->''The message was an electronic shout, the most powerful and tightly-beamed short-wave transmission which men could generate, directed with all the precision which mathematics and engineering could offer. Nevertheless that pencil must scrawl broadly over the sky, and for a long time, merely hoping to write on its target. For when distances are measured in light-weeks, the smallest errors grow monstrous.''
-->-- '''The Burning Bridge''' by Creator/PoulAnderson

Space is big. No, ''[[ScifiWritersHaveNoSenseOfScale really]]'' big. You might think it's a long way to the chemist, [[Franchise/TheHitchhikersGuideToTheGalaxy but that's peanuts compared with space. Listen]]... the only way to have snappy dialogue between characters in different star systems (hell, even to '''''the moon''''') is with faster-than-light radio. This Subspace Ansible (a.k.a. FTL Radio) is also necessary for spaceships using FasterThanLightTravel to have two-way conversations, since actual radio waves ''are'' light (of a non-visible frequency) -- and are therefore slower than the ship.

There are several types of faster-than-light technologies in fiction; however, Subspace Ansibles need to use one that doesn't require sending the ship's engines along with the message. So, they typically use the "shortcut" method: sending ordinary radio waves through an exotic SubspaceOrHyperspace that is smaller than real space.

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. This can help mitigate UngovernableGalaxy.

In some cases, a Subspace Ansible may exist even if FasterThanLightTravel does not. There might be some attempt to [[JustifiedTrope justify]] this, proposing that technology exists to bypass the limits of relativity for information but not matter, but often, it is simply a matter of necessity: although a single-star-system SpaceOpera can get by without FasterThanLightTravel, it takes several minutes for radio waves to travel the distance from Earth to ''Mars'', so the problem of communication remains pressing even if FasterThanLightTravel can be safely shelved.

Presumably, an FTL Radio is also what allows ship sensors to work faster than light, viewing objects that are light-minutes away -- or even light-years! -- in real-time. However, any attempts to explain it are indistinguishable from a HandWave (unless tachyons are involved; then it gets complicated).

The term "ansible" for this kind of near-instantaneous subspace communication system was coined by Creator/UrsulaKLeGuin in her 1966 novel, ''Literature/RocannonsWorld''. "Ansible" is a derivation of "answerable,"; i.e., "messages will be answerable in realtime."[[note]]Others have noted that, either by accident or design, "ansible" is an anagram of "lesbian."[[/note]] Many other science-fiction writers picked up the name after Le Guin.

If PsychicPowers exist in a setting, they often work instantaneously at any distance, and function as a Subspace Ansible. Quantum entanglement is a popular explanation, since QuantumMechanicsCanDoAnything.

!!Straight Examples:


[[folder: Anime & Manga ]]
* In ''Anime/MacrossFrontier'', the Vajra are capable of interstellar communication via their [[spoiler:HiveMind link, which uses symbiotic, fold quartz-carrying bacteria in their entrails to link the whole species together]] instantaneously across the galaxy, without any sort of fold interference or delay. In fact, abusing this [[spoiler:galactic overmind to link up the entire galaxy whether it wants to or not (humanity included) is the major goal of the BigBad.]]
* The [=SolarNet=] in ''Anime/CowboyBebop''.
* The ability of the Emilys from ''Anime/StrainStrategicArmoredInfantry''. [[spoiler:Which led to them being [[NightmareFuel cranially bisected alive]] by human scientist to obtain it. Being HiveMind, they share the pain as well...]]
* Galaxy Network in ''Anime/StarshipOperators'' is suggested to use quantum entanglement in dialogue.

[[folder:Comic Books]]
* In ''ComicBook/{{Legion Of Super-Heroes}}'' comics, communications are relayed through the same Stargate system used for FTL travel, making it possible to have a real time conversation between Legion HQ on Earth and the Legion Outpost in deep space. In the post-Zero Hour, pre-Infinite Crisis Legion, when the Stargate system goes down, people can still travel in "old fashioned" warp vessels, but the only means of communication is Titanet, a relay of Saturnian telepaths.

[[folder:Films -- Live-Action]]
* ''Film/{{Avatar}}'':
** According to the [[TheWikiRule Avatar wiki]], the [[http://www.pandorapedia.com/human_operations/vehicles/isv_venture_star Pandorapedia,]] the ''Venture Star'' has faster-than-light communication technology with a low-bitrate device using quantum-entangling. This is a case of AllThereInTheManual, as this Ansible was never shown or mentioned in the film itself, though it is probably how Quaritch was able to confirm "corporate approval" for [[spoiler:Jake's legs]]. Actual faster-than-light ''travel'' is notably averted.
** Also, in a deleted scene, [[CorruptCorporateExecutive Selfridge]] is threatening Quaritch with termination, claiming that "one phone call" to the home office is enough to get rid of him. This implies that the call would be instant and not take 4.3 years in either direction.
* In ''Film/TheFifthElement'' radio broadcasts and telephone/video conversations are instantaneous.
* ''Franchise/StarWars'', of course. The galaxy-spanning [=HoloNet=] allows people to communicate in real time through holograms despite being separated by thousands of light years. Suitable communications systems on ships connect via relay stations spread throughout the galaxy in a manner similar to the real world cellular network. Users accessing the [=HoloNet=] can also be located via the network, as shown in ''Film/ThePhantomMenace'' and ''Film/AttackOfTheClones''. "Disturbances in TheForce" can also be sensed instantaneously, even if the source is in real space and the Force-sensitive is in hyperspace, as when Obi-Wan sensed the destruction of Alderaan. The case of Darth Vader manipulating Luke to convince him to visit Bespin actually exploited visions of the future rather than this, Luke saw those happening before Han and Leia even arrived.
* In ''Film/SpaceBattleshipYamato'' the Yamato has one, but its range is limited to within the Milky Way. Okita gives everyone one minute each to say goodbye to their relatives on Earth before they continue on.
* Inexplicably possible in the Soviet two-part sci-fi film ''Film/MoscowCassiopeia'', where the teen cosmonauts are able to attend classes via teleconference while in interstellar space. Later, when they end up traveling at near-light speeds and end up at their destination early (from their viewpoint), they talk to mission control back on Earth in real-time. There is also the moment where [[TheMenInBlack IOO]] uses a rotary pay phone and a metal cigar case to show real-time footage of the starship to TheCaptain's parents, but his abilities appear to be far beyond what's possible even in the film's science.

