How powerful could a hard sci-fi civilization be?

[Darth Yoshi]

There are always going to be limits on the detection range of that technology. What are these limits ?

What is the maximum range at which they can detect an earth sized planet ?

With precise enough instruments and powerful enough computers you could probably determine the number and type of planets around every star you see. The problem is actually seeing the star. Trying to see past the galactic bulge, for instance, is pretty much going to be a wash, no matter how advanced you get, simply because the light from the far side of the galaxy is going to get absorbed by interstellar dust, and what gets through will be washed out by the bulge itself.

[Blayne]

I took the original post of this thread to mean a Kardashev IV civilization (The Time Lords are seen as Type IV but in a soft sense, so imagine they have earths technology but in the size of a phone, while we would need the whole surface of the planet turned into a Coruscent type mega city to get the same effect).

A Type-IV civilization would probably be constantly producing a non trivial number of Dyson spheres, matrioshka brains and ringworlds, probably at a minimum as many as the UFP and GE produce star ships. Possibly cover more than one galaxy and use wormhole or casmir tubes to link the farthest edges together like in Supreme Commander.

They could conceivably scrounge up FTL technology and would easily have the power to do, when they already are harvesting the ambient glow of a galaxy for power producing sufficient amounts of anti matter or exotic partcles to achieve Alcubierre's level may be possible.

From Michiu Kaku's "SciFi Science: Physics of the Impossible" there's a lot of "soft" scifi that is actually possible with physics as we know it, just have energy and fabrication challenges that we find prohibitively expensive to solve, but as a Type IV? Possibly trivial.

A Hard Scifi Type-IV civilization I think should be able to scrounge up comparable technology to a soft scifi one, probably just not anywhere nearly as elegant or easy to use.

So a large argument, of detecting and attack mass driver weaponry before they can be fired I consider highly impractical, it would be like trying to find one particularly noisy volvo with a gunrack in New York City... on foot. Because they are already routinely constructive megastructures of that size and telling one apart from another of peaceful purposes vs military may not be an easy task.

[Sea Skimmer]

You took the original post completely wrong then because it clearly said our understanding of physics and engineering limits applies. That puts stuff like Dyson spheres completely out of the question. You also of course plainly ignored all the followup when some interesting workarounds were proposed. Thanks for showing once more why your going to be on probation forever.

[Borgholio]

As far as detecting planets, even with OUR limited tech we are finding hundreds of planets out there with the Kepler telescope. A hard sci-fi civilization would likely have used Kepler-like technology as well as highly advanced optical / infrared space telescopes to identify nearly every planet in the galaxy (aside from the stuff on the other side of the core, maybe...). So knowing the location and orbital mechanics of all the planets in the galaxy for a very long time means they can be targeted easily. As said before, they don't need to identify enemy worlds, just nuke them all.

[Connor MacLeod]

All this talk of 'nuking every planet in the galaxy' brings back flashbacks of all those RDA related Avatar threads and shit, and not in a good way.

[Jub]

Why do we keep assuming a magical wormhole dropping heaps of Star Destroyers into the Hard Scifi galaxy? Wouldn't it be more interesting to suppose that both galaxies pass close to each other, as far as galaxies go, and send teams over to investigate. Star Wars vessels, would be stuck traveling STL because hyper-drives, while impressive, still do have range limits. This means first contact will be made by scout ships provisioned for long voyages instead of both sides going in guns blazing. Star Wars will gain the advantage when it comes time for their ships to go exploring in the new galaxy, but people used to long trips at relativistic streams might have an easier time getting there.

Now what happens with the scouts and who is more able to launch an invasion should one or both sides decide that hostility is called for?

[Sea Skimmer]

That was basically my assumption, the hard sci fi power has expanded throughout all of time, meaning it might well span a billion light years, and eventually comes butting up against the Star Wars Galaxy. Limiting the hard side to one galaxy is just unfair, and at odds with the idea its had massive amounts of time to expand. We should still have stars around in a few billion years right? So it should be expanding for a very long time. If we took such a case, the situation actually favors the empire even more then a wormhole. At least with a wormhole the hard side might have news of the war show up inside its territory, and provide a point against which it can even try to focus its absurdly slow moving power.

If scouts from both sides met in interseller space meanwhile, the Empire will know its at war within at worst maybe weeks or months, more likely days since hyperspace travel between galaxies should be much easier then within them, limited only by the need to make refueling stops, and not the gravity well of random planets. Meanwhile the hard sci fi power... even if the two galaxies are close together, say 10,000 LY, it might need thousands of years to know anything had happened at all. That's just for notice to reach the edge of the galaxy, then it needs 100,000 years to spread across the whole galaxy. Then millions of years to notify other galaxies. All assuming of course that such long range communication is even possible, I'd assuming it is if nothing else the hard sci fi power should be able to build some kind of giant blinker light the size of several solar systems employing billions of fusion bombs.

