Humanity has access to a stargate of unknown origin. Each gate leads to a solar system from which other gates can be accessed, creating a kind of highway spanning some 300 systems. The travel time in solar systems is quite fast, in the solar system you can travel from the sun to the gate always located on the border of the system in about 1 month. How much an empire directed from the earth could grow effectively. I think of a British-style system, governors in systems that have to wait for orders but with autonomy. The fuel for ships is equivalent in abundance to oil, so some systems are more abundant than others, which favors space traffic, since it is quite light, it is considered profitable to transport certain materials and physical goods from one system to another, which is why they have a regular trade. Some governors rebel from time to time, blocking "naval routes" which allows for occasional wars. So how big could the terrestrial empire be? How many systems could it occupy? I would like some free systems for political play and space for "Space port" like city states. Can I achieve?

Edit: Door Connection: There are some bottlenecks, but in general they only delay the time it takes to get from point A to point B. A system can alternatively have 3, 4 or only one door. Powers: The only "empire" would be the terrestrial, on the "outskirts of the empire" are some independent states but they are more like outlaws than well-established governments. There are systems without human presence, systems at the end of alleys

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    $\begingroup$ Sounds like a pretty typical "Age of Sail but in space" sci-fi scenario. Whether it's plausible or not, there's so many peer examples that any size you choose to assume would be accepted by the reader. The one difficulty I see is whether the stargates are patrolled / blockaded or not; no unrestricted travel means no free systems / free ports since their traffic can simply be choked off. $\endgroup$ – GrumpyYoungMan Apr 28 at 15:09
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    $\begingroup$ I think a couple of details are missing: (1) How "connected" are the systems? There are lots of measurements of social networks, such as closure. If your map is like a hierarchical snowflake with only one route between any two systems, then the central star system is going to have a lot of power. If there are multiple paths between any two points, you have more dynamism. (2) Are there any rival powers, either on Earth or on other planets? The farther in the future this is, the more creative we can be with how the empire(s) could evolve. $\endgroup$ – workerjoe Apr 28 at 15:11
  • $\begingroup$ I would say that the Terran Federation and the Star Empire of Manticore are both very plausible, judging after the number of people who bought the books. Plausibility is not a function of the universe described in the story; plausibility is a function of the skill of the story teller. Consider Homer's Iliad and Odyssey: they are about 2,800 years old, are full of powerful and wonderful gods, goddesses, demigods, demigoddesses, monsters, witches, cyclopses etc., and yet people still find them fascinating. $\endgroup$ – AlexP Apr 28 at 15:36
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    $\begingroup$ How much traffic can each stargate accommodate at a once? Do your stargates only accommodate traffic one direction at a time, and how do they determine if another ship is coming while one is going? Is traffic through your stargates policed or are they considered free for all? Can a ship go from one stargate to ANY other stargate, or do they have to take multiple stargates to get to the exact system they want? These can hinder speed of traffic. $\endgroup$ – Len Apr 28 at 15:40
  • $\begingroup$ If on the ground, can a rail-track be used? If so, there's no reason to limit where you work and live - lots of traffic. $\endgroup$ – A Rogue Ant. Apr 28 at 17:12

You can only control what you can directly see. The simplest example is a stage director. The director calls start, stop, and the details in-between. He (or she) judges what the performers do or don’t do. And, if the actors are not providing what the director wants, he (or she) can call security to have them removed.

This scales to star empires. If communication through these gates is by “boat” alone (at a month per system), the folks on the other side of the very first gate are very independent— as many as sixty gates away (5 years); why that’s some entire political careers. And certainly long enough for anyone ambitious to feel comfortable building enough of their own force to beat you, should you be so foolish as to send troops that far away.

Therefore, if all your systems are “mature” (can self-support and thrive) and communication is limited by boat, then past sixty gates the loyalty of your subordinates is strictly voluntary. This can go on for centuries, if the voluntary subordinates continue to feel like it. But in moments of trouble and distrust of the central government, this is around the distance where people can start reasonably getting ideas of successful revolution. Even much closer, if the dissatisfaction with the central government is severe and the central government is perceived as weak, or too spread out to focus on one rebel system.

There’s a calculus going on among the elite in your semi-independent systems that you can not directly control for how much it would cost to take over vs how much perceived benefit there is in doing so.

If communication brings information to you quicker (like minutes instead of months), then it matters to those calculations how quickly you can respond to rebellion. Probably around the same region, you will have troublemakers occasionally flex to count the “police response time” of your forces. The elite in other systems will be paying attention to how long it took to respond to the trouble, and whether your empire was able to focus enough force to get the job done.

For a terrestrial example in 66 AD rebels took over the fortress of Masada, about two weeks’ walking distance from most Roman strength in the regional capitol. It took 7 years for the Roman army to respond. This no doubt encouraged many.

  • $\begingroup$ That is misrepresenting what happened at Masada. The Roman's didn't ignore what had happened, they had other priorities. There's a reason why the period of 66 to 73 is called the First Jewish-Roman War. In 66 they were looking at a province-wide revolt that essentially drove them out of Judea until a force from Syria seized the territory back, then dealing with persistent revolts they had to stamp out, and maintaining order while assorted rebels groups fought each other. Once that was sorted out, they could deal with a bunch of lunatics out in the middle of nowhere. $\endgroup$ – Keith Morrison Apr 28 at 16:44
  • $\begingroup$ It wasn’t the middle of nowhere. In terms of absolute miles, it was closer than Nazareth. And that is my point (maybe I haven’t made it well) that this hypothetical Empire’s ability to focus power and the speed at which they do so among all the priorities at hand will decide the limit of the hypothetical Empire’s reach $\endgroup$ – James McLellan Apr 28 at 17:05
  • $\begingroup$ If you're only thinking about places in terms of strict geography instead of how those places are useful strategically, you're thinking about it wrong. Geopolitically, Masada was in the boonies and not strategically important for control of the province, no matter how close physically it may have been. Nazareth is in a far more fertile and populated area, more centrally located, and thus of far more strategic value. Masada's equivalent in World War 2 would be the Japanese-garrisoned islands the Americans bypassed. It's not that they couldn't take them, they just weren't worth the effort. $\endgroup$ – Keith Morrison Apr 29 at 16:10

What is an Empire?

I think the term is only really meaningful if there is central direction from a capital, or if the capital at least manages to collect rents from outlying systems. Here I use rents in the sense of public-choice theory, not in the sense of landlords providing housing.

If I read your question right, there is no other empire or polity around, just the empire with loyal provinces, provinces temporarily in rebellion, and the unorganized fringe. So the empire doesn't need a navy and army to defend against rivals. It merely seeks to organize economic interchange and to police the fringe.

  • Does your empire have a mostly capitalist economic system? If so, the central world(s) are not really directing the economy, that is left to the invisible hand of market actors.
    Of course the rules could be rigged to benefit the central worlds, with a military to enforce the rules. Patent laws, licensing fees, high-value-added industries in certain regions and not in others ...
    "The game is rotten and the soldiers make sure nobody quits."
  • Do the regional governors come from the central world(s) or are they local? If they are sent from the core, how would they make the locals go along with any rebellion? Do the locals really care which bigwig from the capital rules over them this year or decade? Or can some governors get the local population behind their doomed rebellions? Why? Are conditions so bad that they have nothing left to lose?
  • Or are the rebellions against the representatives of the central world(s)? Every now and then things get so bad that the provincials string the fat cats from the capital up on the nearest lantern pole ...

I think you can get formal loyalty and a limited form of rent over years or even decades of travel time. Think of the Spanish Empire and the Manila Galleon. But that isn't two-way command-and-control.


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