Attack of the BA, or Why the Clone's Astronomy wasn't so bad

[PhantomWolf]

Phil, I noticed that you still have the SW:AotC up on your movie reviews on the front page. I have a couple of beefs with you Bad in it, as explained below. ;)

They are as follows.

Bad:
Someone has tampered with the Republic's archive, removing the planet Kamino, so Obi-Wan doesn't see it in the archive's map. However, the gravitational effect of the planet's star can be seen on the stars around it, which is why Obi-Wan is able to detect it. As Yoda so poetically put it, "Gravity's silhouette remains".

Good:
Well, again, scientifically this is true. Stars have gravity, and that gravity does affect all the objects around it. An advanced civilization, we can assume, could easily detect that effect. My problem with this is that the person who removed the system from the map had to have been very good (and this is even commented in the movie), and yet they forgot to change the stars around it to compensate! That's pretty sloppy on the part of the Bad Guy. Can you say "plot device"? Again, this isn't so much an astronomy error as it is a way to more easily advance the plot based on someone else's Bad Astronomy.

Explaination:
As the gravity does affect the stars about the one that was removed, even though it is is a very minor amount, had this effect been removed from the the archive maps then the other stars nearby would have now been in the wrong place, even if not more than perhaps 100 miles. However, since all ships need to know the exact position of a planet, star, asteroid field or other body to make sure that they don't accidently hit one while in hyperspace (The Star Wars version of Hypersace allows Real Space items to cast Hyperspace Shadows that are just as dangerous as their Real Space objects) this means that had the neighbouring stars, and their planets, been moved to compensate for the missing one, their positions would have been dangerously off. Such a deception would have been found very quickly because the Navcomputers would have been off target, perhaps even enough to put a ship into the planet it is travelling to. However by leaving the stars where they should be (i.e. affected by the now invisible star) they are exactly were the Navcomputer predicts and unless anyone actually looked at the map and realised that those stars were being pulled towards an empty part of space, the deception would have remained un-noticed for a long time (in fact at least ten years.)

Bad:
When Count Dooku leaves the planet Geonosis, he uses a solar sail type ship.

Good:
Solar sails are a theoretical type of spaceship, and have been used in science fiction for decades. Photons of light have no mass, but due to the peculiarity of quantum mechanics, they do have momentum. A solar sail would literally be a huge, lightweight sail (perhaps made of mylar) that can catch light. It uses the light from a star as a sort of wind, blowing the sail. A lot of the physics of solar sailing is like wind sailing on Earth's oceans! NASA is actually looking into the engineering of solar sails. They might very well make a useful method of moving through interplanetary space. You don't need to carry much fuel, since the fuel you use is raw sunlight.

However (and here at Bad Astronomy Central there is always a "however"), note that I said interplanetary space. Solar sails accelerate very slowly. It might take weeks or months to get up to a reasonable speed to move between planets. Dooku uses one to travel to another star system. I hope he's not in a hurry! It'll take decades at least to get to another star. Padme mentions that Coruscant is "halfway across the galaxy" from Geonosis, so that journey by sail would actually take thousands or even hundreds of thousands of years. Dooku better pack an in-flight snack.

For more info on solar sails, there is a webpage about the Planetary Society's solar sail project as well.

Explaination:
Dooku's Solar sail is not in fact powered by the solar winds. Here is a quote from the Star Wars Incredible Cross Sections Guide.

"The delicate reflector-surfaces of most "solar sails" unfurl to moon-like diameters, and are more commonly pushed by tachyon streams and ultraviolet lasers than sunlight. Dooku's unquie sail, however, achieves similar performance across the entire galaxy with a much smaller span and no detectable support system..."

It carries on;

"The sail is powered by an as-yet undetectable source of supralight emisions allowing Dooku's custom ship an independence, and style, unknown by any other current space-farring vehicle."

The Star Wars Fact Files state the following about the ship:

"...Dooku purchased a solar sail of unknown manufacture, which apparently powered itself through a form of supralight emission. The sail was compososed of exotic matter that allowed it to perform far better than a top-quality conventional sail of more than twice the size."

It also states that;

"For interstellar travel, Booku's sloop mounted a typical hyperdrive engine with Class 1.5 rating."

Now arguements about Supralight technology aside, the sail relies on something other than solar winds to travel with allowing it faster acceleration, and it uses a hyperdrive to travel from system to system just as any other Star Wars ship. So while the physics could indeed be argued about, perhaps their Astronomy isn't quite so bad after all.