* The TropeNamer appears in most of Creator/UrsulaKLeGuin's ''Literature/{{Hainish}}'' novels. Le Guin devised "ansible" as a contraction of "answerable."
** In ''Literature/TheDispossessed'' she tells, among other things, the story of its invention.
** In ''Literature/TheLeftHandOfDarkness'' it's clarified that the ansibile needs a significant gravity source to work, so one "end" of the connection is a "stabile" and must be fixed on a planet while the "ansibile" is portable.
** In the world of the Ekumen, there is no faster-than-light space travel, but there are FTL weapons. No living thing can survive FTL but unmanned ships have no problem. In ''Literature/RocannonsWorld'', there are FTL ships packed with bombs whose pilots are effectively suicide bombers, ready to sacrifice themselves in a case of dire emergency.
** Later into the cycle the problem of the FasterThanLightTravel gets solved, but as the means to do so are both [[TelepathicSpacemen psychic]] and [[JourneyToTheCenterOfTheMind mystical]], the results are... varied.
* ''Literature/EndersGame'' is a major example of another writer taking the name from Le Guin. A character mentions that there is a formal name for their FTL Radio, but "somebody dredged the name ''ansible'' [[ShoutOut out of an old book]]." The working principle of an ansible link is something about "[[MinovskyPhysics subatomic philotic links]]" that form between two subatomic particles, which can be stretched infinitely when properly separated. FTL travel doesn't exist though [[spoiler:for most of the series at least]], so the ansibles are really the binding force for the entire interstellar civilization (to the point where one colony declares itself to be in rebellion and does the unthinkable by destroying their own ansible, or so it would seem...)
** These links are also both ThePowerOfFriendship and what holds the universe together.
*** AND how the Buggers/Formics communicate with each other and their drones (they EVOLVED to possess FTL communication!) It makes sense if you read the explanation of how these links work and what they really are.
*** Turns out the Piggies use them to communicate too or at least [[spoiler: the sentient Father Trees do amongst themselves (they can talk to Formic Queens directly too)]]
** Also, the super-AI/alien-hybrid/space-god, Jane [[spoiler: came into being when the Formics tried to create one of these links to Ender himself (during the third war) by going through the psych-analyzer computer program that created Fairy World]]
** In the prequel novels, the existence of instantaneous communication is deduced by [[spoiler:Lem Jukes, CEO of Juke, Ltd., when his father Ukko Jukes, the first Hegemon, appears to be having a meeting with the Strategos and the Polemarch, both of which are located far from Luna, and yet Ukko appears to be treating it as a real-time conversation. Lem then sends an employee to spy on some Hegemony technicians, who reveals the existence of an FTL communications system based on [[QuantumMechanicsCanDoAnything quantum entanglement]]. Basically, the communication involves creating two particles that behave as one, even when far apart. The communication device then observes or causes changes in its particle, which is instantaneously relayed to the companion particle in another device. Initially, the devices were bulky and only worked on a one-to-one basis, requiring multiple devices for communicating with multiple people. Eventually, scientists learned to array particles in a single (slimmer) device that allowed it to be used to contact multiple devices, also increasing the communication link to allow audio-visual communication instead of simple text messages]]. The technology is classified top secret for fear of it falling into the hands of terrorists, whose communications would then be possible to intercept. Anyone, who manages to find out about it is usually conscripted into the IF and sent to serve somewhere far from the public eye.
* James P Hogan uses a similar system (and also worked in the computer industry -- for DEC during the PDP minicomputer days) in his ''Literature/GiantsSeries'' of books where both communication ''and'' FTL travel are accomplished through rotating black holes. ''Toroidal'' black holes. A similar concept is used in his book ''The Genesis Machine,'' in which a Cold War era book about a machine that is initially used to pull information from remote places in real time ''without'' there being a device on the other end to transmit the data is turned into a superweapon to stop the Cold War in its tracks -- by causing a nuclear exchange and destroying the missiles before they hit the ground.
* Creator/RichardKMorgan's ''Literature/TakeshiKovacs'' series features "needlecasts", but no FTL travel. Interestingly, since BrainUploading is routine, people may travel from planet to planet by downloading into a local body.
** The information-only aspect is a power limitation, not an inherent limitation of the functionality. The information is transmitted by energy; the best matter-energy conversion reactors they have can hold open a needlecast portal for at most 15 to 30 seconds, and transmit only blinking light. They find a stable Franchise/{{Stargate|Verse}}-style portal created by the precursors, extrapolate the energy costs, and realize that a hiccup in the portals matrix would crack the planet open like an egg. Hazards of children playing with adult toys.
* In ''Literature/TimeForTheStars'' by Creator/RobertAHeinlein, telepathy is used for instantaneous communication. Eventually, scientists studying the process learn how how it works well enough to create FasterThanLightTravel as well.
* Similarly, in Creator/EEDocSmith's ''Literature/{{Lensman}}'' series, the title Lens enhances the Lensmen's telepathic abilities, thus allowing instantaneous communication between them. There are also a variety of "waves" and "rays" that can be used for FTL communication and sensors by people who aren't Lensmen.
* In the ''Literature/TowerAndTheHive'' series by Anne [=McCaffrey=], PsychicPowers not only provide interstellar communication, but interstellar ''travel'' by psychokinetic [[TeleportersAndTransporters teleportation]].
* In the Charles Stross novels ''[[Literature/TheEschatonSeries Singularity Sky]]'' and ''[[Literature/TheEschatonSeries Iron Sunrise]]'', FTL communication is possible through the use of quantum-entangled particles, however: a) the communication is only possible between paired transceivers, and b) taking "qbits" through an FTL jump destroys the entanglement. This means that useful interstellar communicators have to be shipped the long way 'round, making them ''very'' expensive. (Stross has [[http://www.antipope.org/charlie/blog-static/2010/09/books-i-will-not-write-4-escha.html pointed out on his blog that this situation]] -- where ''setting up'' the communication network is a long and expensive process, but ''once it's done'' it's a much faster alternative to travelling if you can afford it -- is exactly parallel to intercontinental telegraph and steamships.)
* Curious version in Creator/JamesBlish's short story "Beep" (later expanded into the novel ''The Quincunx of Time''). Ansibles are common and cheap to use, if you can stand the loud and annoying beep that accompanies every one. Due to quantum effects, the title beep contain every message that ever was or will be sent, ever, and they can be heard if slowed way, way down and appropriately filtered. The government's primary purpose is to ensure that the events described in the beep come to pass at all costs, to prevent a paradox from prematurely ending the universe.
* The Fatline in Dan Simmon's ''Literature/HyperionCantos'' uses modulated neutrinos (or some such {{Phlebotinum}}) to send messages instantly across interstellar distances. At the end of the second book [[spoiler: God(?) revokes their radio privileges completely, since the transmission medium (the Void Which Binds) is disrupted everytime a message is sent.]]
* Creator/AlanDeanFoster:
** Foster uses the SubspaceOrHyperspace version in his ''Literature/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.
** In his remake of ''Design for Great-Day'', Foster's Solarian Combine is a kind of galactic HiveMind created as a natural extension of intelligent beings learning to live and think in harmony. Said thought processes apparently travel instantaneously, ignoring the speed of light. Of course, they've learned to circumvent this with starships as well; the Combine's ships can traverse a galaxy in a matter of hours, and intragalactic jaunts are considered to be fairly trivial, if not entirely routine.
* Though it never actually comes up, the ''Literature/{{Discworld}}'' series has a bit of fun with this in a footnote. It points out that a Disc philosopher decided that the fastest thing in the universe is ''monarchy'', noting that regardless of distance, the ''instant'' a monarch dies, the heir immediately succeeds them. He further proposes subatomic particles--kingons, or perhaps queenons--but his rough-hewn plans for artificially generating them by torturing a minor noble and using them to send messages vast distances were cut short when [[spoiler:the bar closed.]]
* The first of ''Literature/TheStainlessSteelRat'' novels by Creator/HarryHarrison feature psychics used explicitly as communicators over interstellar distances. Later novels don't seem to rely that much on conversations at distance.
** Some ''DeathWorld'' novels (which, supposedly, take place in the same universe) feature portable psychic locator beacons. Also, every ship is equipped with a psychic transmitter/receiver, making actual psychics obsolete.
* Heightened stellar activity can interfere with FTL communications in the ''Literature/WingCommander'' universe, as shown in the novel ''Action Stations'' (aka "Pearl Harbor {{IN SPACE}}"), but otherwise, the only time there's significant time lag for communicating across interstellar distances is the human steps relaying transmitted messages to/from the comm system and the people ultimately at either end of the line.
* Elizabeth Moon's ''Literature/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 ''Literature/EmpireFromTheAshes'' interstellar "fold-space communicators" are very cumbersome, too big for sub-lightspeed craft and require 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 short range of their ansible -- about a light month -- 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.]] Though comms with light hour range are cheap, small and common, which allows good coordination of space battles.
* The popular ''Franchise/StarTrek'' ExpandedUniverse novel ''Literature/SpocksWorld'' by Diane Duane tells the history of the planet Vulcan, and points out that since Vulcans are [[PsychicPowers psychic]] to varying extents and telepathy is assumed to be instantaneous, telepathy was their first subspace ansible. The limiting factor is that only a small minority of Vulcans are strong enough telepaths for this to be practical.
** In ''Infinity's Prism'', there's a Series/StarTrekVoyager story set in an alternate timeline where ''Voyager'' didn't manage to cross Borg space at the end of season 3, and instead ends up building a new Federation analogue in the delta quadrant. The holographic Doctor becomes a distributed AI with one node sent back to the Vidiians to cure the Phage. That node's updates via subspace take a day (each way, I think) to make the trip to the Doctor's central processing core located near Borg space.
* In Creator/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.
* ''Franchise/TheHitchhikersGuideToTheGalaxy'' itself has the "Sub-Etha" (occasionally written as "Sub-Ether"). In later books, it's even implied that a sort of Internet has been built upon the technology (it's used to automatically update the Guide to the latest edition).
* FTL communication in ''Literature/TheHistoryOfTheGalaxy'' books is achieved using enormous spherical orbital stations, which use powerful generators and transmitters to punch through [[SubspaceorHyperspace hypersphere]] to reach other worlds. During the heyday of the [[TheFederation Confederacy of Suns]], these were networked to create the Interstar, the future version of the Internet. As communication is vital between worlds, no one in their right mind would dare destroy an HF (Hyper Frequency) station, so they aren't even armed. A major plot-point of one novel involves a previously-unknown alien race launching a sneak attack on humanity by taking out the Interstar hub, isolating the human colonies. Ships also have their own HF generators, but those are usually not very powerful.
** Technically, it's possible for anyone with a powerful enough HF generator to send an FTL message. However, the enormous HF stations allow the creation of stable "floating" channels that enable the existence of the Interstar.
* The ''StarWars'' [[Franchise/StarWarsExpandedUniverse Expanded Universe]] has gone so far as to make its prevalence an InvokedTrope in ''Literature/TheCorellianTrilogy''. FTL communications are so commonplace that they're relatively easier to tap into, and so people sometimes use ''lightspeed'' communications over short distances (outer planetary orbits, tops) for security reasons.
** In fact the SW EU plays this straight, subverts it, and averts it, in various places. There's the Holonet, which is instantaneous and built on a network of large, planet-based repeaters. However, it's subject to network failure and communications taps. Direct subspace communication between ships is also possible, but can be much slower and harder to get a signal depending on how distant you are from the other party. Smaller ships like your average shuttles and starfighters, however, usually don't have any kind of FTL radio, since it's too expensive. A "small" transmitter designed for a spy is described as costing more than a high-end fighter craft, so equipping small ships is only done by the wealthy, the well connected, or for military reasons. It's also called out multiple times that this does NOT work for sensors: detection is speed-of-light only.
* White Radio in the ''Literature/MatadorSeries''. Oddly for most of the series, it only transmits video in black-and-white; color is added on the receiving end, and looks kinda fake.
* In the ''Literature/PriscillaHutchins'' series, unlike FTL ships, which can take weeks or even months to arrive at their destination, hyperspace communication is basically instantaneous, which allows expeditions to be coordinated from back on Earth, but means that when something goes horribly wrong, people back home are forced to listen, helplessly.
* Brandon Sanderson's ''Firstborn'' book features a particularly brilliant HandWave. FTL travel is possible by traveling through something called the ''klage''-dynamic, but the speed of ''klage'' travel is inversely proportional to the cross-sectional area of what you're sending through it. So you can have real-time com from one side of the Empire to the other, but that same distance will take a ship months or even years to cross.
* In ''Literature/ArrivalsFromTheDark'', humanity learns to do this at the same time as they get FTL drives, sending instantaneous messages through [[SubspaceOrHyperspace Limbo]]. It's expensive and requires a lot of power, so the SpaceNavy mostly relies on couriers and FTL drones (they tend to be one-shot, since small FTL drives burn out after one use). In later novels, real-time video communication is possible across many parsecs. With the [[HumanAliens Faata]], while they have radio communication equipment, it's only used to communicate with the primitive races they're about to conquer, while they themselves rely on PsychicPowers for communication among themselves. Powerful bio-computers are able to communicate across light years using psychic waves, but even they can't reach across the Void between galactic arms.
* ''Literature/HaloContactHarvest'' has a fun example of this working to somebody's disadvantage. A Kig-Yar (Jackal) {{privateer}} ship finds the human colony of Harvest. All Covenant ships are equipped with a [[{{Precursors}} Forerunner]] device known as a "luminary", which scans for Forerunner energy signatures (and other factors) and automatically relays the data back to the Covenant capital of High Charity; the one here registers Harvest as having lots of Forerunner relics. Tampering with luminaries is forbidden under the pain of death (not the least reason being that they're Forerunner relics and are thus holy); the Kig-Yar attempt to do just that in order to prevent their luminary from letting the Covenant know about their discovery. They fail, which thus eventually leads to a war.
* ''Literature/TheStormlightArchive'': A few years before the start of the story, spanreed [[{{Magitek}} fabrials]] are developed, which link two quills so that when they are both turned on, they will mirror each other no matter how far apart they are; combined with a standardized writing desk, and instantaneous long-distance communication is achieved. While it's used as essentially a telegraph, it actually functions using quantum entanglement, meaning that there is no upper range of the effect. Once the planet progresses more, they will be able to use it as a more traditional ansible.
* ''Literature/WeAreLegionWeAreBob'': Everyone uses the SURGE drive, a reactionless drive that somehow uses subspace to accelerate to ridiculous speeds in realspace. In theory, it could be used for communication, though the people of Earth haven't bothered to look into it. Bill decides to stay behind in Epsilon Eridani to work on it. [[spoiler:He manages to invent an instant subspace radio with a range of twenty-five light years, but unfortunately it needs a working transponder on both ends to work. He sends off plans for the first version to the other Bobs as soon as possible, but by the end of the book only Riker's group has received the plans and built a relay]].
* Creator/AndreyLivadny's ''Literature/PhantomServer'' trilogy has a straight example ''without'' FTL travel, at least in the titular VR game. According to the {{backstory}}, an ancient race only known as the [[{{Precursors}} Founders]] discovered a way to send instantaneous messages through hyperspace, but sending physical objects proves impossible. In order to explore and settle the galaxy, they find an alternative solution. They build automated relativistic ships that travel to other stars and build space stations with biological reconstitution modules. After that, Founders then used BrainUploading to send their consciousnesses across the light years to be downloaded into cloned bodies. Meanwhile, the ships would mine resources on uninhabitable planets or asteroids and [[VonNeumannMachine make more of themselves]], increasing the speed of the exploration. The Founders have long since died out, or, at least, no one knows what happened to them. The game takes place in the Darg System and involves conflicts between several sentient species (primarily humans, Dargians, and Haash), none of whom possess instantaneous communication.
* ''Literature/TheRedVixenAdventures'' uses some form of instant communication, which isn't specified beyond being very expensive.

