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Finding the Galactic Internet

Greg Egan, a jewel in Australia’s science fiction crown, writes in his 1997 novel Diaspora about a mind-bending far future scenario for interstellar travel. The human race has split into those still in biological bodies, those embedded in humanoid robots, and those who choose to live as software running on central computers. I won’t get into the rich details of the novel this morning, but suffice it to say that the diaspora portrayed here involves a thousand clones of a future Earth community sent to explore nearby stars. Different digitized copies of the same characters spin out their own story lines over a background that spans hundreds of light years.

This is one way to get to the stars, reminiscent of Robert Freitas’ nanotech probes that house thousands of human intelligences in spacecraft no larger than needles. It’s a reminder that highly advanced future cultures may have means at their disposal for star travel even if we find no way of getting up to more than a small percentage of the speed of light. It’s also a memo to SETI theorists about what we might look for as we ponder the shape of extraterrestrial civilizations. If biological life is gradually replaced in favor of software and AI, what signatures will we find?


Image: A classic spiral, the Whirlpool Galaxy (M51) is 30 million light years distant and 60 thousand light years across. What sort of communications network might link civilizations here? Credit: N. Scoville (Caltech), T. Rector (U. Alaska, NOAO) et al., Hubble Heritage Team, NASA.

Egan’s work came to mind as I read this Washington Post story about Geoff Marcy’s recent grant from the Templeton Foundation. The grant is one we’ve discussed before (see Finding ET in the Data), and it’s noteworthy that Marcy’s hunt for Dyson spheres is paralleled by grants to Jason Wright (Pennsylvania State) and colleagues Steinn Sigurðsson and Matthew Povich, who will be using data from the Wide-Field Infrared Explorer satellite (WISE), as well as Lucianne Walkowicz (Princeton University), whose team will be looking through Kepler data for unusual light curves that might flag artificial constructions of enormous size.

I’ll naturally track these projects with great interest. But for today, I want to focus on the rest of Marcy’s search. For while Dyson spheres invariably seem to draw the most attention, only a fraction of the $200,000 Templeton grant will be devoted to their discovery. While some of that money will fund the work of a grad student developing code to search the Kepler data for unusual signatures, the rest buys Marcy time at the Keck Observatory at Mauna Kea, where the game shifts to optical SETI as Marcy tries to spot the laser signaling of an interstellar network.

Enter the Galactic Internet

Like Robert Freitas, Timothy Ferris has speculated about self-reproducing probes that could be sent in small packages to neighboring star systems. Here the idea is that the probe mines local resources, perhaps in an asteroid belt around the target star, and builds an observatory that can send information back to Earth. Over the course of time, the probe reproduces and sends a clone of itself still further out. Ferris’ own thoughts on this go back for more than three decades — see his 1992 title The Mind’s Sky: Human Intelligence in a Cosmic Context for more — and include the emergence of a potentially galaxy-spanning network. The probes become communications stations that constantly monitor other such stations, transmitting and receiving data. Each station becomes a library as galactic information is stored and forwarded:

The interstellar network functions independently of any one world. It has a master program, akin to a set of genetic instructions, originally composed by intelligent biological beings or by another computer. This program gives it its charter — to handle traffic efficiently, to store and organize a copy of everything it conveys… to keep expanding the network as the traffic requires, to search for new communicative worlds, and to keep querying worlds that have gone off line to see whether someone may still be there. How, exactly, it goes about doing these things is its own affair; once set in motion the network has a life of its own.

A galactic network begins with the realization that sending short, conversational messages to other systems is not the way to proceed. Instead, messages will be long and content-laden simply because of the amount of time it takes to communicate. We don’t know how long civilizations last, but Ferris notes that even if a culture managed to stay in communications mode for ten million years, that would still represent no more than one tenth of one percent of the age of the galaxy. And that would mean that only one in 1000 of all civilizations that have inhabited the Milky Way is still in existence, formidable odds for those who want to communicate with distant cultures.

Although Ferris has been thinking about interstellar networking since 1975, the emergence of the Internet spurred the notion of what he calls a ‘galactic central nervous system.’ Node connects to node and, potentially, to the nodes of other discovered civilizations, with an efficient network flow that means knowledge of other cultures spreads gradually and without the need for point-to-point contact between each of the discovered civilizations. Each node keeps and distributes the data it collects. In a 1999 essay called “Interstellar Spaceflight: Can We Travel to Other Stars?” Ferris mused on the consequences of such a network for what we see around us:

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.

