I would like to know if a very advanced civilisation could rule an entire galaxy without mastering teleportation or any other method that allows traveling faster than light (unless you give mathematical and experimental evidence that this is possible). By ruling a galaxy, I mean that the galaxy government needs to at least be able to:

  • control the frontier of the galaxy (to avoid invasion, smuggling) ...
  • face a war in any place of the galaxy
  • collect taxes in inhabited solar systems
  • protect its citizens

Note that I don't ask here to explain how could a government conduct all these tasks but rather, if teleportation is a requirement for any civilisation who would like to control an entire galaxy.

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    $\begingroup$ I suggest you visit Isaac Arthur's channel, where he discusses these topics in great length. Consider youtu.be/1LQU69sYd3s and youtu.be/xRB7a89Jh7w for your topic $\endgroup$
    – user44399
    Sep 7, 2018 at 15:41
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    $\begingroup$ As a side note, however, I do believe a human galactic civilization would be very hard indeed to maintain control over without some kind of super-fast travel. A human society embarking on a sub-lightspeed vessel bound for the other side of the galaxy would tend to undergo natural evolution, that is, their genetic make-up would gradually change. They may disembark on the other side no longer human. You could take measures against this, but there's no guarantee everyone would choose to do so. I must stress Isaac Arthur's content, he really does go into great detail with these kinds of topics. $\endgroup$
    – user44399
    Sep 7, 2018 at 15:45
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    $\begingroup$ Are you forbidding all manner of faster-than-light travel, or just methods that specifically "teleport" - i.e. wormholes? $\endgroup$ Sep 7, 2018 at 16:01
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    $\begingroup$ If Alex managed to rule Europe and part of Africa and Asia before the invention of the telegraph... $\endgroup$ Sep 7, 2018 at 16:46
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    $\begingroup$ @Raditz_35, to a reasonable extent it is the responsibility of the answerer to take the OP at his/her word. Everything you mention is utterly irrelevant to the OP's basic question (even before the edit). A frame challenge is one thing, but going out of our way to discredit the question is another. $\endgroup$
    – JBH
    Sep 7, 2018 at 17:41

14 Answers 14


Of course

Until the last 150 years, every nation, government, and condition of rulership was enacted without the benefit of swift transportation and/or instantaneous communication.

In the really big empires, like the Romans, Alexander, Genghis Khan, travelling from edge-to-edge could take months. People on trading missions took years. And yet these empires flourished just fine without the need of telegraphs, telephones, the Internet, cars, jets, trains, or anything else that makes transportation and communication convenient.

If you're developing a story, then you need only look at these ancient methods of ruling large territories. Your modern conveniences increase in a galactic scope, but so does the distance between communities. It's all the same thing.


OK, people are having trouble understanding this answer.

Youbetcha, people at the fringes of governing authority have a nasty habit of ignoring laws, rebelling, even seceding. For some reason people think that the vast distances of space make this impossible to control or stop.

Consider our lives here in the U.S. The government is fighting a constant war for control. Whether it's little things like people speeding or jaywalking or big things like holing up in a rural farmhouse and shooting at FBI agents, the government continues despite the little interruptions.

What's a little interruption on a galactic scale? A whole system in rebellion compared to the millions or billions of systems? Soviet dictator Joseph Stalin allegedly once said to U.S. ambassador Averill Harriman, "the death of one man is a tragedy, the death of millions is a statistic." One system — even thousands of systems — even tens of thousands of systems — is just one of those small things you need to deal with as a galactic empire.

How did our ancient empires solve the problem? By sending out the troops to quell the rebellions. When the rebellions were really bad, they wiped everybody out or scattered them to the wind.

How would you do that on a galactic scale? With robotics. If you have the ability to populate a galaxy, even with sub-FTL engines, you have the ability to send robotic fleets to establish order. And the beautiful thing about AIs is that they can be programmed to be 100% loyal and capable judges of the law.

Who cares if it takes them 50,000 years to get to the rebelling planet? Who cares if it takes 50,000 years to send the message? How incredibly inefficient of a government that can trust robotic solutions to send all the data out from a central point. The robotics could act very easily on their own and the only thing that need be done is periodically update them with changes to the law.

And everybody else? They're simply law-abiding citizens.

I still assert that one doesn't need teleportation to run an empire, not any more than we do (or, more specifically, did) a nation here on Earth. We all seem to be worried about it happening within the lifetime of a ruler, or a magistrate, or a policeman. Considering it likely took millions of years just to populate the entire galaxy, it's no stretch for the "government" to no longer define itself by the length of a human life.

I love the line from the movie Men in Black. "You humans! When will you learn size doesn't matter? Just because something's important, doesn't mean it's not very small."

You humans! When will you learn time doesn't matter? Just because something's important doesn't mean it can't happen over a very long period of time.

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    $\begingroup$ Comments are not for extended discussion; this conversation has been moved to chat. $\endgroup$
    – L.Dutch
    Sep 10, 2018 at 5:13
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    $\begingroup$ > who cares if it takes them 50,000 years to get to the rebelling planet? By which time the rebelling planet has had time to build a couple of their own empires and their own robots which are 5000 generations beyond what empire sent out those 50000 years back. The idea is laughable. You don't seem to realize the immense difference between 10-20 years and even 200, not to speak of 1000s of years. Imagine Britain sending out troops to subdue the US in 177x -- sailing ships and musket soldiers who will arrive in the US by 1995. They will be welcome as a historical rarity and laughed off. $\endgroup$
    – Gnudiff
    Sep 10, 2018 at 5:37
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    $\begingroup$ Because people's lifespan will still be the same. It's probably impossible to build a robotic army that lasts that long. Also, you'll arrive at the descendents of the rebels - by a 1000 generations. That's sufficient time for evolution to change them to technically a different species. No, you do not comprehend timescales. $\endgroup$
    – Gloweye
    Sep 10, 2018 at 7:44
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    $\begingroup$ I have, and you do not show any better understanding of the timescales there. The only society that could span a galaxy would have star-system based governments at best, and perhaps alliances beyond that, but that's where it stops. Your scenario doesn't describe "ruling a galaxy", and therefore it's not an answer to the question, even if it would work. $\endgroup$
    – Gloweye
    Sep 10, 2018 at 7:58
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    $\begingroup$ In cases of rebellion, your system would be woefully incapable of any response as soon as a star system would fall, since response times are long enough for the inhabitants to create a defense superior enough that the travel times will make the re-conquering force obsolete. $\endgroup$
    – Gloweye
    Sep 10, 2018 at 7:58

No, unless you allow for some mechanism of physically going to the places you are ruling, or have a very different (decentralized) political hierarchy.

