I remember reading a work (It was most likley a series of books though not 100% sure) that had a universe where there was technology for FTL spaceflight, but no FTL communications (excluding of course using FTL ship as a courier).

Can someone identify it?

I think it may have been Weber's Honor Harrington world but it's been a long while so I'm not remembering enough details

NOTE: One detail I remember is that at the end, some sort of FTL communication was jury-rigged or initially developed as the plot progressed, but it was limited range

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    There are multiples of those. The Empire of Man universe (The Mote in God's Eye, etc.) for one. Dread Empire's Fall for another. This situation is in no way unique in the literature. Commented Jul 1, 2012 at 12:19
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    More. Scalzi's Old Man's War universe, and while I don't believe it is ever stated Heinlein's Lazarus timeline seems to require this constraint. Halderman's Forever War universe (though there is FTL travel takes inconveniently long). Commented Jul 1, 2012 at 12:45
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    Without a lot more to go on this question is everything that Jeff complained about ID questions being. Commented Jul 1, 2012 at 12:47
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    This question is just too broad. Without more details to go on, then this could be any of at least a dozen universes... Thus, in it's current form it stands as more of a list question, so I closed it. Commented Jul 1, 2012 at 13:27
  • @Pearsonartphoto Alright then. Both DVK and I thought this was much more unique than it apparently is.
    – Izkata
    Commented Jul 1, 2012 at 15:26

3 Answers 3


The Honorverse certainly fits the description - there is FTL spaceflight (riding gravity waves using Warshawski sails or wormholes - sublight travel uses a related gravitic drive called an impeller) but communication either inter- or intra-system is limited to lightspeed. And a similar restriction applies to some of the ship-to-ship weaponry using lasers and gamma ray lasers (grasers) - to paraphrase (since I can't remember the exact quote and I haven't got the books on my Kindle yet)

grasers were a light-speed weapon - the first you knew you were being attacked by one was when you got hit

There are FTL sensors, however, since gravity is ruled to propagate faster than the speed of light, allowing for the detection of ships using their impeller drives, and as the series of books progresses a crude FTL communication method develops for use in-system, using sensor drones equipped with gravity emitters; however the gravity emitters can only generate 'pulses' at a slow rate, and so the drones can only emit, at best, a kind of Morse code. The limited range (in an interstellar context) of gravitic sensors makes this impractical for use between systems.

This lack of inter-system communication (except by, as you say, FTL courier) becomes an important plot point in several of the books, for example in The Honor of the Queen where the only way to send for reinforcements is to despatch a courier to a neighbouring system and then hope the cavalry arrives in time...


The Traveller RPG system features FTL travel through pocket dimensions inflated with hydrogen, this method of traveling precludes FTL communication, which forms the majority of the commerce: ferrying post around.


At the risk of linking to TV Tropes, this page (search for "Aversions With FTL Travel" section) has a healthy list: http://tvtropes.org/pmwiki/pmwiki.php/Main/SubspaceAnsible.

The one I immediately thought of was the settings for the Night's Dawn trilogy, but it could be any of the others.

  • does any of them satsfy the last paragraph? Commented Jul 2, 2012 at 11:56
  • Hmmm...maybe not. Sorry, missed that. The Honor Harrington description sounds closest.
    – Ash
    Commented Jul 2, 2012 at 13:27

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