Can such a network, one that maintains ‘omnidirectional broadcast antennae,’ survive the analysis of work like Jim and Greg Benford’s on economically viable beacons? A more likely scenario seems to be what Marcy is suggesting, that what we might detect is an errant beam rather than a targeted, beacon-like signal. It’s good to have the hunt proceeding for just such an event (and we can’t rule out the possibility that the famous Ohio State WOW! reception was itself an errant signal at radio frequencies). It’s also good to remember that where our own culture may be most visible to any outside civilization is in the occasional, non-repeating sweeps of our planetary radars, engaged in the effort of studying the heavens for potentially dangerous objects.

We’re a long way from building a Ferris-style network ourselves, but it’s worth pondering what the planet might look like when we do get to these levels of technology. And if someone else has built one? Maintaining a watchful attitude at the most likely parts of the electromagnetic spectrum is good practice, and the emerging methods of transit study and data mining for unusual signatures — from the galaxy level down to individual stars — will set new directions for the overall SETI effort.


Comments on this entry are closed.

  • Elf M. Sternberg July 25, 2013, 10:13

    Has nobody ever read Charles Stross’s MAXO Signals? It’s about exactly this scenario… with an unpleasant ending.

  • railmeat July 25, 2013, 10:32

    Great post, this is a fascinating topic. More people are thinking about this than I knew.

    There is practical work being done on implementing this. It is called Delay Tolerant networks. Naturally there is a WikiPeda page (http://en.wikipedia.org/wiki/Delay-tolerant_networking) an IETF informational RFC (http://tools.ietf.org/html/rfc4838), and a research group (http://www.dtnrg.org/wiki/Home).

    An entertaining presentation of this topic is Vint Cerf’s 2001 TED talk: http://www.youtube.com/watch?v=XTmYm3gMYOQ His talk is about a planetary network, leading to an interstellar network.

    To me the Delay Tolerant Networking research looks like progress on making imaginative speculations about interplanetary and intergalactic communications real.

  • Colin July 25, 2013, 11:43

    Are our SETI efforts completely off the mark?

    It seems to me that searching for a signal from another civilization is futile, because as mentioned omnidirectional antenna are going to waste too much power.

    So what about bio-signatures in the atmosphere of another planet? Well to me it seems like our own civilization is trending towards an artificial intelligence future and what is left over will be a much smaller biological civilization.

    Then what about the energy consumption of a civilization? Searching for dyson spheres and such? We are making advancements in electronics all the time that bring energy use by electronics down. If our progeny are to be robotic, maybe they will never develop the need for such huge amounts of power.

    Once we have been to 1,000,000 stars will we become bored of exploring? Is the reason that we have not met ET because they got bored before they got to us?

  • Ned July 25, 2013, 11:59

    You write: “We don’t know how long civilizations last, but Ferris notes that even if a culture managed to stay in communications mode for ten million years, that would still represent no more than one tenth of one percent of the age of the galaxy. And that would mean that only one in 1000 of all civilizations that have inhabited the Milky Way is still in existence, …”

    That is one damnably weird calculation. What kind of assumptions go into something so nonsensical? Is it presumed that the galaxy was immediately inhabitable following its “formation”, whenever that is determined? that civilizations pop up and die out is some chronologically equally spaced time periods? that “X” (however calculated) number of civilizations formed to begin with?

    At least as presented, that “one in 1000” “statistic” is meaningless.

  • Paul Gilster July 25, 2013, 12:32

    Here’s the Ferris quote — as you note, lots of assumptions therein:

    “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 million years, only one in 1,000 of all that have inhabited our galaxy is still in existence.”

  • Rob Flores July 25, 2013, 15:30

    We should consider that maybe we are being too epoch-centric in our
    assumptions of the suitabilty of our galaxy to produce ETI.

    We make the assumption that from the big-bang to 5-7 billion years
    the universe was to thin on metals and possibly too violent to have
    the good conditions for ETI to arise in great numbers.

    But what if our period of the age of the universe is still the prelude to
    greater posibilties of abudant ETIs. What if it is the vast number of
    Red Dwarf solar systems in middle age a few billion years in the future that will give rise to a dense community of ETIs. There are many here who think greatly of Red Dwarfs as habitable abodes. If they are right (I remain
    skeptical) we are making the mistake of mistaking the overture for the
    main feature.

  • ljk July 25, 2013, 15:53

    I recently wrote an article about how we need to change the parameters of SETI if we want it to succeed:


    In essence, the original plan for SETI was to look for beings much like ourselves. They may be out there, but since we are dealing with *alien* beings, the odds are also in favor that they are not much like us in every respect.