[[folder: Live Action TV ]]
* ''Franchise/StarTrek'', as mentioned.
** However, [[TravelingAtTheSpeedOfPlot when the plot required it]] in [[Series/StarTrekTheOriginalSeries the Original Series]], they'd make mention that their messages would take several days to reach a Star Base.
** They touched briefly on the logistics of subspace radio in the ''[[Series/StarTrekTheNextGeneration TNG]]'' episode "Aquiel," where the plot took place in what amounted to a subspace repeater station, an idea later confirmed in ''Enterprise''.
** Communicating over long distances is important for the crew of the [[Series/StarTrekVoyager USS Voyager]], as they're stuck on the other side of the galaxy (and presumed dead), so even subspace communication won't work. After several failed attempts, they eventually succeed via LostTechnology and AppliedPhlebotinum (as well as physically moving closer in the mean time).
** In some circumstances, long-range communications occur in realtime, and in others they do not. Some ExpandedUniverse sources indicate that the signals can 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 ''[[AllThereInTheManual TNG Technical Manual]]'', meanwhile, explains that Starfleet exploratory vessels automatically drop subspace signal boosters as they travel in order to maintain contact with the Federation.
* ''Series/BabylonFive'''s tachyon relays are a complicated bit of AppliedPhlebotinum to justify this. It's established in-story that they're expensive and limited in bandwidth, with the result that most civilians have to rely on (hyperspace) snail-mail.
* The Franchise/StargateVerse uses stuff like this on occasion, and it is explicitly stated that radio waves can travel both ways through wormholes, which work only one way for matter streams.
** Besides simply sending radio signals through stargates, plain old FTL radio is used, the range of which can be determined by one episode which involves relaying an important message to Atlantis by sending someone with a subspace radio to the outer edge of the Milky Way in order to contact the Daedalus, halfway between galaxies.
** Also, in the episode "Tangent," Teal'c and Jack are stuck on a glider that is on its way out of Earth's solar system at a speed where it won't reach its destination for over a century, thanks to a realistic space travel speed. The further from Earth they get, the longer the delay in the radio signal between the glider and Stargate Command. By the time they're rescued, the immediate transmission informing the SGC of that rescue is delayed by almost ten minutes.
** The Ancient Communication Stones, which allow one to not only communicate, but INSTANTLY transfer your entire consciousness from point A to B. Distance does not seem to be an impediment - from thousands of ''galaxies'' away one can report to Stargate Command.
** When the [[HumanAlien Tollan]] were first encountered, one of them used an FTL communication device to send a message to the [[ActualPacifist Nox]]. When Daniel asks Omoc how the Nox are supposed to get it within any reasonable amount of time, Omoc grudgingly (due to the Tollan unwillingness to share technology) takes a tree branch and bends it so its ends touch. Daniel guesses that he's talking about space folding, only for Omoc to disappointedly drop the branch and reply "no".
* Used with subtlety on ''Series/{{Firefly}}''. The orbit-to-land transmissions lack any delay at all, which is impossible if they were ordinary radiowaves. TheMovie has several conversations between Mal in deep space, and somebody else on a far away planet.
* ''Series/DefyingGravity'' is near future and mostly hard scifi, but the ship has instant communication with earth on multiple channels in at least the megabit range (HD video transmissions, internet use, etc), handwaved as being brand new tech that made the mission possible in the first place.
* In ''{{Series/Eureka}}'', after Fargo and Henry build an FTL drive, the government starts planning the ''Atraeus'' mission, the first manned flight to Titan. One episode involves a scientist trying to build a Subspace Ansible for real-time communications and telemetry with the ship. Given that this is Eureka, this ends up causing a big problem (although, not by itself).
** Later on, after [[RidiculouslyHumanRobot Sheriff Andy]] is accidentally transported to Titan, Jack is able to communicate with him via real-time video.
* The ''MightyMorphinPowerRangers'' communicators, which are connected to the Command Center's [[TeleportersAndTransporters teleportation system]], can communicate across incredible distances.
* In a multiple shout out, the ''Series/DoctorWho'' episode "Nightmare In Silver" has a "solid-state sub-ether Ansible-class communicator".
* ''Series/{{Quark}}''. In the pilot episode The Head and Palindrome have to send a 'laser-telegram' to Quark, but it's so expensive that by the time they've finished cutting down the message and sent it the crisis is over.

