# Is it feasible to have a nomadic space civilization? [duplicate]

Could a civilization move from planet to planet like how nomads move from area to area in real life? This is a human civilization which is thousands of years into the future.

• with spaceships alone it would take more than the lifespan of people , with wormholes it would be feasible but incredibly expensive. – user22398 Jul 8 '16 at 12:53
• FTL or noFTL? if FTL how much it costs in energy? – MolbOrg Jul 8 '16 at 13:37
• Check the story of the Quarians from Mass Effect. They are nomads, they may serve as a source of inspiration for you. – The Square-Cube Law Jul 8 '16 at 14:43
• Power Ranger: Lost galaxy had a nomadic colony – beppe9000 Jul 8 '16 at 15:22
• Independence Day shows this from the other side. (ie the nomads decide to move onto our planet) – Simba Jul 8 '16 at 15:33

Everyone seems very focused on resource over-consumption, but that is not the only reason to be nomadic. Some alternatives:

1. Like lokimidgard said, they could be following some sort of life form. I'll take it a step further and say, they could be following/living on something else that is nomadic. For instance, living on a Rogue Planet makes you an interstellar nomad by default. Depending on how mobile your star is relative to the rest of your galaxy, they could live in a Rogue Star System.

2. Religious pilgrimage. I find it very likely that, once interstellar travel becomes readily available, at least one church will mount a "search for God" expedition. Necromongers from Chronicles of Riddick are an example of this.

3. Exploration/mapping the galaxy/universe. Some people just have a grand sense of adventure.

4. Trying to get home. This can be something like Star Trek: Voyager, where they've accidentally traveled far away in the blink of an eye and have to take the long way back; or something like Isaac Asimov's Galactic Empire series, where the knowledge of Earth has been lost, and some people are trying to find it again.

5. Running from an overwhelming enemy, a la Battlestar Galactica.

6. Most places are hostile to you, so you must stay within a controlled environment. The quarians in Mass Effect are a good example of this. Their immune systems are so compromised, they must maintain full-body biosuits at all times. To minimize the risk of contamination, most of the species lives in their nomadic fleet instead of among other races on planets. They feel a fleet is more defensible than domes on a planet.

• To be pedantic, you're way off base about the Quarians. The Quarian's immune system is weakened because they live in a nomadic flotilla, with little to no exposure to contaminants/viruses. They were forced from their homeworld by the Geth. They don't live on in the Migrant Fleet to avoid contamination, the live on the Migrant Fleet because their homeworld is occupied and isolated behind the Perseus Veil. – Mike G Jul 8 '16 at 18:29
• Not true @mikeTheLiar they had weak immune systems on their own planet even, kind of like Native Americans and how disease played a huge part in their downfall. Then being forced off planet just made the problem worse – TaylorAllred Jul 8 '16 at 20:53
• @mikeTheLiar I made no mention how they got to be that way, only that they are that way now ("now" being the time of the games). – Azuaron Jul 10 '16 at 1:04

A nomadic civilization moves around because if they stay too long in one place, they exhaust some precious resource (in your case it can be something vital to their society or technology for example). The main issue with a nomadic space civilization is that they are probably advanced enough to just settle down in a favorable part of the galaxy, and instead of packing their tent and chasing this precious resource every few years, they could just send mining probes to different planets to bring the resources they want to them. Here are a couple solutions:

1) The precious resource they are looking for is quickly exhaustible; if they set up camp on a planet for too long, they would find that they quickly have to send their mining probes farther and farther, making the whole process very inefficient and risky (this resource is vital for them, they don't want to risk having it transported across the whole galaxy)

2) The precious resource they are looking for is located at the centers of stars/gas giants/rocky planets, which cannot be mined by some small mining probes. Extracting the resource requires the might of the whole human civilization.

• Another possibility: the resource they need is the sun itself; once mined the system becomes inhabitable – Annonymus Jul 8 '16 at 15:45
• You assume economic pressure to move on, but it could be social pressure instead. – Peter Jul 8 '16 at 16:22
• @Peter What kind of social pressure would cause them to move around so much? I doubt a civilization so advanced would have a religion – Ovi Jul 8 '16 at 17:02
• @Ovi Could be boredom, could be that they need to move to circumvent laws which would make the rich lose their powers, could be staying too long in one place results in them being attacked, could be that the old generation dies and the new generation won't live on the graveyard of the old generation. By the way, we've long since been advanced enough to have no need for religion. – Peter Jul 8 '16 at 17:13
• @Ovi "I doubt a civilization so advanced would have religion." Do you have any empirical evidence for this claim? =) (Hint: no, you don't, since we've never observed such a thing.) – jpmc26 Jul 9 '16 at 4:13

They could be traders. Once they complete a trade cycle with one planet they move on to the next. Bands of traders roaming the wild dangerous spaces between the stars. Not returning to the same system again for generations.