    Until we can start exploring the galaxy directly, SETI will have to do. At the least we can search beyond the radio spectrum and only G class star systems.

  • Jer July 25, 2013, 15:54

    ..or as a line of re-broadcasting breadcrumb satellites as worldships head off in a certain direction, leaving a consistent and periodic trail in the heavens -or- even a series of concentric satellite drone ‘splashes’ radiating outward in all directions along the ‘way’ seeding an ever thickening line of communication and/or discovery to some inspiring far-future destination. How dense would a 3-d mesh of satellites need to be to analyze the star systems within its sector and report?

  • James Benford July 25, 2013, 16:23

    Correct, Paul! If they use the same technology, the costs of such Isotropic Beacons is higher by the ratio of the angular size of a Cost-Optimized Beacon (theta squared) to all of space, which is 4 pi. This is shown in our paper “Messaging With Cost Optimized Interstellar Beacons” be 10 million to a billion times as much cost! And the Cost-Optimized Beacon examples quantified there are in the 1-10 B$ range. So, Isotropic Beacons will cost 10 million billion dollars to 10 billion billion dollars! Our entire world GNP is less than 0.1 million billion dollars, so Isotropic Beacons would cost a hundred to 100 thousand our entire annual wealth production.

    Citation is: “Messaging With Cost Optimized Interstellar Beacons”, James Benford, Dominic Benford and Gregory Benford, Astrobiology, 10, pg. 475, (2010)

    James Benford

  • Alex Tolley July 25, 2013, 16:42

    “Never underestimate the bandwidth of a station wagon full of tapes”

    Has anyone done any theoretical calculations of laser communication vs sending data objects in terms of energy consumption and bandwidth? If we can store data at the atomic level, then send that data out to its target at say 1% light speed, what is the bandwidth and energy costs compared to beaming data at s9me required power level and reasonable bandwidth? If propelling physical data is the better option (unless speed is paramount) wouldn’t that question the assumptions of beaming (unless beams are used to propel nano-sails to haul the package)?

  • Eric Storm July 25, 2013, 19:16

    Has there been any scientific exploration as to the possibility of quantum pair bonding over distances of light years? It seems quantum pairing might work, and would easily be boosted to reletavistic velocity, if not just the paired atoms themselves, then atoms in very small sensory probes, nanometers in size.

  • Geoff July 25, 2013, 20:53

    If Galactic Internet nodes are self-reproducing, then adding a node is effectively free (wherever there is a local source of energy and materials to work with). So there is no reason not to have a node at every possible point of interest.

    I conclude that if such an arrangement exists, then the nearest node to us will be no further away than low Earth orbit.

  • David Cummings July 26, 2013, 7:11

    Why would an advanced civilization cease to exist after 10 million years? Because its star went supernova? Because a radiation event in its region of the galaxy wiped out life in more than one star system? To ask the questions is to dismiss them. If we really are talking about an “advanced civilization” and they really do reach an age of 10 million years, they are of course going to be spread out enough so that any astronomical event that we have ever observed would be incapable of wiping them out.

    That leaves the incredible possibilities of spontaneous mass suicide or galactic-scale genocide by some other even more advanced race. I guess that for reasons beyond our understanding both of those events are theoretically possible but I would say that it’s more possible that any civilization that reaches a certain level of advancement and is spread out over a volume of space above some critical limit, that civilization is just going to keep existing. Period. The only limits are ones that we can clearly see for ourselves: a) the big crunch [unlikely], b) the heat death of the universe, c) the big rip.

    I’m willing to go out on a limb and say that in the 10 billion year (or so) history of our galaxy, there have never been any 10 million year old civilizations that have gone extinct. I know I can’t prove the statement, but I believe that the statement is more reasonable than its opposite.

  • Adam July 26, 2013, 7:51

    Geoff, that might work, if LEO was hospitable to long-lived Nodes, but it’s not really. No resources for repairs and constant orbital perturbations. It’d need to be in the Asteroid Belt or beyond, though able to spy on the interesting wild-life on Planet 3.

    To minimise transmission energy costs, the Node should have transmitters at a gravity-lens line-of-sight opposite to several nearby stars. Targeting all the stars within ~10 ly, which in turn target the stars near them, and so on, only slightly increases transmission times, but minimises the power and total number of gravity-lens transmitters required.

  • Alex Tolley July 26, 2013, 10:17

    I’m willing to go out on a limb and say that in the 10 billion year (or so) history of our galaxy, there have never been any 10 million year old civilizations that have gone extinct.