In effect the hard sci fi power is incapable of operating as one civilization against a force that can move at high end FTL speed. It would be every system for itself. Its only saving grace is shear size might allow it to keep unknowingly expanding in other directions as quickly as the Empire is blowing it up. At least for a long time until the Empire has mobilized completely vast forces.

[Jub]

That was basically my assumption, the hard sci fi power has expanded throughout all of time, meaning it might well span a billion light years, and eventually comes butting up against the Star Wars Galaxy. Limiting the hard side to one galaxy is just unfair, and at odds with the idea its had massive amounts of time to expand. We should still have stars around in a few billion years right? So it should be expanding for a very long time. If we took such a case, the situation actually favors the empire even more then a wormhole. At least with a wormhole the hard side might have news of the war show up inside its territory, and provide a point against which it can even try to focus its absurdly slow moving power.

If scouts from both sides met in interseller space meanwhile, the Empire will know its at war within at worst maybe weeks or months, more likely days since hyperspace travel between galaxies should be much easier then within them, limited only by the need to make refueling stops, and not the gravity well of random planets. Meanwhile the hard sci fi power... even if the two galaxies are close together, say 10,000 LY, it might need thousands of years to know anything had happened at all. That's just for notice to reach the edge of the galaxy, then it needs 100,000 years to spread across the whole galaxy. Then millions of years to notify other galaxies. All assuming of course that such long range communication is even possible, I'd assuming it is if nothing else the hard sci fi power should be able to build some kind of giant blinker light the size of several solar systems employing billions of fusion bombs.

In effect the hard sci fi power is incapable of operating as one civilization against a force that can move at high end FTL speed. It would be every system for itself. Its only saving grace is shear size might allow it to keep unknowingly expanding in other directions as quickly as the Empire is blowing it up. At least for a long time until the Empire has mobilized completely vast forces.

That makes sense, though in order to invade the Empire/New Republic would have to create ships with crazy amounts of fuel carried, that is, if they intend to use hyperspace to make the trip. Also, depending on where the fleets cross paths along the way, assuming that they do, the HSF scout fleet might send word back about FTL capable ships. This might not reach the first HSF galaxy in time to help, but it might reach the second galaxy so they might know to start researching FTL technology.

Still, barring something crazy any FTL civ will have a large advantage against an STL civ barring some major drawback.

[Sea Skimmer]

If the HSF force needs FTL technology to win then I'd call that end of thread as far as HSF vs Empire goes, the HSF isn't winning with hard tech, needs to beat someone weaker. I do however agree that this is what would most likely actually happen. The Empire isn't bloody likely to be able or willing to take out the HSF at the actual speed of light and so preclude warning completely. But then it also seems pretty likely that the two sides wouldn't go to war out of hand either since the resources of even one Galaxy are so completely massive. Precious little reason exists to fight on an intergalatic scale when we fully well know the Empire isn't even remotely close to using all the planets and systems it has while the HSF is just too damn slow and divided to be able to consider offensive war.

As for fuel, yes, big problem if we assume that ICS figure of 250,000 LY range is typical for Imperial ships. But since they get the fuel from black holes, and have Centerpoint Station which can somehow move black holes, I doubt they have any serious hard cap on how much energy they can produce, and we know the can build massive freighters enmass such as the Trade Federation Fleet. Just imagine a Death Star built as a tanker with the main reactor downscaled and all the superlaser stuff and facilities for armies and such replaced by tankage. That ought to handily support a whole armada of Eclipse hulls across interseller distances until advanced fuel production and storage depots can begin be setup.

[lPeregrine]

All this talk of 'nuking every planet in the galaxy' brings back flashbacks of all those RDA related Avatar threads and shit, and not in a good way.

I don't think it's at all the same. It's not about "that movie sucked, it didn't end in genocide, let's fix that", it's about what is the most practical response to the scenario. The hard scifi civilization has no way to defend against hit and run attacks using FTL to jump in, fire a shot, and jump out before the defenders even know the ship arrived. And even if you take away tactical FTL (through a need to have jump points or gates or whatever) you still probably have ships with magic-level weapons and durability, so any conventional battle is just going to be a massacre, and you still probably have strategic FTL to worry about.

So, with that in mind the only real options for the hard scifi civilization are surrender, or attempt to force a MAD stalemate.

At least for a long time until the Empire has mobilized completely vast forces.

