Salmoneus wrote:I'm not sure that's a good idea. Designing your ship to land is hugely difficult and expensive - imagine trying to float a city! - and there's no real need for it. What you'd actually do is "anchor" in orbit and portage everything down to the planet on shuttle.
[and if a colony ship is a city, you can indeed carry factories with you... indeed, you'd certainly want to do so, rather than having to stock a year or two of everything you might possibly want in advance]
I want to chime in, but I think I need to reread to clarify what were suggestions and what were Whitewings' original thoughts.
(rereads)
Okay, I'm back.
Just a few things.
20,000 years from now - technology will essentially be "magic" to us. Folks that far into the future will be able to make faster than light communications and absorb it through their skin right into neural receptors. Whether its cybernetci implants or some kind of über-CRISPred biotech, they will be there enjoying what will be only merest imaginings to us.
Ki energy/Tesla energ/wutevs… that will also be harnessable in that much time. Heck, Humanity has gone from the bow-drill to microwave ovens in, what, 100,000 years? Your magical spells or whatever will most assuredly be some kind of barely imaginable technology at work for humans.
Also, Whitewings, you have stated that your ships have had FTL (faster than light) travel capability, in order to bridge distances with herculean speeds. So, regardless of a 20,000 year distance between when the first colonists left, and when your sole survivor arrives at that distant settlement, as lomg as the first generation got to its destination by FTL technology, then likewise there ought to be FTL communication.
Thus, folks living in even the most distant space settlements ought to be able to receive near-real-time communications from Earth, or any number of the colony worlds. Therefore, some sort of Lingua Franca ought to be mutually intelligible among colonists and Earthers.
Now, of course, 20,000 yrs is an immense period of time. We have no record of any language that's as old as that today, and as pointed out by Sal, our proto-language reconstructions only go back 5,000 to maybe 7,000 years ago. In your scenario, human languages will have undergone
thrice the amount of time. As was pointed out, a (pure) descendant of Japanese (or any language) is highly unlikely, about as unlikely as anyone speaking a lineal daughter-lang of, say, Denisovan or Neanderthalese.
However, I might argue that, with the overall increase of literacy worldwide, language change may not happen as rapidly over future time as it did in past time. As long as there are networks that keep distant far-flung colonies connected, and repositories of knowledge are likewise accessible to colonists anywhere by means of FTL communication, I would think that might slow language change since these phenomena would buffer against speaker-community isolation, which is a major agent of language differentiation. But then future linguæ francæ, pidgins, patois and creoles that will certainly arise in such a broad swath of time… the possibilities!
I have another point, concerning "prohibitively expensive investments" in Super Swift Sleeper Colony Ships. As with movie franchises and Space Shuttles, I am sure the nations or interested parties providing the outlay for such an expenditure of R&D would not be banking on just one (all ur eggs in one basket is never sound financial advice) final product. It would make more sense to make at least a pair, a trio, a dozen of these at a time, to help cover would could be potentially devastating (cf. Space Shuttle Challenger tragedy) results if it were one ship alone.
One more point. I absolutely do not get how planet/star system-hopping Swift Ships, composed of, as you said Whitewings, crews of mixed nationalities, would, after 19,900 years of hopping, arrive at the conclusion that Edo Japan is exactly what this near-Earth exoplanet needs as a colonial aesthetic. Possibly a number of adult colonists who were traveling somewhere close, say Mars, in the near future, might perhaps find out that they coincidentally happen to be Japanophiles, but how that would help unite & rally them more than the utter joy of exploration, the "against-all-odds" pioneer spirit... I just dunno.
The only possible way I could even slightly wrap my head around that kind of choice that a group of people would consciously make together would be this. They are all some part of a sort of futuristic joint-stock venture whereby, in order to even sign up to be part of the crew or the colonists, you would have to have agreed that this is what you would want to paint your colony. But like Keenir or Sal mentioned, it's kind of like wanting to live like cavefolk while surrounded and immersed in well-nigh magical (by our standards) technology. But if that's the kettle of fish folks wanted, then some sort of a future version of a joint-stock venture would cross national/political/ and maybe even traditionally ethnic divides for such a colony to begin to be feasible.