Interstellar government in hard sci-fi.

[The Romulan Republic]

This topic has some similarities to this one: viewtopic.php?f=4&t=165924

However, here, my focus is more specifically on government and political systems, rather than trade or culture.

The question at hand is: what sort of government (if any) would be possible across interstellar distances, presuming an absence of practical FTL?

I'd assume that a high level of decentralization would be a must. Membership would likely be more voluntary than obligatory, with no real means of enforcing unity against a secession movement given the distances involved. Likewise, I would expect that most affairs would be governed locally, with the higher levels of government mostly concerning themselves only or primarily with things like intersystem communications/trade, colonization and exploration/first contact protocols, and dealing with any major (ie system-level or greater) conflict or calamity, as well as perhaps broad principles of sentient rights.

Probably such an organization, if it even came into being, would be more of an alliance or a loose confederacy than anything else. It might also require some powerful cultural force, such a religious conviction or a shared monarchical tradition, to unite it across such distances, although other, more palatable possibilities could perhaps be devised.

However, these are just preliminary thoughts. Mainly, my question is: would a government across interstellar distances be possible, or practical, under any circumstances, in a setting without practical FTL tech.?

[Simon_Jester]

I honestly think you'd be more likely to see something like what Vernor Vinge portrayed in A Deepness In The Sky. Namely, a loosely affiliated culture of starship operators, who by virtue of being separated from any single planetbound civilization by so many years of time between visits, become their own separate thing. They wouldn't be very good at the whole 'government' thing, but would tend to be the 'mortar' that ties together and creates structural bonds between the 'bricks' of individual star system or planetary governments.

[The Romulan Republic]

That's an interesting concept that I hadn't really thought of.

Another thing that occurred to me:

IIRC, crew on a ship approaching light speed would effectively age more slowly. So you would have a society of (from the point of view of most people) extremely long-lived starship operates, who might be witness to (and thus able to influence) the fate of planetary systems over generations, and act as a sort of "living history".

I wonder if, rather than a traditional government, you might see some sort of Spacer Guilds exercising political and economic influence.

If you wanted to go for more of a science-fantasy vibe, I guess you could have knightly orders in space or something. Travelling/questing between systems over the course of years.

[Formless]

It really just depends, as always, on how hard is hard and what kinds of assumptions you make. The hardest science fiction probably won't have interstellar societies at all, so its a non-issue. You have to first justify people leaving the solar system to begin with, which in soft science fiction is justified with FTL. If you have FTL, then you probably can justify just about any form of government. If you don't, then the question is how are people leaving the solar system? Does time dilation come into play? If so, then there is going to be a big cultural divide between those who live the spacer lifestyle and those who settle on a planet or other colony. Do ships not travel that fast? Then you are probably talking about sleeper ships, in which case there is no such thing as an interstellar government; it just isn't practical. Is there FTL communication? That also changes things. There might not be interstellar government per-say, but there might be interstellar internet and a whole host of interesting possibilities regarding how it is handled and "governed" so to speak. There might be subcultures for instance who spend most of their time in virtual reality interacting with people lightyears away with all that implies for social interactions and culture. Obviously this shouldn't be too surprising to anyone living in the 21'st century, but amplify that by the impossibility of ever traveling to those places you hear about.

And there are more things to take into consideration as well. Do you want to inject transhumanist or cyberpunk themes into your work? If, for instance, someone can live for many centuries then a lot of the assumptions I just made start to fall apart. It might actually become possible for interstellar governance to be a thing again if people can take trips to places lightyears away and still expect their loved ones to be alive when they get back. Can people dissociate their minds from their original body? Mind you, we aren't just talking about mind uploading, but any method of allowing a mind to act independantly of the body; for instance, I remember reading a story a long time back where ther was no FTL travel, but there was FTL communication, and there was the technology for someone to take control of a remote control android body in another solar system while their body at home was put to sleep; thus they could simulate FTL travel but couldn't not actually, and this was plot relevant because it was a mystery story involving someone apparently committing a crime that required actual FTL travel (there was no log of an android being used).

