Physical Conundra: Death Stars

[Illuminatus Primus]

I was reading The Technical Commentaries and I noticed something. The Death Star, according to realistic figures for the energy of Alderaan's destruction (somewhere around the 10^38 J) of which one of the upper limits is equivalent to the annhiliation of 3.8*10^21 kg. Given a rough density of neutronium equal to 4*10^17 kg/m^3, it follows that a mass of fuel directly annhiliated with no loss to inefficiency or waste heat should be around 9.5*10^3 m^3. So a sphere of fuel of neutronium density should have a diameter a little over 26 meters. So volume is not a problem for Imperial energy density. However, this represents 1/1600th of the Earth's mass. (And hence, appreciable gravitation proportionally. The Death Star I must have annihiliated many times this mass in order to destroy Despayre, jump to its roundezvous point with HIMS Devestator, then jump to Alderaan and destroy it, then jump to Yavin and presumably destroy it. Sublight manouvering requires meaningful amounts of energy compared to to planet-destroying.

What kind of effects should this gravitation have had on Alderaan? Yavin and her moon system? A ten-shot fuel reserve (again, not accounting for manuevering and hyperjump, and with little possibility of mid-mission refueling during the events of ANH (and even since the destruction of Despayre) may easily exceed this. Which would make the Death Star possibly easily be more than 1% of the Earth's mass in fuel.

This is saying nothing of the Death Star II which can recharge in "minutes" and is MUCH more volumnous (around 180x, with probably a proportional increase in "bulk" mass). Mike notes in the power generation section that the DS2 easily has 10x the power generation capability of the DS1, and if its assumed to have a similar range and duration of operation to the DS1, then the DS2 could easily be 10% of the Earth's mass? What could this be expected to influence about Endor and her celestial neighbors? What gravitational impact could the destruction of the repulsor lift system Dr. Saxton proposes (if integral to the shield generator that protected DS2) have on the moon? Would the tidal effects alone cause earthquakes on a massive scale and volcanic eruptions?

[Surlethe]

The conventional explanation has always been "hypermatter": as you know, an exotic fuel source. If this "hypermatter" is tachyonic in nature, as suggested by the power generation page at the SWTC, then perhaps it does not interact gravitationally with the universe as baryonic matter would?

Another interesting thought is efficiency: the 1e23 kg figure is an absolute lower limit; the efficiency of the Death Star's reactor could increase the mass of the Death Star's fuel by a factor of as much as two or three.

[Ender]

I believe this topic has come up before, and the answer provided was that while Alderaan and Yavin 4 would have suffered gravitational effects, in both cases the Death Star was not in place long enough for them to have an impact and in the case of Alderaan we didn't see the surface so we couldn't know. The same follows for Despayre - IIRC it is stated to have been uninhabitable by the end of construction, but the reason given is due to space junk in orbit. In any case we never see the surface prior to its destruction.

In the case of the Death Star 2, it was incomplete at the time. In fact we only know that it had enough power for one planet destroying shot and several smaller ones (insignificant by comparison really). So it wouldn't have a full fuel load. But the gravitational effects are yet anopther reason the forest moon should be destroyed.

I've never done the math however, so take that with a grain of salt.

[FTeik]

According to the SW:CL the construction of the DS2 caused groundquakes and lakes spilling out of their bassins.

[Surlethe]

In the case of the Death Star 2, it was incomplete at the time. In fact we only know that it had enough power for one planet destroying shot and several smaller ones (insignificant by comparison really). So it wouldn't have a full fuel load. But the gravitational effects are yet anopther reason the forest moon should be destroyed.

I wonder -- would the planet-destroying shot have been minimum power (2e32 J, IIRC), as opposed to the relativistic scattering of 1e38 J? That could explain why the gravitational effects appeared minimal. Perhaps the Endor repulsor also mitigated the station's gravitational pull.

EDIT: Using the accepted size of the Death Star II, and eyeballing this picture, it appears the DSII is about 3*900 km = 2700 km away from the forest moon of Endor. The acceleration due to the tidal force should simply be the difference between the accelerations on each side of the forest moon. Since the acceleration on the near side is something like 1 m/s/s and the acceleration on the far side is about 0.04 m/s/s (from Newton's law of gravity), we have a tidal force of 0.95 = 1 m/s/s (rounding for good measure). You tell me what that would do to the moon, given that it's a good 0.1G.

[frogcurry]

Heres a question: if the Death Star mass is sufficient to generate noticeable gravity, then does that mean that there would be gravity present in all the internal corridors towards the core/centre?

Obviously artificial gravity would presumably allow this to be cancelled out (although it would take a fair bit of care with design I guess), but if the gravity failed then I assume you would be suddenly exposed to some fairly dangerous forces (being pulled off one of those open exposed walkways for example).

[Ender]

Heres a question: if the Death Star mass is sufficient to generate noticeable gravity, then does that mean that there would be gravity present in all the internal corridors towards the core/centre?

Obviously artificial gravity would presumably allow this to be cancelled out (although it would take a fair bit of care with design I guess), but if the gravity failed then I assume you would be suddenly exposed to some fairly dangerous forces (being pulled off one of those open exposed walkways for example).

Yes, there should be some. In fact, according to my calculations, based off the 1*10^33 watts peak power commonly accepted for the first Death Star, the surface gravity on the DS1 should be a little over 4 Gs. Presumanbly this is why the outer layers are orientated with their decks facing down - to take advantage of that.

