I have a handful of immortals that have spent the last 6000 years stuck on planet Earth. They really, want to get out of here. They missed their chance back in Egypt before The Fall of the Pharaohs**. This time around they aren't going to miss the next opportunity off this rock. They are planning ahead.

In the next 100-200 years, we will develop generation ships to take us to the stars. Explore the cosmos, colonize space and new planets and all that. Everyone is very excited, including the immortals. Currently they are hiding in plain sight, moving every few years/decades etc. Unfortunately the concealment methods they have been using will be reduced on the Generation Ships.

At first they wondered how they would hide on a generation ship, then they realized they first needed to figure out what type of generation ship to travel on. They know that they won't be able to hide their immortality on the initial smaller generation ships. They have experimented, and all signs point to cryogenics not working for them. As long as the Second Fall doesn't happen anytime soon, they have to wait for one of the larger capacity generation ships.

They aren't worried about the design of the engines or fuel. Well they are, but they are more worried about the social structure and spatial planning of the ships. They have been studying up on psychology, urban spaces and social engineering etc. They can become leading experts in the fields necessary to influence how the Ships social spaces and human movements around the ship etc are planned, well before we ever leave the planet.

What sort of generation-ship design would allow a handful of immortals to remain hidden? ***

Answers should take into account the ability to hide a handful of un-aging individuals in a relatively small population (compared to overpopulated Earth), as well as in a confined space. The immortals wish to remain anonymous, they have the same mental health requirements as a typical human (they don't want to go hide in a corner very often). A good answer is one that somehow incorporates multiple concealment redundancies into the ship-design, just in-case someone catches onto them. Users can determine how big the ship will need to be. Answers should try not focus on the method of Engine design/feasibility but rather on the social aspect.

The immortals are willing to be live separately so as to avoid suspicion, and have committed to no reproduction while in-transit. Transit will take 5-10 generations.

**The Fall is when a highly sophisticated civilization falls so far backwards in progress, that later populations believe they are the first to become so advanced.

*** This is not a homework question.

  • $\begingroup$ For what purpose must the immortals stay hidden, are they stigmatized or something? $\endgroup$ Aug 11, 2018 at 8:57
  • $\begingroup$ Do your immortals have children? Do those also become immortal? $\endgroup$ Aug 12, 2018 at 6:55
  • $\begingroup$ @BenPoulter Have you met the Human Race? The immortals don't want to chance being thrown out of the airlock to spend eternity in the vacuum of space. $\endgroup$ Aug 12, 2018 at 14:23
  • $\begingroup$ @PaŭloEbermann, the immortals have committed themselves to not having children during the trip. They don't have to deal with those extra logistics while on board. $\endgroup$ Aug 12, 2018 at 14:24

5 Answers 5


I think the key is that no individual should encounter any particular immortal for a period of longer than a decade or two, whether as a neighbor, coworker, or service provider. After about 20 years it'd be real hard not to notice that the immortal never aged.

Some places to hide in plain sight then, might include:

  • Caring for the elderly: Old people would see the immortals as much younger, and any of them that hung on to extreme old age would probably not notice that the "45-year-old" nurse still looked like a 25-year-old, or they'd blame it on their failing eyesight.

  • Educating young children: Kids in school think all adults are "old" and don't distinguish much between teachers by age, and they may never see the teachers after a few years in school. (The challenge is how to explain why the parents don't notice the teachers don't age. Maybe all the schools are boarding schools?)

Another solution to the problem is to have the immortals live by themselves in one area and rarely interact with other areas. A few ways to do this might include:

  • Self-regulating "guilds": The ships physicians (for example) could be a guild that keeps their trade secrets to themselves. All physicians are sons and daughters of physicians (or so it seems) and they have their private living quarters, so there are no medical schools open to the public and you'd only meet a doctor in his professional capacity. The doctor's guild of course decides who you see for your appointment, so you won't see the same doctor more than ten years apart. Engineers, lawyers, priests, navigators, and others could also be organized into guilds, so everyone sees it as normal. Guilds existed in the middle ages and Renaissance in Europe, so the immortals might influence society to revive the idea.

  • Generation fleets: Immortals foster the argument that for the sake of redundancy, not to mention human freedom, the colonists not put all of their eggs in one basket under the command of a single captain. Instead of generation ships, launch flotillas of hundreds of smaller ships, each self-governing. Trade and culture will flourish because of the differences between ship cultures. Genetics will be healthier in the long run because young people will marry outside of their home ships. One ship will seemingly be very private and keep to itself, but with all the diversity, what's so unusual about that?

  • 1
    $\begingroup$ Generation fleet looks like a good idea, but I'm not sure if locking immortals in isolation for a few hundred years is acceptable. Maybe you mean that immortals will just move from ship to ship, never staying in one place for long? $\endgroup$
    – Alexander
    Aug 10, 2018 at 23:59
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    $\begingroup$ +1 for the elderly point alone :) great answer. I had thought of generational jobs etc but not of reinstating the guilds! $\endgroup$ Aug 11, 2018 at 0:00
  • $\begingroup$ @Alexander it doesn't have to be just one ship. If there are say a thousand ships in the flotilla, seven or eight of them could be captained by immortals, and immortals could sojourn on other ships for years at a time (although they'd probably want to limit visits by outsiders onto their safe-haven ships). $\endgroup$
    – workerjoe
    Aug 11, 2018 at 0:06
  • $\begingroup$ @Joy, Ok, so immortals' ship(s) is(are) not meant as their sole dwelling(s), just as a retreat. $\endgroup$
    – Alexander
    Aug 11, 2018 at 0:11
  • $\begingroup$ I guess it would even work with no ships owned by the immortals, as long as they kept moving continously, but I bet some of them would want to lay low in one place for a century now and then. $\endgroup$
    – workerjoe
    Aug 11, 2018 at 0:20

Hide as the crew of a cryogenic ship.