But how long will that take? The Empire in Star Wars might be able to build ships at an absurd rate, but can they do it without collapsing their own economy? Can they build an army capable of invading and conquering an entire galaxy (or more), since merely destroying everything would be a pretty pointless war? Or will a wartime economy and massive conscription cause widespread rebellion and a new government that is perfectly willing to sign a neutrality treaty with the hard scifi civilization?

Then there's also the fact that Star Wars FTL is absurdly fast in their own galaxy. Remember that "travel through hyperspace ain't like dusting crops" line? Presumably they have excellent navigational data on their own well-explored galaxy, but would they have the same in interstellar space, or in a completely unknown galaxy? How would this impact their use of long-distance FTL? Would it be slower, or would it even be possible at all?

And of course that's just considering the Empire. How about the Star Trek Federation? Still soft scifi, still has FTL and magic weapons and all those nice things, but has a tiny number of ships. Each ship might be able to conquer a system with little opposition, but how fast can they do it on a galactic scale with a small fleet and relatively slow FTL? And of course the logistics issues become even worse, they don't have a meaningful army (and there seems to be little support for making one), so how are they going to occupy their new territory? They certainly can't afford to keep a starship in every system.

[Simon_Jester]

A developed hard SF system would be nigh-invulnerable to Federation/Klingon/whatever attack, if they had the scale of defenses possible when you start building big rings of solar panels around your stars.

[Borgholio]

All this talk of taking thousands or millions if years to communicate in the hard sci fi civilization ignores all the currebt work going into quantum entanglement. Near-instant communication across vast distances, and it really isnt all that fictional anymore. I'd say the hard sci-fi civ would possibly have an easier time communicating than most soft sci fi civs. Star Trek subspace radio for instance, has a measurable time delay that grows as distance increases.

[Sea Skimmer]

Everything I've seen on quantum entanglement in the past suggests it will only work with a closed system, not an open broadcast through empty space subject to random interference. Do you have a link around that explains how it would be able to work point to point, rather then through a cable or other conduit?

But how long will that take? The Empire in Star Wars might be able to build ships at an absurd rate, but can they do it without collapsing their own economy?

They have an awful long time to work with, that doesn't seem like a serious issue for a civilization that already lasted thousands of years and survived at least three galaxy spanning wars I can think of. The Death Star was built in secret, even if it drew on a lot of overt resources that's a silly accomplishment in its own right. We know they have the ability to build all kinds of autonomous war machines and construction systems, a large scale military buildup planned over centuries might take place entirely independently of the civilian economy. Various EU sources imply this is how the Separatists were able to launch a Galactic civil war even though they were based on the rim of the galaxy and not the rich core.

Can they build an army capable of invading and conquering an entire galaxy (or more), since merely destroying everything would be a pretty pointless war? Or will a wartime economy and massive conscription cause widespread rebellion and a new government that is perfectly willing to sign a neutrality treaty with the hard scifi civilization?

Who says the war has to have a point? I already said earlier I don't think they'd fight at all, but that generally isn't the point of threads like this based on 'who could beat xxx'

Then there's also the fact that Star Wars FTL is absurdly fast in their own galaxy. Remember that "travel through hyperspace ain't like dusting crops" line? Presumably they have excellent navigational data on their own well-explored galaxy, but would they have the same in interstellar space, or in a completely unknown galaxy? How would this impact their use of long-distance FTL? Would it be slower, or would it even be possible at all?

An unknown galaxy would surely take time, or many hyperspace drones expended as scouts. Interseller space should be easy, given its lack of tightly packed gravity wells. I certainly think vast scope exists to debate HSF vs Star Trek or even people stronger then Star Trek though I'm personally not too knowledgeable on any on powers stronger then Trek but weaker then Wars.

[lPeregrine]

They have an awful long time to work with, that doesn't seem like a serious issue for a civilization that already lasted thousands of years and survived at least three galaxy spanning wars I can think of.

Sure, they were galaxy spanning, but what percentage was actually involved in the fighting? Now compare that kind of civil war to the invasion that would be required to conquer an entire galaxy (or more), especially if they're actively resisting occupation instead of the civilian population just shrugging and getting on with life with new faces on the money once the space battle is over. You can't just kill the Emperor in one key battle and take over as the new rightful government, you're going to have to build an army capable of simultaneously occupying (potentially) millions of inhabited systems.

Who says the war has to have a point? I already said earlier I don't think they'd fight at all, but that generally isn't the point of threads like this based on 'who could beat xxx'

The war doesn't have to have a point, but I think it's fair to ask "can they actually create the necessary forces before their population gets sick of the whole thing". That factor wouldn't necessarily stop the war from beginning, but it could certainly make a difference in when and how it ends. Say, they might spend a decade on a maximum-effort offensive and conquer hundreds of systems, but face widespread revolt in their home galaxy before they can conquer the millions that remain.

