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An '''ansible''' is a hypothetical machine capable of [[superluminal communication]] and used as a [[plot device]] in [[science fiction]] literature.
==Origin==
The word ''ansible'' was [[neologism|coined]] by [[Ursula K. Le Guin]] in her [[1966]] novel, ''[[Rocannon's World]]''.<ref>{{cite web|url=http://www.worldwidewords.org/weirdwords/ww-ans1.htm|work=World Wide Words|title=Ansible|last=Quinion|first=Michael}}</ref> Le Guin states that she derived the name from "answerable," as the device would allow its users to receive answers to their messages in a reasonable amount of time, even over interstellar distances.<ref>{{cite web | url = http://groups.google.tt/group/rec.arts.sf.written/browse_thread/thread/ac6ae29e85239fb/c1ff58cb2d78073e?lnk=st&q=&rnum=1&hl=en#c1ff58cb2d78073e | title = Etymology of "ansible" | accessdate = 2006-12-08 | last = Goldman | first = Dave | date = Sat, [[7 April]] [[2001]] | format = [[Usenet]] post | work = Message-ID: <dave-0704011253140001@ip154.pdx7.pacifier.com> | publisher = [news:rec.arts.sf.written rec.arts.sf.written] | quote = A few years ago there was some discussion here of where Ursula Le Guin got
the name "ansible" for her instantaneous communication device. Well, I've just started a writing workshop from Ms. Le Guin, so I asked her.}}</ref><ref>{{cite journal | last = Langford | first = David | authorlink = David Langford | year = 1998 | month = August | title = Take Another Look | journal = PCW Today | issue = 10 | url = http://www.ansible.co.uk/ai/pcwplus/pcwtdy03.html | accessdate = 2006-10-24}}</ref> Her award-winning [[1974]] novel ''[[The Dispossessed]]''<ref>{{cite book | last = Le Guin | first = Ursula K. | authorlink = Ursula K. Le Guin | title = The Dispossessed | origyear = 1974 | origmonth = June | edition = mass ppb. | year = 2001 | month = August | publisher = Eos/[[HarperCollins]] | location = New York | id = ISBN 0-06-105488-7 | pages = 276 | quote = 'They print Reumere's plans for the ansible.' 'What is the ansible?' 'It's what he's calling an instantaneous communication device.'}}</ref> tells of the invention of the ansible within her [[Hainish Cycle]].
==Usage==
The name of the device has since been borrowed by authors such as [[Orson Scott Card]],<ref name="egame">{{cite book | last = Card | first = Orson Scott | authorlink = Orson Scott Card | title = [[Ender's Game]] | origyear = 1977 | origmonth = August | edition = mass ppb. | year = 1994 | month = July | publisher = [[Tor Books]] | location = New York | id = ISBN 0-8125-5070-6 | pages = 249 | quote = What matters is we built the ansible. The official name is Philotic Parallax Instantaneous Communicator, but somebody dredged the name ansible out of an old book somewhere and it caught on.}}</ref> [[Vernor Vinge]],<ref>{{cite book | last = Vinge | first = Vernor | authorlink = Vernor Vinge | title = Threats & Other Promises | date = [[1988]]-[[11-01]] | publisher = Baen | location = Riverdale, NY | id = ISBN 0-671-69790-0 | pages = 254 | chapter = The Blabber | quote = 'It's an ansible.' 'Surely they don't call it that!' 'No. But that's what it is.'}}</ref> [[Elizabeth Moon]],<ref>{{cite book | last = Moon | first = Elizabeth | authorlink = Elizabeth Moon | title = Winning Colors | edition = mass ppb. | date = [[1995]]-[[08-01]] | publisher = Baen | location = Riverdale, NY | id = ISBN 0-671-87677-5 | pages = 89 | quote = ...when I was commissioned, we didn't have FTL communications except from planetary platforms. I was on ''Boarhound'' when they mounted the first shipboard ansible, and at first it was only one-way, from the planet to us.}}</ref> [[L.A. Graf]],<ref>{{cite book | last = Graf | first = L.A. [Julia Ecklar] | authorlink = Julia Ecklar | title = Time's Enemy | edition = Star Trek ''Deep Space 9''<sup>TM</sup> : Invasion, 3. mass pbk. | year = 1996 | month = August | publisher = [[Pocket Books]] | location = New York | id = ISBN 0-671-54150-1 | pages = 203 | quote = '...The two Dax symbionts can communicate with each other across space, instantaneously, because they're composed of identical quantum particles. I've become a living ansible, Benjamin.'}}</ref> and [[Dan Simmons]].<ref>{{cite book | last = Simmons | first = Dan | authorlink = Dan Simmons | title = Ilium | edition = hbk. | date = [[2003]]-[[07-01]] | publisher = Eos/[[HarperCollins]] | location = New York | id = ISBN 0-380-97893-8 | pages = 98 | quote = I can see Nightenhelser madly taking notes on his recorder ansible.}}</ref> Similarly functioning devices are present in the works of numerous others, such as [[Frank Herbert]]<ref name="star">{{cite book | last = Herbert | first = Frank | authorlink = Frank Herbert | title = The Whipping Star | origyear = 1970 | date = [[1970]]-[[April]] | publisher = ''Worlds of If'' magazine}}</ref> and [[Philip Pullman]], who called it a "lodestone resonator".