While it doesn't excuse the other BA in the movies (stars racing past on entry to Hyperspace, sounds in space, rather dense asteroid fields, air inside the Space Slug even though its mouth was open) I do feel that in fact they might have got these two right when SW tech is taken into account.

[Glom]

Agreed on the first point. The second sounds rather babbly. But then Stars Wars is space fantasy.

[MajinBuu]

As Glom said first point is pretty good. For the second point you have to assume your audience knows nothing of "star wars science and technology." The movie gives no indication on how Dooku's ship works, and i'm pretty sure the BA is not versed in "Star Wars Technology." Even if he was, he would have to assume the audience is not.

[Glom]

It's also hard to expect BA to know the principles by which Dooku's ship works without explanation in the movie when those principles are made up.

[Wingnut Ninja]

"The delicate reflector-surfaces of most "solar sails" unfurl to moon-like diameters, and are more commonly pushed by tachyon streams and ultraviolet lasers than sunlight. Dooku's unquie sail, however, achieves similar performance across the entire galaxy with a much smaller span and no detectable support system..."


Now, it's hard to tell exactly what they mean since it's so technobabbly, but it sounds like most solar sails carry their own light source with them, like a laser that pushes the sail. That's just plain bad physics; it's like powering a sailboat by blowing into the sail. It would be possible if the laser assembly were back on a planet or a base of some sort and aimed at the spaceship from there, but they don't make it clear one way or the other.

D- for Bad Writing.

[Master258]

It's also hard to expect BA to know the principles by which Dooku's ship works without explanation in the movie when those principles are made up.
Argeed. For the BA to use it he has to go on either what's said in the movie or what it looks like. First point good though.
Sorry I sidesteped of the others.

[PhantomWolf]

It's also hard to expect BA to know the principles by which Dooku's ship works without explanation in the movie when those principles are made up.

I'm quoting Glom though everyone sort of made the same point.

The explanation part of the sail was just to throw in the "idea" of how is was supposed to "work" and I did note that the physics was debatable. ;)

The main point of contention was this part:


However (and here at Bad Astronomy Central there is always a "however"), note that I said interplanetary space. Solar sails accelerate very slowly. It might take weeks or months to get up to a reasonable speed to move between planets. Dooku uses one to travel to another star system. I hope he's not in a hurry! It'll take decades at least to get to another star. Padme mentions that Coruscant is "halfway across the galaxy" from Geonosis, so that journey by sail would actually take thousands or even hundreds of thousands of years. Dooku better pack an in-flight snack.

My arguement would be that one doesn't need to understand the ships to assume a hyperdrive. I'd note that until they Jump from Sullust to Endor in Return of the Jedi there is never any "Proof" that an X-Wing has a hyperdrive, but Luke goes from Hoth to Dagobah to Bespin in Empire Strikes back, then from Tatooine to Dagobah to Sullust in Return of the Jedi, all before any X-Wing is seen entering hyperspace. In the same way, just because we don't see Dooku's ship enter hyperspace, why should we assume that it doesn't have one? In fact the tech manuals say it does.


For interstellar travel, Booku's sloop mounted a typical hyperdrive engine with Class 1.5 rating.

I probably should have made it a bit clearer. :)

[TheGalaxyTrio]

Is it fair to trot out a tech manual?

BA in movies should be judged on what is in the movie and what is common astronomical knowledge.

Can I get a ruling here? Where's the pit boss?

[PhantomWolf]

With all respect to BA, I don't think that saying it wasn't in the movie is a good excuse. As noted above X-Wings weren't shown as being Hyperspace capable untill quite late in Return of the Jedi, yet no-one would have argued that Luke's had not travelled this way from Hoth to Dagobah to Bespin, and then later from Tatoonie to Dagbah to Sullust, all prior to seeing an X-Wing actually do it.

The Tantive IV (Leia's Corellian Blockage Runner) the ISD's and the Death Star were never shown entering Hyperspace, nor was it stated they could in A New Hope, yet again no-one would argue that they could not. Even Vader's TIE-Advanced had a hyperdrive, in fact the only ship shown that didn't the script made referance too, the TIE-Fighter.

Again in Empire Strikes back there is no shot nor referance to the Rebel Transport, the Nebulon Frigate-B, or Bobba's Slave I being able to travel through Hyperspace, such is assumed so with those in Ep 4.

