fire Bending are all wrong!
There is no need to make the bending more "grounded", it already is very scientifically grounded! There is no reason, with the way firebending is in this framework, to gimp them by only using existing sources. They manipulate the properties that control elements, NOT magically the element them self's which seems to be the case in the film. It also shows that the Martial Art forms from the original were prefect (Tai-Chi = Current Flow, Baqua = Push and Pull, Hun Gar = Rooted Geometric, Northern Shaolin = Kenetic Energetic) and thus M. Night has no idea what he is doing with the forms. His claim of trying to ground things such as the bending, culture, ect has no basis since most of the show is pretty grounded and thought out anyhow.
In short, if M. Night cant take five minutes like I did to figure this out...and that he is obviously knows no basic anthropology...how can we trust him to get any other aspect of the show he is adapting right?