There are a lot of things to think about. Questions of governance highlight the absurdities of "Hard" science fiction and brings us into the realm of social science fiction.

[The Romulan Republic]

It really just depends, as always, on how hard is hard and what kinds of assumptions you make. The hardest science fiction probably won't have interstellar societies at all, so its a non-issue. You have to first justify people leaving the solar system to begin with, which in soft science fiction is justified with FTL. If you have FTL, then you probably can justify just about any form of government. If you don't, then the question is how are people leaving the solar system?

I don't think you need FTL to justify extra-solar travel. Sure, some of the more obvious motives are curtailed by the time and expense involved, but there are some possibilities. A system-wide catastrophe, like a black hole or star going nova, is one, of course. Some people will just want to explore new worlds, regardless of weather there's an obvious short-term material motive for doing so, meaning that if the cost drops low enough, an eccentric billionaire or future trillionaire could conceivably fund such an enterprise. Or you might have a persecuted/fringe society or cult which wants to set up their own little version of Utopia, away from all the heathens.

When all else fails, religion will always serve to motivate humans to spend a great deal of money and time on impractical things.

Does time dilation come into play?

Presumably, if you get going fast enough.

If so, then there is going to be a big cultural divide between those who live the spacer lifestyle and those who settle on a planet or other colony.

Discussed, briefly, in the preceding two posts.

Do ships not travel that fast? Then you are probably talking about sleeper ships, in which case there is no such thing as an interstellar government; it just isn't practical.

Probably not a government with actual practical ability to enforce its authority, at any rate.

Is there FTL communication? That also changes things. There might not be interstellar government per-say, but there might be interstellar internet and a whole host of interesting possibilities regarding how it is handled and "governed" so to speak.

Well, this thread as I set it up was postulating pure STL, but I did consider adding a "FTL coms. but no FTL propulsion" scenario. Feel free to discuss how that would change things, if you wish.

There might be subcultures for instance who spend most of their time in virtual reality interacting with people lightyears away with all that implies for social interactions and culture. Obviously this shouldn't be too surprising to anyone living in the 21'st century, but amplify that by the impossibility of ever traveling to those places you hear about.

Yeah, I can absolutely see that.

And there are more things to take into consideration as well. Do you want to inject transhumanist or cyberpunk themes into your work?

Well, I was more just exploring the theoretical implications of this scenario than asking for feedback for a specific story, but yeah, a lot's going to depend on the person writing the scenario.

If, for instance, someone can live for many centuries then a lot of the assumptions I just made start to fall apart. It might actually become possible for interstellar governance to be a thing again if people can take trips to places lightyears away and still expect their loved ones to be alive when they get back. Can people dissociate their minds from their original body? Mind you, we aren't just talking about mind uploading, but any method of allowing a mind to act independantly of the body; for instance, I remember reading a story a long time back where ther was no FTL travel, but there was FTL communication, and there was the technology for someone to take control of a remote control android body in another solar system while their body at home was put to sleep; thus they could simulate FTL travel but couldn't not actually, and this was plot relevant because it was a mystery story involving someone apparently committing a crime that required actual FTL travel (there was no log of an android being used).

There are a lot of things to think about. Questions of governance highlight the absurdities of "Hard" science fiction and brings us into the realm of social science fiction.

Could you elaborate on what you mean by "the absurdities of "Hard" science fiction"?

Beyond that, yeah, these are all good points.

[Formless]

I don't think you need FTL to justify extra-solar travel. Sure, some of the more obvious motives are curtailed by the time and expense involved, but there are some possibilities. A system-wide catastrophe, like a black hole or star going nova, is one, of course. Some people will just want to explore new worlds, regardless of weather there's an obvious short-term material motive for doing so, meaning that if the cost drops low enough, an eccentric billionaire or future trillionaire could conceivably fund such an enterprise. Or you might have a persecuted/fringe society or cult which wants to set up their own little version of Utopia, away from all the heathens.