Again in Phantom Mence, we see the N-1 fighter, again there is no mention of any hyperpace capability and none is shown, and yet in the opening of Clones two have accompanied the Ambassador's Ship. Are we to have assumed that these ships all travelled to Coruscant via sublight?

Time after time in this saga, ships are shown without any referance to them having hyperspace capability, yet such should be assumed. Of the two ships that DON'T have it, one is directly referanced as such (The TIE-Fighter) while nothing is said about the other (The TIE-Interceptor.)

That BA appears to have assumed that Dooku's ship didn't have Hyperdrive capability is against all of the accumulated evidence of the other ships and is, IMHO, bad in itself, which is why I think it should be fixed.

[Glom]

It's BA either way. FTL is impossible. BA's job is to point it out so that he might use it to teach good astronomy. But they made confusion by putting in those solar sails, which are inexplicable without a load of off screen technobabble that would put Voyager to shame.

[PhantomWolf]

It's BA either way. FTL is impossible. BA's job is to point it out so that he might use it to teach good astronomy. But they made confusion by putting in those solar sails, which are inexplicable without a load of off screen technobabble that would put Voyager to shame.

Actually FTL travel isn't BA. You could argue it as BP, but at the same time Hyperspaces are more than just possible in theory, IIRC they have actually passed electrons through them, and should we one day learn more about them, who knows, shunting ships through them might be very possible. Remember that in 1959 the head of NASA stated catogorically that it was impossible to put a man on the moon. Ten years later they were doing just that, and now we are looking towards the first manned mission to Mars. We learn more about Physics every day and where as today we might only be shunting electrons through Hyperspaces, this might not be so is 50 or 150 years time. Something to consider before you claim something as Impossible.

My point still stands though. The paragraph I am disputing contains little in the way of teaching about Astromony, but is merely saying that he'll take decades to get where he is going, ignoring the likelihood that just so every other ship uses hyperdrives, so would this one. This information can still be present without it being incorrect to the film, or are we only interested in accuracy when it favours our arguments?

[Glom]

Hyperspace is just a conceit to make space stories doable. Not that there's anything wrong with that.

[PhantomWolf]

Hyperspace is just a conceit to make space stories doable. Not that there's anything wrong with that.

Investigating Hyperspaces (http://www.mkaku.org/articles/hyper_sci_odyssey.shtml)

The physics of Intersellar Travel (http://www.mkaku.org/articles/physics_of_space_travel.shtml)

Small amount of info on SW Hyperdrive (http://www.starwars.com/databank/technology/hyperdrive/)

[Glom]

Investigating Hyperspaces (http://www.mkaku.org/articles/hyper_sci_odyssey.shtml)

That excellent piece refers to the other seven dimensions, which are not any use for FTL.


The physics of Intersellar Travel (http://www.mkaku.org/articles/physics_of_space_travel.shtml)

It's an interesting piece, but does little to justify the science behind SW hyperdrive. Dr. Kaku essentially admitted that we have to hope there is as of yet undiscovered scientific principles that can make FTL possible.


Small amount of info on SW Hyperdrive (http://www.starwars.com/databank/technology/hyperdrive/)

That requires that in the SW universe, there be another dimension called hyperspace allowing it. That does not currently agree with our universe.

http://www.orionsarm.com/intro/WhyNoFTL.html

It is common for scientist fans to try to justify things after the fact, but there's no escaping the fact that many of these things are conceits on behalf of the writers.

[johnwitts]

Come on Glom. 150 years ago people were being pulled around in carts by horses, and flight was for the birds. Remember, any sufficiently advanced technology will seem like magic.

[Disinfo Agent]

It's BA either way. FTL is impossible.
Is FTL possible? (http://math.ucr.edu/home/baez/physics/Relativity/SpeedOfLight/FTL.html) :)

[Glom]

Whatever upheavals may occur in science in the future, it does not mean that FTL conceits are scientifically accurate. At best, they are scientific wishful thinking.

Back to the original point, BA has every excuse for thinking that those sails were the kind of solar sails we all know and love and not those technobabbly things described. He was right to point out Dooku wouldn't get very far with that. So given the ship has other sublight propulsion that was used to get it off Geonosis and onto Courasant, we must wonder as to the purpose of the sails. We saw the ship deploy the sails and then the scene cut to the ship approaching Courasant and retracting the sails. It is only natural to expect that BA would assume the sails were there for the purpose of getting the ship between the two cuts. I assumed the same thing. If it has conventional sublight propulsion and hyperdrive, what does it need the sails for?