    There should probably be some qualifications here. Terrestrial species exist, on average, about 1 million years. So a galactic civilization of biologicals would either have to prevent evolution happening, including blocking competing species and civilizations, or it would be composed of different species during its life cycle. Or it could be non-biological with controls to prevent evolution happening. Or it could be composed of many species with changing composition.

    Again, this assumes no competition from either new civilizations or of factions within itself. Earth history has no such examples of civilizations that exist from the dawn of civilization until today. Why should you expect the “galactic civilization” to be a priori different?

  • Robert Feyerharm July 27, 2013, 1:08

    If a galactic communication network were built in the far future, and human intelligence can be uploaded into software running on a computer, then wouldn’t it be feasible for interstellar travel at light speed to be achieved by simply beaming yourself from one node to another in the network? From the perspective of the intelligence being beamed, the travel time would be perceived as instantaneous. One second you’re in a computer core on Earth, and after a brief transition you’re in a computer receiving station on Alpha Centauri the next second.

  • Steve Bowers July 27, 2013, 5:29

    An advanced civilisation would almost certainly have full control over its biological evolution, and/or have postbiological elements in the mix. Such a diverse society would need to incorporate competition as part of its development. How would such an advanced civilisation flip over from being successful to facing collapse at any arbitrary point, including the ten million year mark?

    The answer is, of course, we can’t know, but it would be interesting to find out.

  • David Cummings July 28, 2013, 6:25

    Alex, I didn’t put the figure “ten million years” out there, Ferris did. I’m just starting with that and talking about civilizations that have already attained that age.

    I think it’s fair to expect that a 10 million year old civization has — as Steve Bowers points out — long since stopped being a passive responder to evolutionary pressures. I would argue that we, even still in our infancy compared to the kinds of civilizations we are imagining might exist, have already stopped being passive responders to evolutionary pressures. For the most part, “the least fit” tend to survive in the human race along with “the fittest”. Hitler tried to institute a programmed evolution of “survival of the fittest” (which included, in his wacky definition of fitness, traits that presupposed and highly-favored a general lowering of the public IQ) but that blip in human history is receding into the rear-view mirror without affecting the human genome very much (though sadly it did remove a portion of the pool of the Best and Brightest). And yes, on the horizon is the very real possibility (or even high probability) that we will significantly monkey around with our own genes, even to the point where you could say a thousand years from now that we will be a new species, so different from the past version of the human animal that cross-breeding would be out of the question.

    But even if we tinker with the human genome to the point that it must be considered a new species, it will be a species of our own design and it would be very difficult to argue that “Human Civilization” comes to an end just because our genome is altered. (And it might not be wholly altered. There might be those who for whatever reasons choose to stay human-like-today, augmenting their abilities through cyborg gambits rather than genetic modifications thus staying current with ability-trends without having to alter their basic biological selves.)

    But even if we change the genome, we don’t end the civilization. And I would argue that, in fact, our civilization has never ended, not in the last 10,000 years. There is complete and total continuity between the cave drawings of 10,000 years ago and the latest concoctions of web-site art on the internet today. From an alien point of view, in particular, we are one Human Civilization and we are about 10,000 years old. There have been some regime changes, sure. But we have never lost the basic thread of the development of human culture (despite local variances), science and technology. Humanity has not, in the last 10,000 years, ever come to an end. Sure, Rome fell and dynasties changed in China, but to an alien race arriving for a sudden unannounced visit, they would not see any of that as much of a change. They would say “Hello, People” and they would mean all of us, going all the way back to the earliest farmers.

    But getting back to the 10 million year old civilization, which again, is not my idea but the idea of Ferris, I guess it’s possible to imagine a 10 million year old civilization that hasn’t expanded into a fairly large region of the galaxy (at 1/100 of the speed of light they could have colonies as far away as 100,000 light years (does that distance ring any bells with you?) and yes, they may have run into “competitors” along the way but since we are hypothetically granting them the age of 10 million years, I think its fair to say they have long since learned how to absorb or co-exist with “competitors”.

    If you start with the assumption that we are talking about a civilization that is 10 million years old, I think the burden of speculation (can’t really say proof, can we?) is on those saying that a 10 million year old civilization even COULD face extinction. Please, come up with some scenario, no matter how wild, that would wipe out a civilization (and remember, a civilization can be bigger than a biological species and can contain more than one, even by self-modification, or by species-promotion [we may some day choose to promote chimps, but they will be joining our civilization, won’t they] or by incorporation of a smaller alien race into the mix) that has attained the age of 10 million years and the spread of 100,000 light years in any direction (which obviously is larger than our entire galaxy).