[[folder: Tabletop Games ]]

* In a typical ''TabletopGame/{{Warhammer 40000}}'' take on an otherwise innocuous trope, FTL communications within the Imperium are the responsibility of Astropaths, psykers who send telepathic messages to other planets... through ''hell''...
** And frequently, due to the RealityIsOutToLunch nature of [[HyperspaceIsAScaryPlace the Warp]], the messages either arrive too late or not at all or are completely incomprehensible due to the receiving psyker not being able to work it out via space tarot cards or throwing chicken bones or... Well, there's one example of an Imperium ship going to its death responding to a distress call sent by its future self.
** And in one case (Literature/CiaphasCain), a message announcing help was on the way was received... decades after the man leading the rescue fleet had retired and the relevant war had ended. Fortunately, Cain was the only one aware that it was an echo, and said nothing to avoid losing morale. In the end Inquisitor Vail points out that the odds of this happening at the exact time they needed it (it forced the enemy into rash actions which cost them the war) are so utterly remote that it probably counts as a miracle.
* ''TabletopGame/EclipsePhase'''s Quantum Entangled Communicators provide instant communication regardless of distance, but like those in the Creator/CharlesStross example rely on pre-linked, finite "qbit reservoirs".
** Since the vast majority of what's left of posthumanity is still in the solar system most people just deal with a few minutes or hours of lag with radio, laser, or (speed-of-light) neutrino communications. Or [[BrainUploading farcast]] a fork of their ego if they absolutely have to have a real-time conversation. QE comms are mostly used by spies or to contact the few exosolar colonies that have been established.
* ''TabletopGame/{{GURPS}}'': Ultratech has two versions. The first uses quantum entanglement (so it's impossible to intercept) the second is generic FTL Radio.
* The ''TabletopGame/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 signals 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.
** Though the animated series had a few examples of interstellar videoconferencing, which is possible if an extremely expensive relay is used, and is also how the Clans communicate.
** 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]].


[[folder: Video Games ]]