Where is BA anyway? I'm going to look stupid if I go to all this trouble of defending him only for him to arrive and cede the point.

[PhantomWolf]

Whatever upheavals may occur in science in the future, it does not mean that FTL conceits are scientifically accurate. At best, they are scientific wishful thinking.

Back to the original point, BA has every excuse for thinking that those sails were the kind of solar sails we all know and love and not those technobabbly things described. He was right to point out Dooku wouldn't get very far with that. So given the ship has other sublight propulsion that was used to get it off Geonosis and onto Courasant, we must wonder as to the purpose of the sails. We saw the ship deploy the sails and then the scene cut to the ship approaching Courasant and retracting the sails. It is only natural to expect that BA would assume the sails were there for the purpose of getting the ship between the two cuts. I assumed the same thing. If it has conventional sublight propulsion and hyperdrive, what does it need the sails for?

Where is BA anyway? I'm going to look stupid if I go to all this trouble of defending him only for him to arrive and cede the point.

The sails WERE sublight. Most ships have two drives, Sublight and Hyperdrives. Dooku's had onlt a Hyperdrive and used the Sail as its sublight drive. I have no major arguement with BA over the sublight part of his argument. The info on that is only avaible in deeper info not the movie. My main problem is the paragraph that ignores that the ship probably had a hyperdrive. Now by the same token, had this been about ESB and the Falcon travelling from Hoth to Bespin without its Hyperdrive, I'd be agreeing with him 100%.

[edited to add]

Glom, in the opening sence did you assume that the two N-1 fighters had travelled all the way from Naboo using sublight engines? Afterall they are never shown in any of the movies to have hyperspace capability but obviously got from Naboo to Coruscant.

[Glom]

Dooku's ship does have more conventional sublight engines and seen in the film.

Call it bad editing. From Lucas? Never!

[PhantomWolf]

Dooku's ship does have more conventional sublight engines and seen in the film.

Call it bad editing. From Lucas? Never!


Actaully it doesn't, it has basic thrusters to get into space, but they are no use for sublight travel.

[Glom]

Very well. Another thing that wasn't adequately explained. I guess the fault is BA's for trying to review something as science fiction when it has amount as much scientific value as Dark Moon. He'd be better off reviewing the science in LOTR.

[PhantomWolf]

Very well. Another thing that wasn't adequately explained. I guess the fault is BA's for trying to review something as science fiction when it has amount as much scientific value as Dark Moon. He'd be better off reviewing the science in LOTR.

Not at all, but then I guess unlike some peple here, I think that BA is only human and can make mistakes just like the rest of us mere mortals. The information I have presented is very readily available and such things do need to be taken into account. Still it seems that this is getting nowhere so....

[Glom]

The information isn't presented in the films. Secondary literature isn't considered canon.

[milli360]

unlike some peple here, I think that BA is only human and can make mistakes just like the rest of us mere mortals. The information I have presented is very readily available and such things do need to be taken into account.
I think we're all aware that the BA is human. I have his Turing test scores here in front of me. They're not as high as Mother Theresa's were, but he's got Pauly Shore beat hands down.

We all can make mistakes, but I tend to agree with glom that your second point is stretching it a little. Even the SW world explanation has a lot to be desired.

However, I want to object to your first explanation as well. In it, you say


As the gravity does affect the stars about the one that was removed, even though it is is a very minor amount, had this effect been removed from the the archive maps then the other stars nearby would have now been in the wrong place, even if not more than perhaps 100 miles. However, since all ships need to know the exact position of a planet, star, asteroid field or other body to make sure that they don't accidently hit one while in hyperspace (The Star Wars version of Hypersace allows Real Space items to cast Hyperspace Shadows that are just as dangerous as their Real Space objects) this means that had the neighbouring stars, and their planets, been moved to compensate for the missing one, their positions would have been dangerously off. Such a deception would have been found very quickly because the Navcomputers would have been off target, perhaps even enough to put a ship into the planet it is travelling to.
That explanation doesn't hold up, that that sort of deception would have been found very quickly, because of the hyperspace shadows--wouldn't the missing (from the maps) planet have also had a dangerous hyperspace shadow? And it wouldn't have been off just by a few hundred miles--it would have been off by, well, infinity. But it wasn't found so very quickly, was it?

