Motives for interstellar warfare

[Darth Smiley]

[rant]

Well, the title pretty much explains it. What are the plausible motives for a bunch of aliens/people to go out and shoot at each other across interstellar distances?

There are a couple I can think of as possible but implausible. For example the Independence Day aliens seem to want Earth's resources, but it really doesn't make sense. Why go through the trouble when you can just mine asteroids, or uninhabited worlds? The cost of transporting a huge freaking army across space is immense. And without resorting to nukes and asteroid strikes, you NEED a huge army to keep a captured world under control. Bottom line, just not worth the trouble to capture a world for resources when you can find a nice uninhabited one (Mars anyone?)

(Yes, you COULD use a bioweapon. But even that has issues, such as how do you collect samples? or stop enemy counter measures?)

Another possible reason is the classic 'them or us'... one side or the other becomes convinced that the other is a threat to their survival, and attacks in 'preemptive defense'. But this is more of a 'shoots relativistic missile' than 'sends in the fleet' situation, like in The Killing Star. It also tends to be much, much more one sided.

What other major motives do we see in Science Fiction (or can we concoct on our own?)

[/rant]

[Solauren]

#1 - Living Space, same as in Earth history
#2 - Some resources are only avialable on habited planets. For example, slave labor, living creatures.
#3 - If you arrive in an inhabited system and you want the resources of it, native competition is your first concern.

i.e The Independence Day aliens.

I seriously doubt they were going to just strip mine Earth. That was all that was of concern to the POTUS, so he probably didn't care about the rest of the Solar System, or the pilot didn't bother mention that, and was just fucking with him.

(Never take an invader's word at face value)

MOre then likely, there plan was to
#1 - Wipe out Earth. With there superior technology, and wiping out most of the human race via City-destruction prior to the ground invasion, they weren't going to face alot of formidable resistance. Case in point, until they dropped there shields, our strongest weapons had no effect on them, and they only lost a few fighters prior to that.
A few fighters, and they destroyed how much of Earth's defenses? That's one hell of a kill ratio.

#2 - Strip mine Earth
#3 - Strip mine the other planets in the solar system.
#4 - Leave the entire solar system devoid of useable resources, and then bugger off to the next system, possible with a larger fleet by that point.

[Starglider]

Relgion: see the Idirians in the Culture novels.

[Uraniun235]

But without magic substances? Anything alien planet X can give you, you can get or build from asteroids in your own solar system for much cheaper.

Including water?

[Starglider]

Including water?

Yes. The outer solar system is filled with icy bodies; the Kuiper belt, the Oort cloud, assorted icy moons.

[Balrog]

But without magic substances? Anything alien planet X can give you, you can get or build from asteroids in your own solar system for much cheaper.

Including water?

You could try collecting it from random interstellar objects like comets, though you're not going to get anywhere near the kind of load you'd get off a water world.

The most likely reason would seem to be an Ender's Game situation, where the two sides are just so totally different that a misunderstanding leads to war. Religion's also a nice spark to start the fire.

[Patrick Degan]

#1 - Living Space, same as in Earth history

Not a problem with the probable number of habitable worlds in the galaxy and there's always the engineering option of orbital habitats in any star system with abundant metals and a healthy main-sequence star pumping out gobs of free energy.

#2 - Some resources are only avialable on habited planets. For example, slave labor, living creatures.

Robots are cheaper.

#3 - If you arrive in an inhabited system and you want the resources of it, native competition is your first concern.

Why bother trying to plunder its minerals when there are plenty of stars within nearby range where nobody's living and everything there is free for the taking?

i.e The Independence Day aliens.

I seriously doubt they were going to just strip mine Earth. That was all that was of concern to the POTUS, so he probably didn't care about the rest of the Solar System, or the pilot didn't bother mention that, and was just fucking with him.

