Part: One Two Three Four Five
1. Scale Differences
It is worth noting that there is an incredible difference in the scale of the events being discussed, which we can roughly separate into three classes.
a. Planetary scale - In the case of Alderaan, we're talking about a ~12,000 kilometer wide object with a volume of 1E21m³.
b. Death Star scale - The second Death Star, at 160 kilometers in width, would (if completed) have a volume of ~~2.144E15, which is a value over 100,000 times smaller than Alderaan. The first Death Star is smaller still.
c. Starship scale - The exact volumes of the Calamari ships are not known, but should fall in the range of millions or tens of millions of cubic meters (i.e. in the range of 1E6 or 1E7m³). The larger of the two values is still about 90,000,000 times smaller than even the first Death Star.
Thus, the difference between the smallest object and the largest is a factor of about 100 trillion by volume, and about 12,000 by simple length. That said, the fact that there are any correlations at all between the various size classes is striking . . . it's like comparing the impact of billiard balls to that of asteroids. The rules are the same, but the game can play out much differently from the observer's perspective.
It is unfortunate that there are no other observed planetary-scale events, since the DS2's intended destruction of Endor was cancelled. Alderaan is thus quite a unique event for its size. Nevertheless, we can anticipate from the above that the events of each scale should be at least roughly similar to one another, and that Death Star scale events should probably be more similar to the Alderaan events than the ship-killer shots.
(Happily, this is indeed observed in reference to the planar effects. The planetary-scale and DS-scale events all show well-formed ring structures, whereas the starship-scale events show planar effects that are less well-ordered.)
2. Same-Scale Variations
There are also variations within the scales.
DS1 showed a ring with a bright outer boundary, dimmer trailing edge, and a trailing ring. The DS1 main ring also evaporated. DS2 showed a much denser single ring and no evaporation. On starship scales, the Liberty showed a primary explosion at beam impact followed by a sudden planar blast that was luminous and opaque and debris-laden, whereas the smaller Wingless just seemed to poof into planar nothingness. There are several possibilities regarding the variations.
For instance, we could take the Liberty & Wingless example and conclude that a similar-yield effect occurred in both cases. After all, we already knew from comparison to nearby starships (especially Rebel transports) that the Wingless was very much smaller than the Liberty, and if we look at the superlaser beam size in comparison to the two vessels it appears to roughly match up, size-wise. We could thus conclude that the Liberty, due to her bulk, showed more resistance to the beam, whereas the Wingless was simply rendered gone.
Meanwhile, other variations might be more easily explained by looking to the battlestations which produced them.
The only dual-ring events were DS1 related . . . the single-ring events were DS2 related. This suggests that there was a slight difference in the two battlestations in that regard. Then again, the Wingless did seem to show at least a multi-layered planar effect, as opposed to the other two DS2-related examples.
In the images below, note that in the first the DS2 explosion cloud is opaque, surrounded by what looks like a less-luminous (or reflecting) aura. The second image, some 130 frames later, shows the persistence of the explosion cloud with non-luminous areas. This suggests that a good deal of material is present (a la a nebula). Whether this is in the form of chunks of solid matter or simple clouds of gas and particulates is not known, but the latter seems more likely given the appearance.
Now, let's look at the DS1 explosion. The two images below are about 65 frames apart, or half the spread of the above. You can see that the DS1 explosion cloud dissipates much more rapidly, not even fully obscuring the far section of the ring.
These effects alone suggest that the DS2 blast was much more powerful than the DS1 blast over and above mere size difference, virtually vaporizing the far larger DS2 battlestation. DS1, meanwhile, expelled much more large and glowing debris.
There are also battlestation-based similarities in regards to debris. DS1 and Alderaan both showed a great deal of debris, from the DS1 glowing shards to the similar glowing debris and non-glowing bulk material that emerged out of Alderaan.
DS2, meanwhile, shows little more than a gas/particle cloud, with just a handful of chunks of material here and there. The Wingless, of course, shows virtually nothing, and even the Liberty's seemingly-dense explosion is see-through a la the Wingless. Note the obvious frigate engines on the right, as well as the 'corvette' engines (a la Leia's "Tantive IV") visible near the center:
(The above is quite pleasing, incidentally, since had it not been the case one would've been required to explain why the explosion cloud and debris were roughly planar. This would've been inconsistent with the fact that in all other examples there seems to be no interaction between debris clouds and planar effects . . . which is why I was looking for this anyway.)
(The above also happens to coincide with the novel statement describing DS2 as being more than twice as powerful than its predecessor. You see, the reactors were of similar relative scale, and since power systems don't commonly scale up that well this quote has always seemed puzzling. However, if the DS2's destruction mechanism were more efficient than that of DS1, then we could take the quote to mean that the second Death Star was a more able destroyer than the first.)
To summarize, what we have are indications that the DS2's superlaser was more destructive than that of DS1, insofar as debris is concerned. Further, the dual-ring effect seems confined to the DS1. There is presumably a relationship between the dual rings and the less thorough destruction mechanism of the DS1.