I think this is especially true since an attrition strategy would almost be mandatory for the hard scifi civilization. Just be disruptive enough to demand an occupation force in every system, and take advantage of the sheer number of systems that have to be occupied to wear out the invading force. Even if you never win a single battle you still win the war if your enemy is unable to claim more than 0.0001% of your territory.

An unknown galaxy would surely take time, or many hyperspace drones expended as scouts. Interseller space should be easy, given its lack of tightly packed gravity wells.

Oh, it could be done in the end. My point is just that without the navigational information provided by having your civilization in place for thousands of years it's going to be a much slower process. Even if the Empire has absurdly fast FTL on a small scale (say, in the explored region they're focusing their first invasion on) on the scale of conquering the entire galaxy things might slow down to the point where the information wave of their arrival has time to reach the full extent of the hard scifi civilization.

[Sea Skimmer]

Sure, they were galaxy spanning, but what percentage was actually involved in the fighting?

The Vong war and hyperspace war certainly tore clear across the galaxy, the scope of the civil war the movies focus on is less clear, it certainly spanned the galaxy but may only have involved a limited count of systems. On the other hand the speed of hyperdrive kind of forces everyone to be on a constant war footing, since an armada from across the galaxy could show up with little warning.

Now compare that kind of civil war to the invasion that would be required to conquer an entire galaxy (or more), especially if they're actively resisting occupation instead of the civilian population just shrugging and getting on with life with new faces on the money once the space battle is over. You can't just kill the Emperor in one key battle and take over as the new rightful government, you're going to have to build an army capable of simultaneously occupying (potentially) millions of inhabited systems.

I fail to see why occupation would be required. A garbage scow with a single turbolaser and a good sensor suit in orbit could keep a planet suppressed indefinitely if destruction was judged undesirable. Eventually they'll surrender, especially if the Empire offers favorable terms. But as far as an all out fight to the death goes, blowing up everything important on the surface and sending a ship back every 5,000 years to make sure no advanced life has learned how to sharpen sticks ought to work. People are proposing that the HSF force fight by attempting to blowup every planet in the Empire, so this is actually a far more reasonable approach then that.

The war doesn't have to have a point, but I think it's fair to ask "can they actually create the necessary forces before their population gets sick of the whole thing". That factor wouldn't necessarily stop the war from beginning, but it could certainly make a difference in when and how it ends.

I suspect the Imperial population will get sick of a victorious war far away much more slowly then the HSF population will get sick of loosing a war bring fought all around them. Yes, it certainly would matter if this war effects the local economy, but it seems plausible and likely that the Empire would progressively shift to building its forces in the conquered galaxies. The biggest problem would be making sure those forces don't declare independence, but then, even if they did it wouldn't really matter as long as they keep defeating the HSF people.

Say, they might spend a decade on a maximum-effort offensive and conquer hundreds of systems, but face widespread revolt in their home galaxy before they can conquer the millions that remain.

The revolt might be a problem back home, but it doesn't seem like the rebellion ever came remotely close to winning until the Emperor died, and while such long lasting wars as this debate requires aren't typical, it seems reasonable to assume his successors would keep up the war. Or we could just say unlimited supply of clone emperors for TEH WIN! I think that's a bit lame, and that's also why I've made zero mention of the sun crusher. It would be lame as shit to say the Empire just builds billions of the sun crusher sun exploding torpedoes, I forget the exact name, and sends them out on giant tankers to blow up every star in all the galaxies in the adjacent universe.

I think this is especially true since an attrition strategy would almost be mandatory for the hard scifi civilization. Just be disruptive enough to demand an occupation force in every system, and take advantage of the sheer number of systems that have to be occupied to wear out the invading force. Even if you never win a single battle you still win the war if your enemy is unable to claim more than 0.0001% of your territory.

You avoid total defeat. You don't win anything in my book.

Oh, it could be done in the end.

But that's all that really counts.

My point is just that without the navigational information provided by having your civilization in place for thousands of years it's going to be a much slower process. Even if the Empire has absurdly fast FTL on a small scale (say, in the explored region they're focusing their first invasion on) on the scale of conquering the entire galaxy things might slow down to the point where the information wave of their arrival has time to reach the full extent of the hard scifi civilization.

That could well be true, but I don't think information that they are being attacked is really going to matter anyway. If we told Zulu warriors from 1879 they are going to be carpet bombed by B-52s they might devise a strategy that largely avoids losses, but they'd still have no actual means to stop the raids. I did say earlier I think its possible the HSF might be so big it can just expand as fast as it gets blown up, or maybe faster, but this entirely depends on how people think the HSF should be able to get. Also it runs into the problem that the threads gives them all the time in the universe, but that can be interpreted differently. Obviously it would not be very useful to have the battle commence 1 second before the entire galaxy implodes to create another big bang or just before heat death occurs. I've been treating it to mean they've expanded across ~500 galaxies/~1 billion LY, discovered all possible technology and hyper developed everything they have. Obivously if they actually have 60,000 galaxies and 10 billion LY of span, its going to be a damn lot more likely that they can expand to fill the entire universe ahead of the Empire. But still that does not really meaningfully contribute to ability to defeat the Empire.