* It is never explained how exactly communication works in the ''[[VideoGame/FreeSpace Descent: Freespace]]'' games. Seemingly, instant interstellar communications ''do'' occur in that universe, which means FTL communications. Command can also communicate with you as your ship is traveling in ''subspace'', though the messages break up and distort like a bad telephone connection. It presumably uses subspace somehow, since the rest of the galaxy is unable to talk to Earth once their subspace gates are destroyed.
* Similarly, the ''VideoGame/WingCommander'' series explicitly uses FTL radio with no particular explanation given for the differences between how it and jump drives work.
** The [[Film/WingCommander film]] shows there are limitations to FTL radio, as Admiral Tolwyn needs to send a message to the ''Tiger's Claw'', but it is too far away to reach, so he instead transmits the data to Paladin's ship to be delivered by hand.
* ''Franchise/MassEffect'' allows faster-than-light travel by [[MinovskyPhysics giving physical objects zero or negative mass]] or through the use of large and fairly rare mass relays that create long tunnels of space where everything has zero or negative mass. Communications often take place through large numbers of comm buoys deployed throughout explored space, which transmit messages via photons passed through miniaturized corridors of mass-free space. Time lag in real-time communications occurs if transmitter bandwidth is overloaded, though high-level government operatives and military personnel get access to high-end, high-speed channels that allow near-instantaneous communications. Long-range interstellar calls are implied to be highly expensive, judging by one overheard conversation on Noveria.
** [[VideoGame/MassEffect2 The second game]] also features a quantum-entanglement transponder which allows the Illusive Man to contact Shepard instantly while conveniently avoiding the relay network. While this is efficient, as it bypasses the limits of bandwidth and time delay, it is highly inefficient for mass production, as it's basically a two way radio with a truly astronomical price tag - according to EDI "each quantum pair costs almost as much as a comm relay." It also only communicates between the ''Normandy'' and the Illusive Man's hideout. If they wanted to contact somebody else this way, they would need to do more quantum entanglements.
** The existence of Subspace Ansible also {{Handwave}}s the fact that Harbinger is capable of "[[Memes/{{Bioware}} ASSUMING DIRECT CONTROL]]" of individual {{Mooks}}, [[spoiler:despite being a Reaper whose physical form is drifting thousands of light-years ''outside the galaxy'']].
** [[VideoGame/MassEffect3 The third game]] has quantum entanglement communication units practically everywhere, after the Systems Alliance takes apart the ''Normandy SR-2'' and finds out all the enhancements Cerberus made to it. Not only are they slightly inferior (they only work in monochrome, presumably on account of being hastily mass-produced), since a single communication unit can only connect to its partner, the QEC network used to co-ordinate the fight against the Reapers is heavily dependent on large "switchboard" stations that house the partners of many communicators in the galaxy. Guess where Cerberus [[AchillesHeel decides to attack]]?
* The plot of ''VideoGame/CommanderKeen 4'' starts with Billy Blaze building a FTL radio and accidentally picking up a transmission from a group of aliens planning on destroying the galaxy.
* ''VideoGame/EveOnline'' uses [[http://www.eveonline.com/background/communication/ pairs of particles which are synchronized with each other]]: Manipulating one affects the other as well, no matter the distance between the two particles. This was used to create a galaxy-wide network (not unlike the Internet) where latency due to physical distance is not an issue. Carrying one half of a particle pair on a spaceship allows one to "phone home" from any part of the galaxy.
** This is based very loosely on the concept of quantum entanglement. It is possible to create pairs of particles both of which are both in superpositions of quantum states (e.g. spin up and spin down at once) and can be separated by a substantial distance. Observing the spin of one of the particles forces it to collapse into one state (either spin up or spin down, but not both) observations of the other particle are then guaranteed to see it in the other state. The particles seem to have needed to communicate faster than light to make this coordination. Unfortunately, in the real world, this does not help ''us'' communicate faster than light -- when we collapse the state of the first particle we can't force it to enter one state or the other, so it's simply random noise which happens to be correlated with random noise somewhere else in the universe, but not a communication channel.
* 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[[note]]"short" in this case means "couple seconds of advance warning"[[/note]] 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.
* Every (playable) race except the Liir (see aversions with FTL travel below) in ''VideoGame/SwordOfTheStars''.
** Humans the the [[PlanetLooters Zuul]] actually use regular radios to send and receive messages. They just leave relay buoys near [[SubspaceOrHyperspace node space]] points that re-transmit the messages through to the other side. Given this AllThereInTheManual description, this method is far from instantaneous.
** The [[LizardFolk Tarka]] actually start ''without'' one but can quickly research it in order to be able to send orders to their ships while in flight.
** The [[BeePeople Hivers]] use tiny gates hooked up to their PortalNetwork used to send and receive messages. While ship-sized gates require being in the gravity well of a planet-sized object, the mass of the ship is enough for a communication gate.
** All races seem to have FTL sensors, though, which the manual doesn't even attempt to explain. Also, one of the prerequisites for interstellar trade is FTL "Broadband", which carries the side effect of letting you observe allies' combat.
* In ''VideoGame/DeadSpace2'' the player sees a recorded conversation between Isaac and Nicole, which happens in real time between earth and The Ishimura.
* In ''VideoGame/{{Descent}} 2'' has a real time FTL communication connection that somehow [[http://www.youtube.com/watch?v=9KGPSz_Mfac keeps working]] even when the ships warp drive malfunctions and deposits the character in the middle of nowhere with the ship broken.
* In the ''Alien Crossfire'' expansion to ''VideoGame/SidMeiersAlphaCentauri'', the Progenitors have FTL travel and communication technology. However, since their ships were destroyed, the survivors have to re-discover the latter and use it to build powerful FTL transmitters to alert their fraction's fleet. Doing so results in automatic victory for the builder, as the massive fleet that arrives shortly after the message is sent is assumed to crush every other side. It can also be assumed that, after everyone on Chiron undergoes [[AscendToAHigherPlaneOfExistence Transcendence]], the various parts of Planet (including humans) become parts of its HiveMind. The final interlude mentions a ship sent by Planet to rebuild the devastated Earth. This would imply Planet can instantly communicate with its parts across light years.
* ''VideoGame/StarOcean'' mentions that they apply the same gravetic warping to communication signals as they do their ships.
* In ''VideoGame/ProjectFirestart'', protagonist Jon Hawking must fly out to investigate the research vessel ''Prometheus'', near Saturn's moon Titan. His superiors advise him to use the subspace radio to call in status updates -- important since he has two hours to accomplish his mission before they assume the worst and remotely trigger the ship's self-destruct.
* ''Franchise/{{Halo}}'': Played straight by every major faction, though the lore notes that UNSC didn't develop a reliable means of this until several years into the Human-Covenant War.
** Notably, FTL communications for UNSC civilians are slow enough that messages sent through Waypoint (basically an interstellar Internet) often have to be prerecorded.
** Forerunner technology was good enough to enable real-time conversions between people on opposite ends of the galaxy; it's explicitly stated that they used quantum entanglement. Additionally, their sensors were so good that they could provide detailed analysis of a single planet's geology and ecology from light-years away.
** Covenant FTL communications are also near-instantaneous, as they reverse-engineered it from Forerunner tech. However, they have a bad habit of not encrypting their messages properly, which often works to their disadvantage.
** By ''VideoGame/{{Halo 4}}'', the UNSC has recovered some valuable tech from Shield World Trevelyan and a few Engineers familiar with Forerunner tech. Besides ''much'' better slipspace drives, they also get much improved FTL communications, including the ability to maintain communications while still in slipspace.
** The Flood has an esoteric method by which its Graveminds can telepathically control their hordes across multiple star systems; they can even use this to communicate with non-Flood beings on occasion.
* ''VideoGame/StarControl'': the [[StarfishAliens silicon-based]] Chenjesu are described as natural hyperspace communicators. The franchise features also the typical (artificial) FTL 'casters,in seemingly real time.

[[folder: Web Comics ]]

* In ''Webcomic/SchlockMercenary'', the main means of communication is the Hypernet, a refinement of the ansible idea as a packet-switched system that relies on tiny wormholes. It carries all communications in digital form, from real-time video to text mail, and it's [[http://www.schlockmercenary.com/d/20050313.html explicitly said]] that the lag time in the sender's electronics is more significant than the infinitesimal transit time. The cartoonist knows a thing or two about packet switching; his former day job was for Cisco Systems.
* The ''Webcomic/{{Starslip}}'' technical manual asserts that FTL communication is actually an incredibly sophisticated computer that anticipates what the other party will say. "Modern" systems are so good, it can predict and initiate a call at the same time it is placed, light-years away. FTLTravel is almost as preposterously handwaved.
** Only at first though (and hell, the strip is NAMED AFTER their FTL system), the detailed explanation becomes a major plot point and the titular Starslip Crisis when the future declares war on the past to make them stop using it.
* In ''Webcomic/AMiracleOfScience'' the Mars HiveMind developed an FTL communications network so they could be in constant contact with one another and allowed the unaugmented human colonies across the solar system to use it as well. They're capable of FTL travel as well, but they haven't told many others that yet.
* ''Webcomic/EscapeFromTerra'' has "tanglenet" using quantum entanglement, and somehow they were able to make an "internet" that cannot be intercepted.
* In ''Webcomic/AmongTheChosen'' the Quantum Analogue Relay (QAR) is a one-of-a-kind prototype; carried by the starship ''Sabrosa,'' which is itself a one-of-a-kind prototype.
* ''Webcomic/QuentynQuinnSpaceRanger'' features subspace radio and the hypernet, an information network that piggy-backs on the hive mind of an alien species. This species, the Confidantines, have special privileges in the galactic community, such as being immune from interrogation, and anyone who ''does'' try to interrogate one of them will find themselves, their home planet, and possibly their entire species cut off from the hypernet for at least a century. [[DisproportionateRetribution The Confidantines take space-age cyber security very seriously.]]
* In ''Webcomic/{{Drive}}'' most interstellar messages are carried by ships, but there's a recently developed network of relay stations that use the ring drive's space-folding to enable real-time communication [[http://www.drivecomic.com/archive/150123.html across the galaxy]]. However it's expensive enough that it's usually used by the Imperial Familia on-screen.