[PhantomWolf]

That explanation doesn't hold up, that that sort of deception would have been found very quickly, because of the hyperspace shadows--wouldn't the missing (from the maps) planet have also had a dangerous hyperspace shadow? And it wouldn't have been off just by a few hundred miles--it would have been off by, well, infinity. But it wasn't found so very quickly, was it?

Only if you were actually going there. When you think about it, there are billions of stars, not including all the planets, moons, comets, asteriods and so on that fill the Galaxy, each casting a hyperspace shadow and each can do substantial damage to a ship if it hits one. Obviously no computer can keep track of every object so standard Navcomputers only have certain number of "Safe" routes programmed into them. The Pilots tend to follow those routes all the time, unless they have a reason not to (Rebel pilots and smuglers were rather notorious for overriding the safetys on theirs.) Since the routes would have been been created prior to the map tampering, those routes would have avoided the shadows there anyways even had they past through the system. Looking at map, it is actually near the edge of the Galaxy off the end of a trade route, so that means even less traffic wuld be passing through the system. However it does have a number of high profile systems nearby including Ryloth (The Twi'lek home system) and as that system is a high trade one, any incorrect positioning from the archive maps would have lead to trouble very quickly. Now since I doubt that BA has a SW universe map, or detailed knowledge of trade routes etc, there wasn't a lot of point in introducing them prior to this, however I do think tht it does show that my first point was completely valid, that removing the gravity affects of the system on its neighbours would have caused its discovery very quickly once the Navcomputers that relied on that infomation started getting their jump positions in that area wrong.

When you think about it, Obi-Wan was rather mad because he jumped into what was literially an unknown area that could have contained anything. He could have easily hit a planet or comet or something. I guess he was relying on the force. :)

[milli360]

Only if you were actually going there. When you think about it, there are billions of stars, not including all the planets, moons, comets, asteriods and so on that fill the Galaxy, each casting a hyperspace shadow and each can do substantial damage to a ship if it hits one. Obviously no computer can keep track of every object so standard Navcomputers only have certain number of "Safe" routes programmed into them.
That would make the number of necessary corrections even simpler, so the BA's point still stands, then: basically, it was a plot device. No harm in that though.

[PhantomWolf]

Only if you were actually going there. When you think about it, there are billions of stars, not including all the planets, moons, comets, asteriods and so on that fill the Galaxy, each casting a hyperspace shadow and each can do substantial damage to a ship if it hits one. Obviously no computer can keep track of every object so standard Navcomputers only have certain number of "Safe" routes programmed into them.
That would make the number of necessary corrections even simpler, so the BA's point still stands, then: basically, it was a plot device. No harm in that though.

Actually no, because when the drive updates its information and gets the corrupt data, if the positions loaded into it are wrong, then any "safe" routes into that sector are also off. When your hyperjump ended in a star instead of at the planet you aimed for, you'd get the feeling something might be wrong?

[milli360]

That would make the number of necessary corrections even simpler, so the BA's point still stands, then: basically, it was a plot device. No harm in that though.
Actually no, because when the drive updates its information and gets the corrupt data, if the positions loaded into it are wrong, then any "safe" routes into that sector are also off.
I think the BA's point was that that could have been simply compensated for, in the calculation of the safe routes. Seems to me it could have been. Of course, you can devise any number of complicating conditions--that's why the BA called it a plot device.

[PhantomWolf]

Actually no, because when the drive updates its information and gets the corrupt data, if the positions loaded into it are wrong, then any "safe" routes into that sector are also off.
I think the BA's point was that that could have been simply compensated for, in the calculation of the safe routes. Seems to me it could have been. Of course, you can devise any number of complicating conditions--that's why the BA called it a plot device.

Ooooohhh, I see what you are saying, we have been talking at cross purposes. The NavaComputer doesn't work that way (With an actual route hard programed in) but is more like the tracking devices that keep notice of all the space junk above us.

Imagine it this way. All the space junk of a reasonable size is tracked, right. NASA, ESA, RSA and others all use that data to plot safe pathways through the junk and into orbit. Because they tend to head from roughly the same spot these pathwys are pretty much always the same, but the junk moves.

Now imagine what would happen if we shifted all the tracked position of that junk two kilometers to the left. Would you be willing to launch?

[ZaphodBeeblebrox]

Now imagine what would happen if we shifted all the tracked position of that junk two kilometers to the left. Would you be willing to launch?

