Twilight: The Xindi Death Star!

[Patrick Ogaard]

Problems:

1. A planet has within its structure countless fissures which would scatter any NDF effect. The mantle will not experience any sort of uniform disintegration.

2. The Earth's core is nickel/iron; not especially dense on the atomic scale. The reaction would not "stop dead". Furthermore, any such planet-busting weapon dependent upon a chain-reaction would be energised sufficently to induce the reaction in the liquid metallic core.

3. I hate to have to remind you of this, but gravity simply won't disappear. A planet is not a pressure boiler waiting to blow apart. The planetary mass will still tend to coalesce around a central point from mutual gravitational attraction unless acted upon by an extraordinary outside force.

Valid points. Let's see if I can come up with any useful answers.

1. I'm not certain that it's really germane to the situation. I believe the TNG episode relating to this is "A Matter of Time," in which the Ent-D very quickly drills large, tidy holes into the upper crust layers of a planet. The fissure structures of the top layers of the crust should be considerably more pronounced than those of the mantle. There's also the fact that a sufficiently large input of fictional NDF energies should allow even the beam's scattered fragments to disintegrate the material surrounding the fissures.

2. Phasers don't appear to have much luck with nickel/iron. Otherwise there would not be so many dangerous asteroids successfully resisting the power of the shipboard phasers of Voyager and the Ent-D. Also, in most models of the Earth's interior, the core is divided into two distinct layers: the relatively thin layer of liquid nickel/iron of the outer core, and the larger inner core's sphere of nickel/iron that would be liquid if it weren't under such intense pressure from the mantle. It's not unreasonable -- though hardly inevitable -- to conclude that the inner core's exceptionally dense, superheated nickel/iron, liberally laced with what should be the majority of the planet's share of elements more massive than iron, would be highly resistant to the fire of ST beam weapons. What happens to the liquid portion of the core is of secondary importance.

3. In real life, without handwaving magical superscience available, you're absolutely correct. The presence of the mantle's mass, which can not just magically disappear in real life, would certainly prevent the pressure cooker scenario. On the other hand, the alien equivalent of a giant phaser drill disintegrating a large portion of the mantle will release pressure on the inner core, and the inner core would most likely undergo an abrupt increase in volume and decrease in density. Also, of course, a giant phaser drill should qualify as an extraordinary outside force.

On the other hand, there is the entirely real possibility that I might be completely wrong, and it wouldn't be the first time.

[Drooling Iguana]

Perhaps the visibile beam that we saw was only intended to drill below the surface so that a device could be beamed down to finish the job in whatever technobably way you could imagine (a mass lightening field around the planet?) It would explain why the beam cut off halfway through.

What is the point of introducing two additional mechanisms into the picture to try to explain a process which still relies on an induced chain-reaction? And how would a planetary mass-lightening field aid in this process? Consider the course of your logic: the use of a beam to drill into the deeper layers of the target, followed by the introduction of the induced chain-reaction device, followed by the mass lightening field to push away Earth's fragmented mass from the centre.

The whole technical point of the chain-reaction is to take advantage of a process which somehow utilises the material of the target to fuel the reaction because the beam or bomb itself hasn't the requisite energy to do the job directly. But then, a mass-lightening field is employed to push the fragmented planet apart? The amount of energy any such forcefield would require must balance out against the GPE of the mass to be lightened —which means that it would be far simpler to employ a beam powerful enough to blast the planet apart through sheer brute force. Which negates the need for a chain-reaction weapon in the first place.

It might be a chain reaction, it might not. I'm just throwing out ideas here, since calling the thing a "chain reaction" really doesn't explain anything.

[Darth Wong]

I'm just throwing out ideas here, since calling the thing a "chain reaction" really doesn't explain anything.

Wrong. An exothermal chain reaction will continue to produce energy after the weapon is shut off. That is a clear prediction which matches observation.

[Jason von Evil]

Here's some better screencaps of the episodes, taken from a HDTV.

http://provocativeintertainment.t35.com ... 8/screens/

[Patrick Degan]

Problems:

1. A planet has within its structure countless fissures which would scatter any NDF effect. The mantle will not experience any sort of uniform disintegration.