(Never take an invader's word at face value)

MOre then likely, there plan was to
#1 - Wipe out Earth. With there superior technology, and wiping out most of the human race via City-destruction prior to the ground invasion, they weren't going to face alot of formidable resistance. Case in point, until they dropped there shields, our strongest weapons had no effect on them, and they only lost a few fighters prior to that.
A few fighters, and they destroyed how much of Earth's defenses? That's one hell of a kill ratio.

As Lawrence Krauss once pointed out in deliciously graphic terms, the aliens didn't even need to launch fighters. They could have devastated Earth and killed off its population simply by orbiting their big ships around the planet (tidal braking) and skimming the surface with the slightly smaller ones (letting bow-shock friction do all the work of burning the surface clean). But then again, if the aliens do what is scientifically plausible and logical, the movie is probably quite short.

#2 - Strip mine Earth
#3 - Strip mine the other planets in the solar system.
#4 - Leave the entire solar system devoid of useable resources, and then bugger off to the next system, possible with a larger fleet by that point.

But again, why bother? If minerals are your only goal, there are plenty of stars with uninhabited worlds which can be strip-mined orbiting a star of respectable energy output and you don't have to go to any trouble to wipe out natives since there aren't any.

[TithonusSyndrome]

Sure, there's plenty of resources in the vastness of space, but if they're cheaper and more accessible to take from one place, then it might be more cost effective to go to war over them anyways. It's a bit like asking why the powers of colonial Europe would ever want to go to war when they had all of their holdings abroad.

[Ariphaos]

Sure, there's plenty of resources in the vastness of space, but if they're cheaper and more accessible to take from one place, then it might be more cost effective to go to war over them anyways. It's a bit like asking why the powers of colonial Europe would ever want to go to war when they had all of their holdings abroad.

So, why does Sol stick out over countless surrounding red dwarfs?

The only reason someone would wage a war for typical resources is a homogenization scenario. Beyond that, supernova remnants might be fought over, for rare isotopes. You can also make up unobtanium for it.

If FTL requires a map that matters (stargates, fixed wormholes, etc), systems have strategic value. Religious and other idealogical means have already been described, including 'kill them before they kill us'. The last is also rather boring - just point your star at their planet, though if they are of similar technical advancement they might be able to move it sufficiently.

[Ford Prefect]

Not a problem with the probable number of habitable worlds in the galaxy

Out of curiosity, what is the probable number of habitable world's in the Milky Way?

[Plekhanov]

Sure, there's plenty of resources in the vastness of space, but if they're cheaper and more accessible to take from one place, then it might be more cost effective to go to war over them anyways. It's a bit like asking why the powers of colonial Europe would ever want to go to war when they had all of their holdings abroad.

That analogy just doesn't work, first of all the colonial powers in Europe were right next too each other so the resources expended in travelling to get to war were minimal, the same obviously can't be said for interstellar combatants.

The European powers also had long histories of power struggles and warfare between them which resulted in disputed territory & bad feeling between them which helped fuel conflicts. European wars were by no means always rational affairs launched after the combatants worked out if they'd be 'cost effective'. The same level of bad blood is most unlikely with interstellar combatants.

[GrandMasterTerwynn]

#1 - Living Space, same as in Earth history

Not really. The typical starsystem is packed full of raw materials and energy just waiting to be transformed into habitable space. Even if you had a distinct preference for planets, you'd probably seek out the ones where the natives are barely beyond the single-celled organism stage, and the galaxy should be positively lousy with those, and rather devoid of competitors at your technological level. Even warfare within your species is unlikely on the interstellar level. Sure you might want to fight over colonizable systems . . . but depending on how hard your sci-fi is, starships would likely be so obscenely expensive that these battles will be largely waged in courtrooms and stock markets.

#2 - Some resources are only avialable on habited planets. For example, slave labor, living creatures.

No. Slaves are an incredibly inefficient way of getting things done. Not only do you have to care for them and their unique biochemistries, but you have to be on the lookout for slave revolts and things of the like. The only feasible reason an interstellar-level civilization would engage in slavery is either because they use it as psychological terror weapon, to enforce their superiority on someone they've already beaten in war, or because they do all their fighting by proxy. And if, say, you were a little gray alien from Zeta Reticuli, and you wanted a billion Earth cows, all you'd really need to do is buy or steal enough for adequate genetic diversity (50 in this example) and then make 999,999,950 more through the miracle of cloning, all on a planet, or a planet's equivalent of orbital habitats under your control.