Two, maybe.

Twenty, uh, no.

Two Hundred, um, you're Nuts, right?

[milli360]

Ooooohhh, I see what you are saying, we have been talking at cross purposes. The NavaComputer doesn't work that way (With an actual route hard programed in) but is more like the tracking devices that keep notice of all the space junk above us.
I'll agree about the cross purposes. :)

Does the SW world also provide the details about how the missing star was detected from the gravity silhouette?

[Moose]

Just a thought about the sails...

Dooku's yacht already has sublight engines strong enough to reach escape velocity (canon), as well as a hyperdrive for intersystem travel (tech manuals and common sense), why bother with a third method of propulsion that provides no advantages over conventional methods?

What if the purpose of the sails isn't propulsion? What if it is a method of gathering "free" energy from a solar source to suppliment an otherwise smaller reactor/fuel supply?

There is precendent in canon: Tie Fighters with their more rigid solar panels.

There is also precedent in the real world: Toyota's hybrid, the Prius (Honda has an equivalent, but I don't know what it's called) which suppliments it's traditional engine through accelerations with stored and reclaimed energy.

Solar panels on a sailboat to operate the navigational equipment...

Etc.

The advantage of this hypothesis is that it is not only possible, but you don't have to posit anything new for this to work, just that you can "unfurl" (or more likely, given the shape of the sails, inflate?) a non-rigid solar panel.

[PhantomWolf]

Ooooohhh, I see what you are saying, we have been talking at cross purposes. The NavaComputer doesn't work that way (With an actual route hard programed in) but is more like the tracking devices that keep notice of all the space junk above us.
I'll agree about the cross purposes. :)

Does the SW world also provide the details about how the missing star was detected from the gravity silhouette?

They "found" it by the gravity affect on the surrounding systems then backtracking to the spurce of that effect. That's why I was saying that Obi-wan had to be brave, He jumped into a system blind, no idea where anything was. He could have easily ended up in the middle of a planet (well not really, all hyperdrives have safeties that are supposed to drop the ship out of Hyperspace to prevent that, but some over-ride them so if they mis-judge it can result in that sort of thing.)

[milli360]

Does the SW world also provide the details about how the missing star was detected from the gravity silhouette?
They "found" it by the gravity affect on the surrounding systems then backtracking to the spurce of that effect.
Right, but they furnish no details? That's the inverse problem--it's a very hard problem.

[PhantomWolf]

Does the SW world also provide the details about how the missing star was detected from the gravity silhouette?
They "found" it by the gravity affect on the surrounding systems then backtracking to the spurce of that effect.
Right, but they furnish no details? That's the inverse problem--it's a very hard problem.

Not beyond Yoda telling Obi-wan to seak out the centre of gravity, or something similar (I'd have to re-watch the scene. I think there might have been more between Obi-wan and Mace Windu in a deleted scene, but again I'd have to re-watch it.

[Irishman]

Is it a plot device? Sure. But your first point still stands. I think you make a reasonable argument for why the gravity shadow would still be evident, but nobody would be looking for it. Consider - the Navicomp does the data lookup and computations. Nobody bothers checking that the stars are where they should be. They rely on the Navicomp. So as long as the Navicomp works correctly, the database that displays a map can be altered. Because unless you're extra sharp, most people won't notice the skew to the stars in the map. So as long as the Navicomp has good data and can plot a safe route, you're fine.

Of course, that leaves the unfound method Obi-wan could have used to find the planet - checking the Navicomp computations manually, or looking at the source code and pulling a spreadsheet of the values, or some other way to pull the correct data hidden in the Navicomp files that nobody bothers to look at but must be there. ;)

The solar sail issue is questionable. Sure, that wasn't an accurate representation of a solar sail. However, as mentioned, SW is Science Fantasy. I mean, what is a lightsaber? So while it would be valid to point out that if it was supposed to represent a solar sail it had some problems, one must allow the caveat that it isn't a solar sail but some other unexplained technology (just like the lightsaber, Yoda's hover chair, the landspeeder, hyperdrive, blasters, etc. ad naseum).

[milli360]

Is it a plot device? Sure. But your first point still stands. I think you make a reasonable argument for why the gravity shadow would still be evident, but nobody would be looking for it.
I thought PhantomWolf's OP was trying to counter the BA's comments. The BA seems to admit that that's true.