History Main / SubSpaceAnsible

Amazingly, quantum entanglement seems on track to provide this in real life; scientists have figured out that if you split a muon and induce one half to spin clockwise at a certain rate, the other half will spin counter-clockwise at an identical rate. This works no matter how far apart the two halves are.

* FTL communication is possible in ''Literature/EmpireFromTheAshes'' but very cumbersome, not available in sub-lightspeed craft and requiring exotic synthetic materials that starships aren't equipped to make. The mutineers sabotaged Dahak's and stole the only spares, so Dahak was forced to throw together a mundane lightspeed device instead in his attempts to phone home. [[spoiler:The lack of an ansible is one of the Achuultani's greatest disadvantages, forcing them to slowly advance through a system of preplanned rendezvous points and delaying reports back to their homeworld by centuries.]]

* In addition to allowing starship travel, the [[PortalNetwork jumpgate network]] in the ''[[VideoGame/{{X}} X-Universe]]'' series acts like a subspace ansible, allowing lightspeed radio signals to travel across the galaxy fast enough for real time communication. (This is mainly because a sector's gates [[SciFiWritersHaveNoSenseOfScale are rarely more than 100 kilometers apart]].) The fact that this is not true FTL communication becomes a plot point: after the gate network shuts down following ''X3: Albion Prelude'', interstellar communication in real time becomes impossible and all organized interstellar governments in the X-Universe[[note]]except the Earth State, whose population is mainly confined to the Sol System[[/note]] break up instantly.

* FTL communication is possible in ''EmpireFromTheAshes'' but very cumbersome, not available in sub-lightspeed craft and requiring exotic synthetic materials that starships aren't equipped to make. The mutineers sabotaged Dahak's and stole the only spares, so Dahak was forced to throw together a mundane lightspeed device instead in his attempts to phone home. [[spoiler:The lack of an ansible is one of the Achuultani's greatest disadvantages, forcing them to slowly advance through a system of preplanned rendezvous points and delaying reports back to their homeworld by centuries.]]

* EclipsePhase's Quantum Entangled Communicators provide instant communication regardless of distance, but like those in the CharlesStross example rely on pre-linked, finite "qbit reservoirs".

* Elizabeth Moon's ''VattasWar'' series featured the operation of these [[spoiler: as well as the sudden non-operation of them]] as a major plot point. Notably, interstellar FTL comm is possible, but not local FTL comm, due to the ansibles being full-scale space stations. [[spoiler: At least at first.]]

** In some circumstances, long-range communications occur in realtime, and in others they do not. Some ExspandedUniverse sources indicate that the signals cna be effectively instantaneous if the signal strength is high enough, but this requires a repeater network to maintain over more than a few tens of lightyears.

* The plot of ''VideoGame/CommanderKeen 4'' starts with Billy Blaze building a FTL radio and accidentallly picking up a transmission from a group of aliens planning on destroying the galaxy.

* ''{{Halo}}''. All messages are carried on ships that travel between planets. Described as the futurisitc Pony Express.

* MikhailAkhmanov and Christopher Nicholas Gilmore's novel ''Captain French, or the Quest for Paradise'' averts both interstellar communication and FTL travel. In this 'verse, space travel is a rarity due to the prohibitive costs involved. Also, while there is a way for a ship to jump to near-light speeds that make it seem only seconds pass for the traveler, decades (sometimes, centuries) pass for everyone else. It also requires one to move to the edge of a system on sublight (several months) before activating the drive in order to avoid CriticalExistenceFailure. The titular character mentions that, in 20,000 years (aging has been "cured" long ago) of traveling through space, he has intercepted about 20 interstellar messages (sent via ordinary radio), and none of them contained anything of value to him. He explains that building and maintaining large orbital arrays is too costrly for most planetary governments, much less private persons, and provides virtually no return on the investment. The only people to travel between stars are colonists on one-way trips, occasional missionaries, and space traders. There are only a few hundred space traders in existence, and all are treated as royalty on most worlds, as they are the only ones who bring news from other worlds (even if those news are centuries old).

* The ''VideoGame/{{Homeworld}}'' verse is implied to have FTL communication (the ''Veer-Rak'' alerting the ''Kuun-Lan'' which is in another system that Hiigara is under attack at the beginning of ''Cataclysm'', for example) but it's never explained. FTL sensors however, are a bit sketchy: the manual of the first game explains that the Mothership has a cobbled-together short-range[[hottip:*:"short" in this case means "couple seconds of advance warning"]] sensor that can see if the ship is passing near a high-mass object in realspace but they have to drop out of hyperspace to actually see what it is. ''Homeworld 2'' has Advanced Sensor Arrays buildable on Hiigaran super-capital ships that can detect enemy ships in hyperspace.

* Recently[[hottip:*:published 2 December 2011]], scientists have discovered that [[http://www.livescience.com/17264-quantum-entanglement-macroscopic-diamonds.html Entanglement is possible in macroscopic scale]]. Quantum entanglement experiments make it seem as if systems are somehow "communicating" faster than light through correlations between their states, although if quantum mechanics is correct it's (provably) impossible to actually use this to send information faster than light.