Of course, there is the multi-layer planar effect of the Wingless to consider. If we tried to understand that as being similar to the dual rings, we could end up with a contradiction. Such an attempt wouldn't make much sense, though, since the phenomena are so different:
a. The Wingless shows glowing planes, not well-formed rings.
b. The second or trailing rings were either moving at the same or greater velocity than the first rings, whereas the Wingless's outermost planar layers were the high-velocity examples.
. . . and so on. However, this question can lead us toward a unifying idea. Suppose, if you will, that Alderaan's secondary blast and related second ring had occurred almost instantly. In such a case, we would not have seen the first ring at all, since the secondary ring would've overtaken it and merged with it before we observed it. It is possible, then, that the DS2 single-ring example is nothing more than the second ring . . . or, in other words, that the DS2's destruction mechanism was closer to being the same as DS1's, but simply more accelerated. This could also relate to the greater efficiency of the DS2's destruction mechanism, since a more rapid mechanism might indeed produce the greater destruction efficiency observed.
Going back to the Wingless, we could then conclude that there actually was a multi-stage effect in progress, but that the malformed rings (i.e. planes) did not merge as proper rings would. The fastest segment of the orange cloud would thus be what, in a larger example with well-formed rings, might've been the second ring.
3. More on Material Disappearance
Disappearing material makes little sense, obviously, unless you're talking about something like phasers or transporters (which we aren't). We're thus left with only a few possibilities, and only a few of these make any sense whatsoever.
It can't be shattering of the objects, since that would be expected to leave visible signs. Then again, it could be possible that the pieces were sent to some high velocity, but even then we should see the effect of such a thing on nearby objects or material. It can't be vaporization for the same reasons.
We could try to suppose that it was mass-energy conversion where the energy is conveniently outside the visible EM spectrum, but that also doesn't work. To explain why requires a little math:
Let's say, for example, that 20 percent of the DS2 station disappeared. If the station was 70% complete, and if we assume that 10% of its volume was solid material with a density of iron, then that would result in a mass of about 235,068,000,000,000,000kg that has to be converted to energy. As per Einstein, that's 2.1E28J (about 5 billion gigatons) of EM energy to account for. Now, let's say that DS2 had somehow swung out to a geostationary orbit of about 35,000 kilometers (which appears to be much higher than what we see in the film). At that range, the inverse square law tells us that we'd still be looking at an energy intensity of 1.3 terajoules per square meter at the closest part of the atmosphere, dropping off to about 1TJ/m² exactly at the horizon.
Using the horizon intensity value and getting the surface area of Earth (as if it were a circle), that would be a total of 1.3E26J hitting the planet. (That, incidentally, is what the sun puts out, in all directions, in about a third of a second). Had this been deposited evenly throughout the entire volume of air of the facing side of Endor (assuming Earth-like conditions, as per this), then given air's specific heat capacity of 1005J/kg K, the atmosphere would've heated up by almost 50,000 degrees Kelvin (or 90,000 degrees Fahrenheit). However, the atmosphere is virtually opaque (or nearly so) most of the non-visible parts of the spectrum except for radio. One would not expect the EM emission from such an event to be in the radio part of the spectrum, but more in the area of X-rays or gamma rays. These generally can't penetrate too deeply into the atmosphere, meaning that the much lesser volume of air would receive the energy . . . the upper atmosphere would cook off. In any case, it is clear that the surface would've been much brighter and warmer, in short order.
Needless to say, this would've been rather noteworthy when viewed from the surface, over and above the fact that it would have rendered everyone blind and crispy. Instead, we saw the Death Star in the regular, plain-old sky, and happy Ewoks below. So, material disappearance and the mass-energy conversion obviously aren't the same event.
Let's ponder the other possibilities regarding material disappearance. Of course, we've already eliminated the notion that it could be direct mass-energy conversion, but there remain other possibilities:
"Collapse" might be a misnomer in regards to Alderaan and especially for the Death Star events, really, since the velocities (and thus accelerations) involved would be profound. "Momentary super-gravity" would come closer to describing it. But if it were gravity causing the acceleration, then the masses of the bodies would've had to increase to ridiculous levels in order to produce disappearance in less than a second (or about a single frame in most cases). However, since Alderaan, DS2, and the ship-destroying shots all show nearby ships or material behaving normally (i.e. not behaving as if they just ended up sitting beside something trying to act like a black hole), then gravity cannot be the culprit. At Alderaan, whatever happens seems only to affect the solid material, not the surrounding debris and gasses . . . the same seems to be true of the Liberty and DS1.
The technology of the Empire has not been seen to employ common Trek concepts like phasing or subspace. However, one of the underlying concepts of the Star Trek vs. Star Wars discussion is that the two universes both operate via the same basic physical principles (a statement made so that neither side can say "oh, well, the enemy entered our galaxy and then their tech stopped working"). We could theoretically extend this so that the Empire did use such things . . . but that's generally an unattractive option.
The Star Wars universe does have its own 'technobabble' spatial domain, however, in the form of hyperspace.