Realize that cryogenic is the more advanced form of ship. It allows people to travel in their own lifetimes. If a civilization has workable cryogenics, it won't bother with generation ships. So your idea of waiting until they switch from cryogenic to generation ships won't work. You actually may be waiting until they switch from generation to cryogenics.

You point out that cryogenics don't work on the immortals. That's fine. You don't care. So long as you can overprovision the cryogenic ship to support the immortal crew outside cryogenics, they can act as the crew. They won't be able to have kids for the period that they are on the ship, but they're immortal. They aren't in a hurry.

Your immortals can design, launch, and crew their own cryogenic ship. When they get to the destination, they unfreeze all the colonists. The colonists don't know that the immortals never entered cryosleep.

The critical thing here is that instead of hiding amongst normal people, here you are hiding as a separate group of people. The sleepers won't expect other people to age, so immortality won't matter. Because the immortals provide the entire waking crew and designed the ship, no one else needs to know that they were awake the whole time.

  • 2
    $\begingroup$ +1. I have played around with them on a cryo ship. Mostly the reason I haven't gone that route yet, is because they don't want to wait out the development time of fully working cryo (for normal humans). They worry a Second Fall will occur before that. That's why for now I'm exploring the generation ship ideas for them. It may turn out that they just have to chance it, and wait a little longer than they want to :) it would add some stress/drama to their decision, which is always good. $\endgroup$ Aug 11, 2018 at 11:12
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    $\begingroup$ @EveryBitHelps: If you specifically want to avoid cryo, you could reason that the technology was not fully developed the last time around, and therefore your immortals are not sure that it is even possible. So they have to use generation ships, because cryo might never happen. $\endgroup$
    – Kevin
    Aug 11, 2018 at 23:00

Only immortals are on the ship.

Presumably some of these immortals are filthy rich. Once the technology exists, one of them masquerading as an eccentric billionaire (or maybe no masquerade) commissions a generation ship to be built for him and his handpicked cadre of friends. The public line: he will sleep through the trip and awaken on a paradise planet. This dude has pulled stunts like this before. The engineers are happy to take his money and build his little ship.

Once en route the immortals can relax - for the first time in a long time.



All the immortals pretend to be members of some religion that wears a mask all the time. This may be a religion that they started. It should also have its children educated privately without ever leaving their chambers. They also have their own separate health care and burial rituals.

On the ship, no one actually knows what the immortals look like without their masks. So every so often, announce that an immortal died. The "dead" immortal switches to a new department as a new adult.

Perhaps there is a five year vow of silence or something so as to make it less likely that the immortal is recognized. They may have rules limiting conversation between the masked and unbelievers. Or maybe they only "talk" in sign language.

They may have extra participants in body disposal and medical so that they can catch problems. For example, if one of the masked is injured. Or to fake up a body disposal when an immortal "dies."

This is a variant of what they were presumably doing with the larger population. Stick around for a while and then when their lack of aging becomes noticeable, abandon that identity and move to a new one. The masks allow them to extend the period where a lack of aging won't be noticed.

Or perhaps they don't make distinctions in personal identification. So the masked may be constantly switching jobs. People won't be expecting to know with whom they are dealing. Their "religion" makes them deliberately interchangeable.

  • $\begingroup$ This could work, but it is somewhat dependent on a highly pluralistic and religiously tolerant host population. The danger, however, is that someone might try to join the religion. You would likely need to refuse them in order to maintain an effective charade, which would create suspicion. $\endgroup$
    – Kevin
    Aug 11, 2018 at 23:05
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    $\begingroup$ @Kevin you could have non-immortals also wearing those masks, and participating ceremonies, without problems. They don't need to know that the others don't age. Having some of them actually dying might even help. $\endgroup$ Aug 12, 2018 at 6:57

If they could become experts in robotics and develop very lifelike androids. The android AI only has to be good enough to market itself, and they only need to make one sale.

They have plenty of time to pull this off, so the the AI can be rules-based and just have very complicated rules. The immortals work hard to produce androids which look very similar to themselves and seem intelligent from a distance. Then they hire salesmen to sell the androids to work in food service on the generation ship. When the salesmen have made a sale, they replace the lookalike androids with themselves at the last second, and spend the next 5 generations posing as very complicated androids.

Back on earth, they've already put into motion a plan to destroy their android "factory", and fake their own deaths, so no future ships will have these same model androids and nobody will be able to figure out that the androids weren't as good as the marketing suggested.

During their time on earth, as technological leaders, they can also influence the design of the ship so as to give the androids a decent boarding space. Alternatively, they could design a large unused cavity (or maintenance storage area) into the ship, accessible from where the androids will be expected to reside. Food and restrooms will be easy to access since the androids will presumably live in the back of the restaurant where they serve. They can always just block off the bathroom "for cleaning" when they need to go. One of them could be an android specialized in living amenities, and secretly issue clothes and bedding to the others while the others secretly issue food to that one.


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