I'm working on a universe where FTL exists but arrival times can be unpredictable to say the least. On average FTL trips are conducted at 4C but ships can take much longer to arrive than that speed would suggest. No ship has ever been confirmed to be entirely lost but very rarely ships thought long lost turn up decades after their projected arrival window, and there are ships that have been MIA for over a century and turned up.

In a universe where such delays are possible and indeed a 20% arrival variance is accepted as the cost of doing business at FTL speeds what is a reasonable length of time over which the language of signal traffic might stay recognisable?

As reference use modern rates of change in software language etc... and consider that in this universe four years between worlds is a long trip involving several stops in normal space and 8 years, and six or seven waypoints, should get you right across the slightly over 30 lightyears that constitutes the core of human colonised space. Timescale is in absolute, real-space time, travellers experience no time in FTL transits whatsoever. Answers should also consider whether it matters what kind of signals they are, i.e. would real-space navigation aids stay static longer than commercial channels and the like.

Note: I have specified modern rates of change to conform answer to a slightly stagnant cultural setting in which the rate of advancement has slowed dramatically due to outside influences.

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    $\begingroup$ Languages can be learned. Many millions of people can read Latin, which stopped being used as an everyday language some 15 centuries ago. File formats (as I suppose that's what you mean by "signal language") can be documented. Storage media can be standardized and made durable, especially when used for storing messages which can be delivered decades later. And protocols tend to be durable; for example, IPv4, the protocol which carries most of data on the internet (as of 2017), was introduced in 1983. $\endgroup$
    – AlexP
    Oct 9, 2017 at 14:03
  • $\begingroup$ I'm a bit confused by your question. Assuming that apparent time slows down for the traveller, (or is your universe using absolute time?), then as you reach FTL, time ceases. At a nominal 4C, I guess we can assume subjective time remains ceased, right? (ie, stellar passengers are effectively in stasis during transition). Your culture's technology also has some incredible technology that has incredible accellerates/decellerates without any of the normal drawbacks of inertia. Remember the synchronisation of technology would require the same propagation as the travellers. $\endgroup$
    – Konchog
    Oct 9, 2017 at 15:39
  • $\begingroup$ @Konchog My apologies have clarified, timescale is absolute, passengers and crew experience no time at all while in transit. $\endgroup$
    – Ash
    Oct 9, 2017 at 15:58
  • $\begingroup$ As an aside, you have addressed a particular 'terminology' problem that will be encountered more and more, as sci-fi advances. What do we call a universal reference time? And what would the unit be? The universal reference, of course, would be the star map. Weather we stay on earth, or travel at almost light speed to Alpha Centauri, when these two people meet, the distance from earth to Alpha Centauri will be exactly the same on a star map for both of them, both before and after the trip, and will have changed equally for both of them. $\endgroup$ Oct 9, 2017 at 23:35
  • $\begingroup$ ctd The time it took to move from point A to point B, however, will be different. Relative to one viewer, it may have taken five years, but for the other, it may have taken 50 years. Would the standard unit of time become, perhaps, 'time for the Earth-Alpha Centauri distance to change by x astronomical units? And call that a celestial tick? Therefore, for both the traveler and the earth-based observer, one celestial tick would be the same, as far as astronomical navigation was concerned. The star map would look as it should, based on the time lapse. $\endgroup$ Oct 9, 2017 at 23:45

6 Answers 6


Potentially Forever

In software, usually the simplest methodology survives and is built upon perpetually. I know that is going to spark some debate but there are plenty of cases where its true like the prolific usage of HTTP.

In all likelihood what is more likely to change isn't the communication protocols but the applications built to understand and utilize them. In your case a 1st generation starship might require a Com officer who can talk to other ships through a Command line Interface, while a 5th generation starship might have an app that a captain can simply talk to vocally to auto communicate with other ships. Likely, 5th generation captain (lacking the technical skills) would be at a loss trying to figure out how to interface with that assuming the app wasn't designed with backward compatibility. However, if there was a programmer on the 5th gen ship, it is possible he could easily create some bridge.

This is most likely to occur in commercial ships who would prefer to cut costs through automation and reduction of necessary skilled labor.