Your situation is simply a greater macroscopic scale than a local government on a planet.

Consider the following: Laws are passed that maintain order. Tax and economic laws apply to the place you are governing. Borders must be moderated to follow the law. These concepts apply to the galaxy the same way it does to any country on Earth.

  • When a person is breaking laws, they must be detained or punished.
  • When a person does not pay their taxes properly, they must be detained, audited, or punished.
  • When an outside force is invading and attacking your citizenry, a mobile military unit must be deployed to stop that outside force.
  • When a person does not pay their dues, they can have their possessions taken as collateral.
  • ...

You need to be able to enforce these laws and only physical presence can ultimately enforce them and bring them to their legal conclusions.

On top of these things, your galactic infrastructure also requires communication. Communication can only happen at the speed of light. The Milky Way is ~100,000 light years across. This means moving at the speed of light, an invading intergalactic army means SOS calls will take a maximum of 100,000 years to reach the governing body, and traveling at light speed back to the source of that SOS will require another maximum of 100,000 years (and much longer than that below the speed of light). And that's only for this scenario. Imagine the others.

This cannnot work.

With faster than light travel, actually traveling somewhere to propagate that message would be faster than sending the message through radio waves. Without it, the invading force in my example would have 200,000 years to wreak havoc.

You can solve some of these dilemmas by having the governing body split evenly across the galaxy, but they would not be able to communicate with each other faster than the speed of light so there may be some detriment here.

The rate at which a new law would propagate would be limited to the speed of light.

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    $\begingroup$ s/maximum/minimum/ ? $\endgroup$
    – npostavs
    Sep 7, 2018 at 21:09
  • $\begingroup$ @npostavs I updated my post to be more clear. $\endgroup$ Sep 7, 2018 at 22:11
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    $\begingroup$ I think this is even more simple than "governance". I would say you can't even have "a civilization" where it takes 100k years to communicate. Even if they magically started as such, within 500 years they would be a million separate civilizations. $\endgroup$ Sep 8, 2018 at 0:07
  • $\begingroup$ It still seems like you should be talking about minimum times, not maximums (e.g., the parenthetical you added is basically explaining that you described the minimum-time scenario, even though you used the word "maximum" in the description). $\endgroup$
    – npostavs
    Sep 8, 2018 at 1:22
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    $\begingroup$ @npostavs Maximum is appropriate for the sentence on speed-of-light distress calls, since the SOS may not originate at 100,000 light years from the governing body (that's the maximum distance between any two points in the galaxy). For the travel time to get back, it's not the minimum either since again the distance could be anything up to 100,000 light years. 100,000 years is therefore the "maximum minimum travel time" (the worst-case for distance at the best-case for speed). I agree maximum is a bit confusing in that sentence, but s/maximum/minimum/ doesn't improve it. $\endgroup$
    – Ben
    Sep 8, 2018 at 3:22

Yes. With technology!

Specifically, Replicated Mechanized Police guaranteed to be the same everywhere, throughout the galaxy.

This will also work with any length of human lifespans; even just the ~75 years we have today. Nobody has to be immortal or long-lived. Travel can be sub-light speed (you may need suspended animation, or generation ships), Communications can be just light speed. You don't need FTL or teleportation or wormholes or anything else that is effectively FTL; no FTL.

What you need is an intelligent robotic police force that enforces the rules of the galaxy (ruthlessly when necessary) as the central ruling authority expands throughout the galaxy. So there IS no central authority making decisions for the whole galaxy; the original designers of this scheme built machines that enforce their law.

These robots can be as intelligent as humans but without emotion: Specifically the types of emotion that would drive them to seize power or enslave the humans. So they have no ambition, need no self-realization or "freedom" to choose their own path, they are neither happy or unhappy, ever, but they are capable of human level analysis, are capable of recognizing lies or subterfuge or treason, etc. They are machines that do their job, for millions of years, without any need for central supervision. Communications from the central authority arrive AT light speed, reliably and securely, but no faster.

Presume there are no bugs in this machinery, nothing happens to make any of them go rogue. They can harvest raw material from asteroids, stars or planets and are self-replicating, but to match a proportion of the humans they supervise; they never self-replicate out of control, and have no problem dismantling or deactivating their oldest units to conserve energy should fewer of them be needed.

They also do not follow Asimov's rules of robotics: If circumstances warrant it, they will kill in self-defense, or kill criminals to enforce the rule of law as they see it.

The law is laid down by the central authority, which is presumably highly advanced, and followed throughout the galaxy.

The central authority can give such units (again at least as intelligent as humans) some measure of autonomy for unusual situations, they can make fair decisions based upon some criteria, e.g. making the decision that preserves the most human life. Being as intelligent as humans, they don't get confused or tricked by dumb paradoxes and won't do anything stupid or insane like enslave all humans or kill them all. They will make decisions that will seem both sane and prudent to the vast majority of humans.

The galaxy is ruled: You don't need FTL communications if the Ruler of each star system is effectively the same exact person that will make the same exact decisions as would another Ruler across the galaxy, given the same situation. Or for that matter, as would another ruler in any other galaxy.

