Radvic's Analysis of Implosion Seal Demonstrated Damages and Methods for Achieving Said Damage
Abstract
This post address the problem of implosion seals. Specifically that the mechanism implosion seals work off of are hilariously more powerful than they are described as being in the story. The damage implosion seals cause is due to the way they force things into the same space, creating explosions of energy. This post attempts to determine "how much space would a 20 meter radius implosion seal need to unstore it's contents into in order to achieve the damage stated in the chapter we saw it used." For reference, the (so far as I know) sole passage describing the damage caused by an implosion seal is here:
I find that reducing the volume of a 20 meter radius sphere to a 18.7 meter radius sphere is enough to cause the damage stated in story.
Introduction
In real life, there are very few cases where something like this happens, because compressing gas much is prohibitively energy expensive. The pressures increase astronomically as the radius of the sphere the air takes up decreases. The closest real life example available is things like compressed air
accidents. But even these rarely reach the sorts of pressures implosion seals may reach trivially. For example, the video shows a nearly lethal explosion at ~100 psi, or ~7 atm. Implosion seals as currently stated get pressures up to 64,000 atm. Clearly, implosion seals deal with things outside the realm of real life experiences. This means we will need to look at several models to determine what exactly they do.
Intuitively, it is easiest to just say they work as an
ideal gas, according to the
kinetic theory of gases, and so then we just need to determine what happens during the adiabatic expansion of the gas, look at the
blast wave created by such a thing.
Aside from traditional gas and pressure concerns, there may be problems with putting too much air into a single place and forming exotic matter like black holes or white dwarfs. As humans lack the energy and containment to reach the kinds of pressures which implosion seals will need to do the damage described, it is not immediately obvious if these things will or will not form. Thus, after using more traditional gas methods to determine the energy, we will look at the resulting conclusions on the amount of pressure that it creates, and if that will do something with nuclear physics.
Methods
This section examines the amount of damage which releasing a bunch of gas of a certain pressure would do. We use two models to translate from the damage description to a determination of how much space the seal unstored its contents into. First, we will examine
blast overpressure and how it would damage the forest in the only canon description we have for the damage of the seal. Next, we will use an explosive damage
calculator to find the equivalent amount of TNT which would produce this amount of blast overpressure. Finally, we will determine how much work must be done on a system at constant temperature to add the amount of energy the seal must give off.
Forest Damage Analysis
First, we compare to the damage a nuclear weapon does to a forest as in table 5.149 in this book on nuclear
weapon damage descriptions, specifically, that severe forest damage is caused by winds of 130-140 mph. According to
this source a 5 psi overpressure blast difference should be sufficient to cause sustained 150 mph winds. So, to have knocked down all the trees in a "perhaps thirty meters across" section, there must be a 5 psi blast overpressure out to 15 meters from where the implosion seal was set off.
Note: I had initially intended to examine the cratering described in the chapter to determine the blast strength, but in real life, most nuclear cratering is caused by vaporization (
Chapter VI), which, presumably, implosion seals aren't doing (unless the QMs actually intend for a single implosion seal to be equivalent to a nuclear weapon).
Damage Conversion to TNT
Now that we know we need a 5 psi overpressure blast, we can use this
explosives impact calculator to calculate how much equivalent explosives of TNT we would need for the a 5 psi overpressure blast (or Reflected Pressure, as they term it). 5 psi is 35 kPA, which guess and check determines is about 4 kg of TNT. So, to do the damage described in the chapter, we need a blast equivalent to 4 kg of TNT from a single 20 meter radius implosion seal.
TNT Conversion to Sphere Reduction
Now, we need to determine how much energy adding air of a constant volume to a system is equivalent to. Implosion seals have been stated to release air at the same temperature they took the air in, but at a smaller volume. For the purpose of this calculation, we will only examine the energy the seal adds in the storage. This is justified by claiming that the seal is broken in a very low pressure environment, so the energy up to the first atmosphere is irrelevant to the explosion. We can calculate the energy added by the implosion seal's volume changing act by calculating the work required to do the compression. This work will be released by the burst implosion seal as energy when the seal breaks. We can calculate the work done on a system of constant temperature via the
isothermal compression and expansion equation:
W = nRT ln(Vf/Vi)
Where n is the number of moles of gas (in mol)
R is the ideal gas constant (8.314 4598 J mol
-1 K
-1)
T is the temperature (in K)
Vf is the final volume (in m^2)
Vi is the initial volume (in m^2)
and W is the work done (in J)
Solving for Vf we find
Vf = Vi e^(W/(nRT))
Then, plugging our numbers (T = 293 K, Vi = 20^3 * 4 / 3 * pi m^3 = 33500 m^2, n = 33500 mol, W = - 4 kg of TNT = - 1.6 e7 J (via
this conversion) we get
Vf = 27500 m^3
or, a sphere of radius 18.7 meters.
Esoteric Effects Check
This sort of seal will not result in pressures greater than 5 atm, so is within the bounds of modern air compressors and thus will not cause any esoteric effects on its own.
Conclusion
So, to cause damage to the trees as described in Chapter 12 Part 2, or approximately 4 kg of TNT, implosion seals absorbing air from a 20 meter radius sphere should release their air in a 18.7 meter radius. This would not increase the air pressure of the area they release things in by more than a 2 atm, so would avoid any esoteric effects (like accidental fusion) at this level. Note that this would also be sufficient to kill anyone present in this area, but likely not to create the described crater.
Comments and Critiques
Anyone reading this can help by checking my numbers and logic, or making slightly different assumptions (e.g. trees destroyed to a larger radius etc). I've tried to explain what's happening and source all the places I used to find this out, so, in theory, anyone could check it and comment reasonably on it.
With that said, there are three fairly obvious issues which can be raised against the above model. Ultimately, I think each of them has an answer (which is why I used the above model). The problems and solutions are as follows:
First, it turns out that cratering is mostly caused by vaporization (
Chapter VI). So, to achieve the damage a crater would imply, we probably actually need to vaporize something, which I don't think is what an implosion seal is intended to do. This is why I went with "dozens of trees were knocked down"a crater was made of 15 meter radius and 1 meter depth." The difference in damage based on "made a huge crater" and "made a berm of trees" is large, I would estimate 2 or 4 orders of magnitude. If
@eaglejarl @Velorien @OliWhail wants to use the crater depth and width as the decider of how strong implosion seals are going to be instead of tree destroyed values, I would estimate that by determining the magnitude of bomb which creates such a crater at optimal cratering depth, and then perform the "TNT Conversion to Sphere Reduction" to determine how much the sphere's volume must be reduced. A fairly easy way to explain the difference in damage the crater implies from the knocked down trees is to say that the local chakra voles had a nest in the area which collapsed.
Second, the assumption of "we can ignore the first atmosphere unsealed" by implosion seals is quite suspect. If we assume that the background is at 1 atm, suddenly the implosion seal gains a fair amount of power, since it's creating a large area of 2 atm (aka 300+ mph winds). This would sustantially increase the damage caused by an implosion seal, making a more accurate description of the damage it does to a forest "hundreds of trees were knocked down" rather than "dozens of trees were knocked down."
Third, it is unclear how sustained the blast from an implosion seal would be. This significantly changes the required pressures to knock down trees, and thus the amount of psi the blast must have. If the pressure wave is unsustained for instance, then it likely needs to be substantially larger, since trees won't fall over if exposed to 140 mhp winds for only 0.03 seconds. 4 kg of TNT doesn't knock over trees like this because it only gives out a shockwave, instead of a sustained flow. I'm assuming that since the implosion seal actually adds air to the situation the airflow is more sustained.