[lPeregrine]

The Vong war and hyperspace war certainly tore clear across the galaxy, the scope of the civil war the movies focus on is less clear, it certainly spanned the galaxy but may only have involved a limited count of systems. On the other hand the speed of hyperdrive kind of forces everyone to be on a constant war footing, since an armada from across the galaxy could show up with little warning.

Conceded on that point, I haven't bothered to keep up with the EU since early/mid-Vong war.

I fail to see why occupation would be required. A garbage scow with a single turbolaser and a good sensor suit in orbit could keep a planet suppressed indefinitely if destruction was judged undesirable. Eventually they'll surrender, especially if the Empire offers favorable terms.

I agree that it probably doesn't take much of a force to secure a system (at least for the Empire) thanks to long-range turbolasers + FTL, but that's still a ship. It still has to be built, supplied, given a crew, brought into the HSF galaxy, etc. And it still can't really DO much once it's there, it can probably stop outgoing planet killers, but can it, say, protect a mining operation in the system's asteroid belt? More realistically you're probably going to have some kind of orbital presence, some ground troops protecting the local Imperial government building, etc. Now multiply this by a few million, if not billions.

And of course this is going to be a much bigger problem for other opponents. For example, the Federation and its much lower starship count is going to have a hard time putting even a garbage scow in a meaningful number of systems.

But as far as an all out fight to the death goes, blowing up everything important on the surface and sending a ship back every 5,000 years to make sure no advanced life has learned how to sharpen sticks ought to work. People are proposing that the HSF force fight by attempting to blowup every planet in the Empire, so this is actually a far more reasonable approach then that.

Well, to be clear, my proposal isn't so much an all out fight to the death as an offer of a neutrality treaty backed up by a few billion relativistic planet killers, with a hope of forcing a MAD stalemate where neither side is willing or able to make a serious attempt at conquering the other.

You avoid total defeat. You don't win anything in my book.

Why not? Look at the strategic objectives: the HSF civilization has no hope of invading and conquering without FTL, and launching a planet killer attack in anything but a MAD scenario would be utterly pointless. The only meaningful objective they could possibly have would be to obtain a neutrality agreement while keeping their civilization intact. In that sense, a scenario that costs them ten thousand planets out of millions in exchange for the end of the invasion accomplishes their objective.

That could well be true, but I don't think information that they are being attacked is really going to matter anyway.

It matters in the sense of the question of whether the HSF civilization can communicate news of the invasion in time to get the planet killers launched before FTL forces arrive and stop them. If it takes long enough you have a scenario where the "we're being invaded by magic enemies we can't defeat, launch everything in a year if you don't hear otherwise" message gets out, and the invaders have to choose between accepting the stalemate or putting their defenses to a real test with entire planetary populations at stake.

Now, the effectiveness of this strategy is up for debate depending on the opponent, but it's not hard to imagine a scenario where they're capable of using it.

Also it runs into the problem that the threads gives them all the time in the universe, but that can be interpreted differently. Obviously it would not be very useful to have the battle commence 1 second before the entire galaxy implodes to create another big bang or just before heat death occurs. I've been treating it to mean they've expanded across ~500 galaxies/~1 billion LY, discovered all possible technology and hyper developed everything they have. Obivously if they actually have 60,000 galaxies and 10 billion LY of span, its going to be a damn lot more likely that they can expand to fill the entire universe ahead of the Empire. But still that does not really meaningfully contribute to ability to defeat the Empire.

TBH I'd argue for an even smaller civilization. The space between galaxies is just too large of a discontinuity when you don't have FTL, so I think it would be hard to argue that it's still a single entity in any meaningful sense. I suppose the HSF civlization might throw some seed probes into other galaxies just because they can, but I think they'd end up being separate entities.


Edit: I guess you could imagine a civilization operating on a really slow time scale where a span of a billion light years is all unified in a single entity even without FTL, but what would that even look like? Would it even be anything similar enough to the inhabitants of the Empire that they could interact with each other? Or would they arrive in the first "empty" HSF galaxy and go about their business, completely unaware of the civilization existing alongside them? Or, if they're used to considering such absurdly long time periods, they could simply "win" by surrendering and waiting the incredibly short (to them) time before the Empire ages and dies, and then go right back to their normal existence with barely a historical footnote to record the invasion.

