A Galactic Internet
September 26, 2008

Timothy Ferris is a popular science writer. In Interstellar Spaceflight: Can We Travel to Other Stars?, he starts writing about space travel but ends up speculating about an interstellar internet.

Living as we do in technologically triumphant times, we are inclined to view interstellar spaceflight as a technical challenge, like breaking the sound barrier or climbing Mount Everest – something that will no doubt be difficult but feasible, given the right resources and resourcefulness.

…[But] the technical problems involved in traveling to the stars need not be regarded solely as obstacles to be overcome but can instead be viewed as clues… that point through other ways to explore the universe.

The high cost of interstellar spaceflight suggests that the payloads carried between the stars… are most likely, as a rule, to be small. It is much more affordable to send a grapefruit-sized probe than the starship Enterprise. Consider spacecraft equipped with laser-light sails, which could be pushed through interstellar space by the beams of powerful lasers based in our solar system. To propel a manned spacecraft to Proxima Centauri, the nearest star, in 40 years, the laser system would need thousands of gigawatts of power, more than the output of all the electricity-generating plants on Earth. But sending a 10-kilogram unmanned payload on teh same voyage would require only about 50 gigawatts – still a tremendous amount of power but less than 15 percent of the total U.S. output.

What can be accomplished by a grapefruit-sized probe? Quite a lot, actually, especially if such probes have the capacity to replicate themselves, using materials garnered at their landing sites… The probe would mine [an] asteroid and use the ore to construct a base of operations, including a radio transmitter to relay its data back to Earth. The probe could also fashion other probes, which would in turn be sent to other stars. Such a strategy can eventually yield an enormous payoff from a relatively modest investment by providing eyes and ears on an ever increasing number of outposts.

[Another] clue – that radio can convey information much faster and more cheaply than starships can carry cargo – has become well known thanks to SETI, the search for extraterrestrial intelligence. SETI researches use radio telescopes to listen for signals broadcast by alien civilizations…

When SETI was first proposed… in 1959… the object most frequently raised to the idea of interstellar conversation was that it would take too long. A single exchange – “How are you?” “Fine.” – would consume 2,000 years if conducted between planets 1,000 light-years apart. But… conversation is not essential to communication; one can also learn from a monologue… We learn from Socrates and Herodotus, although we cannot speak with them…

In 1975, when I first proposed that long-term interstellar communications traffic among advanced civilizations would best be handled by an automated network, there was no model of such a system that was familiar to the public. But today the Internet provides a good example of what a monologue-dominated interstellar network might be like and helps us appreciate why extraterrestrials might prefer it to the arduous and expensive business of actually traveling to other stars.

The most profound gulf separating intelligent species on various star systems is not space but time, and the best way to bridge that gulf is not with starships but with networked interstellar communications.

The gulf of time is of two kinds. The first is the amount of time it takes a signal to travel between [civilizations]. Therefore, it makes sense of send long, fact-filled messages rather than “How are you?”

The other gulf arises if… communicative civilizations generally have lifetimes that are brief by comparison with the age of the universe… Even if we manage to survive for a robust 10 million years to come, that is still less than a tenth of 1 percent of the age of the galaxy.

Any other intelligent species that learns how to determine the age of stars and galaxies will come to the same sobering conclusion – that even if communicative civilizations typically stay on the air for fully 10 millions years, only one in 1,000 of all that have inhabited our galaxy is still in existence. The vast majority belong to the past. Is theirs a silent majority, or have they found a way to leave a record of themselves, their thoughts and their achievements?

That is where an interstellar Internet comes into play. Such a network could be deployed by small robotic probes like the ones described earlier, each of which would set up antennae that connect it to the civilizations of nearby stars and to other network nodes… one could get in touch with many civilizations, without the need to establish contact with each individually. More important, each node would keep and distribute a record of the data it handled. Those records would vastly enrich the network’s value to every civilization that uses it.

If there were any truth in this fancy, what would our galaxy look like? Well, we would find that interstellar voyages by starships of the Enterprise class would be rare, because most intelligent beings would prefer to explore the galaxy and to plumb its long history through the more efficient method of cruising the Net. When interstellar travel did occur, it would usually take the form of small, inconspicuous probes, designed to expand the network, quietly conduct research and seed infertile planets. Radio traffic on the Net would be difficult for technologically emerging worlds to intercept, because nearly all of it would be locked into high-bandwidth, pencil-thin beams linking established planets with automated nodes. Our hopes for SETI would rest principally on the extent to which the Net bothers to maintain omnidirectional broadcast antennae, which are economically draining but could from time to time bring in a fresh, naive species – perhaps even one way out here beyond the Milky Way’s Sagittarius Arm. The galaxy would look quiet and serene, although in fact it would be alive with thought.

In short, it would look just as it does.

Here is a PDF of the full essay.

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