Or follow the pattern of the tramp steamers. The tribe lives on board hauling cargo from one place to the next, then getting a new cargo to haul onward from there. Holding a grand fleet meet every generation to trade among themselves and prevent too much inbreeding.

They could even be mercenaries, paid to fight all across the galaxy but never welcome to settle anywhere. Always moving on to the next war.

• The problem here is what would they trade? Any stable society worth trading with would already have everything they need. What could be worth carrying between ports when it would take YEARS to arrive? – Jason K Jul 8 '16 at 20:04
• @JasonK there was actually another thread about this, what goods are actually worth moving – Separatrix Jul 8 '16 at 21:02
• @JasonK - even if they have everything they need, that's not the same as anything they want.They could be trading in non-essentials, like luxuries and exotics, news and mail, passage for people, and so on from other systems. If there weren't too many of them competing, they might be able to trade for supplies, fuel and repairs... which is all they'd need to keep going, they don't have to get rich off of it if it is a lifestyle choice. – Megha Jul 11 '16 at 9:01
• @Megha That is all well and good, but merchants aren't nomads. Merchants run a specific route with (somewhat) known risks in order to raise the capital to fund the expedition. Unless FTL exists, transit between star systems is gonna take YEARS, far longer than any analogous trade network on Earth. Barring some sort of exotic pharmaceutical, ultra rare element, or animal, almost anything could either be transmitted via radio wave (mail, news, blueprints for new tech, art, etc) far faster and cheaper than it could be physically moved. – Jason K Jul 11 '16 at 14:18
• @JasonK, the time period is defined as "thousands of years in the future", why would they not have FTL? – Separatrix Jul 11 '16 at 14:19

## Imagine an all-consuming swarm, spreading outward in all directions at 99.98% of the speed of light

Well, it's hard to argue what will motivate people/sentiences hundreds or thousands of years into the future. For one, we can't even know if they'll be mostly flesh-based rather than digital.

Nonetheless, we can make some back of the envelope calculations. To prevent disbelief with what's to follow, I'll start by pointing out that there's more economic activity happening in Slovenia today than there used to happen in the entire world 1000 years ago.

The world economy is currently growing at 4%, and has been for about half a century. A more tepid 2% growth, sustained for a thousand years, would make our economy a mere 290 million times larger. That is to say, your average individual would have about as much income as the entire present United States at their disposal. A very naive projection of our present economy and growth forwards at the same 4% rate would suggest an economy about 57 million billion billion times larger in 1000 years time. I can't quite grok what i could do if I were 50 million billion billion times richer, but I bet I could do a lot. Keep in mind that the actual values might be (a lot) lower per capita (depends on population/sim growth relative to econ growth), but it's the overall civilizational capacity we're concerned with here really.

Our (US) current energy intensity (amount of energy it takes to generate \$1 of output) is about 9000 kJ/\$. In the high growth scenario, and assuming absolutely no improvement in our energy intensity (in the real world energy intensity does improve over time), our civilization would require about 4e37 Joules to generate that huge GDP mentioned earlier. All well and good, except that's about 1000 years' worth of our Sun's total energy production. (With the more tepid 2%, we'd still be using only 0.1% of our Sun's energy output)

So, now that we got these order of magnitude estimates done, we can answer your question in a more informed way. If our civilization will continue to grow at the rates of the past half-century (or faster) we will quickly reach the point where even building a Dyson sphere around the Sun will not provide enough energy. Unless some (currently unknown and unenvisioned) superior energy generation method is developed over the next thousand years, humanity's voracious energy requirements will eventually outstrip the capacity of the Earth and even that of the Solar system as a whole.

For a civilization that consumes $$4 \times 10^{37}$$ Joules, the energy required to accelerate a 100 ton ship to 99.98% of c (and thus make interstellar voyages possible within a reasonable subjective time -- effective apparent velocity of 50c in the direction of travel) would require a pitiful $$4.4 \times 10^{23}$$ Joules, or a millionth of the energy used by the civilization every second. We could send out a thousand such probes each second, and use 0.1% of GDP.