[Sky Captain]

How useful relativistic planet killers would be? Empire easily could spam interstellar space around every important system with recon drones to detect incoming RKV attack and warn system defense forces. Then warship jumps close to a calculated path and blasts RKV. Any leftover debris and cloud of relativistic plasma could be dealt by planetary shields.

[Simon_Jester]

By the way...

You took the original post completely wrong then because it clearly said our understanding of physics and engineering limits applies. That puts stuff like Dyson spheres completely out of the question.

Could you expand on that? What's your thinking that goes between the first and second sentences?

[lPeregrine]

How useful relativistic planet killers would be? Empire easily could spam interstellar space around every important system with recon drones to detect incoming RKV attack and warn system defense forces. Then warship jumps close to a calculated path and blasts RKV. Any leftover debris and cloud of relativistic plasma could be dealt by planetary shields.

That's why sensor range is a very important question. If you can spot the planet killer from halfway across the galaxy stopping it is trivial. If you have to be within a light-second of it you're screwed, the volume of space you have to search is just way too huge. You'd be relying on blind luck to find everything, and for every shot you find you're probably missing thousands (or worse) aimed at the same target.

And don't forget that a fully developed civilization could potentially throw billions of shots at you, all with their own engines so they can go on indirect flight paths (fire at an angle, use the engines a few hundred years later to get back on course). They're such a useful weapon that it's reasonable to think that every settled system (or deep space habitat) would have at least a few planet killers to ensure MAD if another faction in their civilization launches a similar attack against them, and there are a lot of stars in an entire galaxy.

So, the question becomes how badly do you want to win the war? Are you absolutely certain that you can stop 100% of the incoming shots? Because if you can't, you're going to be losing a lot of inhabited planets.

[Sky Captain]

A lot also depends on how effective planetary shields are against RKV. If shielding can take one without problem then it is only imprtant to spot RKV only with enough warning time to power up the shield.
Since planetary shields can stand up to civiliazation ending level of firepower from Imperial ships they also should be able to protect from RKV attack of comparable power. If RKVs were effective against shields Empire would use them against rebellious planets since with their technology fielding RKVs would be trivial.

[Sea Skimmer]

By the way...
Could you expand on that? What's your thinking that goes between the first and second sentences?

I was talking about solid ones, alongside the mentioned ring worlds. These are not possible structures, at least not unless they are in fact held together by vast numbers of engines that remove stress from the connections and make them more like a group of moored ships then anything we would call a structure today. That would also make them pretty pointless.

[Connor MacLeod]

Star Wars vessels, would be stuck traveling STL because hyper-drives, while impressive, still do have range limits. This means first contact will be made by scout ships provisioned for long voyages instead of both sides going in guns blazing. Star Wars will gain the advantage when it comes time for their ships to go exploring in the new galaxy, but people used to long trips at relativistic streams might have an easier time getting there.

Yes, they do have FTL limits on their engines, but not in the sense that 'there is an absolute limit' type of thing. The main reason that SW was suppoesd to be limited to its galaxy was that silly 'hyperspace barrier' crap. There's actually reason to believe travel between galaxies is possible: the Vong did it, more than a few other races from 'outside' the galaxy did it (those aliens who produced Vuffi Raa.) and the Outbound Flight project was going to leave the galaxy as well, IIRC. Are we assuming for some reasons they're only going to be building the starships they've only ever built before and are completely incapable of coming up with a new design, and if so, why?

Moreover, if the SW galaxy is outside the hyperdrive range of this other galaxy, then how did the two come into contact at all to begin with? STL travel is not exactly commonplace in Star Wars, and unless the two are in some sort of range it's unlikely that the SW ship would just 'stumble' across the galaxy on accident.

Really this is a huge unknown because we don't quite know all the reasons and parameters behind those long ranges and how it all works out. For example, there could be an inverse relationship between speed and range (EG going faster uses fuel far less efficiently. Or any number of factors tied to the differences in reactors or whatnot.) Hyperdrives can be run on a variety of fuel sources and not just on hypermatter.. the hypermatter seems to be used as both a fuel source and for other purposes as far as FTL goes.

As for fuel, yes, big problem if we assume that ICS figure of 250,000 LY range is typical for Imperial ships.

I wouldn't assume that. The Acclamators had a 250,000 LY range, but the Venators had only 60,000 LY. And the various Separatists ships had (IIRC) 30,000, 40,000 and 150,000 LY. And those ranges reflect full fuel supplies IIRC, so we're also talking 'max range before running empty'. Which also means that hyperdrive range can be further limited by other performance requirements (acceleration needs, offensive and defensive requirements, etc.) EG an Venator that 20K LY has 40K LY of range left, but if he has to use the max engine/shield/guns option for any lenght of time (~3 hours is what I remember being Curtis' endurance for max-power ISDs) that could be cut down dramatically (so much the ship may not even be able to make it home.) In the SW galaxy this isn't an issue, but in other scenarios its up for debate.