<ref name="amber">{{cite book | last = Pullman | first = Philip | authorlink = Philip Pullman | title = The Amber Spyglass | origyear = 2000 | edition = His Dark Materials, 3. mass pbk. | date = [[2001]]-[[10-02]] | publisher = [[Del Rey Books|Del Rey]] | location = New York | id = ISBN 0-345-41337-7 | pages = 156 | quote = 'Well, in our world there is a way of taking a common lodestone and entangling all its particles, and then splitting it in two so that both parts resonate together.'}}</ref> The "subspace radio," best known today from [[Star Trek]] and named for the series' method of achieving faster-than-light travel, was the most commonly used name for such a faster-than-light (FTL) communicator in the science fiction of the [[1930]]s to the [[1950]]s.{{Fact|date=February 2007}} One ansible-like device which predates Le Guin's usage is the "Dirac communicator" in [[James Blish]]'s [[1954]] short story "Beep". [[Isaac Asimov]] solved the same communication problem with the "hyper-wave relay" in [[The Foundation Series]]. [[Stephen R. Donaldson]], in his Gap Series, introduces Symbiotic Crystalline Resonance Transmission, clearly ansible-type technology which, unfortunately, is very difficult to produce and limited to text messages.
Le Guin's ansible communicated instantaneously, and so do most other authors'. Notable exceptions are the [[BattleTech technology|HyperPulse Generator]] of the [[BattleTech]] universe and the ansible in the Vinge short story "The Blabber", which merely communicates faster than light — in a universe where that is believed impossible.
===In Le Guin's work===
In ''[[The Word for World is Forest]]'', Le Guin explains that in order for communication to work with any pair of ansibles at least one "must be on a large-mass body, the other can be anywhere in the cosmos." In ''[[The Left Hand of Darkness]]'', the ansible "doesn't involve [[radio]] waves, or any form of [[energy]]. The principle it works on, the constant of [[simultaneity]], is analogous in some ways to [[gravity]]... One point has to be fixed, on a planet of certain mass, but the other end is portable." Le Guin's ansibles are not mated pairs as it is possible for an ansible's coordinates to be set to any known location of a receiving ansible. Moreover, the ansibles Le Guin uses in her stories apparently have a very limited [[bandwidth]] which only allows for at most a few hundred characters of text to be communicated in any transaction of a dialog session. Instead of a microphone and speaker, Le Guin's ansibles are attached to a keyboard and small display to perform [[text messaging]].
===In Card's work===
Orson Scott Card's [[Ender's Game series]] is probably the most widely read work to use an ansible.{{Fact|date=December 2007}} ("The official name is Philotic Parallax Instantaneous Communicator," explains [[Hyrum Graff|Colonel Graff]] in ''[[Ender's Game]]'', "but somebody dredged the name ''ansible'' out of an old book somewhere").<ref name="egame"/> His description of ansible functions in ''[[Xenocide]]'' involve a fictional subatomic particle, the [[philote]], and contradicts not only standard physical theory but the results of empirical [[particle accelerator]] experiments. In the "Enderverse", the two [[quark]]s inside a [[pion|pi meson]] can be separated by an arbitrary distance while remaining connected by "philotic rays". This is similar in concept to [[quantum teleportation]] due to [[quantum entanglement|entanglement]], although even that is not capable of faster-than-light communication. Also, in the real world, [[quark confinement]] prevents one from separating quarks by more than microscopic distances.
===In reality===
There is no known way to build an ansible. The theory of [[special relativity]] predicts that any such device would allow communication from the future to the past, which raises problems of [[causality]]. For this reason, most physicists believe that they will eventually be proven impossible. [[Quantum entanglement]] is often proposed as a mechanism for superluminal communication,<ref name="amber"/> but our current understanding of that phenomenon is that it cannot be used for ''any'' sort of communication—superluminal or otherwise—because of the [[no cloning theorem]] in [[quantum mechanics]]. See [[time travel]] and [[faster-than-light]] for more discussion of these issues.
==References==
{{reflist}}
==See also==
* [[No cloning theorem]]
* [[Tachyon]]
==External links==
*[http://www.jessesword.com/sf/view/16 Ansible] from the [[Oxford English Dictionary]] [http://www.jessesword.com/sf/home Science Fiction Citations project]
*[http://www.technovelgy.com/ct/content.asp?Bnum=342 Ansible] at Technovelgy
*[http://news.ansible.co.uk ''Ansible'' Home Page] (fanzine)
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