When all else fails, religion will always serve to motivate humans to spend a great deal of money and time on impractical things.

I think when you do the math on traveling at relativistic speeds, or look at the nuances of sleeper ships and keeping them running for millennia, it becomes harder and harder the more you know to believe anyone is leaving this solar system in the next thousand years. Especially when you look at some of Freeman Dyson's ideas on how much of the solar system we could actually be using in as little as the next few centuries.

Probably not a government with actual practical ability to enforce its authority, at any rate.

A government that can't enforce the law isn't really a government. I suppose if you had long lived rulers you might be able to justify space empires built primarily on some sense of abstract loyalty, but it wouldn't qualify as a nation in the modern sense. Indeed, the concept is far more medieval when you get to the heart of it.

Could you elaborate on what you mean by "the absurdities of "Hard" science fiction"?

That its an ill-defined term and any attempt to refine the definition beyond "technology and physics obsessed" stories runs afoul of personal perceptions of plausibility, realism, and what scientific discoveries are acceptable to speculate on. For instance, some people might allow FTL as an acceptable break from reality in a Hard science fiction setting so long as it is handled properly. Others might not even allow relativistic travel because the rocket equation is such a harsh reality. It depends on the individual. At the end of the day, all Science Fiction is speculative in nature, so perfect realism is out of the genre's reach forever. But among those who consider themselves fans (or more often in my observation, fans of the concept) of Hard science fiction there is this absurd notion that personal perception does not play a part in deciding what is Hard and what is soft, and this very forum has had debates about this in the past. Of course, then you end up discussing things like this very thread and it comes up that in fact, it totally matters whether FTL is a thing or not, or whether Relativistic ships are allowable or whether interstellar colonization is even a thing that can truly be considered "Hard science fiction."

This may be one of my personal bugbears, but it is relevant insofar as "social" science fiction is often more conservative about breaking known science than "hard" science fiction, because physics isn't the main interest of those who write it. Things like psychology, society, and (relevant to this thread) governance are the primary topic. Yet sometimes the term is used as a synonym for Soft science fiction. Its another absurdity.

[The Romulan Republic]

I think when you do the math on traveling at relativistic speeds, or look at the nuances of sleeper ships and keeping them running for millennia, it becomes harder and harder the more you know to believe anyone is leaving this solar system in the next thousand years. Especially when you look at some of Freeman Dyson's ideas on how much of the solar system we could actually be using in as little as the next few centuries.

Oh, agreed that any utilitarian advantage or financial motive is dubious at best (barring a "destruction of the system is imminent" scenario).

That's why I brought religion into it. I mean, you could argue that the Great Pyramids or the gothic cathedrals weren't the wisest use, pragmatically, of Europe's money, or of the decades it took to build them.

A government that can't enforce the law isn't really a government.

Indeed.

I suppose if you had long lived rulers you might be able to justify space empires built primarily on some sense of abstract loyalty, but it wouldn't qualify as a nation in the modern sense. Indeed, the concept is far more medieval when you get to the heart of it.

Yeah, I thought about that as well.

Perhaps some sort of space feudalism (God, that sounds so hokey), where wealthy individuals finance their own interstellar colony expeditions, with the founding family ruling as System Lords (to borrow a term from Stargate) and kings in all but name, but owing theoretical loyalty to a monarchy back on Earth?

But that seems a bit contrived, as "insert culture from Earth's past into the future" scenarios tend to.

That its an ill-defined term and any attempt to refine the definition beyond "technology and physics obsessed" stories runs afoul of personal perceptions of plausibility, realism, and what scientific discoveries are acceptable to speculate on.

Well, there will always be disagreements on what constitutes "hard" sci-fi, I suppose.