A military ship would likely have someone technically competent enough to figure out the bridging. Because of the likely technical sophistication of a starship and the already significant emergence of cyber warfare it is highly likely military starships would have multiple tech savvy crew members.

There is another factor which is the physical method they communicate over. A commercial freighter may adopt a cheaper faster physical communication apparatus that the 1st gen doesn't have and remove all other provided no regulation interfered with that (Laws may require all ships to keep RF receivers for standardized communication). So its possible two different generation commercial vessels couldn't physically communicate with each other. A military vessel would like contain every communication apparatus simply for Signals Intelligence.

  • $\begingroup$ Let me make sure I understand, a gen one ship wouldn't, possibly even couldn't face interface protocol issues with a newer system but a newer gen five model may have problems when it encounters older systems that haven't been upgraded, this is pre-edit, reading additional material now. $\endgroup$
    – Ash
    Oct 9, 2017 at 14:22
  • $\begingroup$ Yes and no, this largely depends on how its all coded. It could be that the 5th gen ship sends lots of incomprehensible data to the 1st gen along with the verbal data. That incomprehensible data would be used by the automated app to do whatever it needed to do but that vocal data would still be there. A trained officer could reasonably extract it provided it isn't encrypted. $\endgroup$
    – anon
    Oct 9, 2017 at 14:28
  • $\begingroup$ A shift in signals medium could be a thing, in the specific scenario I'm thinking about it would actually be the reverse, going back to broadcast RF instead of tight-beam visible light laser communications. $\endgroup$
    – Ash
    Oct 9, 2017 at 14:29
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    $\begingroup$ If they don't have the physical apparatus, then they cant communicate. Though they could align their windows and do morse code with a flashlight. $\endgroup$
    – anon
    Oct 9, 2017 at 14:31
  • $\begingroup$ Encryption, thank you that was the word I needed. Going from commercial and navigation signals being sent "in-the-clear" to encryption on all traffic would provide the perfect reason for what I have in mind. $\endgroup$
    – Ash
    Oct 9, 2017 at 14:32

It would (presumably) be recognised at a very early stage that moderate, serious or even extreme delays were possible. If so it would seem sensible to put measures in place to ensure that communications could always be maintained for all ships over time.

As a starting point every ship should be equipped with an emergency communication / navigation system that used basic technology from the dawn of the FTL era. This would consist of radio based antenna transmitter and receiver plus standardised radio telecoms equipment and communications protocols such as ASC and similar. The key feature would be that this equipment would never be upgraded or changed.

In this way ships suffering long delays would always have a fall back means of communication with any ship in any system even if the more advanced communications they also carried failed them.

Taken to extremes if the delay went much beyond 100 years newer emergency communications systems might need to be “upgraded” to ensure they remained compatible with older systems. To illustrate this point if after 200 years the spoken language became noticeably different the “upgrade” might include providing translation manuals or systems to help understand what the older ships were talking about even if the basic communications hardware remained exactly the same.

It might still be possible to upgrade the emergency equipment if really necessary by having a third modern emergency coms system and maintaining all 3 systems (state of the art, modern emergency and ancient emergency) until it was known that no ships were absent from before the modern version was brought into use.

So in answer to your question I would say that provided sensible precautions such as the above were taken, communications could continue almost indefinitely.

You might be interested in the science fiction novel Children of Time by Adrian Tchaikovsky in which a starship carried an “archivist” whose role was to be awakened from hibernation from time to time to help deal with situations when communications from past civilizations needed to be understood. https://www.goodreads.com/book/show/25499718-children-of-time


You can have a functional signal system for a very long time regardless of any cultural, technological, and linguistic changes. But it will require implementation of four things.

1. Standards

Communication standards will help:

  • to limit the number of communication channels and methods;
  • to increase compatibility of equipment within fleets;
  • to decrease the variation of equipment;
  • to facilitate communication among ships of different generations, produced by different manufacturers, etc.

Standards may slow down innovation and its practical use, but they make space flights safer for everyone.

2. Regulations

Regulations are meant to enforce standards. This can be done by some global authority like galactic government or it can be self-regulation done by manufacturers and captains.

