Lazarus wrote:I was under the impression that SW technology has plateaud, with new developments being new applications of already established technology, or scaling up of technology?
Size matters. In the Death Star, the Empire was trying a lot things on a scale that had never been successfully implemented before. The thickness of the shield is really enormous, even by planetary shield standards. Since technology is rarely
precisely scalable, misbehavior in the techonology is sure to crop up on groundbreaking projects like the DS I, as well as overlooked details (like that dang thermal vent!).
Regardless, I fail to see how these shields could be impervious to capital ships, but not to fighters?
Again, size matters. Stress induced by a particular shield may be fatal on the size scale of capital ships, but survivable (if not gentle) on the scale of small, one-man fighters.
Taking your measurements to be reasonably accurate, I fail to see how this thickness changes the situation?
The thickness is important because of the greatly increased scale of what they were doing. Remember, technology is rarely precisely scalable. It may be that when the Empire scaled up a planetary defense system to the thickness of the DS's shields, they discovered that the technology started to misbehave, but the engineers did not consider the misbehavior serious in the face of the DS's mission, so they didn't spend the time or green on correcting it. (Or maybe the misbehavior was predicted well in advance, but considered not worth the effort to correct. Either way, it didn't get done.)
I agree that your theory about there being gaps due to such a great thickness is not illogical, but where is the flaw in the idea that the shield had been left up at navigational strength since reversion from hyperspace? This would easily explain the buffeting the fighters experienced, as they slipped through the shield due to their shields being stronger than the particular point where they were passing through the shield.
I'm not claiming that the DS's shields were or were not at navigational levels. I simply stated that the shields were at a sufficiently low level that a starfighter could punch through it with its systems and pilot reasonably intact if its shields were powered double-front.
As to why I introduced shield thicknesses in the first place, it was to show that the average speed of the starfighters at the time were on the same order as the "effective sublight speed" as incoming interstellar gas and dust when the DS is traveling at hyperspeed, and therefore the kinetic energies of the starfighter particles are on the same order as the gas in dust. Without knowing how shields work, we cannot know if shields interact with matter because they are traveling at some relative velocity (which may be superluminous), or they interact because the matter has some characteristic ratio of kinetic energy/rest energy associated with its motion (which is a monotonic function of relative velocity). Real world physics says that energy is a stronger determiner of whether things happen than speed.
Why do we have to revert to the holes theory?
I don't think there are holes left in the DS I's shields on purpose, not with that overpowered reactor of theirs. If there are holes at all, the abovestated misbehavior in the DS's shield is the most likely culprit.
Wyrm wrote:
I think "hole in the shield" neatly encapsulates the meaning of "places in the shield that are substantially weaker than other parts."
No, it doesn't. For example, a given wall is a foot thick. At one point there is a hole through it, such that you can reach through to the other side. At another point the wall is only half a foot thick, but despite this, you still cannot pass objects through the wall at this point. Are these two points the same? Nope. The interference zones are referred to as being 20% reductions in power, not holes. There is a distinct difference. I fail to see how you could become confused between these two situations, as they are quite clearly different.
Bad analogy. You're describing a shield that is
thin in some places, instead of an interference zone. Remember, we are considering that the DS's shields are made out of plates that are full thickness, but (in your description) because they overlap, there is a volume extending all the way through the shield that is weak compared to the rest of the shield. If it's 20% weaker, it's because the shielding effects are uniformly 20% weaker over this entire volume, not because it is zero until you penetrate 20% of it, and then suddenly it's up to full strength. A better one would be a wall that's oak in some places and cork in others.
This interference zone thing was introduced by Spartan. However, I don't know where you're getting this 20% reduction in power figure. If the mismatch between two sections of a shield is particularly bad, there can be
total destructive interference, which would result in 0% power. That's certainly a 'hole' in the shield in anyone's book.
Finally, consider that fields rarely have sharply defined boundaries. This means that, even though the volumes where the shield is considered to be "full strength" don't overlap, edge effects might cause the field of the shields to bleed over into the supposed 'gap'. We'd still call the gap a 'hole', even though it's filled somewhat with shielding effects.