  • $\begingroup$ you still need some speedy method for deploying those robots across the galaxy. If FTL is feasible, assuming it is "F" (fast) enough, then FTL and robots may compensate for the lack of teleportation. Communication through FTL channels may pass legislation updates and situations updates in almost real-time fashion. $\endgroup$ Sep 8, 2018 at 6:10
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    $\begingroup$ @ChristmasSnow No, the rules of this game are no FTL! I presume people and robots can be deployed at, say, 0.95 light speed. Fast enough, perhaps with suspended animation for long trips. And the whole point of my post is there IS no central authority; there is replicated mechanized authority that is guaranteed to be the same everywhere. Your suggestions break the rules of the game; to devise a galaxy wide authority without any form of FTL travel or communications. $\endgroup$
    – Amadeus
    Sep 8, 2018 at 11:02
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    $\begingroup$ @ChristmasSnow The civilization might not have spanned the galaxy since forever, but grew out of a star system sized civilization. With growth, the law enforcement robots are spread too, with the same pace as the civilization. They do not need to be distributed at one moment. Once spread everywherer, one should hope the initial set of laws have been good enough to serve for eternity. Even if updates are necessary, there is no need for them to spread faster than light. If you pass a new law, any place you can reach will have adopted the law long before the moment of your arrival. $\endgroup$
    – M. Winter
    Sep 13, 2018 at 15:10
  • $\begingroup$ @M.Winter Agreed, that is my thinking on this scheme. And it is possible circumstances in one region are unique enough, something strange happens or is encountered (e.g. some new form of life, or scientists in this region develop a new form of technology), that laws must be made or revised. In that case they would broadcast the circumstances, the nature of the new technology or life, and detail how they have added to or changed the law. Law Enforcement elsewhere, being identical, would have come to the same exact conclusion so they adopt the new law when they get it (or already have it!) $\endgroup$
    – Amadeus
    Sep 13, 2018 at 15:23

Yes, it would be possible, for beings with extremely slow metabolisms. If a million years to them is like one year to us, then they can travel across the galaxy at slower-than-light speeds in what feels to them like a few days, and communicate via radio on similar timescales. Of course, they’ll have to cope with stars being born, ageing and dying over the course of a few thousand subjective years.


It's all a matter of definitions. There really is no arbitrary limit on how wide an empire can be. However, there is a natural relationship between response time and the growth of threats. You don't have control over things which happen faster than you can respond to.

A galactic empire like this would need to deal with fast growing threats (such as insurrections) locally. Obviously they would not be able to bring the entire brunt of the galactic empire to bear against some little insurrection in one corner of the galaxy. But they don't need to. All they need to be able to do is bring enough power in to quell the rebellion. That might be only local ships within a few decades travel.

By necessity, this means any such rule will have to be either by a distributed governance, or threat of complete utter anhilatory force. You either want a local force responding within a few years or so, or a long established track record of obliterating entire species for transgressions millions of year prior. Respect or Fear. Carrot or the Stick. Either way, your civilization will have to be impressive in that respect.

A full on war from outside, on the other hand, may take time. Presuming your opponents don't have teleportation or FTL mastered, they may need millions of years to prepare an attack. This gives you time to move your fleet through the galaxy with reasonable response times. If your opponent surprises you? Well, that's the nature of war.

The real trick is just to think slow. You and I are used to thinking of 30 years as a long time. To a nation, 200 years is a medium amount of time. To China, 1000 years may be a medium amount of time. To a civilization the size of a galaxy, a medium amount of time might be a million years. Our entire lives would be but a blip to their way of thinking.



A galaxy is very, very, very big. 100,000 light years. That means that, if you want an information or a signal to travel to one end to the other side of the galaxy, it will take at least 100,000 years.
The nearest solar system is 4.24 light-years from us. The nearest (potentially) apt to harbor life is approximately 40 light-years from us.

What does that mean ? that if we consider our situation as the average situation, it could take between 4 and 40 years to CONTACT another planet. If anything goes wrong, their answer would arrive between 8 and 80 years after you send an SOS. And that just the nearest planet. If you're the planet on the border, you're just sending a message to the local town.

Even if we could go to the speed of light, it would take way to much time to move from one point to another to prevent problems. Respectively, believing this history answer, it took 6 weeks to go from England to the Americas. Ultimately, England wasn't able to prevent the independence of the colonies. Now Imagine that it would take at least take 26 times longer to react about anything. The independence war would almost be over when the firsts British armies would have put foot on land.

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    $\begingroup$ OUR galaxy is very, very big. 100,000 light years. But galaxies come in many, many sizes. The largest galaxies are more than a million times the size of the smallest galaxies. Of course even the tiniest galaxy is unimaginably vast. $\endgroup$ Sep 7, 2018 at 17:02
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    $\begingroup$ "it took 6 weeks to go from England to the Americas. Ultimately, England wasn't able to prevent the independence..." Please note that with India it was possible. Probably more distant than Americas, colony in India still was colony after some independence wars. $\endgroup$
    – ADS
    Sep 8, 2018 at 22:19

This is a very long answer, but it does suggest several ways to make ruling a galactic government with slower than light travel less impossible, and perhaps even possible.

1) increase the life span of humans and/or aliens living in the galactic government.

If it takes thousands to tens of thousands to hundreds of thousands to millions to tens of millions of years for sub light space ships to travel across a galaxy, a human ruled galaxy would not be possible until at least that far in the future of when those humans were as advanced as Earth in 2018. Humans wouldn't have even reached the farthest parts of their galaxy until that long after having invented interstellar ship travelling at some fraction of the speed of light, which won't happen until they are more advanced than Earth in the year 2018.

So I would certain hope that by then those humans would have made the discoveries and inventions that seem the most desirable of all to me - methods of extreme life extension or even immortality.

You may remember that famous science fiction series Cities in Flight by James Blish. In the chronologically first novel in the series, Earth people discover both the "spindizzy" that makes faster than light travel possible and the first of the antiagathic (anti death) drugs that enable humans to live for centuries or millennia. In the novel titled They Shall Have Stars (1956) or Year 2018!.