[[folder: Web Original ]]
* In ''WebOriginal/OrionsArm'' messages can be sent faster than light via [[OurWormholesAreDifferent wormhole]]. One side effect of this is that some entities use systems of wormholes to cheat the normal limitations on processing speed which makes them far more powerful than they could possibly be otherwise.

!!Aversions With FTLTravel

[[folder: Literature ]]
* One of the entries in the Literature/XWingSeries has the squadron tapping in on a pirate conversation. They figure out how far apart the two conversing parties are by the length of the pauses, and by doing so, pinpoint their locations.
* In Creator/PoulAnderson's ''Literature/TechnicHistory'' novels and short stories, there is no "interstellar equivalent of radio" and all messages have to be carried by courier spaceships.
* Stephen Harper's Silent Empire Quadrilogy exists in a universe with FTL flight, but no FTL communication. This necessitates the use of psychics for communication. This universe has a thriving slave trade for the same reason.
* Ditto in ''Literature/TheGapCycle'' by Stephen Donaldson. Courier drones are the order of the day -- although the Amnion do briefly try to use some sort of experimental "symbiotic crystalline resonance device" as an FTL Radio.
* The Literature/CoDominium universe and ''Literature/TheMoteInGodsEye'' by Larry Niven and Jerry Pournelle.
* ''Literature/HonorHarrington'' has courier ships to carry messages between star systems, but because of the delay, there's no way to control battle groups in multiple systems with military precision. Early in the series, the kingdom figures out how to create a comm system using gravity pulses (or rather a hyperspatial "echo" of them that travels at 64''c''), but this only works within a system, and initially is roughly as fast (in terms of bandwidth) as Morse code. The technology undergoes multiple improvements, and in the later books is capable of carrying video.
** At one point, a Manticoran diplomat intentionally exploits this trope just to issue a calculated insult to a Solarian admiral, by [[LeaveTheCameraRunning keeping his video feed on]] and using the lengthy comm delays to kick his feet up on a nearby piece of furniture and catch up on some casual reading.
** The ''next'' Solarian admiral to come calling gets a shock when Honor talks to him via an FTL buoy, when he thought they were just a myth.
* David Feintuch's ''Literature/SeafortSaga'': while FTL travel existed in the form of "N-Waves" propelling a ship, even human-level computer AI couldn't run a ship (robotics not being advanced in Feintuch's 'verse). Physical mail was carried by the ships traveling to extrasolar colonies, while ordinary radio was used in-system.
* Creator/HBeamPiper's Terro-Human Future History. News and communications travel with FTL starships -- taking months to get to their destination, and months to get an answer back -- but no FTL radio exists. This has a major impact during the System States War, in his novel ''The Cosmic Computer'', where planning and controlling fleet and army movements has to be done for a theater of war thousands of light years across. In fact, the Terran Federation's "Manhattan Project" is to create a super-powerful computer capable of evaluating not only military but social and economic factors and effectively predict the enemy's future actions, so that the Terran generals can determine just where to send troops and ships.
** It can be said that Piper and other writers who have FTL travel but no FTL radio setups in their works often do so to justify why the protagonists must handle the issue at hand and can't just call back to base for help/relief/support from more qualified personnel.
** They come the closest in the Empire story "Ministry of Disturbance", where a scientist discovers a method of teleporting a particle. Unfortunately, the only story following "Ministry of Disturbance" took place several thousands of years after that one and on a backwater planet, so Piper never managed to explore the consequences of this new technology.
* In Peter F. Hamilton's ''Literature/NightsDawnTrilogy'', it is possible that certain alien races have developed FTL communications, but humans certainly have not. Information is couriered around by manned starships.
** In his ''Literature/CommonwealthSaga'', constantly-maintained planetside wormholes allow very rapid transportation and communications from one end of the Commonwealth to the other. The most common method of traveling from planet to planet is by ''train'', spaceships having been made redundant.
* In ''Franchise/{{Dune}}'', the Spacing Guild is responsible for getting information from place to place. In the [[Literature/PreludeToDune books by Frank Herbert's son]], Navigators and his human twin manage to contact each other FTL with a device one of them cooked up, but that never caught on, mainly due to the unfortunate side effects (namely, the navigator half died of pressure induced hemorrhaging, while the brother actually fried his brain from the inside out). It was shown that two Navigators could communicate directly mind to mind in realtime, but they also died later.
* Creator/LoisMcMasterBujold's [[Literature/VorkosiganSaga Miles Vorkosigan]] novels use wormholes as shortcuts through space; unfortunately, there's no way to send messages through a wormhole without recording them and putting them on a ship. High traffic routes have regular courier ships shuttling the mail back and forth through the wormholes. On low traffic routes, your mail may sit for weeks for someone to come along and carry it on. Once on the other side, a message may be beamed at the speed of light to the next wormhole (if there's a permanent station there) or it may be carried on a ship the whole way.
** The lack of FTL communication plays as a plot point a few times; in ''Literature/TheVorGame'', Miles uses the time lag between communications to [[MindScrew play with the head]] of his compulsive plotter opponent, [[spoiler: Cavilo.]]
* In Creator/IsaacAsimov's ''Nemesis'', the humans left on Earth eventually discover faster-than-light travel, but point out that there is no way to send radio waves through hyperspace. This leads to difficulties communicating with the Nemesis colonists.
* Averted in Creator/CJCherryh's Literature/AllianceUnion 'verse (including the Literature/ChanurNovels). Communications between star systems can only be done via FTL courier, and FTL travel is only possible between the outside edges of star systems. When a space ship arrives at the edge of a system and travels inwards it takes a long time for light-speed messages to reach the inner system (or vice-versa), with the time shortening as the ship hurtles forward at a considerable fraction of the speed of light.
* In ''Literature/TheLostFleet'' series, the delay in receiving electromagnetic signals plays a large role in the various spaceship battle tactics shown. For example, at the opening of the first book, Geary uses the massive delay in communication with the enemy to buy the time he needs to rearrange the title fleet for a TacticalWithdrawal. Even then, the fleet barely makes it.
* In ''Literature/{{Hellspark}}'' by Creator/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.
* Creator/LRonHubbard's ''Literature/BattlefieldEarth'' features the Psychlo Empire, a civilization linked by the miracle of teleportation. Here's the thing, though - the rules of teleportation make opening two "links" to the same planet [[TeleporterAccident dangerous]], so the Psychlos set up a strict schedule of when their worlds can link up with the capital. This means that the disparate worlds of the empire have to function on their own for a year or more, until they reach the hours-long window to exchange communications and supplies and personnel. Aside from the inherent problems with this scenario, this means that once the protagonist bombs the Psychlo homeworld into a new sun, there's no way for the rest of the empire to know about this until they try to open a teleport link to it and instead get a facefull of atomic fire.
* In Creator/JohnScalzi's ''Literature/OldMansWar'' trilogy the CDF is only able to communicate between systems using courier drones.
* Most of the writings of Creator/TimothyZahn fall into this category. The Literature/{{Blackcollar}} books, ''Literature/{{Spinneret}}'', ''Literature/TheCobraTrilogy'', ''Literature/TheConquerorsTrilogy'', etc. all feature settings where FTL travel is possible, even common, but FTL communications depend on actual ships making the trip.
* The lack of FTL sensors and communication in the ''Literature/StarCarrier'' books despite the presence of FTL travel both limits and allows certain tactical maneuvers, such as the standard opening move when a fleet arrives to a system controlled by the enemy involving the launch of several fighter wings at near-c velocities with the rest of the fleet following at slower speeds. The idea is that the enemy, also lacking in FTL sensors would only get a few seconds' warning of the arrival of the fleet before an AlphaStrike of nuclear-tipped missiles launched by the fighters at relativistic velocities wipe out a good number of their ships. Communication between system is achieved by courier ships that have better FTL drives.
* Creator/GeorgeRRMartin's "Thousand Worlds" ScienceFiction setting has mankind spreading across a swath of the Milky Way in faster-than-light starships, but communications between planets in different star systems can only be accomplished by plain old snail mail. One novella ("Nightflyers") mentions an information packet that was in transit from a distant world to the protagonists' planet for ''twenty years''.