For instance, some people might allow FTL as an acceptable break from reality in a Hard science fiction setting so long as it is handled properly. Others might not even allow relativistic travel because the rocket equation is such a harsh reality. It depends on the individual. At the end of the day, all Science Fiction is speculative in nature, so perfect realism is out of the genre's reach forever. But among those who consider themselves fans (or more often in my observation, fans of the concept) of Hard science fiction there is this absurd notion that personal perception does not play a part in deciding what is Hard and what is soft, and this very forum has had debates about this in the past. Of course, then you end up discussing things like this very thread and it comes up that in fact, it totally matters whether FTL is a thing or not, or whether Relativistic ships are allowable or whether interstellar colonization is even a thing that can truly be considered "Hard science fiction."

Well, I would tend to go with something like "Anything that does not explicitly contradict the laws of nature as they are generally understood by contemporary science is permissible." Though even then, I dare say there'd be a lot of grey areas where a scientific consensus is lacking.

This may be one of my personal bugbears, but it is relevant insofar as "social" science fiction is often more conservative about breaking known science than "hard" science fiction, because physics isn't the main interest of those who write it. Things like psychology, society, and (relevant to this thread) governance are the primary topic. Yet sometimes the term is used as a synonym for Soft science fiction. Its another absurdity.

I don't see why the social sciences should be any less legitimate grounds for speculation than the "hard" sciences.

[Swindle1984]

I would assume that the home world would maintain an advantageous position because, while the colonists were traveling to their destination and attempting to set up a functional society and all the infrastructure it needs, the home world would have been making several centuries of technological progress. The home world would also be the sole source of additional colonists, supply drops, and technical data on all that new technology for quite some time, as it's highly unlikely a newly established colony would be building its own colony ships any time soon, if ever. The home world could simply threaten not to send any more immigrants, supplies, or technology to the colony, leaving them entirely on their own, if the colony refuses to play ball. The home world could even potentially send a ship full of soldiers armed with weapons centuries ahead of whatever the colonists are armed with in order to enforce their rules, as long as the soldiers didn't mind the trip being one way, stayed loyal to the government upon arrival, and you didn't mind waiting several centuries for them to put down any independence movement.

The problem is, what does the colony even have to offer the home world if we're talking about sub-light travel? Beaming scientific data about their new home back to Earth is all well and good, but it's hardly the same as the resources the European colonies in America and Africa sent back to their respective homelands. A dumping ground for malcontents and undesirables, ala Australia? Just pack them in a ship and send them off, who cares what kind of reception they get once they arrive? It's not your problem anymore; you'll be long dead by the time they arrive, and they're never coming back anyway. And even if the colony ship was refueled, packed with gold instead of passengers and supplies, and sent back to Earth, is that really economically feasible?

I imagine that, unless the government/corporations/wealthy individuals responsible were able to afford subsequent ships carrying additional colonists and supplies, any colony world would be entirely cut off from Earth except for radio/laser messages that take years to travel back and forth. The colonists wouldn't care about Earth culture or entertainment and would be solely interested in new technical data about all the improvements in technology and science they've made in the meantime, and perhaps snippets of news regarding 'current' events, while all the colonists would have to offer in exchange is scientific data and news about the wellbeing of the colony and whether or not sending another ship would be worth it. And the answer would be, it'd pretty much only be worth it if you were either one of the passengers on the next colony ship, or the colony ship was a means of getting rid of a problem, such as overpopulation, prisoners, etc. that you couldn't feasibly resolve by a more practical means.

[Simon_Jester]

That's an interesting concept that I hadn't really thought of.

Another thing that occurred to me:

IIRC, crew on a ship approaching light speed would effectively age more slowly. So you would have a society of (from the point of view of most people) extremely long-lived starship operates, who might be witness to (and thus able to influence) the fate of planetary systems over generations, and act as a sort of "living history".

I wonder if, rather than a traditional government, you might see some sort of Spacer Guilds exercising political and economic influence.

If you wanted to go for more of a science-fantasy vibe, I guess you could have knightly orders in space or something. Travelling/questing between systems over the course of years.