* The ''{{Battletech}}'' universe has Hyper Pulse Generators ([=HPGs=]), which send messages between star systems instantaneously. It works by creating artificial hyperspace jump points (natural ones being null-gravity locations at a star's zenith or nadir or in [=LaGrange=] points) to transmit tight-beam transmissions to a receiving HPG. It's been stated in canon that sending a message via HPG can often take anywhere from a few days to weeks, but that is mainly because the cost of transmission is so high, the operators will wait for a large number of messages to be sent at once.

** A secret technology developed by the Star League before HPGs but abandoned when HPGs were more practical was the "Black Box" devices. Instead of point-to-point, the Black Boxes worked instead by broadcasting much like a radio, but into hyperspace. The Federated Commonwealth acquired and developed the technology to secretly break the monopoly on interstellar communication via HPGs by the "officially politically neutral" quasi-religious organization known as [[NGOSuperpower Comstar]].

* The ''{{Battletech}}'' universe has Hyper Pulse Generators ([=HPGs=]), which send messages between star systems instantaneously. It works by creating artificial hyperspace jump points (natural ones being null-gravity locations at a star's zenith or nadir or in LaGrange points) to transmit tight-beam transmissions to a receiving HPG. It's been stated in canon that sending a message via HPG can often take anywhere from a few days to weeks, but that is mainly because the cost of transmission is so high, the operators will wait for a large number of messages to be sent at once.

* The ''{{Battletech}}'' universe has Hyper Pulse Generators, which send messages between star systems instantaneously. It's been stated in canon that sending a message via HPG can often take anywhere from a few days to weeks, but that is mainly because the cost of transmission is so high, the operators will wait for a large number of messages to be sent at once.

* In ''Hellspark'' by JanetKagan, there is FTL travel but no FTL communication. Messages have to be physically transported, and there are severe penalties for interfering with a ship carrying mail. Expeditions planning to spend time away from the regularly-travelled routes may take unmanned message drones, but these are expensive and hard to replace, and are kept in reserve for emergencies.

** Just don't mention the TV series, which had a realtime video conference using said [=HPGs=].
** That would be a HPG relay, set up by using two [=HPGs=] at once. It has been used in the novels and is noted to be very expensive.

* ''TabletopGame/Warhammer40000'' again. The Tau have FTL travel, but since they don't have psykers like the Imperium or Eldar they have to bounce their signals off relay beacons the old-fashioned way.

If the setting has both subspace and hyperspace, then typically subspace will allow nearly-instant communication, but can't be used for travel. Even in ''Franchise/StarTrek'', which uses subspace for both, real-time conversations take place between characters who are days of FTLTravel apart. This allows plots to be written as if SpaceIsAnOcean. On the other hand, just as not all FTL methods are equal, neither are all FTL comms. A humble 10''c'' is technically FTL, but it'll still take about 5 months for a message to reach Earth from an Alpha Centauri colony. Raising the speed of transmission to 365''c'' turns the travel time down to 4 days, but still an eternity for any poor spacers calling for reinforcement, and God forbid you need to call for help from anywhere further. Having a determinate speed rather than [[TravelingAtTheSpeedOfPlot that of plot]] can shape a story's events.

** The existence of SubspaceAnsible also {{Handwave}}s the fact that Harbinger is capable of "[[CatchPhrase ASSUMING DIRECT CONTROL]]" of individual {{Mooks}}, despite being a Reaper whose physical form is drifting thousands of lightyears ''outside the galaxy''.

* AlanDeanFoster uses the SubspaceOrHyperspace version in his ''HumanxCommonwealth'' series. "Space plus" is hyperspace and is used for FasterThanLightTravel - it can also be used for communication but at the same speed as starships. "Space minus" is subspace and can be used for near-instantaneous communication, but at a very high energy cost. Later in the series, it's revealed that SufficientlyAdvancedAliens figured out how to travel in space minus as well.

* {{Star Ocean}} mentions that they apply the same gravetic warping to communication signals as they do their ships.

* In TimothyZahn's ''Literature/TheConquerorsTrilogy'', there are two possible FTL speeds for ships allowed by physics, but faster-than-light communications are impossible for humans.
** Humans quickly deduce, due to the coordination of the attacks, the alien Zhirrzh have a cheap, accurate method of FTL communication [[spoiler:their Elders]]. This understandably terrifies the humans. We also see a minor side-effect of this communication [[spoiler:radio waves cause Elders pain and can kill them-- which is considered an unthinkable atrocity]] caused consequences that ripple through all of the novels.

* Most of the writings of TimothyZahn fall into this category. The {{Blackcollar}} books, ''Literature/{{Spinneret}}'', TheCobraTrilogy, TheConquerorsTrilogy, etc. all feature settings where FTL travel is easy, but messages can't travel any faster than the ships carrying them.
* Most of the work of TimothyZahn is an example. {{Blackcollar}}, TheCobraTrilogy, TheConquerorsTrilogy, ''Literature/{{Spinneret}}'', all feature settings where FTL travel is possible, even common, but FTL communications depend on actual ships making the trip.