Although it doesn't look like anti death drugs will be discovered this year, we can hope that they will be discovered long before 2118, and long before 3018, and long before 20,018, and long before 200,018, and long before 2,000,018, which would be almost the earliest possible date for a galactic government to be established.

So if people expect to live for centuries, millennia, or even much longer, it will make it a lot easier to have a galactic government where messages travel at the speed of light and space warships travel much slower than that.

2) Make your interstellar government hierarchical, and/or federal, and/or feudal, in structure.

It seems to me that an interstellar government would probably be hierarchical long before it ruled an entire galaxy. Even the government of a single star system should be highly hierarchical if there are many artificial space habitats in the system.

Possibly the ruler of a single habitat would be a habicrat ("habitat ruler") and the ruler of ten habitats would be a "habicrat of habicrats", or "second level habicrat", or "habicrat to the second power", and the ruler of 100 habitats would be a "habicrat of habicrats of habicrats", or "third level habicrat", or "habicrat to the third power", and so on up to the stellacrat or "star ruler" ruling the entire star system.

If a stellacrat rules an entire star system, a single, binary, or multiple star system and its planets and space habitats, a "stellacrat of stellacrats" or "second level stellacrat" would rule ten star systems, a "third level stellacrat" would rule 100 star systems, and so on and on up to a "seventh level stellacrat" ruling a million star systems. Since galaxies have about one million stars to one trillion stars, a "galacticrat" or "galaxy ruler" would be the equivalent of a "seventh level stallacrat" to a "thirteenth level stellacrat".

Since the popular imagination tends to confuse outer space and heaven, it is possible that the immediate subordinates of a stellacrat and/or those of a galacticrat might be called after various levels in the medieval hierarchy of angels.

In a star system with many space habitats, the immediate subordinates of a stellacrat might be 10 "stellar Seraphim", with 100 "Stellar Cherubim" below them, 1,000 "Stellar Thrones", 10,000 "Stellar Dominions", 100,000 "Stellar Virtues", 1,000,000 "Stellar Powers", "10,000,000 "Stellar Principalities", 100,000,000 "Stellar Archangels", and "1,000,000,000 "Stellar Angels", and below them various levels of habicrats.

In a galaxy with billions of star systems, the immediate subordinates of a galacticrat might be 10 "Galactic Seraphim", with 100 "Galactic Cherubim" below them, 1,000 "Galactic Thrones", 10,000 "Galactic Dominions", 100,000 "Galactic Virtues", 1,000,000 "Galactic Powers", "10,000,000 "Galactic Principalities", 100,000,000 "Galactic Archangels", and 1,000,000,000 "Galactic Angels", and below them various levels of stellacrats.

3) Have local elections within a star system, and also elections on an interstellar scale if space ship speeds and the life spans of the citizens allow it.

Within a star system, it would only take hours for news to travel at the speed of light, unless it was a binary or multiple star system with widespread stars or the outer cometary halo is colonized, in which case it could take months for news to travel at the speed of light.

Thus it is possible for elections to happen throughout a star system and for those elected to take office relatively soon after the election, weeks, months or possibly years at sublight speeds.

But having elections throughout an area that is ten light years across means that the news of the political platforms could take ten years to reach the voting places before the election, and ten years for the results to reach every place, and then possibly decades for those elected to office in the central government to reach the location of the central government.

Thus people would likely be voting for a government that would take office in fifty years or a century after the start of the election, and would have to be very long lived for that to seem normal to them.

And if the area of voting was 100 light years across that would mean voting for a government that would take office centuries or millennia in the future, so the voters would have to be much more longer lived for that to be acceptable to them.

In a galaxy like ours with a disc about 100,000 light years in diameter, it would take 50,000 years for news of a political party's platform to reach the outer rim if the convention was held in the center of the Galaxy, and 50,000 more years for news of the election results to reach the center of the galaxy, and who knows how many hundreds of thousands or millions of years for those elected to the central government to reach the galactic capital. So galaxy wide elections would probably be held at least a million years apart, and the electorate would have to be extremely long lived for that to seem like a short enough interval to them.

Thus it is possible that elections would only be held in a star system wide scale. And probably also on many lower levels below the system wide government.

4) Even within a star system, there should be various levels of government.

The United States of America has basically four levels of government (ignoring some exceptions like over 500 tribal governments): federal, state, county, and municipal, and holds elections for all four levels.

According to Wikipedia's List of Administrative Divisions by Country, there is a great variety in the number of levels of administrative divisions between different countries. Usually, countries with larger populations and/or areas have more levels of administrative divisions that countries with smaller populations and/or areas, but there are many exceptions.

The 10 largest countries by area are: Russia (3 levels of administrative divisions), Canada (3), China (5), the USA (3), Brazil (2), Australia (2), India (4), Argentina (2), Kazakhstan (4), and Algeria (2).

The 10 smallest countries by area are Vatican City (zero levels of administrative divisions), Monaco (2), Nauru (1), Tuvalu (1), San Marino (1), Lichtenstein (1), the Marshall Islands (1), Saint Kitts and Nevis (2), the Maldives (2), and Malta (2).

The 10 largest countries by population are: China (5 levels of administrative divisions), India (4), the USA (3), Indonesia (4), Brazil (2), Pakistan (4), Nigeria (2), Bangladesh (4), Russia (3), and Japan (4).

The 10 smallest countries by population are: Vatican City (zero levels of administrative divisions), Nauru (1), Tuvalu (1), Palau (1), San Marino (1), Lichtenstein (1), Monaco (2), Saint Kitts and Nevis (2), The Marshall Islands (1), and Dominica (1).

Note that Monaco with an area of 2.02 square kilometers and a population of 38,300, and Brazil with a land area of 8,460,415 square kilometers and a population of 209,550,000, both have two levels of administrative subdivisions.