3. Backward and forward compatibility

Windows is famous for its backward compatibility, i.e. it is possible to run old programmes on newer computers with new versions of the OS.

LTE is an example of forward compatibility. The standard was developed to accommodate future innovation. Another example is television.

This must be made a part of the standard to ensure that all new devices can receive and interpret a signal from old devices and vice versa.

4. Artificial lingua franca

Technologies change, but languages change as well. I believe that linguistic changes will be much faster and more dramatic in a space-faring civilisation spanning dozens of stars versus our planet.

An artificial language comprising about 1500-2000 words (IIRC, this is the number of words that allow for meaningful conversation in any modern language) will solve the linguistic side of the communication problem.

Why create an artificial language? It has several advantages:

  • it can be kept static;
  • each word has one and only one meaning;
  • the grammar can be kept simple and easy to learn regardless of one's native language.

An artificial language is easier to learn and to use. It also helps to avoid misunderstandings. A carefully constructed language will also have the benefit of no homophones, homographs, or homonyms.

  • $\begingroup$ I'll have to agree to disagree on point 3. with regards to Windows but otherwise you make several good points, I like the idea of a lingua franca and it's probably even necessary but I'm holding out against it, it's been done so badly so often. $\endgroup$
    – Ash
    Oct 10, 2017 at 10:06
  • $\begingroup$ @Ash, if you don’t like Windows (although, you probably never faced a MacOS update...) think television. It worked out quite well. $\endgroup$
    – Olga
    Oct 10, 2017 at 11:04
  • $\begingroup$ No I like Windows well enough I just remember a few cases were it's flaunted compatibility features have been somewhat lacking over the last few years in particular. $\endgroup$
    – Ash
    Oct 10, 2017 at 11:14
  • $\begingroup$ You can learn from their mistakes ;) Although, even the most flawless equipment and software will not help if you don’t speak the same language. You can try to invent a universal translator, but, frankly, I hated the idea since the original series. $\endgroup$
    – Olga
    Oct 10, 2017 at 11:30
  • $\begingroup$ Yeah there is no good option for maintaining universal communication. $\endgroup$
    – Ash
    Oct 10, 2017 at 11:33

I would suspect that, in a world where century delays are expected (if not common) the powers that be would certainly build in legacy translators into their systems. That is, even as the systems develop and evolve, a criterion would be that older systems would be accommodated. Much like Windows 10 can run much DOS software, if even through DOS simulators, unless the program were hardware specific. But there would be exceptions. Running GeoWorks, for instance.

In our world, lighthouses are still used, even though radar, radio beacons, and GPS have made them obsolete for modern navigation. There are still boats that need them.

But methinks you might have another problem. In 100 years, the intended destination would be nowhere near where it would be expected. Unless the spacecraft had some method of keeping track of 'standard' time, and KNEW they were 100 years late, they would have a difficult time making contact, and knowing exactly where they were. Astronavigation, and having a very detailed star map that could be projected into the future, with standardized locator beacons, would be essential, I would posit. Much like a boat that is lost would use lighthouses and other known, charted beacons to get their bearings. It would be imperative to maintain these navigation aids.

  • $\begingroup$ I think you have veered WAY off the OP's question $\endgroup$
    – anon
    Oct 9, 2017 at 18:26
  • $\begingroup$ @anon I fail to see how proposing absolutely standardized navigation beacons, the technology of which might change, but the signal never does, is not related to the OP question of the length of time signal traffic might stay recognizable. Lighthouses, as a signalling system, have lasted for millennia. If perpetuity (universality) is built into the beacon, and the system, the signal recognition will last as long as the equipment is maintained. $\endgroup$ Oct 9, 2017 at 23:22
  • $\begingroup$ You're both right Justin has answered the question and then raised a completely new issue for me to work on, I feel an essay coming on, "on matters concerning spacial jump accuracy with regard to time-like displacement" I actually do know the in-universe answer to the problem I just haven't written it down yet. $\endgroup$
    – Ash
    Oct 10, 2017 at 9:43
  • $\begingroup$ @JustinThyme It's fine if the destination is not a co-ordinate so much as a set of conditions; I want to arrive at this distance, from a star of this mass, orbited by planets of this mass in approximately these positions as described by a three dimensional gravitational curvature model for the space you're aimed at. If you get the model wrong, for example by forgetting a gas giant, that in itself can contribute to extended delays as the location is not "ready" in your standard arrival window. $\endgroup$
    – Ash
    Oct 24, 2017 at 17:39
  • $\begingroup$ @Ash You bring up an interesting problem. Currently, astronomers use an earth-centric co-ordinate system Celestial Equatorial Coordinate System, not quite a universal system. In the dead times in the middle of the night, I sometimes muse about a map of the Universe based on Field Theory, where everything is mapped out in some huge 3D representation of gravitational 'blips' or 'nodes' as they effect and move about each other. Not stars, planets, moons, black holes, galaxies, but gravitational points. $\endgroup$ Oct 24, 2017 at 18:27

