It's easy to find search results for how long it would take without FTL - but I'm wondering how long it would take with FTL, and there don't seem to be many estimates for that. Some very rough estimates I've seen are 100,000 years (Quora, SpaceBattles), since that's how long the Milky Way is, but then there are secondary concerns such as building colony ships and making the colony self-sustaining. I'm still working on the particulars of how FTL travel works in my world, but individual vessels can travel by warp speed and hyperlanes can be built that are capable of propelling ships faster. Space governance is possible with FTL travel and communication speeds.

I guess the speed of travel is somewhat arbitrary as it depends on the speed of the fictional technology - so exactly the speed of light is 100,000 years, 2X the speed of light is 50,000, etc. For reference, we can look at Star Trek speeds of travel. The United Federation of Planets had colonized a decent chunk of the Galaxy by the 2300's (SciFiStackExchange), and had accomplished this in around 220 years (UFStarfleet.org). The prediction by the Voyager to travel 70,000 light years back to Earth was 75 years (with stops), traveling at 9.975 warp which is around 1680 times light speed (SciFiStackExchange). Consequently, estimates for travelling from one side of the galaxy to the other in Star Trek seem to be in the 70-75 year range (YahooAnswers). By comparison, traveling across the galaxy in Star Wars, with it's ridiculously fast speeds (some estimates are at millions of times the speed of light), can be accomplished in days or only hours (Reddit). As a result, most of the galaxy in Star Wars has been colonized (SciFiStackExchange).

Colonization would of course begin pre-FTL within the solar system (like Mars, the Moon, space habitats, etc.). Some estimates state that it would take around 1,000 years to terraform Mars (Quora), so let's assume that once FTL is discovered ships are sent out to only the most hospitable worlds first, where terraforming is unnecessary or minimal. The question then becomes: how long does it take to colonize a new world?

The length of time to build a colony ship has been worked out before on this site as doable in less than 40 years (source). With an FTL-capable civilization, maybe we could bump that number even lower. The next secondary question is how long would it take to colonize a planet before it's self-sustaining - estimates are hard to come by, but this post says around 350 years (source). Perhaps this too would be reduced due to the speeds of FTL travel, since the Federation obviously did it in far less time. Neil DeGrasse Tyson also supposedly said colonization would be at an exponential pace due to colonies themselves colonizing other worlds eventually (SpaceBattles).

My reason for wanting to know this is I'm building a world where there are multiple alien cultures and factions (a la Star Trek), and I'm wondering how long it would take before one culture starts to have trouble colonizing because all the territory has already been claimed by another. There would be less conflict if there was plenty of space for everyone to share, but it would also be less interesting if anyone could get anywhere in the galaxy in the blink of an eye. I'm looking for a good medium, for the stake of drama, but also realism.

The numbers may be somewhat dependent on arbitrary fictional technology, so maybe it would be helpful to frame the question with known references: how long would it take for the Federation (Star Trek) to colonize the galaxy? How long would it take for the Empire (Star Wars) to colonize the galaxy? How long would it take us, if we discovered FTL at exactly 1x the speed of light, to colonize the galaxy?


closed as too broad by Aify, Pingcode, Mołot, Joe Bloggs, Separatrix Jun 7 '18 at 7:18

Please edit the question to limit it to a specific problem with enough detail to identify an adequate answer. Avoid asking multiple distinct questions at once. See the How to Ask page for help clarifying this question. If this question can be reworded to fit the rules in the help center, please edit the question.