Monaco has 1 Commune and 10 quartiers, while Brazil has 26 estados and one distrito Federal and 5,569 municipios.

So if the Earth was united by negotiation and/or conquest at the present time, any of the present national governments that continued to function would become another level of administrative division, and thus in various parts of the world there might be between one and six levels of administrative divisions below the world government. Of course it is possible that intermediate levels of administrative divisions might be formed, such as continental governments. If each continent had a continental government then there would be between two and seven levels of administrative divisions below the world government in various regions.

And if the solar system becomes populated by billions and trillions and quadrillions of people living in many millions of space habitats, there could be ten or more levels of administrative divisions, and there could be local elections in every administrative division.

And if people live really long extended lifetimes it might be possible to hold elections in administrative divisions that cover interstellar space and many star systems. The longer people live, the more they might tolerate infrequent and long lasting elections. They would have to have lifespans of millions of years for galaxy wide elections to be possible.

5) Local elected governments within star systems should have the most power over the lives of their citizens, and thus sometimes anger those citizens the most.

So the plan for a galactic government, since it may not be certain if it is possible to hold elections in larger areas than a single star system, would have to be to have a multi-levelled government within each star system with elections at each level, and most of the things that matter to people should be decided at one or more of the levels within the star system.

Thus when people get dissatisfied with their government, it will be a local government that they are dissatisfied with. So they will overthrow the local government and not the central government of the galaxy, and they will overthrow the local government by electing a new administration instead of by a revolt which could turn into a revolt against the central government of the galaxy.

6) Keep military force from higher levels of government within each star system to protect against invaders and to crush rebellion.

And presumably there would be units of the central government's space navy stationed in every star system to stop any attempts to revolt against the central government, and to guard the star system against any possible invasion.

These units would be sent from the star system with capital of the governmental administrative division immediately above the star system, and presumably the families of the crews would be kept in suspended animation or something until the crews returned from their tour of duty. The families would also be possible hostages if the garrisons revolted.

The star system with the government center of this next highest administrative division would be garrisoned by space navy units sent from the star system with the government center of the next highest administrative division above that, and so on and so on.

If each administrative division rules X administrative divisions below it, it would have to send X number of fleets to the government centers of the administrative divisions below it. Thus the resources needed by each star system that was the center of an administrative division would be the same.

At least that would be the cases if there was a faster than light drive, one fast enough that a voyage across the galaxy would take less than a year, for example.

If spaceships travel at speeds less than the speed of light, maybe 99.99 percent of the speed of light, or 10 percent of the speed of light, or 1 percent of the speed of light, or maybe even only 0.1 percent of the speed of light, the higher up star systems would have to devote more personnel and resources to sending fleets to their immediate subordinates.

The longer the distance the fleets had to travel, the longer the trips will take. The longer that the people in this galactic civilization live, the longer the missions to garrison other worlds they can tolerate. If people can tolerate a round trip time of X years, and if the transit time is Y years, X years minus 2 Y years equals Z years, the number of years they can spend garrisoning a different solar system.

Suppose that a local government sends a garrison to a star system five light years away, at half the speed of light, and a total trip time of 10 years. If the members of the garrison can tolerate 30 years away from home, Y and Z will both be one third of X, and at anyone time there should be one garrison on duty, one returning, and one on route to the destination star, so if they do that for nine other star systems they will have to support twenty seven garrisons and fleets at any one time.

And if Y equals 10 times Z, X will equal 21 times Z, so the system sending the garrisons and fleets will have to support 21 times as many fleets and garrisons as the number of systems it garrisons.

And if Y equals 100 times Z, X will equal 201 times Z, so the system sending the garrisons and fleets will have to support 201 times as many fleets and garrisons as the number of systems it garrisons.

And if Y equals 1,000 times Z, X will equal 2,001 times Z, so the system sending the garrisons and fleets will have to support 2,001 times as many fleets and garrisons as the number of systems it garrisons.

So for this system to work methods of equalizing the personnel and resources that the various levels of governmental star systems will have to devote to keeping their immediate subordinates garrisoned will have to be found.

6a) ships from farther away travel faster than ships from nearer, in proportion so that trip times turn out to be about the same.

If the ships can accelerate for half the journey and then decelerate for half the journey, for example, that would be the case.

On a scale much smaller than the thickness of the galactic disc, the galaxy will be three dimensional. Thus doubling the dimensions of a sphere or cube of space will increase the volume of that space, and the number of stars within it, by eight. So perhaps star systems are grouped by eights, sixty fours, five hundred and twelves, four thousand and ninety fours, etc., etc.

And the star system that rules a group of eight stars might be permitted to send fleets and garrisons to its subordinate systems at an average speed of one percent of the speed of light. Thus its fleets will spend an average of one hundred years times the distance in light years in each one way voyage.

And the star system that rules a group of sixty four stars might be permitted to send fleets and garrisons to its subordinate systems at an average speed of two percent of the speed of light. Thus its fleets with spend an average of fifty years times the distance in light years in each one way voyage, and since the average distance will be about twice as far, will spend about the same time on average. Thus they will need to support about as many fleets and garrisons.

And the star system that rules a group of five hundred and twelve stars might be permitted to send fleets and garrisons to its subordinate systems at an average speed of four percent of the speed of light. Thus its fleets will spend an average of twenty five years times the distance in light years in each one way voyage, and since the average distance will be about twice as far, will spend about the same time on average. Thus they will need to support about as many fleets and garrisons.

Assuming that the thickness of the galactic disc is 1,000 light years, a cube of space as thick as the galactic disc would be 1,000 light years on a side and would contain 1,000,000,000 cubic light years of space. There are estimated to be about 0.004 stars per cubic light year in the neighborhood of the Sun, so there would be about 4,000,000 stars in a cube 1,000 light years in a side.