#3 - If you arrive in an inhabited system and you want the resources of it, native competition is your first concern.

No, again. There would be substantial pressure to seek systems where the most sophisticated form of life is blue-green algae, or maybe non-sapient life, if you're feeling up to fucking around with mature ecosystems. Native life, in this case, simply doesn't stand a chance. There wouldn't be a reason to go after an industrialized planet, because the natives are busy fouling things up with their native and undoubtedly inefficient processes. Attempting to go after developed systems maintained by other interstellar powers would likely be obscenely expensive that building a starship whose primary purpose (shooting at other ships) involves the distinct possibility that ship might get blown up would be seen as an extravagant waste. And even if you were to target spaceflight-capable (but not interstellar) civilizations, the disparity of powe is such that you could drive them back to their home planet, lock them in, and spend the next 10,000 years cleaning out the rest of their solar system at your leisure . . . whilst dropping the occasional asteroid on them to ensure they stay back in the Stone Age. Or just drop one large asteroid on them and be done with it.

#1 - Wipe out Earth. With there superior technology, and wiping out most of the human race via City-destruction prior to the ground invasion, they weren't going to face alot of formidable resistance. Case in point, until they dropped there shields, our strongest weapons had no effect on them, and they only lost a few fighters prior to that.
A few fighters, and they destroyed how much of Earth's defenses? That's one hell of a kill ratio.

Why go through the trouble? It's not as if Earth today could stop an alien species from dropping a large asteroid or two, or ten. Or accelerating smaller projectiles to significant fractions of c. An interstellar race could wipe out Earth and never have to even meet humans on the field of battle.

#2 - Strip mine Earth

Thus adding an energy penalty of some 62 MJ per kilogram of material boosted into orbit. It'd be easier to mine asteroids.

#3 - Strip mine the other planets in the solar system.

Thus adding an energy penalty of similar scale to that added by strip mining Earth. It would still be easier to mine the asteroids and comets.

#4 - Leave the entire solar system devoid of useable resources, and then bugger off to the next system, possible with a larger fleet by that point.

As inherently pointless as this is, it could easily be accomplished without ever meeting the natives. Especially given the gross disadvantage Earth would be at.

[Gigaliel]

Alien invasions would be quite pointless unless life were so ludicrously common that Earth's underdeveloped system was a rare treasure. Even then they could just ignore Earth. One wonder why we've never noticed any of this life. In this scenario, all nearby stars would already be being harvested. Such massive expansion does not seem to have a point, but that's never stopped intelligence before.

Another possibility is the morality angle where the aliens 'conquer' the primitives and attempt to uplift them to be members of the interstellar community. Perhaps an appeal to biodiversity? To shelter us from the aliens who would try to use our star system for themselves? This would probably make a more compelling story, since any other scenario means conquest/extermination is easy and/or pointless.

As for the possibility of interstellar war in general, it will most occur during the initial colonization phase to determine who gets rights to the star. I say this because interplanetary warfare is vastly easier, so it would probably continue until one side has been kicked out of the system.

On the other end of the scale is when the core worlds have depleted their resources and now have the 'mere' output of their star left. If the outer settlements stop exporting raw materials, things could get antsy with civil wars in star systems and opportunists attempting to take their neighbors stars.

There's also the possibility of people getting a little too greedy and mining the stars themselves for materials. By that point a 'predatory expansion wave' would be possible, depending on how feasible star-mining is. After all, once the star's gone there's no reason to stay.

That isn't too silly with exponential growth and advanced robotics, but it's a bit far in the future. Stellar mining especially, all the consequences would be interesting.

[GrandMasterTerwynn]

As for the possibility of interstellar war in general, it will most occur during the initial colonization phase to determine who gets rights to the star. I say this because interplanetary warfare is vastly easier, so it would probably continue until one side has been kicked out of the system.