This is really a matter of commonsense. Spaceships travel at an average FTL speed of 4 c. Now if the problem is keeping in touch with a shared communications language or as may well be the case shared communications protocols, then the answer is straight forward.

Augment your signal traffic with electromagnetic communications. Radio and laser communications will do fine. The OP didn't mention FTL communications, so it seems reasonable to assume they don't exist in this fictional world. EM signal arrival times are predictable compared to FTL spaceships so this will guarantee a steady and reliable flow of information and data across human-colonized space which is out to fifteen light years from Earth.

In this case, outlying colonies will only experience a cultural drift in their language that is out of step with the central worlds by about fifteen years with respective to EM communication. We can assume a continuous dual one-way exchange of information, data and language. Neither world will ask a question and then wait for an answer before replying (that would be silly). While FTL ship traffic and communications will be out of step by, on average, only seven plus years between the inner and outer worlds.

Ordinary spoken and written language doesn't significant shift over timescales of seven and thirty years. New idiolects, slang and jargon will emerge over those timescales, but not enough to render ordinary language incomprehensible.

Changes to communications devices like navigation beacons, radio and laser communication, and their technical protocols will take place using sensible, practical methods. There will be agreed standards in communications and software across human-space. Basically the way we do it today, but with longer time delays. Problems created by every colony system developing and implementing their own home-grown communications and software protocols are too great for anyone with a grain of commonsense to even think of doing so.

Side-note: There will be the development of home-grown communications protocols in some systems. Because of the usual reasons that what they've got is better than everybody else's. These "improved" protocols will be used locally in their own system. But they will still use the standard protocols to deal with incoming FTL vessels. While campaigning to have their protocols adopted across human-space.

Provided that, in the long run, there is an ongoing exchange in communications across human-space it is quite unlikely that linguistic drift and changes in communications protocols will lead to a situation where there is comprehensive failure in communications. Certainly there should be a capacity to communicate with FTL ships that turn up a century late. But considering this is a well-known feature of this world then appropriate steps will be taken to accommodate it.

  • $\begingroup$ @Ash It's a rare occasion to be edited by the querent. Many thanks for doing so. You have improved & enhanced my answer. The link helps immeasurably. $\endgroup$
    – a4android
    Oct 10, 2017 at 12:00
  • $\begingroup$ Oh okay, I quite often go through and check grammar etc... English is my first language which seems to not be the case for many so I help where I can. Yeah I figure if I have to look up a word chances are other people will too so I link where I can. $\endgroup$
    – Ash
    Oct 10, 2017 at 12:15
  • $\begingroup$ @a4android Just serves to indicate that the OP is actually reading your response to the OP question. I sometimes wonder exactly how many answers are actually read by the OP? $\endgroup$ Oct 10, 2017 at 14:43
  • $\begingroup$ I get the impression that once they decide they've got an answer they're happy with a lot of people ignore anything new as chaff. $\endgroup$
    – Ash
    Oct 10, 2017 at 14:45

In this universe FTL exists but arrival times can be unpredictable to say the least. So a mechanism for this could be chaotically fluctuating macroscale worm-holes - ie, like a vibrating string, but of arbitrary length - so that gives you your variation in arrival date. Being worm-holes means that the physical distance is not necessarily a limiting factor, however - rather one needs to find (or navigate) a shorter path through the underlying structure of the universe (of which this is a 'hologrammatic projection into 4-space', if you will). The advantage of that is then you don't need to give up so heavily on causality and other FTL problems. The disadvantage is that it's still 'magic'. A great example of a novel that uses a similar (but non-fluctuating) approach is Miéville's "Embassytown". This gives you an 'olde worlde exploration' feel (using space as a metaphor for the sea) to travel - with ships sometimes getting lost.