[[folder:Anime & Manga]]
* Communication across large distances is virtually impossible in the ''Anime/{{Macross}}'' universe; it is actually a plot point in ''Anime/MacrossFrontier'', where even relay buoys must contend with "fold interference" that delay or disable communication entirely. However, the [[NeglectfulPrecursors Protoculture]] and the Vajra have their ways around that (see above).
** This actually seems to be a retcon. Earlier series had more or less instant FTL communication across the galaxy to the point that various fighter and ship designs were completely standard thanks to simply downloading them via a galaxy spanning internet. It was also specifically stated in ''Anime/{{Macross 7}}'' that the issue wasn't that no one knew what was going on, but that even with a call for aid it would take months at best for anyone else to arrive to reinforce the colony. The sudden addition of all these range limits and interference and such in ''Frontier'' really came out of nowhere seemingly driven entirely by rule of drama.

[[folder:Films -- Animation]]
* The time taken for messages to reach to the other recipient is practically the entire point of ''Anime/VoicesOfADistantStar''. Mikako and Noboru are separated by FasterThanLightTravel without a corresponding method of faster-than-light communication, meaning that Mikako's messages take first a month, then six months, then eventually ''eight years'' to arrive. Only at the very end, when Mikako has been stranded in space for eight years and Noboru, now twenty-four, has finally gotten assigned to a spaceship himself, does the fleet finally gain FTL communications capabilities.

[[folder:Films -- Live-Action]]
* ''Film/{{Alien}}''. The Nostromo and other ships are out of contact while on the frontier, and are thus on the spot, for taking on the terrors that wait on whatever God forsaken planet the crew finds themselves on.
** However, the sequel, ''Film/{{Aliens}}'', explicitly uses FTL communication, as the ''Sulaco'' is expected to report back to Earth on a daily basis, and the lost contact with Acheron is noticed after a matter of days, not decades. Since this communication is not explicitly accomplished by means of FTL drones or somesuch, the presence of an ansible is implied.
*** In the Extended Edition opening, one of the colony higher-ups on LV-426 says that "[i]t takes two weeks to get an answer out here", implying that the speed of messages is no more than one week either way (as the delay may be partially due to ExecutiveMeddling or other delays on the end of the replier).

[[folder:Live-Action TV]]
* Notable in its absence in ''Series/{{Andromeda}}'', where communication over interstellar distances requires a living courier.
** It's mentioned that they attempted to use Slipstreams for FTL radio, but that it didn't work very well, so they went back to couriers.
** This is because Slipstream is highly unstable. Traveling through it requires one not only to be a good pilot but to be ''lucky'' (something about quantum physics). It is stated several times that a machine, even an AI, is unable to successfully navigate in Slipstream, as machines can't guess. An attempt was made to map out Slipstream, but it failed.
** In one episode, [[TheCaptain Hunt]] laments the need to wait for a reply when the ''Andromeda'' is more than a few light-minutes away.
--> '''Dylan Hunt:''' I hate physics.
* ''Series/{{Battlestar Galactica|2003}}'' apparently relies solely on radio ([[CallARabbitASmeerp referred to in-story]] simply as "wireless") for ship-to-ship communication, and faster-than-light comm does not exist; ships on recon missions must be provided with rendezvous points before departure lest they never be able to find the fleet again.
** However, the presence of some kind of FTL transmissions is implied with the Cylons. They possess tracking beacons mentioned early on that can be traced after an FTL jump (see the Olympic Carrier in the first regular episode), plus the very nature of Resurrection technology requires FTL transmissions, as the Resurrection ship/hub is often shown as being in different ''star systems'' from the point of the Cylon's death and yet works relatively fast.
** It's shown in the pilot that the colonies actually ''possess'' this tech, but Galactica and it's fighters were specifically built without it during the first war. The reason is shown clearly when all the newer ships are remotely hacked and effortlessly destroyed by the Cylons.

[[folder:Tabletop Games]]
* ''TabletopGame/{{Traveller}}'', where all interstellar messages have to be delivered by courier (although those can still jump). This has a natural impact on the way the universe works.
** Deliberately invoked in The Fifth Frontier War, a tabletop board game based on the Traveller universe. Players were required to plot moves multiple turns in advance. The presence of Admirals, intelligence gathering, or other factors could reduce the preplanning by one or two turns.
*** Note that this is almost exactly the same problem faced in H. Beam Piper's universe.
* ''{{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.
** Taken to hilarious extremes with Da Orks. They have FTL travel too (sort of) but in terms of communications technology [[SchizoTech they fluctuate between]] "FM radios" and ''war drums''.
* The "Pony Express" style system can also be used in ''TabletopGame/BattleTech''. It was the only way to communicate before the advent of the Hyperpulse Generator (noted above in the aversion-free section), and also experienced resurgence during the recent "Dark Age" where sabotage against the entire HPG network effectively disabled a significant majority of it. It's also used for backwater worlds without a HPG.
* In ''TabletopGame/{{Mindjammer}}'' 2-space can be used for FTL travel but not communications, in most systems the local [[TheAlternet Mindscape]] is kept synchronized with the rest by use of ships called Mindjammers that download a complete copy of the Mindscape each time they leave a system and upload as they enter a new one. The only exceptions are the Core systems connected by [[PortalNetwork 3-space FarGates]].

[[folder:Video Games]]
* ''Franchise/{{Halo}}'': For most of its history, the UNSC had to rely on FTL ships to carry messages between planets. ''Literature/HaloContactHarvest'' describes this as being like the Pony Express. As noted elsewhere, the UNSC eventually develops the technology to play this trope straight by the time ''VideoGame/HaloReach'' takes place.
* The Liir (dolphin-like aliens) from ''VideoGame/SwordOfTheStars'' use communication drones equipped with FTL engines. For gameplay reasons, there is no delay even at very long distances that require many years for the ships themselves to cross. (In game, the engines work by teleporting the object an enormous amount of times per second by small amounts, so that the ship is technically not accelerating or moving, but appears to go at up to FTL speeds.)
** The drones have a much smaller mass, meaning teleportation calculations would be much quicker (i.e. faster "movement").
* In addition to allowing starship travel, the [[PortalNetwork jumpgate network]] in the ''VideoGame/{{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. In the ''X-Encyclopedia'', it's stated that several 16 years after the jumpgate network collapse, the Paranid Empire managed to contact Argon Prime and Nishala, the former seats of the Argon Federation and Kingdom of Boron, via drones traveling near the speed of light.

