Bad and good science in Avatar!

[Tsyal Maktoyu]

No, but I wonder if any EMF emissions from Eywa can interfere with nearby electronic equipment, like how such interference can come from electronics. Maybe a cell tower wasn't the best example, maybe something more like a microwave to a pacemaker. Or a constant, low level EMP. Not enough to destroy electronics (that kind of power would kill Eywa and any creatures attached), but enough to muddle flight electronics and tracking systems.

[Irtaviš Ačankif]

As I have said, Eywa does not EMIT anything. A microwave emits microwaves, but Eywa just sends signals around well-insulated cables.

What I meant is that something like a network will not interfere your instruments. Did your TV get static because of a wired LAN? Wireless might cause problems, but Eywa is fully wired.

By the way, why are we talking about Eywa as if it were a device?

[Tsyal Maktoyu]

Of course Eywa does not transmit anything wirelessly (sans phermones and the like) on purpose, but EMF eminating from the electrical circuitry of the neural network can still be there. Microwaves themselves stay within the cooking chamber, but EMF from the device can still effect nearby equipment. Here's another example, you ever use an appliance next to...say, a television, and gotten static? That's what I mean. Of course, if the electroneural network is sufficiently insulated, like while in the soil and in regular trees, it wouldn't be a problem, but special trees like the ToV or ToS likely have noticable EMF fields. Biological life would not be hurt by it (like how people are not hurt by EMF, or even EMP), and the current would be low enough for Na'vi to use safely, but navigational equipment would be effected in the vicinity of it. Though it would be interesting to see if the uninsulated queue of Na'vi are effected by the EMF around these trees. Maybe that is why we hear "ghostly" sounds around these trees, even before the Na'vi make tsaheylu.

[Eyawng te Klltepayu]

Nice to see so many ISV Venture Star fans here!


http://www.projectrho.com/rocket/realdesigns.php#avatar


James Cameron will be making a little jaunt of his own soon- he has reputedly laid down $150mn for a flight around the moon!

[Clarke]

As the magnetic field lines are radiating away from the magnet, I actually am more inclined to believe that inverse square is more correct. Therefore, write this down: the magnetic field strength at the Tree of Souls is 9,600 Teslas.

But there isn't such a thing as a magnetic monopole. Since the magnetic source is a dipole, then one end (hopefully the closer end) will be repelling the mountain, but the other end will be attracting it. I simplified things by using only 1 dimension,  and ended up having to combine fractions sitting over r² and (r+d)². (d's the distance between the poles.) And that gives a fraction over r²(r+d)² = d²r²+2dr³+r⁴.
I'll let you work out what B_ground is. It's not pretty.  

screw realism. we have floating mountains.

Look down.  

[Irtaviš Ačankif]

Sorry, you are wrong. Since the mountain is made of a superconductor, it will be repelled no matter which end of the magnet you point at it. This is not about attracting ferrous substances.

The magnetic pressure is direction-agnostic: just take the magnitude of the mag field at the location of the mountain and don't worry about its polarity.

[Ean Hufwetulyu]

this is very good. i have started doing research for my masters' thesis over of these issues.

[Clarke]

Sorry, you are wrong. Since the mountain is made of a superconductor, it will be repelled no matter which end of the magnet you point at it. This is not about attracting ferrous substances.

The magnetic pressure is direction-agnostic: just take the magnitude of the mag field at the location of the mountain and don't worry about its polarity.

Magnetic pressure is unsigned, sure, but the whole reason you've got pressure in the first place is because of the potential energy field around the magnet, and that potential energy will drop off really quickly if the force drops off as fast as r⁴. (F=dV/ds, after all.) The Meissner effect can't do magic; it still needs a magnetic field to work on.

this is very good. i have started doing research for my masters' thesis over of these issues.

What's your thesis on? 

[Ftxavanga Txe′lan]

this is very good. i have started doing research for my masters' thesis over of these issues.

What's your thesis on? 

I'd be interested in knowing this, too.

[Ean Hufwetulyu]

The science and princple behind the link chamber, the avatar bodies, and how the drivers are able to operate the bodies. I figured that the brain can emit a certain fequency and can be piggy back on a wavelenght to other body. (sorry for misspelling in a hurry)

[Ftxavanga Txe′lan]

Sounds really fascinating!