Note that unless the spaceships are capable of flight at, like, 99.something percent of the speed of light, time dilation isn't enough to stretch lifetimes out into several centuries or millenia, unless the crews are spending nearly all their flight time in cryogenic suspension or something.

And travel speeds like that are, uh... not very much hard SF.

Also, READ VERNOR VINGE HE IS GLOURIOUS.

More generally, it's worth noting that this question is just as valid and worthy of being asked if we imagine any hard-SF society that does not assume "everyone is a brain upload into a giant computer," including one in the insanely distant future of millions of years from now. After spans of time sufficient for an interstellar colony world to have grown to full industrial and economic competitiveness with the homeworld.

[Sea Skimmer]

Yeah at any hard sci fi velocity the time factor isn't a big deal, even 40% of C doesn't do much and that's about the maximum you are likely to get out of a feasible engine and spacecraft that's able to decelerate on arrival, and even that's really pushing matters. Graphs and tables here
https://www.fourmilab.ch/cship/timedial.html

The idea of hard sci fi pure spacefareing people having special influence doesn't make sense either, because people constantly moving in space will have much smaller resources then people tied to planetary systems, less access to information and less diversity. Also while they live longer in relative terms, they do not experience more time for personal experience, so it's not like they get smarter or something. They remain normal people, and in fact far from being in a position to be super citizens they will be left behind intellectually by the higher rates of progress by planetary system populations.


If people leave the solar system they are just going to be on there own in governmental terms. Military alliances might exist in the very long term, trade would have little importance given the resources of a single solar system and extreme time delays, barring discovery of very large amounts of very rare raw materials. Anyway the whole point of expanding to the stars is to keep expanding so one disaster can't wipe out all mankind, which means spreading across at least several hundred light years. At that point even keeping in touch communication wise would become very difficult and hell... people probably would stop caring about news that was hundreds of years old.

[Swindle1984]

At that point even keeping in touch communication wise would become very difficult and hell... people probably would stop caring about news that was hundreds of years old.

"Has Earth sent us the specs for that new terraforming atmospheric generator they told us about?"

"Not yet, we just finished downloading this month's tightbeam transmission. Let's see... what the hell is a Cardashian and why do we care?"

[K. A. Pital]

As others said, depends a lot on the hardness level, but as defined (no FTL), here is an answer from elsewhere,

Hardest SF: transhuman crewed or crewless ships, space as a frontier, no unified government unless with extreme brainwashing / cultural conditioning / technological self-mo, extremely complicated communication once distances start exceeding the first few light-years. This is just one option, but it is a lot like trade between city-states. Planets exist, they have their government or governments, and inbetween are sublight ships ferrying goods between established settlements and colonists or explorers to new ones, but as such, space society is irrepairably fragmented by its vastness.

There will not be an effective interstellar government, or any at all, and even cultural allegiances will lose all meaning very soon on the universal timescale.

[Q99]

About the best you could hope from is constantly transmitting data at each other to maintain some kind of cultural ties.

[The Romulan Republic]

Well, as discussed in the thread I linked to in the OP, probably the most valuable (not necessarily the only one, but by far the most obvious and practical) commodity for trade across interstellar distances by FTL is knowledge. Data. If two societies have different technologies/cultures (which, given the isolation, they realistically would), then they have something to share that can travel at the highest possible velocity (light speed) with no ill effects, and which will cost a lot less to send than a cargo hold full of raw materials or manufactured goods (which they would likely generally have access to or be able to produce themselves).

Edit: Really, see it as the ultimate extension of our current, increasingly information-based, economy.

[Q99]

Well, as discussed in the thread I linked to in the OP, probably the most valuable (not necessarily the only one, but by far the most obvious and practical) commodity for trade across interstellar distances by FTL is knowledge. Data. If two societies have different technologies/cultures (which, given the isolation, they realistically would), then they have something to share that can travel at the highest possible velocity (light speed) with no ill effects, and which will cost a lot less to send than a cargo hold full of raw materials or manufactured goods (which they would likely generally have access to or be able to produce themselves).