Not really. In any semi-plausible interstellar warfare, it's always the invader who holds the high ground, as there's little you can do to stop him from parking out at the edge of a system's Edgeworth-Kuiper belt and slinging fractional-c projectiles into the system, or just boosting comets inward, forcing the defender to spend his time swatting incoming projectiles. (Well, I suppose if the defender has any mass-drivers of his own, he could shoot back at the invading ships. And this may, in fact, discourage invading a system if your starships are expensive enough. Although, you could drop off your small fry well outside the system and hope you've done it in a region of space the defenders aren't watching... since a bunch of maneuvering spaceships with the power generation necessary to launch fractional-cee projectiles are going to stick out like a sore, and very bright thumb. And since a space habitat, planet, or asteroid is going to be a big, obvious IR target on a predictable trajectory, you could probably smash all the meaningful infrastructure in the starsystem you're trying to invade hours, days, weeks, maybe even months before the defenders can get their navy out to you. Sure, it'll suck to rebuild all that infrastructure, but if you've got the sort of industry that can afford to build spaceships that could possibly get blown up, then rebuilding a space habitat isn't going to be much of a problem for you. And if the defending system has any sort of unified government, their tolerance for casualties and collateral damage may be such that they'll be begging for mercy before you get around to smashing everything.

[Patrick Degan]

Not a problem with the probable number of habitable worlds in the galaxy

Out of curiosity, what is the probable number of habitable world's in the Milky Way?

That of course would depend upon the definition of "habitable" and which biology you'd be talking about.

I think, though, that the Rand Corporation once did a crude analysis many years ago on the subject and their calculations came up to a figure of a possible 3 million Earth-type worlds in our galaxy, with our conditions for life to exist. I don't know what criteria were used to arrive at this figure, though, so take it as you will.

[Nephtys]

Them or Us seems like the most probable scenario to me. Most human nations are paranoid enough of each other, but what about a completely unknown alien intelligence? Tensions are going to go up long before they go down. With no common history, language or even biology, very little is going to prevent one side from glassing the other if they think they can get away with it cleanly.

[Nyrath]

Out of curiosity, what is the probable number of habitable world's in the Milky Way?

That sort of depends upon your definition of "habitable."

If by habitable you mean a world possessing an environment comfortable for a human being in their shirt-sleeves, Stephen Dole derived a figure of about 1.15 x 10^-5 human habitable solar systems per cubic light year.

If by habitable you mean a world that it is not quite impossible for some kind of exotic extremophile life form to exist, my calculations with the HabCat database suggest a figure of about 5.14 x 10^-4 alien habitable solar systems per cubic light year.

An acquaintance of mine did some calculations based upon The Cambridge Atlas of Astronomy, and concluded that the milky way's disk plus the bulge had a volume of approximately 8.17 x 10^12 cubic light years. The disk, bulge, and halo had a volume of approximately 5.24 x 10^14 cubic light years.

[Gigaliel]

As for the possibility of interstellar war in general, it will mostly(Ed: Bad Gigal) occur during the initial colonization phase to determine who gets rights to the star. I say this because interplanetary warfare is vastly easier, so it would probably continue until one side has been kicked out of the system.

Not really. In any semi-plausible interstellar warfare, it's always the invader who holds the high ground, as there's little you can do to stop him from parking out at the edge of a system's Edgeworth-Kuiper belt and slinging fractional-c projectiles into the system, or just boosting comets inward, forcing the defender to spend his time swatting incoming projectiles. (Well, I suppose if the defender has any mass-drivers of his own, he could shoot back at the invading ships. And this may, in fact, discourage invading a system if your starships are expensive enough. Although, you could drop off your small fry well outside the system and hope you've done it in a region of space the defenders aren't watching... since a bunch of maneuvering spaceships with the power generation necessary to launch fractional-cee projectiles are going to stick out like a sore, and very bright thumb. And since a space habitat, planet, or asteroid is going to be a big, obvious IR target on a predictable trajectory, you could probably smash all the meaningful infrastructure in the starsystem you're trying to invade hours, days, weeks, maybe even months before the defenders can get their navy out to you. Sure, it'll suck to rebuild all that infrastructure, but if you've got the sort of industry that can afford to build spaceships that could possibly get blown up, then rebuilding a space habitat isn't going to be much of a problem for you. And if the defending system has any sort of unified government, their tolerance for casualties and collateral damage may be such that they'll be begging for mercy before you get around to smashing everything.