One could posit that the disappearing matter is somehow shifted into the hyperspace domain. This need not be a propulsive effect . . . Han noted in ANH that a ship in hyperspace can fly through stars or bounce too close to supernovae, destroying the vessel. This implies a connection of some sort between the two domains, one which the superlaser might monopolize.
On the other hand, it could be that there is a conversion of the missing mass directly to energy. The two could be directly related . . . i.e. the mass could be converted directly to energy which is then mostly translated into the hyperspace domain.
Alternately, the matter-energy conversion could occur in the hyperspace domain, with only some of that energy appearing in normal space. (Something similar, albeit in reverse, might even serve to explain the function of those seismic charges from AoTC.) However, the appearance of that energy would have to be localized to those areas where we see the explosions, so this is too convenient an option.
Neither concept is perfect. If we assume, for instance, that all the instances are of collapse, then things just get weird since the likely culprit (gravity) can't be the cause. On the other hand, if we assume that it is all some sort of transition, then we have no clear explanation for the rapid collapse of the Alderaanian surface short of assigning the effect as being part of the transition. The latter is probably the best option, but it is still displeasing.
As a result, it would seem that the material which disappears effectively vanishes.
4. DS2 Radiant Energy Limit
We can use a similar maneuver as used above to guesstimate an upper limit for the radiant energy of the DS2 explosion. (This, of course, will not account for the kinetic energy of any debris.) To do so, we will assume that the Death Star's explosion shouldn't have raised the temperature throughout the nearest part of the atmosphere by more than 50 degrees Kelvin (i.e. 90 degrees Fahrenheit). Obviously, the Rebels and Ewoks didn't seem to experience anything remotely like this level of temperature increase, or the sort of sudden gusts that would be associated with such a thing, but we'll use this as an upper limit.
First, let's put the Death Star closer to its true orbit, moving it to 3,500km from Endor.
Next, for this calculation we'll skip the bit about the visible part of Endor (since at that range much less than 50% would be visible), and simply deal with the 1m² column of air directly under the station, extending from the surface to the point at which the atmosphere could be said to have stopped. Via the formula for determining air density at different heights plus a little integration, the total mass of the air in this column is about 10,200 kilograms. To raise the temperature of this air by one degree would require 10,251,000 joules, or 10.2 megajoules. To raise it by fifty would thus require about 525 megajoules (again assuming that all of the energy is deposited throughout the entire atmosphere, top to bottom).
Since we're using a 1m² column of air anyway, determining the intensity is easy . . . 525 megajoules per square meter. We can thus use the surface distance and work backwards to determine the radiant energy limit of the DS2 blast via use of the inverse square law.
S / 4pi(r^2) = I S = I x (4pi(r^2))
Plugging in the known intensity (I = 5.25E8J/m²) and the 'radius' (3,500,000m) yields an upper-limit value for the total radiant energy of 8.1E22J, or about 19,500 gigatons. (The value is actually just over 19,300 gigatons, but what's a couple of hundred gigatons between friends?)
Because we're talking about surface temperature increase, the total energy could be a bit greater, since the upper atmosphere would probably handle most of the energy . . . but then, there can't be so much energy as to cook off the upper atmosphere, since of course we see the explosion and our heroes look up to witness it. That, plus the fact that nothing remotely like a 50 degree increase was observed, implies the true value would likely be some small fraction of the 19,500 gigaton value.
5. Superlaser Beam Raw Energy Constraints
As noted elsewhere, there is no obvious disruption of the clouds in the area of the DS1 superlaser's impact. This severely limits the raw energy content of the beam. The heat of a pure energy beam of planet-destroying proportions would certainly evaporate clouds, at the very least. If you've ever seen video clips of nuclear weapons detonations, then you've probably seen the way the clouds quite rapidly evaporate away from it as the ice crystals in those clouds are melted, and the droplets vaporized. A planet-killing beam ought to not only evaporate clouds, but rapidly burn off the atmosphere.
Given a volume of the superlaser beam (perhaps 5 kilometers wide, as scaled
against the Death Star), then we can calculate an upper limit on the raw energy
content of the beam. If we assumed that the atmosphere was pure
liquid water near the freeze point and at normal sea-level conditions, simply to
avoid raising the entire 235.6km³ volume (a mass of 235,600,000,000,000,000g) by
100 degrees Celsius would require that the DET superlaser deposit no more than 98,575,040 TJ into the atmosphere.
That is simply to avoid vaporization of the near-freezing water. Converting from terajoules, that is no more than
Bulk liquid water, of course, would be harder to vaporize than the water in clouds, so 23.5 gigatons is a profound overestimation. Naturally, clouds contain much less than that amount of water. A rough estimate from perusing online suggests that the droplets of clouds are in the micron range, and that these have a density of around 100 per cm^3. Ice crystals in clouds would be of similar proportions.
On the other hand, if the superlaser beam bloomed significantly in transit (i.e. did not remain focused, and thus got much wider), the real value could actually reach the 23.5 gigaton range. However, a raw energy level of 23.5 gigatons is way, way, way too insufficient to result in a planetary explosion.
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