It would contain eight smaller cubes with about 500,000 stars in each, sixty four cubes with about 62,500 stars in each, five hundred and twelve cubes with about 7,812.5 stars in each, Four thousand and ninety four cubes with about 976.5625 stars in each, thirty two thousand and sixty eight cubes with about 122.07031 stars in each, and two hundred sixty two thousand one hundred and forty four cubes with about 15.258788 stars in each.

Then four of the cubes with sides of 1,000 light years could make a rectangular volume with sides of 2,000 by 2,000 by 1,000 light years, containing about 16,000,000 stars; four of those volumes could make a higher volume with sides of 4,000 by 4,000 by 1,000 light years containing about 64,000,000 stars; four of those higher volumes could make a yet higher volume with sides of 8,000 by 8,000256,000,000 by 1,000 light years with about 256,000,000 stars; four of those yet larger volumes could make a still larger volume with sides of 16,000 by 16,000 by 1,000 light years containing about 1,024,000,000 stars; four of those still larger volumes could make an even larger volume with sides of 32,000 by 32,000 by 1,000 light years containing about 4,096,000,000 stars; four of those even larger volumes could make a vaster volume with sides of 64,000 by 64,000 by 1,000 light years containing about 16,381,000,000 stars, and four of those vaster volumes could make a galactic realm with sides of 128,000 by 128,000 by 1,000 light years containing 65,536,000,000 stars.

So by doubling the dimensions of each successive level of administration, there could be about 15 levels of administration above the level of single star systems.

If the galactic capital system sent out garrison fleets with speeds of 99.99 times the speed of light, the next level down could send out garrison fleets with speeds of about 0.50 the speed of light, the second level down could send out garrison fleets with speeds of about 0.25 the speed of light, the third level with speeds of about 0.125 the speed of light, the fourth level with speeds of about 0.0625 the speed of light, the fifth level with speeds of about 0.03125 light speed (abbreviated c), the sixth level with speeds about 0.015625 c, the seventh level with speeds of 0.0078125 c, the eighth level with speeds of about 0.0039062 c, the ninth level with speeds of about 0.0019531 c, the tenth level with speeds of 0.0009765 c, the tenth level with speeds of 0.0004882 c, the eleventh level with speeds of about 0.0002441 c, the twelfth level with speeds of 0.000122 c, the thirteenth level with speeds of 0.000061 c, the fourteenth level with speeds of 0.0000305 c, and the 15th level with speeds of 0.0000152 c.

If a capital of a 15th level down sector had to send ships up to 10 light years away at a speed of 0.0000152 c, the one way trip would last 657,894.73 years. If the galactic capital system had to send ships up to 64,000 light years away at 0.9999 of c, the one way trip would last 64,006.4 years. So that would actually be an advantage of ten times for the galactic capital system as compared to the lowest level sector capital.

6b) Have the population live longer the higher the level of the world they live in. Humans willing to undergo only the slightest body modifications, because of their desire to remain almost totally normal, might have lives extended to about 500 years, for example, and would live in the vast majority of star systems.

Those rare humans willing to be modified somewhat more might live for about 1,000 years, and they would tend to congregate in the systems that were capitals of the first administrative level above sing star systems. And the navy personnel send to garrison star systems in that small administrative unit would be recruited from them.

Those even rarer humans willing to be modified somewhat more than that might live for about 2,000 years, and they would tend to congregate in the systems that were capitals of the second administrative level above single star systems. And the navy personnel send to garrison the capital star systems for first level administrative units would be recruited from them.

And so on and so on, with rarer and rarer humans willing to undergo more and more extensive modifications and to become less and less human or normal for the sake of more and more extended lives, and living in the capitals of higher and higher levels of administration, and being sent on longer and longer voyages to garrison lower level worlds.

6c) Increase the tax revenue of higher level worlds.

If light speed communications and slower than light travel is the rule, there should be very little interstellar trade, and very little interstellar taxation. But maybe there is some degree of interstellar taxation.

first level: Perhaps each star system collects 99 percent of its taxes for itself, and sends 1 percent of its tax revenue up to the capital star system of the administrative level above it.

second level: That capital system collects the same amount of taxes as any other system, and keeps 99 percent of it, and also keeps 99 percent of the taxes sent from 100 other worlds. Thus it receives a total of 200 percent as much tax revenue as an average star system, and keeps 99 percent of it and sends the equivalent of 2 percent of the tax revenues of an average world to the next higher system.

Third level: The next higher star system (above 10,000 star systems) might receive the equivalent of 2 percent of the tax revenues of an average star system from each of 100 lower system for a total of 200 percent, as well as collecting 100 percent of the taxes of an average star system from itself, for a grand total of 300 percent of the tax revenues of an average star system. It sends one percent - or 3 percent of the taxes of an average star system- to the system above it.

Fourth level: The system above it (which is above 1,000,000 star systems) collects 3 percent of the taxes of an average star system from each of 100 lower systems, plus 100 percent taxes from itself. So it receives 400 percent of the tax revenues of an average system and send 1 percent of that, or 4 percent of an average system revenue, to the next higher system.

Fifth level: The next higher system (which is above 100,000,000 star systems) collects 4 percent of the taxes of an average star system from each of 100 lower systems, plus 100 percent taxes from itself, for a grand total of 500 percent of an average system's taxes, and sends 1 percent of it, or 5 percent of an average system's taxes to the next higher system.

Sixth level: The next higher system (which is above 10,000,000,000 star systems) collects 5 percent of the taxes of an average star system from each of 100 lower systems, plus 100 percent taxes from itself, for a grand total of 600 percent of an average system's taxes, and sends 1 percent of it, or 6 percent of an average system's taxes to the next higher system.

Seventh level: The next higher system (which is above 1,000,000,000,000 star systems)is the galactic capital and collects 6 percent of the taxes of an average star system from each of 100 lower systems, plus 100 percent taxes from itself, for a grand total of 600 percent of an average system's taxes, and keeps it all.

Actually there are only supposed to be about 200,000,000,000 to 400,000,000,000 stars in the Milky Way Galaxy. There are many ways to modify that arrangement so that the capital system of the galaxy receives much more tax revenue than that.