[Ean Hufwetulyu]

Irayo

[Irtaviš Ačankif]

Thank you. I'd be doing a re-calculation of the force today. Stay tuned!

Eywa ngahu!

[Irtaviš Ačankif]

B_ground = 94,400,000 Teslas

Now that is big!

Concerning the emf questions, let me put it this way. Your power line creates minimal interference on your TV, right? This means that the current must be above a few amperes to create interference. Let's say that the current is 10 A. Would the Na'vi survive such a shock? Humans won't, of course. Perhaps the Na'vi nervous system is sufficiently insulated to prevent electric shocks.

By the way, I am thinking of Quaritch making a Tsaheylu Interference Machine that will make the Na'vi lose control of there ayikran and such. That would be a very effective weapon.

[Human No More]

Admittedly, the tides is something I don't know much about, so I can't comment much there, although I would suggest Pandora's orbital distance is sufficient to make it less strong than it may seem.

On the complaint about the technology, I would say skxawng is all too apt though (why do people name themselves with a fairly serious insult? ).

The Technology of RDA and the Atmosphere of Pandora - BAD!

In the beginning of the movie we see the RDA shuttle zooming down to Pandora. Hey, that is not supposed to be the way shuttles re-enter! Doing so would create a disaster similar to that of Space Shuttle Colombia - tens of "fresh meat" and super-expensive Avatars burning up in the atmosphere and evaporating into vapor that's probably gonna end up in some Toruk. Several seconds later we see the shuttle land - no re-entry protection tiles AND no charring of the aircraft! Wow...are the shuttles made of pure refined unobtanium?

Not true. The underside of the shuttle looks similar to modern tiles actually. The entire structure is a heat-resistant composite material. Unobtainium is a superconductor.
We don't see any actual atmospheric entry - passing through a cloudbank is not re-entry. The shuttle was acting partly as a glider during that phase, then switches to vertical over time as it approaches to save power.

The exo-pack thingy cleaning the air of toxins including the infamous hydrogen sulfide is also pretty skxawng. Sure, it will prevent hydrogen sulfide poisoning through breathing, but how about severe skin irritation? I don't want to take a walk on Pandora only to find my skin burned like a 2-hour sunburn from neck to toes.

H2S doesn't enter through the skin particularly well - it can cause skin irritation in its liquid form, but the level that might pass through the skin while as a gas is lower and could conceivably be countered by development of a drug which protects against a low amount, but not the lethal concentration encountered by breathing it. A filter removing H2S is perfectly plausible, and for CO2 even more so  as that would just be a miniaturised CO2 scrubber.

The Samson helicopters are also pretty bad designed. If the rotors tilt forward, yes, the helicopter will follow and tilt forward as well, but it wouldn't stop. The 'copter would just go in somersaults forward. I don't see Trudy leveling out the rotors when the helicopter starts going forward - it stays in the pointing-ahead configuration.

That's how all helicopters work. Vertical lift actually needs more power than when moving forwards because rotors are aerofoils, much like aircraft wings. The tail rotor in single rotor helicopters is only to stop them from spinning, and can even be absent in dual-rotor helicopters extant today (e.g. Chinook and Ka-50). If you level the rotors in ANY helicopter, it will stop given time as friction slows it. They tilt forwards to move, which also increases lift.

Hell's Gate has some bad science too. For example, the pressure inside is clearly higher than outside - when Quaritch yells "Mask on!" and kicks open the door, air just blasts out of the complex. Of course, this can be explained since Pandora's atmosphere has a lower pressure than that of Earth, but are those RDA guys skxawng enough to try to maintain a perfectly standard Earth atmosphere at 101.3 kPa inside Hell's Gate? Why don't just filter out the carbon dioxide and hydrogen sulfide and leave the ~80 kPa nitrogen/oxygen/xenon atmosphere as it is? Additionally, having a pressure differential means that a small scratch on a window will make it explode AND that people exiting Hell's Gate would suddenly have their ears pop quite violently.

