Limits On Interstellar Communication

"The 'instantaneous' pulses emitted by a ship in hyperdrive are detectable at an extreme range of about a light-year. They can be modulated to carry information. Unfortunately, within a few million kilometers quantum effects degrade the signal beyond recovery; even the simplest binary code becomes unintelligible."
-Poul Anderson, Flandry's Legacy (New York, 2012), p. 132.

However, the interstellar civilization in Anderson's For Love And Glory has an instantaneous hyperbeam. I remember that there was some limitation on the use of hyperbeam but not what it was.

In the Man-Kzin Wars period of Larry Niven's Known Space History:

"'Someday they'll miniaturize hyperwave equipment to the point where it'll fit into a spaceship.'"
-Poul Anderson, "Inconstant Star" IN Niven, Ed. Man-Kzin Wars III (New York, 1990), p. 211.

And, later in that history, Beowulf Shaeffer, exploring the galactic center alone in a spaceship, speaks to his puppeteer employer instantaneously by hyperphone. (Too easy.)

Anderson's Starfarers features an instantaneous and transtemporal communicator and Ursula Le Guin's future history has the instantaneous ansible. However, the true master of interstellar communication is James Blish:

his ultraphone is FTL but not instantaneous;

his CirCon radio and Dirac transmitter are instantaneous;

in one application of the Dirac transmitter, it receives messages from the past and future as well as from the present;

his Heart Stars empire and Angels also have instantaneous interstellar communication.

This is the kind of systematic treatment of a theme that we often find in Anderson's works.

Going Hyper

When fictional characters travel in a jet plane, the technical parameters of their journey are laid down by factors external to the fictional text whereas, when an sf writer invokes "hyperspace," he can say what he wants. Thus:

in Poul Anderson's History of Technic Civilization, travelers take time to cross interstellar distances faster than light and cannot communicate by hyperspatial pulses across more than a light year;

in Anderson's For Love And Glory (New York, 2003), travelers take no time to jump across even greater distances and can communicate between planetary systems by hyperbeam;

Isaac Asimov, Larry Niven and others have their different versions of hyperspace - indeed, Niven rightly raises further questions about his version later in the Ringworld series.

In FLAG, a spaceship melodiously says:

"Stand by for hyperjump,'" (p. 88)

- and, in Ensign Flandry, a ship's captain announces:

"'Stand by for hyperdrive. Stand by for combat. Glory to the Emperor.'" (Young Flandry, p. 172)

But they are talking about different kinds of hyperspace.

Interstellar Communication

The Inter-Being League uses subspace radio.

There are subtronics in "Sargasso of Lost Starships" but a transonic communicator in "The Star Plunderer" and the rest of the Technic History has modulated hyperpulses whereas there is a hyperbeam in For Love And Glory.

There is an "ansible" in Ursa Le Guin's Hainish future history.

Compare James Blish's Dirac transmitter and other interstellar communicators. Also, Communication. For more on his CirCon (circum-continuum) radio, see ASK Haertel.

Hyperdrive And Hyperwave

"Inconstant Star," Chapter VI.

We have to learn the rules of interstellar travel and communication in each new sf series:

in Poul Anderson's Technic History, hyperpulses can be modulated to carry information only across one light year;

in Anderson's For Love Of Glory, there is an instantaneous interstellar hyperbeam;

in Anderson's "Iron," set during the Man-Kzin Wars period of Larry Niven's Known Space future history, why do spaceships with hyperdrives communicate by radio even though there is interstellar communication by hyperwave?

"'If only we could stay in touch!'
"Ryan shrugged. 'Someday they'll miniaturize hyperwave equipment to the point where it'll fit in a spaceship.'
"'Why haven't they already?' she protested. 'Or why didn't it come with the hyperdrive?'
"'We can't expect to understand or assimilate a non-human technology overnight,' Yoshii told her in his soft fashion. 'As was, it took skull sweat to adapt what the Outsiders sold your world to our uses...'" (p. 211)

Kzinti acquire hyperdrive from human beings who bought it from Outsiders who do not travel through hyperspace but could have acquired the drive to trade with anywhere in the galaxy.

In Anderson's Aftter Doomsday, the superlight drive spreads between civilizations like dandelion seeds.