| abstract
| - Space is big. No, really big. You might think it's a long way to the chemist, but that's peanuts compared to space. 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 Faster-Than-Light Travel 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 Subspace or Hyperspace 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 Star Trek, which uses subspace for both, real-time conversations take place between characters who are days of FTL Travel apart. This allows plots to be written as if Space Is an Ocean. On the other hand, just as not all FTL methods are equal, neither are all FTL comms. A humble 10c 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 365c 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 that of plot can shape a story's events. In some cases, a Subspace Ansible may exist even if Faster-Than-Light Travel does not. There might be some attempt to 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: while a single-star-system Space Opera can get by without Faster-Than-Light Travel, it takes several minutes for radio waves to travel the distance from Earth to Mars, the problem of communication remains pressing even if Faster-Than-Light Travel 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 Hand Wave (unless tachyons are involved; then it gets complicated). The term "ansible" for this kind of near-instantaneous subspace communication system was coined by Ursula K. Le Guin in her 1966 novel, Rocannon's World. "Ansible" is a derivation of "answerable", i.e. "messages will be answerable in realtime". Many other science-fiction writers picked up the name after Le Guin. If Psychic Powers exist in a setting, they often work instantaneously at any distance, and function as a Subspace Ansible.
|
![[RDF Data]](/fct/images/sw-rdf-blue.png)