So small damage doesn't cause the external air to rush in or exchange. Look in the battle when Trudy and Quaritch's helicopters both take bullet damage without needing exopacks to be used. A small pressure differential is easily survivable for humans (larger ones are internally equalised when flying in an aeroplane), especially with the airlocks for normal travel in and out. A window will not explode just because there is a slightly higher pressure inside, especially not when they are CLEARLY reinforced.

[Human No More]

The floating mountains of Pandora float apparently because of the strong magnetic field levitating them. A magnetic field strong enough to levitate mountain-sized superconductors (assuming they are pure unobtanium) should be strong enough to suck all of the RDA machinery to the Tree of Souls. The enormous magnetic flux that would be generated by moving would mess up with people's brains and nervous systems, making them a hallucinating skxawng at least and a corpse arcing on itself with 100-amp electric currents at most.

Not necessarily - neither do they have to be pure. You're assuming unobtainium follows currently extant superconductors - Unobtainium is clearly an excellent superconductor with its application on Earth - lifting the mountains is not an issue.

However, maybe unobtanium has an extremely low density and floats by itself...think of a rock that is lighter than air...?

No. Magnetic fields also do not kill humans like some people have previously believed (even JC made this mistake himself in one interview).

By the way, don't get offended by the "skxawng"s. I am practicing using a Na'vi word every post, and "skxawng" seems to be the easiest to use. Another thing, did you notice that in the movie, Jake pronounced "skxawng" without the ejective, like "skawng"?

Yes. He also made a mistake in its definition - it does not mean 'moron' - that is a human analogy. It's a lot more insulting than that, it means "one who does not See".

Superconductors do not interact with each other, certainly - but nobody ever suggested that. We were talking about Pandora's normal magnetic field. AFAIK, the Meissner effect is not fixed based on field strength for all known superconductors - even before Unobtainium's properties make it a unique one.

I have pointed out logical and other flaws in MANY arguments against Avatar, here is a (very) small selection: http://www.tree-of-souls.com/general_avatar_discussion/4176-my_open_email_intuitor.html

[Toruk Makto]

The cannon definition of skxawng per Dr. Frommer is "moron, idiot".

[Irtaviš Ačankif]

The floating mountains of Pandora float apparently because of the strong magnetic field levitating them. A magnetic field strong enough to levitate mountain-sized superconductors (assuming they are pure unobtanium) should be strong enough to suck all of the RDA machinery to the Tree of Souls. The enormous magnetic flux that would be generated by moving would mess up with people's brains and nervous systems, making them a hallucinating skxawng at least and a corpse arcing on itself with 100-amp electric currents at most.

Not necessarily - neither do they have to be pure. You're assuming unobtainium follows currently extant superconductors - Unobtainium is clearly an excellent superconductor with its application on Earth - lifting the mountains is not an issue.

However, maybe unobtanium has an extremely low density and floats by itself...think of a rock that is lighter than air...?

No. Magnetic fields also do not kill humans like some people have previously believed (even JC made this mistake himself in one interview).

By the way, don't get offended by the "skxawng"s. I am practicing using a Na'vi word every post, and "skxawng" seems to be the easiest to use. Another thing, did you notice that in the movie, Jake pronounced "skxawng" without the ejective, like "skawng"?

Yes. He also made a mistake in its definition - it does not mean 'moron' - that is a human analogy. It's a lot more insulting than that, it means "one who does not See".

Superconductors do not interact with each other, certainly - but nobody ever suggested that. We were talking about Pandora's normal magnetic field. AFAIK, the Meissner effect is not fixed based on field strength for all known superconductors - even before Unobtainium's properties make it a unique one.

I have pointed out logical and other flaws in MANY arguments against Avatar, here is a (very) small selection: http://www.tree-of-souls.com/general_avatar_discussion/4176-my_open_email_intuitor.html

No. Superconductors are superconductors, and anything that has a resistivity of zero HAS to follow the equations. Unless, of coure, it has a negative resistivity, which would violate the First Law of Thermodynamics. There is no such thing as an "excellent" superconductor, by definition superconductors' R is exactly 0. Is there a more perfect zero and a less perfect zero? The only reason why unobtanium is so valuable is because it is a ROOM TEMPERATURE superconductor.

