Brainstorming a sci-fi setting, and justifying interstellar war

[Gradine]

Honestly, the biggest logical cause of intergalactic war in a post-scarcity galaxy is the existential threat of pre-emptive annihilation. It is relatively easy, from an aeronautical physics perspective, to fling a big enough object fast enough at any given planet to just wreck everyone's day. Wiping out a potential threat before they do it you becomes an appealing, if also appalling, choice. Doesn't give you a lot of cause for smaller-scale warfare, though.

Beyond that, limiting safe FTL to specific lanes/routes makes control of specific territory significantly more important.

The easiest answer though is not go the post-scarcity route. War often has economic motives, and economics doesn't really play a role without scarcity. Of course, resources could be theoretically (or even practically) possible or even available, but artificially curtailed by those in control of those resources in order to maintain economic and social stratification. Artificial scarcity is one way that elites maintain their profit margins in the face of infinite supply. If you ever wanted to see what this actually looks like in action, try to check out a bestseller as an ebook from your local library.

 

[MarkB]

One thing to bear in mind is that, while Mechs may not make sense as the nearly-sole, primary means of combat engagement, they could still make sense as just one part of a larger military. For your game, you don't need to justify why Mechs are the premier combat machine always, everywhere. You only need to justify why they're being usefully employed here and now.

 

[Deset Gled]

This is potentially legit but it implies that for some reason people need to live on planets. That multigenerational space habitats are non-viable for some fundamental reason (mental health?) and that terraforming is not an option.
This, then is why no one is employing planet killers or nukes from space.

Space habitats are non-viable for a lot of very serious reasons. Abnormal gravity is really bad for heart health or any kind of development, increased radiation has obvious issues, and the long term effects of limited diet, no exposure to fresh air and sunlight, etc, are very real.

And terraforming? Pffft. That's just science fiction.

 

[Mustrum_Ridcully]

I feel like some "problems" start if you assume anyone has the ability to achieve relativistic speeds. What if they don't?
Battletech jump ships are actually perfect for that, as are Stargates. You have a mobility cheat code, basically. None of these ships achieve relativistic speeds in any conventional way, using thrusters and reaching high percentages of c. They just blink from A to B without passing the space in-between. So you can't make orbital bombardments with relativistic kill projectiles. You don't have the tech for making things go that fast.

You can't drop asteroids from orbit, because either the gate isn't in orbit, or your jump ship cannot jump into orbit, the asteroid must be moved with rockets from weeks away from your intended target, giving plenty of time to destroy or deflect it.

Even Star Trek warp drive or Star Wars hyperdrive kinda suggests you're cheating with subspace or hyperdrive and the kinetic energy of these ships might not be in any way related to what they'd be by relativistic or newtonian mechanics. So flying at Warp 9 into a planet might actually only hit as hard as flying at it at Mach 9 might. Ouch, but not "please spare my civilization" (well, for Star Trek, the antimatter stored aboard these ships still pose a problem. Even at speed 0.)

Okay, that cares of all the orbital trickery of devestating a planet "easily", or threatening to do so. So even if you don't actually care about what's down there, it takes a lot of effort to do so, because you need to protect your killer asteroids. The defender has the disadvantage of needing to shoot its defensive measures upwards against the gravity well, but the advantage of a huge surface it can launch from.

The real problem remains probably is - what is worth fighting for if you have an entire planet or star system at your disposal in the first place, and there are plenty of them that aren't in use right now?
One thing that's obviously valuable is habitable worlds. It will take us a long time to actually build self-sustainable space habitats, if it's possibe at first place at scales smaller than a full planet. Terraforming is super-hard. But if the habitable planet is the source of conflict, sounds like it will really mean a lot of genocide in the setting, every planet being overpopulated? Harsh. And maybe nothing where just "honor fights" would be used, it's a fight for survival..
Or is it actually about the people themself? Do you want them alive, but for some reason under your control? Like you want everyone to be your religion? (Maybe a sci-fi psionic religion, where if everyone learns a particular way of thinking, a psychic power awakens that can do things, like piercing the veil of our existence into a new form of existence?) Maybe strictly regulated "honorable" warfare is required, because you don't want to lose too many people, and the goal is to prove your way of thinking is the proper way?

 

[MGibster]

One thing to bear in mind is that, while Mechs may not make sense as the nearly-sole, primary means of combat engagement, they could still make sense as just one part of a larger military. For your game, you don't need to justify why Mechs are the premier combat machine always, everywhere. You only need to justify why they're being usefully employed here and now.

In the Battletech universe you still have military forces made up of combined arms including conventional vehicles (tanks, trucks, hover vehicles), aircraft like helicopters, bombers, & fighters, naval units including submarines, and of course the good old fashioned infantry. In game, mechs are justified because they're quicker than conventional vehicles and tougher. I'm certainly not going to argue it's realistic, but there's at least some in-universe justification for their use. Of course the game tends to focus mechs rather than anything else. I've seen stats for a submarine in Battletech but I've never seen one used.

 

[Tonguez]

One thing to bear in mind is that, while Mechs may not make sense as the nearly-sole, primary means of combat engagement, they could still make sense as just one part of a larger military. For your game, you don't need to justify why Mechs are the premier combat machine always, everywhere. You only need to justify why they're being usefully employed here and now.

yeah, one thing the sci-fi game I mentioned before was self contained Asteroid Mining Mechs (GRAMPuS) dropped from orbit. In one scenario PCs had to face a modified GRaMPuS that had been modified by a pirates led by Grutte Pier. It became an excuse for PCs to use their own mech suits too, primarily for deployment on asteroids, trojans and remote planetoids.

 

[Dannyalcatraz]

Honestly, the biggest logical cause of intergalactic war in a post-scarcity galaxy is the existential threat of pre-emptive annihilation. It is relatively easy, from an aeronautical physics perspective, to fling a big enough object fast enough at any given planet to just wreck everyone's day. Wiping out a potential threat before they do it you becomes an appealing, if also appalling, choice. Doesn't give you a lot of cause for smaller-scale warfare, though.

OTOH, true “post-scarcity” might not really be possible. It may only be true in a relative sense. For instance, the antagonists in the Bear novels are engineering on system-wide levels. Using drones to destroy civilizations leaves the planetary/system resources intact for use later- essentially, like a scaled-up neutron bomb.

 

[Epic Meepo]

The real problem remains probably is - what is worth fighting for if you have an entire planet or star system at your disposal in the first place, and there are plenty of them that aren't in use right now?

"Someone is wrong on the Internet. They must be corrected. Assemble the mech army."

 

[RangerWickett]

In the Battletech universe you still have military forces made up of combined arms including conventional vehicles (tanks, trucks, hover vehicles), aircraft like helicopters, bombers, & fighters, naval units including submarines, and of course the good old fashioned infantry. In game, mechs are justified because they're quicker than conventional vehicles and tougher. I'm certainly not going to argue it's realistic, but there's at least some in-universe justification for their use. Of course the game tends to focus mechs rather than anything else. I've seen stats for a submarine in Battletech but I've never seen one used.

Oh man, the vehicle rules are silly, because they max out at the same 100 tons as mechs. Even in the 1960s our small gunboats were running about 250 tons.

 

[MGibster]

Oh man, the vehicle rules are silly, because they max out at the same 100 tons as mechs. Even in the 1960s our small gunboats were running about 250 tons.

Pretty much everything was on the mech scale. So you'd end up with a 100 ton fighter with what were, practically speaking, extremely short ranged weapons measuring in the hundreds of meters.