For example, if 0.0001 of every system's taxes goes to the galactic capital system, it would receive at least 20,000,000 times the taxes of an average star system; if another 0.0001 of every system's taxes is divided among the next level capitals below the galactic capital, they would each get 20,000,000 times the taxes of an average system, divided by their number; if a third 0.0001 was divided among the third level capitals each would get 20,000,000 times the the taxes of an average system, divided by their number; and so on.

If the top ten levels of capital systems each receive and distribute among themselves 0.0001 of the total galactic tax revenues each year, that comes to 0.001, a tenth of a percent, of the total galactic tax revenues, equal to the total tax revenues of 200,000,000 average systems. That should help compensate for the higher level capital systems having to send their garrisons farther away for longer periods and thus having to have more garrisons in transit at any one time.

6d) Capital systems are selected for the potential to have larger populations, wealth, and resources than ordinary star systems. And if the science is advanced enough millions of years in the future the capital systems can be rebuilt to support larger populations, wealth, and resources than ordinary star systems.

Seek out and read Larry Niven's 1974 article "Bigger Than Worlds", which has been reprinted many times.


And go to the PlanetPlanet site and read the section "Ultimate Solar System" where solar systems with more and more habitable planets are imagined. The author claims that all these solar systems are possible, that they could keep on existing if they were formed, but the more habitable planets they have the less likely they are to come into existence naturally, and the rarer and rarer such systems would be if forming naturally, instead of being created by planetary engineering on a vast scale.

The more spectacular systems are described as "engineered", since it seems statistically impossible for such extreme systems to form naturally and they could only exist if created by incredibly vast works of cosmic engineering.


Thus the higher and higher capital systems could be selected and even engineered to have more and more resources to keep fleets and garrisons in the dependent systems.

6e) The people of the capital planets believe that the ultimate horror is an independent government capable of making war on others, and thus are intensely determined to do whatever it takes to keep their subordinate systems from revolting.

6f) A combination of some of the above.

So these are my thoughts on how to hold a galactic government together with light speed communication and slower than light travel.

  • 1
    $\begingroup$ For the levels below a star system (i.e. for groups of habitats), one problem is that those will be all moving around their star, so unless you all have them chained up in the same orbit, the 10 or 100 habitats ruled by a second or third level habicrat won't stay near each other. For your bigger levels (groups of star systems) this also applies, though the galactic orbits are a lot slower in relation. $\endgroup$ Sep 8, 2018 at 11:56
  • $\begingroup$ @Paulo Ebermann The orbit of the Sun around the galactic center takes over 225 million years, and it would take millions of years for a star to drift into and out of the smallest level of administration. Even immortals can get used to a change in which sector their star system is administered by every few million years. And many space habitats might be grouped together permanently - by orbiting around one of the many large Jovian or Neptunian Trojan asteroids, for example. And habitats that orbit far from the Sun might remain together in the same sector for thousands of years at a time. $\endgroup$ Sep 8, 2018 at 16:52

It would have to be loose in some ways, strict in others, and very hierarchical. It's unlikely that a system on the Rim would care about sending taxes that would hit the Imperial Palace in fifty thousand years, with no response coming for another fifty thousand. Certainly the system would feel completely abandoned if an invader came and no defense forces arrived for a hundred thousand years.

Figure a time horizon. A subordinate will want to do as ordered to avoid punishment that comes in X years. This means that no system can rule another more than X/2 light-years away. If X is 40, that means that we need lots and lots of layers of hierarchy. Given a system fifty thousand light-years from the capital, there will have to be 2500 intermediate layers Each layer will have to be able to inflict harsh punishment on the layer immediately below it, which looks to me like it concentrates military force close to the center.

It's not going to be easy, and it's not going to be stable.


There is no way for a galaxy government to work without faster than light something.

The obvious requirement for creating the society are faster than light travel but this can be dispensed with if the expansion is at sub-light speeds.

Teleportation at FTL speeds would fix the problem as well as FTL space ships but the only reason we would want these is communication. Moving produce, soldiers, weapons over interstellar distances will invariably be more expensive than fabricating locally.

So let us focus on communication, this would allow for a system of government that has information to sell in exchange for power to govern. As the information becomes less innovative (everything has already been invented) the far flung worlds become less reliant on the government. However while there is still information currency the rulers could hold some power over the people in exchange for wikipedia updates.

However a universe with FTL travel and/or teleportation will kind of figure out time travel too and this is bad enough that it is not likely to happen in practice and generally hard to handwave all the problems they entail away with known science.

BUT what if all we added to the known mix of colony ships was a FTL messaging system that works outside of known science then there would be very little to handwave.

So I suggest telepathy between a specific line of clones that were natural telepathic twins. Some clones are sent with every generation ship and lots of cloned eggs in storage and the clone is the royal radio set who can repeat everything his clones think and broadcast to any of them. Over time new twins are found and their clones can spread out for another radio channel. Each planet that finds a set of telepathic twins can start a new local kingdom and they all keep tabs on the home base.

Thinking this civilisation has any chance of fighting off enemies is silly unless they are spotted in transit and rocks thrown at them well in advance.


No, a galactic empire without FTL or telportation is not viable.

There are a number of answers here, speculating on some wishy washy robots or probes, however, a civilization -- and by extension -- an empire -- is defined very much by a common culture. Where it is several cultures -- as in, eg, British empire's presence in India,-- the imperial one is the one that is holding the empire together (for better or for worse).

This question was specifically addressed in a book "Profiles of the Future" by the famous scifi author and scientist Arthur Clarke, who had a chapter specifically devoted to conquering Space:

He starts by pointing out that even colonizing Solar System would involve problems, such as lag in communications, but the difficulties are not insurmountable.