So yes, given the assumption of maintaining or exceeding current prevalent rates of growth, the civilizaton of our descendants (be they flesh or machine-based) will spread like a swarm of locusts across the galaxy, consuming raw materials at what to us would appear an apocalyptic rate.

• Comments are not for extended discussion; this conversation has been moved to chat. – Serban Tanasa Jul 8 '16 at 16:09

Planet to planet only if they are being chased, or if by "nomadic" you mean over the course of centuries. If they stay away from planets, then nomadic life is virtually a guarantee.

Consider what space would look like as a terrestrial landscape. Space itself is a harsh desert, totally inhospitable with no water, food, or shelter. Planets are tall mountains, difficult to ascend and descend, but loaded with resources at the top. Asteroids and moons are little oases scattered about, easy to access and locate, but very, very, very far from one another.

So a nomadic tribe has to decide to either hop from little oasis to oasis, or invest the massive resources to scale a mountain. They are not going to invest all that energy (getting into and out of a planetary gravity well) to just take a few things and move on. Now if they were content with harvesting asteroids and the like, that would make for a proper nomadic structure as each spot only has a very finite resource pool and may be limited in selection (ice asteroid, heavy metal one, etc), but if they are going to tackle planets that is a major undertaking. So unless they are slowly being chased by some sort of hostile Fermi Paradox life cleansing force, they will pick a planet and stay there for generations, until they have exhausted it. Not really "nomadic" by our understanding.

Of course if they have magic drives that allow them to easily enter gravity wells and FTL between solar systems then anything is possible.

They could cultivate some kind of space animal. Those animals wander through the galaxy and the nomads would follow them. For more inspiration see Wikipedia.

• This is really similar to the Outsiders from Larry Niven's Known Space universe, which spend all their time following Starseeds and trading with any species they come across. – AndyD273 Jul 8 '16 at 16:34

The nomads could be refugees.

At the heart of every good story is conflict, e.g. man vs. man, man vs. nature or man vs. himself.

For example:

• Man vs. Man: the nomads could be fleeing war, religious persecution, slavers etc.
• Man vs. Nature: the nomads could be fleeing from a star expanding, a virus, diminishing resources etc.
• Man vs. Himself: this is harder to do with a group, but for an individual you can imagine them going into isolation to face their personal demons
• man vs. machine rebellion, too. – Chieron Jul 8 '16 at 15:30

It is feasible, but there are several factors to consider.

First, let's define our terms. From Wikipedia, a nomad is:

... is a member of a community of people who live in different locations, moving from one place to another. Among the various ways Nomads relate to their environment, one can distinguish the hunter-gatherer, the pastoral nomad owning livestock, or the "modern" peripatetic nomad. ...

... Pastoralists raise herds, driving them, and/or moving with them, in patterns that normally avoid depleting pastures beyond their ability to recover.

Nomadism is also a lifestyle adapted to infertile regions such as steppe, tundra, or ice and sand, where mobility is the most efficient strategy for exploiting scarce resources. ... These nomads sometimes adapt the use of high technology such as solar photovoltaics to reduce their dependence on diesel fuel.

Sometimes also described as "nomadic" are the various itinerant populations who move about in densely populated areas living not on natural resources, but by offering services (craft or trade) to the resident population. These groups are known as "peripatetic nomads".

From this, we can see there are three traditional categories of nomads:

1. Those who depend on some form of animal husbandry, but have yet to confine their animals to farms and bring the food to them (rather than them to the food).
2. Those who cope with scarce natural resources by increasing the area they range over.
3. And the most modern of them, those who follow economic resources, not natural.

(Obviously, few are likely to fall strictly into one category and none of the others.)

Number 1 is not going to be a motivation for space nomads because traveling with animals requires bringing them on space ships (properly farming them). As for number 2, there are ways to work it into a space-borne nomadic society, but resources can't be the only reason for their roaming. Perhaps their mining methods are advanced enough to live off the resources of foreign worlds, but too crude to easily extract much more than whatever can be seen from orbit. Perhaps their are not many worlds humans can fully survive off (a very realistic issue) and the few worlds suitable to human life may not welcome the idea of settling the nomadic groups (in the same way few countries welcomed the Jews, Gypsies, etc). This could force them to travel among multiple worlds to get everything they need. Head to world A to collect enough air for a few years, head to world B to collect enough water, etc. Number 3 is straight forward enough. It is pretty easy to imagine a group living as nomads as a result of living on the peripheries of civilization. Perhaps it's as simple as not wanting to pay taxes and live under "the system"/"the machine", or maybe they're not welcome in the civilized world (per number 2).