Alternatively, (if you are looking for roughly 12-months distances between 'ports') you could actually set the universe into a non-FTL that is towards the centre of a Pop III globular cluster - so that distances are shorter, and then you don't need to abandon relativity at all. This would allow for a 'new world' oceanic feel, great skies, and no huge plot-holes concerning causality, radio, time-travel, etc.. You would still need an inertialess drive in order to accelerate/decelerate fast enough. Maybe there's a side-effect of the inertialess drie which causes some form of chaotic time compression, giving you the +-20% variations.. So there's still plenty of magic there.

Depending on either of the above scenarios depends upon whether or not things like 'beacons' or 'light-houses' would work, of course. The former - anything goes - the latter, I assume, would use normal electromagnetic radiation, and work just like modern radio lighthouses do - there's an old standard, which works, so it won't change.

As for signal language, Morse was around for way over 100 years without any change. The keys on the typewriter are probably going to be fixed while civilisation lasts (and yes, there's loads of sci-fi that mention the legacy), so signal transmissions tend to be rather stable, for all the reasons that you imagine. I think, even though Morse is now archived, if you were to send a distress signal in morse, you would still be using electromagnetic frequency, and people would still be able to work it out. Interplanetary emergency frequencies are far less likely to change over time, and there are always hobbyists listening out for 'old-school' style messages, especially considering the challenges of your space-flight.

As for upgrades and updates - technology is going to be distributed as fast as people can travel, since people can travel faster than light! LeGuin's "Dispossessed" features the invention and development of the first working Ansible - which allows for the many colony worlds to form a true federation for the first time, because they are suddenly able to communicate text, and later speech, in realtime (I love the book, but a huge plot-hole is that it assumes all planets are stationary in relation to each other, which is not true - so even ansible-voices should be reproduced with some form of doppler effect)

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    $\begingroup$ My FTL mechanics are just fine thank you, as in they're internally consistent enough to work and I'm never going to explain them so they don't really matter anyway, also they full well outside the purview of the question here asked. So with all due respect either answer the question that's actually being asked or go elsewhere, please. $\endgroup$
    – Ash
    Oct 9, 2017 at 17:42
  • $\begingroup$ Sorry, @Ash - didn't mean to offend. But you are still being unclear. You talk about 'absolute' time - which means that the passage of time is unchanging, regardless of velocity, but then state that travellers notice no passage of time. One, or the other may be true. Both is a contradiction, no? I do also answer your question on the last two paragraphs. ;-D $\endgroup$
    – Konchog
    Oct 9, 2017 at 17:44
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    $\begingroup$ Absolute time as in universal clock time, the time experienced by the universe versus travel time experienced by the ship in transit which is zero, due in no small part to the fact that "travel" is a loosely used term. The ship is at it's starting port then, some time later, it is at it's destination, unfortunately the mechanism leaves something to be desired in certainty concerning the time-like displacement of your return to "flat-space". Sorry only got as far as paragraph two where having seen nothing that resembled relevant material I commented and went to look at other things. $\endgroup$
    – Ash
    Oct 9, 2017 at 17:54
  • $\begingroup$ So, a universal clock-time indicates an Aristotelian physics (where time is concerned!) right? So, what limits light-speed (ie, massless motion in a vaccum)? $\endgroup$
    – Konchog
    Oct 9, 2017 at 18:03
  • $\begingroup$ Assume universal locked frame of reference FTL without the possibility of time travel, in other words the rules as we know them. Several methods are possible for tracking time across light-years to spite dilation effects. $\endgroup$
    – Ash
    Oct 9, 2017 at 18:14

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