Now, the above problems with shield-on-shield interference and shielding gaps are mere speculation, but if true, I imagine them to be well-known and have ready solutions for the shield configurations used in planetary defense. This is why such shields are able to trap starfighters. Four years later, the DS II had either solved the problems of the DS I, or the Death Star Project Shield Development Team had fallen back to shield configurations they could readily solve all of the development problems in the alloted time and budget. In the DS I, they were apparently trying something that they hadn't quite worked the bugs out yet, but the bugs where not thought to be serious. (They were.)
Wyrm, I agree with your analysis of possible one way shields, if I understand it correctly!
If you understand what a "perfect engine" is, why they're not allowed, and why the apparatus I described is a perfect engine, then you understand the thermodynamic argument.
An example of this could be from HttE, where hangar bay shields are dropped to allow the TIE fighters through, because if they were left up, then some considerable harm would befall the ships pilots.
That would fall under "meat safety", I think.
However, throughout the series the Chimaera fires its weapons whilst its shields are up, and this state of affairs is continued through every instance of space combat I can think of. Random example-the attack on the Lusankya in The Bacta War: the Lusankya's shields are up, however it is described as firing waves of turbolaser and iron cannon blasts towards the attacking craft.
As opposed to bronze cannons?
If there were independant shields for each weapon, which would be dropped as the weapon fired, then there would be some sort of patchwork of shields in operation. This is clearly not the case, as the Lusankya's shields are said to consist of 6 individual shields: Forward, Aft, Port, Starboard, Dorsal, Ventral.
I'll buy that argument.
The book also describes ray shields:
'Ray shields will absorb blasts from laser cannons, turbolasers and other energy weapons. Since these shields consume a tremendous amount of energy, they are raised only when battle is imminent. Shield energy permeates the ship's hull and wraps the vessel in layers of energy that may extend anywhere from a few millimetres to several centimetres away from the hull.
Well, it's wrong. The Gungan shields in TPM were ray shields (that's why the TF droid army had to resort to stepping
through it to attack the Gungans, remember?), yet the large amazilla-mounted generated shields had a
bubble structure. Movie trumps everything.
Wyrm's hugely thick shield theory was based on the idea that the 'magnetic field' was a shield of some sort. The description of shields above suggests otherwise, coupled with the fact that the turbulence begins a short while before any reference is made to the field, and the order given to switch deflectors on. I say again, the fighters did NOT have their shields up as they went into the field. If it was a particle shield, this would obviously have been suicidal.
You do know I was coordinating the events as described in Connor's reference (ANH novel, Page 189) with the events on the screen, do you not? Also, you do know that most fields are continuous over space, so the shield wouldn't reach its full strenth and ship-frying effectiveness immediately? The shield starts buffeting starfighters at around 2200 km (the outer echelons), but would not be at the level where it would cause serious damage quite yet. This is part of the "edge effects" I described earlier.
NRS Guardian wrote:The way I see particle shields is they're rather like a protective atmosphere where it's thickest at the surface and grows more difuse as distance from the surface increases, however the greater the depth the stronger it is at the surface and the more volume there is to stop stuff. Also the more power is put into the shield the thicker the field is, so by decreasing power the field can be made thinner and more easily penetrated. Thus by lowering the energy the field is thinned allowing stuff to more easily approach and enter. In additon while it's thickest at the surface the closer you are to the hull the less shield you have to go through to get at the hull. Also, like an atmosphere if you hit it at a great enough speed or steep enough angle you're going to be stopped by it, however the thinner it is the faster and steeper you can go through it. Thus probably what people in-universe mean when they talk about holes is that at a reasonable speed you can penetrate the shield while not having to worry about missiles or fighters coming at your "unprotected hull" at fractions of c. Especially considering you "lower" your shields to allow fighters and missiles to launch and fighters to come aboard, all relatively low speed events.
Remember the afforementioned Wedge's Gamble? That had shield layers. So, how does this mechanism give shield configurations with this kind of internal structure?
EDIT: Clarified which of the honorable Sen. MacLeod's references I was refering to.
My bad for misassigning credit to Spartan.
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