But since they get the fuel from black holes, and have Centerpoint Station which can somehow move black holes, I doubt they have any serious hard cap on how much energy they can produce, and we know the can build massive freighters enmass such as the Trade Federation Fleet.

I think you're confusing what the AOTC:ICS said was involved in creating the gravitic components of repulsors with fuel. Though I'd guess they probably use 'natural' fuel sources (EG stars, or maybe black holes) to make hypermatter fuel in the same way you might use that to create antimatter.
Some vessels have run on black holes (World Devastators) though.

Just imagine a Death Star built as a tanker with the main reactor downscaled and all the superlaser stuff and facilities for armies and such replaced by tankage. That ought to handily support a whole armada of Eclipse hulls across interseller distances until advanced fuel production and storage depots can begin be setup.

Alot of this depends entirely on the distances between the two galaxies, the political factors (how much is the SW galaxy willing to devote to achieving victory?) and the manner they go about prosecuting the war. As I said already, I kinda doubt they're just going to do nothing but build ISDs and hurl them at the enemy simply because that's all they know. If they can't reach the target with existing ship designs (or if those designs prove incapable of beating the enemy) then they'll just devise some other means of achieving it. It comes down to how much effort they need to invest to reach the galaxy, not whether or not they can do so.

And I should note there's lots of ways SW can go about fighting this war. Build a hyperspace capable starfighter, but instead of putting the usual systems in you just put in a droid brain/computer control and guidance system, an engine of some kind (and enough fuel to achieve the objective) and fill the rest of the volume with some sort of warhead. 'Voila' hyperspace missiles with potentially multi-LY ranges.

Hell with their FTL comms ability, their automation capabilities, etc. It's quite possible they could simply just launch a bunch of expendable FTL bombs at the opposing galaxy.

A developed hard SF system would be nigh-invulnerable to Federation/Klingon/whatever attack, if they had the scale of defenses possible when you start building big rings of solar panels around your stars.

I'm not quite sure what you're envisioning as 'nigh-invulnerable' exactly. I mean if its a galactic-scale STL civilization spanning thousands or tens of thousands of LY, then I imagine the ST side might be defeated by the sheer distances involved (given their FTL performance) but I'm not sure why you infer that the ST side would be incapable of attacking them if the STL side had 'sufficient scale of defenses'.

[Connor MacLeod]

I don't think it's at all the same. It's not about "that movie sucked, it didn't end in genocide, let's fix that", it's about what is the most practical response to the scenario. The hard scifi civilization has no way to defend against hit and run attacks using FTL to jump in, fire a shot, and jump out before the defenders even know the ship arrived. And even if you take away tactical FTL (through a need to have jump points or gates or whatever) you still probably have ships with magic-level weapons and durability, so any conventional battle is just going to be a massacre, and you still probably have strategic FTL to worry about.

So, with that in mind the only real options for the hard scifi civilization are surrender, or attempt to force a MAD stalemate.

You're missing the point. Let me reiterate:

What is the strongest science fiction faction a socially, politically, intellectual and morally enlightened civilization, that has passed all significant threats of extinction, defeat?

Note bolded. And the STL civilization (I despise the term 'hard' sci fi, since it evokes imagery of precisely of dick waving.) seems to be focused solely on hurling relativistic genocide packages across the galaxy to destroy anyone who MIGHT be a threat. Why not go whole hog and envision the Hard sci fi version of the Imperium of man? Why wait for them to come to you and just throw them out the minute you could start building them!

Now 'defeat' could be handled in alot of ways. It could mean 'bringing the other side under your control or influence.' If we go with the sort of civilizaiton, say Terwynn is envisioning, then they supposedly have these fantastic predictive capabilities, immortality, and all sorts of other neat toys and engineering capabilities. So why can't they greet the SW (or whatever FTL soceity they run across) side openly and peacefully, and then fight them on other terms? Economically, diplomatically, politically? I could see Terwynn's civilization being able to fight the GE on those terms far better, and the FTL issue isn't quite so decisively one sided.

I suppose this does depend on your morality of course, since that can be subjective, but I'm pretty sure few people agree genocide is a good thing Instead, such a 'morally and intellectually enlightened' society might approach it from the POV of 'conversion' - trying to win over or conquer the other side through means other than physical, destructive conflict.