Edit: Really, see it as the ultimate extension of our current, increasingly information-based, economy.

Oh, FTL communication is ok?

Because that opens a lot. Given enough bandwidth, what you do is send... people. Information patterns, build body on site. Actual personal exchange, if tightly bottlenecked.


Hm, guess that can be done with lightspeed communication too, but it's much harder to get enough bandwidth with any known method.

[Solauren]

Without someform of FTL, the closest you can come to a Interstellar government is the source of the tech needed for interstellar colonization keeping some, or all, of the technologies guarded secrets.

An example of this is the movie Interstellar, where Cyrogenic freezing was a classified information, and the only public articles about it spoke in a theoritical sense.

That wouldn't be much for co-ordination, but it would limit possible military conflicts between colonies of the same species.

[K. A. Pital]

Well, as discussed in the thread I linked to in the OP, probably the most valuable (not necessarily the only one, but by far the most obvious and practical) commodity for trade across interstellar distances by FTL is knowledge. Data. If two societies have different technologies/cultures (which, given the isolation, they realistically would), then they have something to share that can travel at the highest possible velocity (light speed) with no ill effects, and which will cost a lot less to send than a cargo hold full of raw materials or manufactured goods (which they would likely generally have access to or be able to produce themselves).

Edit: Really, see it as the ultimate extension of our current, increasingly information-based, economy.

So is communication lightspeed or FTL?

If lightspeed, think about riders sent from one city-state to another. Messages would be travelling a really long time, which would mean short chats woudl not be possible. Data would be transmitted in enormous volumes, books, cultural heritage, all that stuff, but it would be kind of like a library exchange. One big library sends books to another great library. By the time they arrive, they mightbe found curious, entertaining, etc., and even have an effect on politics - but immediate reaction and interaction are impossible.

If FTL, then it is more like an interstellar internet. But then you kick either causality or relativity down the well and lower the hardness from "no FTL" to "still, we use FTL for XYZ".

[The Romulan Republic]

Well, as discussed in the thread I linked to in the OP, probably the most valuable (not necessarily the only one, but by far the most obvious and practical) commodity for trade across interstellar distances by FTL is knowledge. Data. If two societies have different technologies/cultures (which, given the isolation, they realistically would), then they have something to share that can travel at the highest possible velocity (light speed) with no ill effects, and which will cost a lot less to send than a cargo hold full of raw materials or manufactured goods (which they would likely generally have access to or be able to produce themselves).

Edit: Really, see it as the ultimate extension of our current, increasingly information-based, economy.

Oh, FTL communication is ok?

Because that opens a lot. Given enough bandwidth, what you do is send... people. Information patterns, build body on site. Actual personal exchange, if tightly bottlenecked.


Hm, guess that can be done with lightspeed communication too, but it's much harder to get enough bandwidth with any known method.

Sorry, that was an error on my part. Typo. I meant STL- no FTL, as outlined in the OP.

Although, honestly, the possibilities for FTL coms. only are also interesting, and worth discussing.

[K. A. Pital]

You do realize any kind of ansible poses similar problems with regards to causality and relativity as FTL travel itself?

There is not much to discuss, other than if there is nothing moved outside of messages, it would still mean no interstellar government is possible or needed. A tighter cultural exchange is the only difference in that scenario and the no-FTL one.

[Q99]

Rather than interstellar, I see hard sf as better suited to interplanetary, heavily developed systems.

Developing Pluto of all places is easier than getting to another star system after all. Lower long term reward to be sure, but still, you could have tons of colonies throughout a single system, making governing them complex in both numbers and time delays. You can talk to anyone in a reasonable time but getting to them can take awhile.

[Sea Skimmer]

Rather than interstellar, I see hard sf as better suited to interplanetary, heavily developed systems.