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    $\begingroup$ Are you... are you trying to solve for a mixed travelling salesman/gossip protocol problem with arbitrary inputs on a galactic scale? $\endgroup$ – Pingcode Jun 7 '18 at 6:32
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    $\begingroup$ I VTC'd this as too broad, but misclicked POB. The galaxy is HUGE, and you're asking for too much in the same question. "How long does it take to colonize a new world" already is too broad on its own, as it would depend on far too many variables such as the planets own characteristics and the technology level of the colonists. Star Trek and Star Wars also have very different methods of FTL. For us, discovering FTL probably wouldn't help us colonize the galaxy - at least not for another several hundred years. $\endgroup$ – Aify Jun 7 '18 at 6:37
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    $\begingroup$ Im with aify on this one. By simply building zillions of multi-kilometer long habitable stations around our sun it would be a few thousand years before leaving the solar system even made sense as a necessity. Im not saying we wouldn't mind you, we might just because the option becomes available, but the same tech levels for FTL interstellar colonization could be far more cheaply applied right here in our system for very long time periods before our solar system became "full." $\endgroup$ – TCAT117 Jun 7 '18 at 6:49
  • $\begingroup$ 40 years to make a colony ship, 350 years before a colony is self sustaining, travel happens at c. There’s a few more missing variables: how long before a colony starts producing colony ships, how many colony ships can one colony make at once, and what precisely are your minimum criteria for wanting to colonise a planet? $\endgroup$ – Joe Bloggs Jun 7 '18 at 7:01
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    $\begingroup$ For the moment I’m VTC as too broad (you need to specify a fair bit more before we’re just making stuff up for you) and recommending you remove the questions about other fictional groups (both of which have relatively comprehensive timelines you can dig into) $\endgroup$ – Joe Bloggs Jun 7 '18 at 7:04

The resources available in a solar system similar in size to ours means potentially trillions of individuals could exist there if you built a sort of psuedo dyson-swarm of habitat stations utilizing the matierials at hand. (metals, gases, minerals etc etc). It would be a very very long time before a system became truly "full" because habitation doesnt need to be terrestrial-centric. Furthermore, if we get into really really out-there hard sci-fi with a high level technological singularity occurring its possible your species advances past the point of requiring a physical existence in meat-space and your civilization becomes impossibky massive dysonsphere super computers built around black holes whose "habitat" is a functionally infiniteley large virtual realities. The upper limits for what we can describe as "habitable" reach ludicrous extremes when the realm of whats theoretically possible are included.

As far as how long it would take to do so? Thats going to be heavily opinion based, since a lot of the sort of technologies involved are highly theoretical. If you had von nueman machines building pre-fab cities and populating them with industrial scale cloning it could be very fast. A few decades even. If you have fire-fly style "lone ship of rugged pioneers lands on an uninhabited rock to live off the land" style colonization its going to take exponentially longer if it even works out at all.

The biggest existential threat is likley not going to be over available living space, but that hyper advanced civilizations like the dyson-spheroid entities buldozing over others on accident without noticing or caring. Imagine you find an ants nest at a pic-nic and dump some of your bar-b-que lighter fluid over thier nest and torched it. You just oblitorated thier entire known universe more or less effortlessly simply because they were mildly irritating. Likewise, you humans new series of dyson-swarm habitat colonies are absorbing .023% of the gamma radiation emitted by a nearby star a dyson spheroid toddler of a mere 3 billion years of age was planning to use as a tertiary power source for its chronometer. So it accelerates a 1kg packet of nuetron star matter to 99.9% C into thier sun and goes back to doing its black-hole dyson spheroid elementary homework of calculating pi to the 10^10000000000000th decimal place.

The problem with a fictional universe that includes multiple alien societies isnt explaining how there is enough room for all of them, but rather why one of them hasn't reached a ludicrous level of development and simply annhilated the rest for being irritating and pilfering the hydrogen and silicate crumbs from the inter-stellar entities' cosmic picnic.


I know this will probably be closed because what your asking for is way to broad. But if you wanted to look into it more, you will need to figure out what a colony needs to be self sufficient in the first place (or very close to it) and what technology you have available that can help and support the colony.

Take for example a machine that can convert materials into different materials. If you made a machine like this, then you could potentially colonize any planet, and use it to replicate the machine and you would spread across the galaxy like wildfire.

Start with the basics. How do I get my colonies food, shelter, oxygen, water. What technology level do you want them to be at? and do you want it to be self sufficient. If I want them to have cars, will I supply all the cars, or will they need machines to mine ore, process it, and build cars? Does the colony need to be able to send messages back to earth or where ever? Do I want to provide the colony with access to all human knowledge so they can rebuild everything on their own, or will they need to get access to special resources via earth or specialists?

You need to build it up slowly, but you can have wave a lot of it if you have super advance technology like 3D printers that can print anything, energy to matter converters and perpetual motion energy generators you can just focus on the construction time and travel time. Otherwise you also need a lot of supporting machines and industries to get a colony up to modern times.


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