But how long will that take? The Empire in Star Wars might be able to build ships at an absurd rate, but can they do it without collapsing their own economy? Can they build an army capable of invading and conquering an entire galaxy (or more), since merely destroying everything would be a pretty pointless war? Or will a wartime economy and massive conscription cause widespread rebellion and a new government that is perfectly willing to sign a neutrality treaty with the hard scifi civilization?

It's going to depend on how big a STL civlization they're facing, and their capabilities? See, this is the problem I'm having here. As others have noted since page one, this is a ludicrously open-ended discussion, and the parameters so broad you can basically handwave any sort of 'hard' sci fi civilizaiton into existence that could probably beat the GE at some point, and the only way the GE can win is if it somehow can beat them all. A bit lopsided, really, and it reminds me uncomfortably of a 'moving the goalposts' sort of thing.

That isn't to say that economics, industrial and even political factors don't matter on the GE (or any universes) side: They make a HUGE difference. Even having all those massive resources doesn't guarantee the Empire will use them efficiently (they rarely do - greed and corruption and generally not having any serious threats to confront can do that, I suppose.) nor that it will treat the opposition as a legitimate threat automatically. But those are just more open ended variables to address, and the conversation is murky enough.

More to the point, the SAME applies to the other side of the debate as well, even though it consistently appears to me we're assuming the hypothetical 'hard' sci fi civilization is in 'god mode' or something (human factors, resource and economic limitations, etc. apparnetly don't exist anymore, for some reason.)

The best indicator I can come up with as far as economics go is that Palpy curtailed a great deal of the Holonet to fund and supply his military buildup (because IIRC from WEG stuff, the Holonet was supposed to be a huge, expensive project the Old Republic maintained.) WE might figure the Death Stars and similar superweapons represented a fair fraction of that budget, but it doesn't factor in everything else it might have been devoted to, human greed and other related factors, how it was spent, or what fraction of the Holonet it actually represented. There was also the bit from the Imperial sourcebook about the Death STar (first one) represnting enough resources to devote to a score of Sector Groups, but that leads to some truly absurd resource figures (thousands of sector groups in the galaxy, to give you an idea, from that SAME source.) which may or may not be true.

[Jub]

Star Wars vessels, would be stuck traveling STL because hyper-drives, while impressive, still do have range limits. This means first contact will be made by scout ships provisioned for long voyages instead of both sides going in guns blazing. Star Wars will gain the advantage when it comes time for their ships to go exploring in the new galaxy, but people used to long trips at relativistic streams might have an easier time getting there.

Yes, they do have FTL limits on their engines, but not in the sense that 'there is an absolute limit' type of thing. The main reason that SW was suppoesd to be limited to its galaxy was that silly 'hyperspace barrier' crap. There's actually reason to believe travel between galaxies is possible: the Vong did it, more than a few other races from 'outside' the galaxy did it (those aliens who produced Vuffi Raa.) and the Outbound Flight project was going to leave the galaxy as well, IIRC. Are we assuming for some reasons they're only going to be building the starships they've only ever built before and are completely incapable of coming up with a new design, and if so, why?

Moreover, if the SW galaxy is outside the hyperdrive range of this other galaxy, then how did the two come into contact at all to begin with? STL travel is not exactly commonplace in Star Wars, and unless the two are in some sort of range it's unlikely that the SW ship would just 'stumble' across the galaxy on accident.

Really this is a huge unknown because we don't quite know all the reasons and parameters behind those long ranges and how it all works out. For example, there could be an inverse relationship between speed and range (EG going faster uses fuel far less efficiently. Or any number of factors tied to the differences in reactors or whatnot.) Hyperdrives can be run on a variety of fuel sources and not just on hypermatter.. the hypermatter seems to be used as both a fuel source and for other purposes as far as FTL goes.

That's pretty much what I figured they would end up doing. Either they build some sort of carrier to bring warships across the void, or they build new ship classes that are able to make the journey themselves and refuel themselves on site. The bigger issue is convincing people to man these missions at all when the galaxy yet has unused resources that are far closer and easier to exploit.

People from the STL side, those that are inclined to explorer at any rate, already know that going to a new star is pretty much a one way trip. Thus finding people to move between galaxies instead of stars should be easier for them. Of course that doesn't mean they'll accomplish much of an invasion when they arrive in the Star Wars galaxy, but they're the side more likely to make the trip at all.

[Borgholio]

Everything I've seen on quantum entanglement in the past suggests it will only work with a closed system, not an open broadcast through empty space subject to random interference. Do you have a link around that explains how it would be able to work point to point, rather then through a cable or other conduit?

It doesn't currently work point to point, since it takes a fair bit of time to even know that the spin of the particle has changed. Lots of the stuff so far discussed in this thread as staples of the hard sci-fi civilization are currently just theoretical or in their infancy. At least quantum entanglement communication is more plausible than subspace radio.