    I just don’t think it can be done. If an advanced civilization reaches the 10 million year mark, they are going to want to hang around to watch the End of the Universe and I don’t think anyone or anything is going to stop them.

  • Alex Tolley July 28, 2013, 17:19

    @David Cummings – It seems to me that you have changed the meaning of “civilization” if you claim that human civilization is singular, not multiple as usually described. W have no experience of any civilization with more than one species. (We might have if our competitor hominids hadn’t gone extinct). While “galactic cultures” are a staple of SF, we really don’t know if they would really work.

    As you may know, the popular view that humans have stopped evolving has shown to be incorrect, it is arguable that we are evolving faster than ever. This is a good thing, IMO. But the consequences are that we will potentially diverge into various “post-human” species. Whether this is natural or artificial evolution doesn’t change that. Could we maintain a common culture despite this divergence?

    If “galactic civilization” just means that there is not complete collapse as one culture/species after another becomes dominant, then there is not much to disagree with. Can such a civilization reach 10 million years – given that whole new species will appear and disappear during that time – really exist? I don’t know. If it is a given that it has, perhaps using the Copernican principle, it will survive another 10 million years. But to see the end of the universe – color me skeptical.

  • Rob Henry July 28, 2013, 17:23

    David Cummings, you mention that interesting episode of Nazi Europe, when there was a state view of where human evolution should be leading (forget any weakness in their selection biases, as these would have been ironed out when more advanced genetic techniques became available). Currently we have a laissez faire approach, whereby concerned parents will forgo the long term approach in favouring the just the F1 generation.

    I seem to share the same biases as you, and because that former episode turned out badly, imagine that the latter case is the norm. The problem is that what’s an improvement one generation on might be deleterious in the long term. Will this approach make us overly competitive and without charity? Might it do the opposite and create a society that is perpetually happy with its lot, even though the world around us is disintegrating?

    Whether we die with a bang or a whimper, the important thing to note is that because the effect is caused selection pressures from so many, it should be present in all our colonies albeit at differing rates. The idea here is that the trend can only be corrected when we are forced to return to survival of the fittest, ie when civilisation collapses.

  • Peter Chapin July 30, 2013, 20:00

    If 10 million year old civilizations are immune to extinction that would seem to make the Fermi Paradox all the more pressing. If every civilization that made it to 10 millions years (or whatever) is still around… where is everybody?

  • Eniac July 30, 2013, 23:02

    In the context of a Galactic Internet, the “Cost of Beacon” argument breaks down completely. All you need is one beacon in each system, able to transmit to a few AU distance. Or, even more effectively, an obviously artificial object of asteroidal size in a long-lived orbit. A giant shiny balloon with writing on it would do. Real low-tech. We could build and launch that, today.

    Similarly, the “Limited Lifetime” argument is nonsensical as soon as you allow that civilizations may split, multiply and spread. The “same” civilization (subject to definition of “same”) may not be around, but its descendants and successors forever will be. With all their histories and cultural artifacts forever stored, spread, and made available to anyone in (you guessed it) the Galactic Internet.

  • Kent Rigel August 3, 2013, 11:52

    I’ve encountered this concept in several works of science fiction, in different formats.

    Bill Napier’s ‘The Lure’, where the protaganist speculatively deduces that a data-rich ET signal observed at a neutrino detection facility was sent by a node in the Oort cloud and that the lack of space-faring civilizations is because when you can just ‘get the signal’ and all the information bouncing around the universe, generated by the species in it, you don’t need to go anywhere. Peter F. Hamilton’s ‘Fallen Dragon’ has a intelligence/creature which is one of untold uncountable number, each one an offspring filled with the knowledge of it’s progenitor and then launched into the black, eventually to fall into the well of another star repeating the process, gathering more knowledge all the time, sharing it with any other of its kind it encounters, massive redundancy – and these intelligence/creatures give their information to pretty much any organism which inquires for that information, no strings attached. Robert Charles Wilson’s ‘Spin’ has the Oort Cloud seeded with nanotech that self-replicates, disperses into the galaxy like pollen and establishes itself in the Oort Clouds of other star systems, relaying the information back (the Earth is under massive time-dialation by the eponymous ‘Spin’ phenomena) only to discover that the network is coopted by a pre-existing/competing network… leading the protagonist to suspect that the agents behind Earth being placed under time dialation are machine intelligences, von Neumann machines and they probably are dispersed the same way.

    It’s a rich paradigm for science-fiction with much potential for story-telling, but also gladly a concept that real scientific pursuit is investigating based on just how probable the existence of such a phenomena would be if there is indeed sufficiently numerous civilizations out there in the universe.