[[folder:Web Comics]]
* In Webcomic/{{Freefall}}, it's specifically said that the only way to communicate between star systems is by sending messages via ship. As most interstellar travel is via sublight vessels (FTLTravel being quite expensive, and possibly dangerous going by the drive's name: Dangerous And Very Expensive [[[FunWithAcronyms or DAVE]]] drive), this means that a message and its response could take up to many months, as the ship carrying it travels on its normal route.

!!Aversions Without FTLTravel

[[folder:Anime & Manga]]
* ''Anime/{{Planetes}}'' features a phone on a lunar colony with a Windows-esque progress bar on a video screen that gives the delay between messages between the Moon and Earth (about a second and a half)
* ''Anime/StellviaOfTheUniverse'' has this as a plot point. Videomail between Foundations travels slower than light, so it takes hours for the messages from Shima and Rinna to reach each other.
* ''[[Anime/VoicesOfADistantStar Voices of a Distant Star]]'' subverts this by structuring the entire plot (and title of the work) around the delay in communication.

* In ''Film/{{Passengers|2016}}'' after Jim is accidentally woken up 30 years into a 120-year voyage on a SleeperStarship he sends an email to the customer service office for the company that built the ship, and then the computer says the message will take about 25 years to reach Earth and a reply should arrive in 55 years. And he just spent six thousand dollars on that one transmission.

* ''[[Literature/TheSpaceOdysseySeries 2001: A Space Odyssey]]'', in which an interview with astronauts on their way to Jupiter has to be edited together to remove the long delay times in the conversation.
* Creator/GregEgan's ''Literature/SchildsLadder'' features a universe with neither FTL communication nor travel. Being written by Greg Egan, most interstellar travel is done by transmitting your [[BrainUploading mind]], with only a few "anachronauts" crawling around in starships to investigate the future they find along the way; either way all travellers are doomed to miss decades of time. One planet solves the problem by putting the entire population into what amounts to slow-motion until the traveler returns.
* Creator/MikhailAkhmanov and Christopher Nicholas Gilmore's novel ''Literature/CaptainFrenchOrTheQuestForParadise'' 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 costly 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 ''Literature/RevelationSpaceSeries'' lacks either FTL traveler or FTL communications; interstellar travel is only possible via impossibly precious lighthuggers that can continuously accelerate at roughly 1g for years with the use of the BlackBox Conjoiner Drives. The plot of ''Literature/RevelationSpace'' is kicked off when the ''Nostalgia For Infinity'' arrives at Yellowstone, the [[EndOfAnAge former hub]] of human civilization, searching for Dan Sylveste in order to coerce/hire him to save the ship's [[CyborgHelmsman cyborg captain]] from the [[TheVirus Melding Plague]], not realizing that Sylveste left the system thirty years prior.
* The ''Literature/GreatShip'' universe being MundaneDogmatic, lacks either FTL travel or communications. The scientists that seized control of the derelict [[PlanetSpaceship Greatship]] routinely beam messages back to Earth via communication lasers which will take over a thousand years to be received. The huge communication delays are generally no more than an annoyance because, hey, you're TransHuman and [[TimeAbyss are gonna outlive civilizations]]. It does however become a plot point at the climax of ''The Well of Stars'', where [[spoiler: the Greatship is seized by {{Starfish Alien}}s and its true reactionless engines are activated; it'll take a human fleet thousands of years to catch up with the Greatship as it flies into intergalactic space]].
* Implied in the ''Literature/RedDwarf'' novel ''Better Than Life'', in which the delay caused by talking to someone through time dilation is compared to making a person-to-person call to Mars.

[[folder:Video Games]]
* Usually, the ''Franchise/{{Metroid}}'' games avoid this by having no form of communication through space, but in ''VideoGame/MetroidPrimeHunters'', it's stated that a signal was sent to various bounty hunters via a telepathic frequency.

[[folder:Web Original]]
* Our universe in ''Literature/FineStructure'' used to allow FTL communication (and FTL travel), and nobody knows when [[spoiler: the Imprisoning God excised FTLC from reality.]] That is the reason there are only nine FTLC engineers on Earth.

[[folder:Western Animation]]
* In the episode "All This and Gargantua-2" of ''WesternAnimation/TheVentureBrothers'', there is a "conversation" between Sgt. Hatred on Earth and Dr. Venture on an orbiting space station. In a subversion of ContinuityEditing, lines are weirdly repeated, and they talk over each other.
-->'''Sgt. Hatred:''' Doc, I am calling from ''Earth''. There's like a huge delay; will you just wait for it?

[[folder:Real Life]]
* RealLife, so far. [[http://www.colbertnation.com/the-colbert-report-videos/167610/may-08-2008/garrett-reisman This clip]] shows how tricky surface-to-orbit conversations can be without an ansible to hand.
** Even Digital Satellite TV (e.g. [=DirecTV=], Dish Network) is delayed about 4 seconds relative to the cable feed the shows come from. This delay is mostly due to the processing time necessary to compress the data on-the-fly, however; the actual signal-propagation delay to and from the satellite is only a quarter of a second.
* As of 2 December 2011, scientists have discovered that [[http://www.livescience.com/17264-quantum-entanglement-macroscopic-diamonds.html quantum 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 reason why quantum entanglement cannot be used for FTL communication is this: imagine you have two entangled particles. Particle A is with you and Particle B is many light-years away. Obviously, you can easily measure Particle A to find out something about its state (say, its spin). Once you know the spin of A, the spin of B is determined and anyone measuring the spin of B will definitely measure the opposite of what you measured. To use this for communication, you would have to somehow "force" particle A to take on a certain spin. But, this is fundamentally impossible as any interference will collapse the particle's wavefunction, breaking the entanglement.
*** However both China and ISS partnership claimed to have had some success changing one atom and having the other one change. China claims to have even successfully communicated with its satellite no if ands or buts. It should be mentioned that the exact details of these experiments haven't been released yet and China was more interested in using quantum entanglement communication [[MundaneUtility to make hack proof communications than FTL communications]].
** In other words, imagine you take two cards: the ace of spades and the ace of diamonds. You shuffle them, give one to your friend, then fly to the other side of the solar system. By looking at your card you know instantaneously what card she had (because it needs to be the opposite of yours), but no information was transmitted.
* This trope is OlderThanTheyThink:
** One solution to UsefulNotes/TheLongitudeProblem, which similarly involved trying to transmit information (Greenwich Mean Time) over vast distances (the ocean) beyond the scope of modern technology (handwritten letters), was to keep a wounded dog in a cage on a sailing ship. A person in London would dip its bloodied bandage into what was called "[[SympatheticMagic the powder of sympathy]]" at a prearranged time, whereupon the dog would yelp at the same instant. In case it wasn't blindingly obvious, this theory never caught on with the scientific community.
** Similarly, grisly rumours, perhaps inspired by the "powder of sympathy" theory, emerged during the Cold War that both the USSR and USA were testing out the fringe idea that psychic communication not only worked, but worked instantaneously, by separating a mother animal from her newborn young, which went to sea on a submarine whilst the mother stayed at home in a research lab. At prearranged times, one of the baby animals would be killed whilst the home lab monitored the mother for a sign of sudden unmistakable distress. Baby rabbits and kittens have been suggested as the most likely test subjects.