Interesting point there, it would seem the offense has quite the advantage, as you've stated. I suppose this could lead to interstellar warfare of a different kind, with intercepts of possible constructor vehicles via mass drivers shooting via fine clouds of metal very, very fast to make sure you hit something that far out. Of course, the offense could simply take multiple possible approaches from different directions to overwhelm their defenses with heat signatures. That would require a lot of constructors and a lot patience, but this is space warfare so that's a given.

[Coyote]

That would be a frustrating but painfully realistic story: powerful, advanced aliens show up in our star system, and we have days of partying, probably no few riots, all sorts of reaction as attempts are made to communicate... then we just watch, helpless, as they cut through the asteroid belt, strip-mine the jovian belts, slurp all the water off of Titan, then leave, without ever so much as a glance in our primitive-ass direction.


Or another one, of all the ironies, would be if they came here to convert us to their religion.

[Darth Wong]

Or another one, of all the ironies, would be if they came here to convert us to their religion.

Sci-fi villains generally don't have that motive, which is too bad. It could make for interesting writing. DS9 kept hinting that it might go this way, but it always pulled back. The Bajoran religious fanatic storylines faded away. The Dominion religion turned out to be nothing more than a racial supremacy ideology. Wouldn't it have been cool if someone was actually out to convert the Federation, and they took advantage of loose Federation immigration policies to do it.

[Dillon]

Or another one, of all the ironies, would be if they came here to convert us to their religion.

Sci-fi villains generally don't have that motive, which is too bad. It could make for interesting writing.

See seasons 9&10 of Stargate SG1.

[Lord of the Abyss]

Living space/resources for out of control replicators/breeders, living or robotic.

Instinct/programming. Starfire Arachnids, Anne McCaffrey's Hivers, Weber's Kanga, Sabrehagen Berserkers and various other species/machine races that attack others because they are made or evolved to do so.

Religion/ideology, as mentioned.

Paranoia. "They might be able to kill us someday, so kill them first !"

Plain old power lust.

[Balrog]

Or another one, of all the ironies, would be if they came here to convert us to their religion.

Sci-fi villains generally don't have that motive, which is too bad. It could make for interesting writing.

See seasons 9&10 of Stargate SG1.

He said generally, not always. Personally I suspect people don't want to touch on the subject of forced conversion to religion because it's a, um, 'touchy' subject.

[Battlehymn Republic]

Not that sci-fi lacks many religious zealot races. Though it's usually more of the "destroy destroy glass glass" sort.

But I'm not so sure if it's "touchy." I think it'd just be harder to develop a realistic alien culture and religion and make the race relatable to us. And make the conflict more interesting than "most people see the light except for a few oldliner fundies lol what ludds!" Just why did some people hold on to traditional religion in B5 even after they found out about the role of the Vorlons and the Shadows, anyways?

[Plekhanov]

Not that sci-fi lacks many religious zealot races. Though it's usually more of the "destroy destroy glass glass" sort.

But I'm not so sure if it's "touchy." I think it'd just be harder to develop a realistic alien culture and religion and make the race relatable to us. And make the conflict more interesting than "most people see the light except for a few oldliner fundies lol what ludds!" Just why did some people hold on to traditional religion in B5 even after they found out about the role of the Vorlons and the Shadows, anyways?

Why are there still Jehovahs Witnesses after all those failed end of the world prophesies? Why do people continue to give money to disgraced televangelists?... the answer is of course that their beliefs are structured in such a way as to be largely immune from evidence.