How to Ansible

I’ve already looked at how to teleport and how to make an FTL drive and the next step is how to make some kind of space-radio that will allow your reports to Space Command HQ get there in a reasonable time.

Interestingly this takes a bit more thought than the first two. Teleporting doesn’t necessarily require anything to go faster than light, an FTL drive does but also involves some great big hulking machinery to do it. Sure, if you have an FTL drive, you could physically send your hard copy report but that’s not really what we are after with an ansible.

Story-wise, ansible’s are less important to a conventional narrative than an FTL drive. Travelling faster than light allows protagonists to get where they need to be. An ansible, on the other hand, allows people in different places to know what is going on and rather like mobile phones in modern stories, that isn’t always helpful. SF historians please correct me if I’m wrong, but I’m pretty sure the first case of an ansible as a plot device was in Ursula Le Guin’s Rocannon’s World, but even here Le Guin has to separate her protagonist from the device for most of the story. Rocannon is cut off from communication and only after a long and somewhat fantastical quest, can he send a vital message home.

But writers can still make clever use of a setting where FTL communication is possible but FTL travel is impossible, limited or difficult. Orson Scott Card makes clever use of ansible technology in his Ender novels for example. The default for space opera is FTL communication as an after thought and it is often deployed inconsistently with even more vagueness around its limitations or the underlying technology. Star Trek has ‘subspace’ communication whose range and availability seems wholly determined by plot needs.

Unlike the previous two posts, this is a short list. I’ll assume that there could be ways of hacking the entries for teleporting and FTLing to courier messages and worry just about how to make a space CB radio. Duplicate techniques will only be when the same fictional physics could be used to maeke something radio-like rather than a drive for a ship.

  • A new theory of physics. This may take a whole book to come up with, as well as an exile from a shabby anarchist utopia but if you have a principle of simultaneity  in your General Temporal Theory that works along side General Relativity then you’ve cracked ansible technology. Well done Shevek!
  • Quantum Entanglement. Maybe physics already has the answer! The parameters of entagled particles are connected as a whole system. The state of one of a pair of particles relates to the state of another, even when seperated at a great distance. In itself this is not spooky, it souds analogous to tearing a piece of paper in two — the pattern of rips on one piece match the rips on the other. The spooky part is that the parameter in question aren’t determined until somebody measures them because of quantum pixies or something. At that point, the parameters of the entangled particle also become fixed, even if the particle is a long way away. Spooky action at a distance! Unfortunately, even if this effect does somehow propigate faster than light it doesn’t actually seem to be possible to communicate with it.
  • Warp space. “Wait,” I hear you say, “you said you weren’t going to repeat things from the previous lists.” Yes, yes this implies a method for travelling faster than light and I’m assuming this uses the same (probably impossible) technology. However, this time your spaceship is going to stay where it is and use the warp drive to send ripples through space-time that effectively travel faster than light!
  • Tachyons. I’ve also mentioned these hypothetical superluminal particles before. Assuming such things existed and assuming we had some way of interacting with them then maybe you could send a message with them.

That’s all I’ve got!


20 thoughts on “How to Ansible

  1. One of the most interesting explorations I’ve seen of this theme was by James Blish – in his short story “Beep”, later expanded into the novella “The Quincunx of Time”. Blish’s “Dirac communicator” is just a technobabbly instant-message machine, but what makes it interesting is its side effect – which I won’t spoil here if you haven’t read it.

    One of my own interminable Trek fanfics had a communications system between time-travelling villains which might bear on this – one side of the partnership, in the future, had a formidably complicated anti-chroniton rubber science generator which sent his messages backwards in time, but his partner, in the past, had nothing more complicated than a recording of her side of the conversation, which she left in a place where she knew it’d be picked up. Given the causality violations inherent in FTL travel, an FTL messaging system could be developed to exploit them.

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    1. Yes, Le Guin got some of the idea from Blish’s “Beep” (still a swell story), but she did more with it. Particularly since ansibles worked instantly, but her ships only had NAFAL (Nearly As Fast As Light) drives and thus took quite a long time to get from planet to planet. And ansibles only worked on planets, not ships, so you never knew what was going on till you got there.

      Must admit that when I saw the title, my first thought was “You send a news item or a SASE to David Langford?”


  2. One I remember from We All Died at Breakaway Station by Richard C Meredith where the titular station was used as a comms relay. The idea was that FTL messages could somehow be imposed over an existing electromagnetic connection between the relay and source/destination.

    The book centres on protecting the station so critical information on the location of the enemy homeworld can be relayed to Earth for a counterattack. If the base is destroyed or loses the connection it will take the same length of time to re-establish as any transmission at light speed. A bit contrived but sets up the dramatic tension nicely. The only ships available to defend it are two beaten up cruisers crewed by walking (or rolling) wounded that were escorting a hospital ship to Earth.

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  3. The problem with using quantum entanglement is you have to know *when* to measure the system at the “receiving” end. If you measure too early you collapse the system anyway and the entanglement is gone, so the “transmitter” can no longer influence the qe system from their end.
    All the ways we know for notifying the party at the “receiver” end that it’s time to measure are limited by lightspeed.
    (Talking about this stuff is now part of my day job as an IBM Q Ambassador, believe it or not!)

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    1. I love how the underlying physics is very deep but practically all the schemes to exploit this turn out to be equivalent to two people opening up seperate envelopes with a pre-written message in each.

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    2. And Kevin forgot to mention that he’ll be giving his Q talk at Worldcon! Without math so it’s not scary.

      Not that he’s BUSY or anything right now…

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      1. Ah, shucks.

        I’m lucky in that I have this science talk (I wrote it last year for Helsinki) approved for presentation as well as the one that all IBM Q Ambassasors have to hand. This one lets me use more of my props. 🙂


  4. Granted, I’ve seen flip versions of this where FTL travel was possible but FTL communications was not.

    One version from the old ‘Albedo’ comic book (funny animals but relatively hard science) had no FTL communications, and an FTL ‘jump’ drive that required you to be out at the edges of the solar gravitational well to activate it. Actual travel was nearly instantaneous, but the closer you were to the star, the more ‘tidal stresses’ worked on the ship as you got kicked out of the system. And you could only travel to the next star in line.

    Their solution was that not only did all ships carry news archives on their computers to keep everybody up to date, but there were ‘message torpedoes’ installed on satellites operating in distant solar orbits if something needed to be sent immediately. Problem is, of course, that those torpedoes were single-use, and getting out to refill the satellites was an expensive undertaking, so usage was pretty much limited to emergencies.

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      1. Message torpedoes and courier ships are an old and hallowed tradition in SF. Ships can go into hyperspace, but information has to obey the speed of light — unless it’s in physical form on a ship.

        It kinda anticipated/paralleled a situation we still have today:

        (The husband used to pilot the proverbial station wagon full of tapes down the highway, except it was a pickup truck.)


  5. Hm, the mima (essentially an ansible, also capable of transmitting emotions IIRC) is a definite plot point in Martinson’s Aniara, roughly a decade before Rocannon’s World (ooooih, darn, there’ll probably never be a 1956 retro-Hugo, and I don’t know if “DP, LF” was a thing, but if it was and there is, that is definitely worth nominating).

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