How it would alter as you moved through a nonhomogenious structure, I have no idea. I'd imagine you'd see far stronger attraction near the fuel tanks owing to the extreme concentration of mass there. I based off what I've read about how the coreolis force would affect people, I suspect that you might even get a feeling os being "spacesick" as the low level tidal forces would mess with internal fluids, making you feel a bit nauseous (sp?) and maybe disorientated enough to walk a bit funny. But that is just a guess.

[Enola Straight]

Speaking of power figures...

Whenever you shove a certain amount of mass or energy into a certain amount of space, infinite gravitational collapse occurs and you end up with a quantum singularity...a Black Hole.

Isn't the Death Star's superlaser so strong that all points along the shot vector collapse into singularity?

[Kristoff]

According to my poor math/physics skills 1E+38J equals about 1.1E+21kg and singularity of that mass would have Schwarzschild radius of 1.64 µm.

[Tychu]

I believe this topic has come up before, and the answer provided was that while Alderaan and Yavin 4 would have suffered gravitational effects, in both cases the Death Star was not in place long enough for them to have an impact and in the case of Alderaan we didn't see the surface so we couldn't know. The same follows for Despayre - IIRC it is stated to have been uninhabitable by the end of construction, but the reason given is due to space junk in orbit. In any case we never see the surface prior to its destruction.

In the case of the Death Star 2, it was incomplete at the time. In fact we only know that it had enough power for one planet destroying shot and several smaller ones (insignificant by comparison really). So it wouldn't have a full fuel load. But the gravitational effects are yet anopther reason the forest moon should be destroyed.

I've never done the math however, so take that with a grain of salt.

in the new Lethal Alliance game for the DS and PSP (i have the DS version so graphics might be the case) the planet was a prison planet to begin with so the Empire might not have cared about what it was doing on the surface and from the game the surface outside the prison was barren. no flora life was seen.
The Death Star was also in a low orbit around Despayre much closer to the planet then it was when it was orbiting Alderann

[XaLEv]

Speaking of power figures...

Whenever you shove a certain amount of mass or energy into a certain amount of space, infinite gravitational collapse occurs and you end up with a quantum singularity...a Black Hole.

Isn't the Death Star's superlaser so strong that all points along the shot vector collapse into singularity?

Kuroneko has posted before on that subject:

http://bbs.stardestroyer.net/viewtopic. ... on#1512565

The bomb on Hiroshima was around 15Kt, which is more than one-billonth of the 500Gt yield given, meaning, if the above calculatin were correct, the Little Boy had at minimum 1e95kg mass. This is so patently ludicrous as to have the mass of at least 10^53 Milky Way galaxies delivered on a plane. There is only one purely theoretical limit to the power generation that even magic-tech would not overcome, that being around 1e52W, with anything attempting to saturate it turning into a black hole, the horizon preventing further the delivery of the energy output. No physical process can surpass this limit, but neither Death Star even comes close to it--one would have to destroy billions of Alderaans per second to do so. Hypermatter cannot solve this, as it is still only a pseudomagic storage device, and has to be converted to 'real' mass-energy at some point. Any problems with Star Wars weapons yields are not found through relativity (as the OP attempted to do), but rather engineering and materials science. With suspention of disbelief in those areas, the problem disappears.

[Sriad]

Also, one of the rules of black hole formation is that you need to have all the mass/energy needed inside the potential event horizon of the black hole that will form before a collapse will occur. With the Death Star beam (hundreds of thousands of kilometers long) you would need many thousands of solar masses for it to happen.

[Shroom Man 777]

Hrm, it'd make the Death Star an even more terrifying superweapon. Going near Alderaan like that, causing all sorts of earthquakes, tidal waves, making the people scream and shit their pants and then blowing the entire world up? Pure dickery.

[Elheru Aran]

Hrm, it'd make the Death Star an even more terrifying superweapon. Going near Alderaan like that, causing all sorts of earthquakes, tidal waves, making the people scream and shit their pants and then blowing the entire world up? Pure dickery.

Given how briefly they were in the Alderaan system before they shot the planet, I doubt there was much time for the gravitational effects to be noted.

Although one has to note that we don't know exactly when they entered Alderaan orbit, so...

[TithonusSyndrome]

Wouldn't the debris from both Death Stars have comparable effects, then? Or did enough of it reach escape velocity to not reform into anything large enough to create such effects?

[Surlethe]

Wouldn't the debris from both Death Stars have comparable effects, then? Or did enough of it reach escape velocity to not reform into anything large enough to create such effects?

Well, the argument for the Endor Holocaust is made pretty strongly at the SWTC. I also seem to recall some mentions of the Death Star I's flaming debris crashing down onto the forest moon of Yavin, but the Death Star had just cleared Yavin when it exploded, so I'd imagine most of the debris was pulled into the gas giant or remained in orbit.

[Elheru Aran]

Wouldn't the debris from both Death Stars have comparable effects, then? Or did enough of it reach escape velocity to not reform into anything large enough to create such effects?

Well, the argument for the Endor Holocaust is made pretty strongly at the SWTC. I also seem to recall some mentions of the Death Star I's flaming debris crashing down onto the forest moon of Yavin, but the Death Star had just cleared Yavin when it exploded, so I'd imagine most of the debris was pulled into the gas giant or remained in orbit.

In the EU they mention Death Star wreckage on Yavin 4 a few times, especially in the Young Jedi Knights series where a TIE pilot from Death Star I crashed upon the forest moon after the battle. Most of the novels I've read mention accurately enough that the wreckage went mostly into Yavin itself.

Avoid 'Glove of Darth Vader' like the fucking evil and crime against nature that it is, though...