2. The Earth's core is nickel/iron; not especially dense on the atomic scale. The reaction would not "stop dead". Furthermore, any such planet-busting weapon dependent upon a chain-reaction would be energised sufficently to induce the reaction in the liquid metallic core.

3. I hate to have to remind you of this, but gravity simply won't disappear. A planet is not a pressure boiler waiting to blow apart. The planetary mass will still tend to coalesce around a central point from mutual gravitational attraction unless acted upon by an extraordinary outside force.

Valid points. Let's see if I can come up with any useful answers.

1. I'm not certain that it's really germane to the situation. I believe the TNG episode relating to this is "A Matter of Time," in which the Ent-D very quickly drills large, tidy holes into the upper crust layers of a planet. The fissure structures of the top layers of the crust should be considerably more pronounced than those of the mantle. There's also the fact that a sufficiently large input of fictional NDF energies should allow even the beam's scattered fragments to disintegrate the material surrounding the fissures.

2. Phasers don't appear to have much luck with nickel/iron. Otherwise there would not be so many dangerous asteroids successfully resisting the power of the shipboard phasers of Voyager and the Ent-D. Also, in most models of the Earth's interior, the core is divided into two distinct layers: the relatively thin layer of liquid nickel/iron of the outer core, and the larger inner core's sphere of nickel/iron that would be liquid if it weren't under such intense pressure from the mantle. It's not unreasonable -- though hardly inevitable -- to conclude that the inner core's exceptionally dense, superheated nickel/iron, liberally laced with what should be the majority of the planet's share of elements more massive than iron, would be highly resistant to the fire of ST beam weapons. What happens to the liquid portion of the core is of secondary importance.

3. In real life, without handwaving magical superscience available, you're absolutely correct. The presence of the mantle's mass, which can not just magically disappear in real life, would certainly prevent the pressure cooker scenario. On the other hand, the alien equivalent of a giant phaser drill disintegrating a large portion of the mantle will release pressure on the inner core, and the inner core would most likely undergo an abrupt increase in volume and decrease in density. Also, of course, a giant phaser drill should qualify as an extraordinary outside force.

It's not internal pressure but gravity which is the force at play in this situation. It wouldn't matter how much of the mantle was removed by whatever technobabble means you can imagine —the mass of the core would remain unified by its own gravitational attraction. And it is very unreasonable to imagine "superdense" nickel/iron. Atomic density is directly a function of an element's nucleonic composition. It does not vary as a result of gravity or pressure.

[Patrick Ogaard]

It's not internal pressure but gravity which is the force at play in this situation. It wouldn't matter how much of the mantle was removed by whatever technobabble means you can imagine —the mass of the core would remain unified by its own gravitational attraction. And it is very unreasonable to imagine "superdense" nickel/iron. Atomic density is directly a function of an element's nucleonic composition. It does not vary as a result of gravity or pressure.

The usual geological model pegs the pressure of the inner core at around 3.6 Megabar, with a temperature of approximately 7500 Kelvin. That same model maintains that the outer core is primarily composed of liquid nickel and iron, while the inner core's nickel-iron is kept solid by the immense pressure of overlying material, despite the high temperature.

You're right that it's unreasonable to imagine "superdense" nickel/iron. The only context in which I've seen superdense used is in reference to degenerate matter, AKA neutronium, and I'm not aware of any evidence for or theories regarding neutronium composing any part of the core. That's why I did not refer to the solid iron of the inner core as being superdense, but rather "exceptionally dense." A compact solid at a temperature that would reduce that solid to a roiling, rapidly expanding cloud of vapor at sea level is exceptionally dense to someone with a BA instead of a BS. I was thinking in terms of g/cm^3, where temperatures of up to 7500 K and pressures of 3.6 Megabar should produce some increase in density even in a solid, producing an exceptionally dense solid.

Regardless, I think we're at the point where scientific calculators are customarily whipped out, furious calculations are made and spiffy formulae are produced. And that's the point at which I'd make a fool of myself regardless of whether my idea is provides a suitable explanation for the observed effects or is a total load of bunk.