Have you read the thread, HNM? The magnetic field is much larger than imagined by JC & C. Yes, sure, a hundred-tesla magnetic field would be relatively harmless. But how about 94,400,000 Teslas? I admit that I have made much mistakes in my first post - read the thread! Somebody actually gave me karma for this! 

As for the skxawng thing, do note that a very notable person on this board has his full name as such: "Skxawng." Additionally, I believe that since "Neytiri called [Jake] a skxawng" it won't be an extremely severe insult. An example of a severe insult would be nì'ul kame tskxe or (my invention) oel ngati kamänge.

Additionally, I am not insulting Avatar. I am an Avatar fan like you all are. However, maybe Avatar the film is just a big propaganda film from the Na'vi who want us to believe that they are sinless, their world is pure, and that humans should go away. Who knows? 

[Clarke]

Bground = 94,400,000 Teslas
Now that is big!

...Resulting in a field energy density of 7 x 10¹² GJ/m³. Lead has a density of 1 x 10¹² GJ/m³. Remember what I said about not Death Star'ing Pandora?  

By the way, I am thinking of Quaritch making a Tsaheylu Interference Machine that will make the Na'vi lose control of there ayikran and such. That would be a very effective weapon.

There are probably more effective weapons, if we're allowed to not stick to 21st century firearms. IMO, the most effective would be microwave laser beams. Instantaneous, invisible, completely accurate over long distances, and carbon-fibre bones don't help when bits of you start boiling off.

Not necessarily - neither do they have to be pure. You're assuming unobtainium follows currently extant superconductors - Unobtainium is clearly an excellent superconductor with its application on Earth - lifting the mountains is not an issue.

Ye cannae break the laws o' physics, Cap'm! You can't have a better-than-perfect conductor!

No. Magnetic fields also do not kill humans like some people have previously believed (even JC made this mistake himself in one interview).

They do when the magnetic field in question is measured in kilotesla. Water is diamagnetic, after all. If you expose a human to a 1kT magnetic field, it will probably just explode. (Go directly to Eywa, do not pass Go, do not collect 200 [million] dollars.  ) The magnetic fields required support mountains appear to be measured in megatesla. At that point, we might as well be using Nikola spinning in his grave as the power source.  

Superconductors do not interact with each other, certainly - but nobody ever suggested that. We were talking about Pandora's normal magnetic field. AFAIK, the Meissner effect is not fixed based on field strength for all known superconductors - even before Unobtainium's properties make it a unique one.

The Meissner effect is based on excluding a standing magnetic field, and AFAIK, will fail at high enough stresses. Pandora's natural magnetic field is simply not strong enough to suspend a whole mountain on.

I have pointed out logical and other flaws in MANY arguments against Avatar, here is a (very) small selection: http://www.tree-of-souls.com/general_avatar_discussion/4176-my_open_email_intuitor.html

I read that, and you're wrong on several points. However, I won't drag them over here unless you want me to, since it's a very long post, and most people here read ToS anyway, apart from one idea that really grates me as a physicist:

The Venture Star cannot be fueled by anything other than James Cameron's burning money. The VS is apparently fueled by antimatter; fair enough, that's in the Valkyrie-class design, and theoretically works. What doesn't make any sense is Unobtanium being more expensive than that antimatter. Unless something really bizarre comes up in the next 140 years of physics, (like violation of conservation-of-energy bizarre) Unobtanium antimatter must be the most expensive substance to manufacture, since you must put in 100% of its energy content yourself. No normal-matter substance requires that. Even worse, you say that Unobtanium is a compound, which means I don't even have to construct the atoms myself, which gets rid of 99.999% of the energy cost. (Probably more. I could do the math if you want me to.) I only have to arrange existing elements into a specific shape, and that is trivial compared to the production and storage of even anti-hydrogen. Not to mention orders of magnitude less dangerous.

[Irtaviš Ačankif]

But anyway, I still LOVE Pandora and Avatar! 

Any equation on measuring the force on a diamagnetic substance like water at a given magnetic field strength? I suppose that some sort of diamagnetic constant would be involved...