It is when we move out beyond the confines of the Solar System that we come face to face with an altogether new order of cosmic reality. Even today, many otherwise educated men -- like those savages who can count to three but lump together all numbers beyond four -- cannot grasp the profound distinction between solar and stellar space. The first is the space enclosing our neighbouring worlds, the planets; the second is that which embraces those distant suns, the stars. And it is literally millions of times greater.

There is no such abrupt change of scale in terrestrial affairs. To obtain a mental picture of the distance to the nearest star, as compared with the distance to the nearest planet, you must imagine a world in which the closest object to you is only five feet away -- and then there is nothing else to see until you have travelled 1000 miles.

He then says that it is quite conceivable that people will travel stellar distances -- either when we build ships that can move at near light speeds, generation ships or whatnot.

But now consider the effects of the inevitable, unavoidable time-lag. There could only be the most tenuous contact between the home [] and its offspring [..] There would never be News from the other [colony], but only History.

No [] Alexander or Caesar could ever establish an empire beyond his own reach; he would be dead before his orders reached his governors. Any form of control or administration over other [colonies] would be utterly impossible and all parallels from our own history thus cease to have any meaning. It is for this reason that the popular science-fiction stories of interstellar empires and intrigues become pure fantasies, with no basis in reality. Try to imagine how the War of Independence would have gone, if news of Bunker Hill did not arrive in England until Disraeli was Victoria's Prime Minister, and his urgent instructions to deal with the situation reached America during President Eisenhower's second term. Stated in this way, the whole concept of interestellar administration or culture is seen to be an absurdity.

All the star-borne colonies of the future will be independent, whether they wish it or not. Their liberty will be inviolably protected by Time as well as Space.

In the following pages of the same chapter, he addresses also why he thinks even FTL will not help (to build a common culture over galactic distances), but as it is outside the scope of the question, I will leave it out.


Yes it is very possible to rule a galaxy without needing FTL

There are a trillion stars in a typical galaxy, you need a self-replicating probe sent to each one (not a difficult task if you know how), within 100,000 years they would have reached all the stars in your star system.

Then you can create Dyson Swarms around each star, harnessing the energy of the entire galaxy. This is now a Kardashev Type 3 civilisation.

Such a civilisation, harnessing the energy of it's galaxy, can now coordinate, detect, and take collective action on a prospective invasion. With such power at its command you also have the added benefits of:

  • incredible amounts of living space
  • incredible ability to last through the ages
  • incredible amounts of computing power

However having said that, it's more likely that your civilisation will become trans-human at that stage, this will be it's greatest challenge. Humans arriving at swarms on the galaxy edge would be very different from those that colonised earlier.

Of course, you needn't stop at just the galaxy. You could equally send your probes to nearby galaxies too, if you're willing to wait 100,000 years whats a few more?

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    $\begingroup$ Can you expand on why achieving a Type 3 civilization helps hold together a galactic society? It seems like each major cluster of Dyson swarms could still break up into their own sovereign units. $\endgroup$
    – Harabeck
    Sep 7, 2018 at 20:59
  • $\begingroup$ "they would have reached all the stars in your star system." i assume this is a type? $\endgroup$
    – Ummdustry
    Sep 7, 2018 at 22:18

Its very unlikely that any empire would be able to maintain its control over galaxy without some sort of FTL travel.

Someone brought up the fact that empires have been able to be maintained when travel took months/years, but the travel time is much greater. It would take generations to travel across the entire galaxy. Even if the technology for immortality was discovered, unless reproductive rates were drastically reduced, there would still be a countless amount of new people being born. These new people would not necessarily have any loyalty to the empire, and there would be little to gain from staying within it.

Taxation would be largely pointless. Any natural resource would take generations to arrive at which point the demand for said resource would probably have changed. Any manufactured goods would be probably be extremely obsolete by the time they arrived (it would also be difficult to maintain the goods in a usable state over such a long period of time)

Pretty much any military action by the galactic empire would be completely pointless. The only situation where sending a military force would be remotely useful is if there was a stalemate situation with some external threat. Otherwise any conflict would be long since over. As for subjugation forces, their military tech would probably be outdated and there would be no strong guarantee that they would maintain their loyalty to the empire.

Another factor that people are ignoring is that linguistic drift will almost certain occur. It won't be a deal-breaker, but it will make communication difficult.

There is one possible way a galactic civilization could work. Quantum communication does not have the limitations of the speed of light. If the galactic empire deliberately kept technology levels very low outside of its seat of power, it could theoretically maintain control by spreading advanced fabricators throughout the galaxy. By remotely controlling these fabricators, they could build drones or be the only source of goods that the local population needs.


Yes, you can have this, if it is an empire of robots or cyborgs that do not value individualism (like the Borgs in Star Trek). But it's a must that they do not do experiments with their rules structure (different from one solar system to another), or you will end with different groups that at some point will enter in conflict. And they all follow a strict set of rules all over the place, a set of rules that does not change (because change takes so much time to get from one side of the empire to another).

Or similar with an organic specie that does not value individualism for the workers (like super massive ant colonies, that could evolve to space travel). But in this case I cannot see the evolutionary need for the queen to reach the entire galaxy. Maybe if she can somehow detect the end of her planet (like a neutron star collision in the future, where she still has time to send workers to prepare other planets), but then if she moves somewhere else then the need to expand stops.

As soon as you have multiple queens (something that might drive them to expand outside the home world) you will not have an empire, but multiple in conflict for expansion. Or you could have maybe queens working together, but it would not be so much an empire, but more like a free trading galaxy of super queens.

I cannot see it working with humans who have a natural drive for individualism and hierarchical structures. We can work together, but only as long as we all feel that we can profit from the governing structure. We like to have communities, but we need to "feel" connected with the rest. Our empathy does not really stretch for the hypothetical unknown.


If you permit instantaneous telepathy, your rulers don't have to be there if they can just exchange thoughts from their representatives on each planet. ObSF: Time For The Stars

  • 1
    $\begingroup$ Can I ask why I was downvoted? $\endgroup$ Sep 10, 2018 at 16:30

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