Agreed on that; and relatively little sci fi gives attention to what might happen if we had colonies in the oort cloud become significant powers. Now that we know that body includes stuff the size of Pluto it's pretty plausible for that to happen in the very long term and thus create a more interesting military and political geography then the linear alignment of the named planets.

Otherwise you need at least a little magic for FTL propulsion and communications.

As far as trade with FTL communications only goes, it would still probably just be largely limited to cultural exchanges, and some largely one way exports of AI programming from the larger settlements to the smaller. In theory you could cooperate on engineering projects but in reality by the time we have the automation and engineering to colonize other solar system we probably will have already discovered and automated most of what systems engineering is. That' what we need to do to make such high endurance colony ships plausible. And while new niche applications will be constant, those will be very very specific and probably seldom relevant or worthwhile enough to encourage intersystem cooperation.

[Simon_Jester]

You do realize any kind of ansible poses similar problems with regards to causality and relativity as FTL travel itself?

There certainly is a problem with FTL messages, in that for most if not all possible FTL messages, there exists some frame of reference in which a message can appear to arrive before it was sent. I don't remember if that applies to literally all FTL messages, or only to some. The treatment of the math that I remember in which the problem arose only talked about frames of reference in which sender and receiver are at rest relative to each other, or approaching each other. I don't remember if it applies to objects whose relative velocity points away from each other.

[K. A. Pital]

Rather than interstellar, I see hard sf as better suited to interplanetary, heavily developed systems.

Agreed on that; and relatively little sci fi gives attention to what might happen if we had colonies in the oort cloud become significant powers. Now that we know that body includes stuff the size of Pluto it's pretty plausible for that to happen in the very long term and thus create a more interesting military and political geography then the linear alignment of the named planets.

Spoiler

Was heavily used in the Expanse before they went the stargate way, it had a relatively hard start.

Then it became soft.

[Formless]

You do realize any kind of ansible poses similar problems with regards to causality and relativity as FTL travel itself?

There certainly is a problem with FTL messages, in that for most if not all possible FTL messages, there exists some frame of reference in which a message can appear to arrive before it was sent. I don't remember if that applies to literally all FTL messages, or only to some. The treatment of the math that I remember in which the problem arose only talked about frames of reference in which sender and receiver are at rest relative to each other, or approaching each other. I don't remember if it applies to objects whose relative velocity points away from each other.

According to Cosmic Inflation, it is actually possible for two objects to be "moving" away from one another faster than the speed of light, although they aren't actually moving at all so much as new space comes into existence between them faster than light can move through that new space. Of course this only happens between objects which are on opposite sides of the observable universe from one another; but it means that any communication between them is only possible if Faster than Light communication is possible. And in this sense, if I understand correctly, it would appear as if completely new information had appeared ex-nihilo from a causality perspective.

As to why FTL communication causes causality paradoxes, at 4:40 of this video Carl Sagan elegantly explains an example situation where it would appear from one reference frame as if causality had been violated, all because of relative motion and reference frames. While the example assumes that light itself is being sent faster than its normal speed, as I understand it the same should happen if a ship were to send a warning signal of any kind to the other ship at faster than light. The problem is that from the perspective of the ship receiving the signal, the message appears to come from a position ahead of the ship sending the signal-- in other words, it appears to come from the future. We are always in motion, so this is always a potential problem. The signal always appears to come from a position where the sender isn't.

[AniThyng]

Rather than interstellar, I see hard sf as better suited to interplanetary, heavily developed systems.

Agreed on that; and relatively little sci fi gives attention to what might happen if we had colonies in the oort cloud become significant powers. Now that we know that body includes stuff the size of Pluto it's pretty plausible for that to happen in the very long term and thus create a more interesting military and political geography then the linear alignment of the named planets.

Spoiler

Was heavily used in the Expanse before they went the stargate way, it had a relatively hard start.

Then it became soft.

So what you're saying is it climaxed