The Visibility Presumption
19 October 2012
How “visible” is any given industrial-technological civilization from the perspective of interstellar distances? In this context, “visible” means some technological sign that can be detected by technological means. Most obviously this includes any electromagnetic spectrum emissions, but might also include large scale engineering and industrial projects that could be discerned at interstellar distances.
SETI is based upon what we will here call the visibility presumption. SETI can’t really operate in any other way; if you’re going to conduct a search at the present, there are only so many things you can do with current technology at interstellar distances.
In the future (and not all that long from now — in the next ten to twenty years), as I have mentioned in other posts, we will be able to take the spectrum of the atmospheres of exoplanets and from this information we will be able to conduct a genuine Search for Extra-Terrestrial Life (SETL, presumably) by identifying biochemistry in exoplanet atmospheres. Such techniques might also reveal the activities of a civilization prior to the kind of electromechanical technologies that typify industrial-technological civilization and imply the mastery of electromagnetic spectrum emissions.
For the time being, such investigations are just beyond present technology and, as a result, extraterrestrial life that falls below the threshold of industrial-technological civilization with a mastery of electromagnetic technologies is “invisible” to us. In other words, such sub-technological civilizations, or life without civilization, lacks SETI visibility.
Many have commented that, in light of SETI visibility, what we call the search for extraterrestrial intelligence ought to be called something like the search for extraterrestrial technology or the search for advanced extraterrestrial civilizations — but we can keep the familiar SETI acronym by thinking of it as the Search for Extra-Terrestrial Industrialization.
Employing our technology to search for signs of an alien technology is essentially to search for a peer civilization, i.e., another industrial-technological civilization: we are staring into the heavens and trying to find ourselves in the mirror. Not exactly ourselves, but something that would identifiable as life, as intelligence, as rationality, as civilization, and as technology. The visibility presumption implicitly incorporates all of these variables and assumes that the parameters of each variable will be just enough to challenge our assumptions without being so profoundly alien as to be unidentifiable by us as species of a familiar genus.
Recent thought concerning the emergence of a post-human future in the wake of a technological singularity has given a great impetus to the discussion of beings or institutions so changed by rapidly evolving technology that either we would not be able to recognize them, or they would not find us sufficiently interesting to communicate with us. In other words, the technological singularity could make xenocivilization invisible to us or make us essentially invisible (in the sense of being beneath notice) to a xenocivilization, thus posing a challenge to the assumptions of the visibility presumption that another industrial-technological civilization in the galaxy would be a peer civilization and visible to us.
Since I have posted quite a bit recently about the Fermi paradox, I have taken the trouble to look up one of the more thorough books on the topic, If the universe is teeming with aliens… where is everybody?: fifty solutions to the Fermi paradox and the problem of extraterrestrial life by Stephen Webb. The author divides up the solutions according to three broad categories, “They Are Here,” “They Exist But Have Not Yet Communicated,” and “They Do Not Exist.” The Wikipedia entry on the Fermi paradox also incorporates a long list of possible responses to the silentium universi.
Solution No. 28 in Webb’s book, and also mentioned on Wikipedia entry, is that xenocivilizations experience a technological singularity and therefore engage in the cosmic equivalent of Tune in, Turn on, Drop out. Here is what Webb writes:
“Vinge argues that if the Singularity is possible, then it will happen. It has something of the character of a universal law: it will occur whenever intelligent computers learn how to produce even more intelligent computers. If ETCs develop computers — since we routinely assume they will develop radio telescopes, we should assume they will develop computers — then the Singularity will happen to them, too. This, then, is Vinge’s explanation of the Fermi paradox: alien civilizations hit the Singularity and become super-intelligent, transcendent, unknowable beings.”
Stephen Webb, If the universe is teeming with aliens… where is everybody?: fifty solutions to the Fermi paradox and the problem of extraterrestrial life, New York: Praxis Publishing Ltd, 2002, p. 135
This is in itself a complex response to the Fermi paradox, because different people understand different things by the “technological singularity,” and it could just as plausibly be argued that a species experiencing a technological singularity would have its ability to communicate within the known universe exponentially increased and improved, which in turn poses the Fermi paradox in an even stronger form: if alien technological intelligence is so advanced, and has so many technological and intellectual resources at its command, why is it still unable to communicate across interstellar distances? (The protean character of the singularity thesis — anyone seems to be able to make of it what they will — is one reason that I have characterized it as a quasi-theological belief.)
Once the Fermi paradox is posed again in a stronger form, we must have recourse to other familiar responses, such as the singularity makes them lose interest in the outside world, or the technological singularity destroys the civilization in question, and so forth.
Does the idea of a technological singularity or a post-biological future (for ourselves or for some other xenobiological species) fundamentally challenge the visibility presumption?
Recently in Cyberspace and Outer Space I suggested that any civilization expanding beyond its native planet (or other naturally occurring celestial body that is the home of life elsewhere) would almost certainly have some kind of pervasively present radio or EM spectrum communication system — an internet for the solar system, which Heath Rezabek has called a solarnet — and such a network would be highly visible, and perhaps even unintentionally visible, even at interstellar distances.
This can be formulated in even a stronger form: because civilizations that remain exclusively based on their native planets are highly vulnerable to natural disasters, and therefore potentially vulnerable to natural disasters of sufficient scope and scale to result in extinction, such civilizations could be expected to have shorter lifespans and to therefore be less represented in the universe. In other words, exclusively planetary civilizations would be disproportionately selected for extinction.
What we would expect to find in our survey of the cosmos are those long-lived civilizations with the most robust survival mechanisms — redundancy, dispersion, diversity — and robust survival mechanisms of redundancy and dispersion will mean communication between dispersed centers of the civilization in question, and this communication would likely have a high visibility profile — although it could be argued that one survival mechanism would be to go to ground and remain silent so as not to be exterminated by hostile civilizations.
The same considerations of survivability would apply to any civilization that experienced a technological singularity and had subsequently made the transition to post-biological being. While it is fun to imagine mega-engineering projects like a matrioshka brain, a ringworld, an Alderson disk or a Dyson sphere, such massive projects would be very vulnerable, even for an advanced civilization. Horace said that you can drive out Nature with a pitchfork, but she keeps on coming back, and this remains true even at cosmological scales.
One of the arguments made for the Matrioshka brain scenario is that of keeping the whole structure of a massive super-intelligent entity compact in order to reduce communication times between its parts (the speed of light would be where the shoe pinches for a Matrioshka brain), but no super-intelligent entity, biological, post-biological, or non-biological, would put all its eggs in one basket unless its technological hubris had reached the point of considering itself invulnerable. Such hubris would eventually be punished and the brain would go extinct in one fell swoop. Natural selection does not and would not spare technological entities, though it would operate on a cosmological scale rather than at the familiar scale of planetary niches.
It would make much more sense to make the same effort to construct many different megastructures that remain structurally independent but in continuous communication with each other. Since electrical or fiber optic cables strung in space would be even more vulnerable than structures, these independent megastructures would be hard-pressed to find any more robust and survivable form of communication than good old EM spectrum communications, and if multiple megastructures employing massive energy levels were in continuously in communication with each other by way of EM spectrum communication, such a xenocivilization would have a very high visibility profile unless it made a conscious effort to suppress its visibility — which latter is a distinct response to the Fermi paradox.
The technological singularity or post-biological beings do not, in and of themselves, apart from distinct assumptions, argue against the visibility presumption.
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