But!

There is another factor in nomadic life worth mentioning. The first three categories sound all nice and neat for people living centuries ago, but why do people live as nomads in the 21st century, with its cities and mass produced goods? Culture. Tradition. People very often live one sort of life or another, subscribe to one sort of philosophy or another, etc regardless of how optimal it is to living comfortably. So, even though many countries with significant nomad populations actively try to discourage nomadic living, people very often discard external pressure and stick to living in a way they feel is true to their background.

It's possible your nomads do the same (in their futuristic setting). They may simply live the way they do because they chose to, not because they need to. In that case, it's as feasible as their drive to not be tied to one location or another.

One final note: your question is about feasibility, so I should point out that planet hopping like nomads on Earth move from one living location to another is probably not the most feasible thing to do. It's very costly to climb in and out of planetary gravity wells. Space nomads would probably be just that, nomads in space. While plenty of them would probably land on planets as needed. Nomads aren't known for their copious amount of resources. They would probably prefer asteroids, comets, and small to moderate sized moons. They would probably only resort to landing on a planet (or planets) if it has a resource that they can't easily get elsewhere or if non-planetary sources are too far away from their other resource sites. In other words, members of a nomadic spacefaring society could, quite possibly, spend the majority of their lives in spaceships.

How long does it take to completely deplete the resources of a planet ?

Nomads change places only if they exhaust the resources (food, water, ...) existing in the previous location. In your case we are talking about planets, so to completely consume the resources of a planet during let's say 3 years, it has to be one of these propositions :

1 - Small and tiny planets :

The galaxy in which your nomads live contain only small planets with few resources, so they need to change places many times during their life cycle.

2 - Swarms of nomads (overpopulation) :

The traveling civilisation is actually a big one, hundreds of billions of people can easily exhaust the resources of a planet in no time, then move to the other in an endless cycle.

3 - Lazy and passive civilisation :

What's wrong with working in farms to grow vegetables and fruits and breed animals, doing so will assure a more stable future for the whole civilisation.

## Probably not

I'm going with the contrarian view on this one.

I'm not arguing that there's no plausible reason for a nomadic space civilization to develop, I'm arguing that it wouldn't be physically practical to do this.

### Industrial Base

Think about the industrial base that the United States requires to keep its space infrastructure going. With 150 million workers in the largest economy of the world, the US can barely (with the help of Japan, EU, & Russia) keep a single modest space station going. Still some of the population complains about the effort of keeping that outpost running.

Consider the economy as a pyramid of workers. Each level provides a necessary level of infrastructure to keep the higher levels running. The base level might be providing basic goods and services for survival (e.g. food & water).

In such an economy, space infrastructure and its components will always be at or near the top.

So how do you maintain such a huge industrial pyramid when your entire labor forces lives on the infrastructure it is maintaining?

In addition to the problem mentioned above, remember that your nomadic civilization also has to contend with the necessity of providing much more for its work force just to keep it alive. Now providing power, air, water, radiation, etc. (all of these things provided "free" on a planet) requires additional layers of labor to provide to your citizens.

After providing for all of these things, how much of your labor force is left to create microchips, 6-axis NC machines, medicine, doctors, septic tank pumpers, etc.?

• The difference here is that a very very small percentage of the world economy is devoted to the space industry. The closest example of such a unified production effort would be during WWII. In a four year period, the US produced over 56000 Shermans while the Soviet Union produced 65000 T34s. If such an effort was levied towards the space industry, we could easily build large, complex spacecraft. – Kys Jul 8 '16 at 17:00
• @Kys I don't think that's a good example because it's about mass production of already well understood technology. A better example would be the space race. The Soviets announce they'll launch a satellite in 1955, by 1969 we have Neil Armstrong walking on the Moon. In 14 years we went from never been in space to walking on the Moon. By the time the Apollo program ended in 1972, sending people to the Moon has become kind of routine... – ventsyv Jul 8 '16 at 20:47

Once you are advanced enough living in space makes a lot of sense. For one there is no gravity well to overcome, it's a stable environment (no weather, plenty of energy and materials) and you can move around freely. If you want to have some sort of large interstellar empire, you almost certainly will have large proportion of your population living in space. From there is not a huge stretch to imagine a sub-culture of deep-space explorers develop. You can build a religion around it revolving on being the first human to reach/explore a world or just be the one that has reached the furthest or something along those lines.