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The intelligence in ETI—What can we know?
Acta Astronautica 78 (2012) 37–42
Contents lists available at SciVerse ScienceDirect
Acta Astronautica journal homepage: www.elsevier.com/locate/actaastro
The intelligence in ETI—What can we know? William Edmondson School of Computer Science, University of Birmingham, Birmingham B15 2TT, United Kingdom
a r t i c l e i n f o
abstract
Article history: Received 28 February 2011 Received in revised form 25 November 2011 Accepted 1 December 2011 Available online 4 February 2012
This paper follows a train of thought initiated in a recent paper [7]. The work sets out a theoretical perspective on the possibility of cognitive universals underpinning the behaviour of animals with brains. Consideration of what we can know of intelligence in beings elsewhere in the universe obliges us to recognise universal and local factors relevant to SETI. Linguistic communication turns out to be genuinely constrained by circumstances even though the existence of linguistic activity will be universal in intelligent beings. The implications for activity in SETI are reviewed. An alternative approach to SETI—described in a recent paper ([9], but see also [8]) is contrasted with the messaging approach, and the conclusion is drawn that an ETI would opt for the alternative. & 2012 Elsevier Ltd. All rights reserved.
Keywords: Intelligence Cognitive Science Embodied Brain SETI CETI
1. Introduction In response to a seemingly casual remark in Chomsky’s Rules and Representations, [2] to the effect that cognitive universals might exist, which could account for language and other behaviours (and the learning of behaviours), a set of universals – General Cognitive Principles – has been proposed [7]. The significance of the proposals is that they frame a functional specification of the brain. In what follows we will consider this specification as the basis for reviewing what we can know of intelligence in beings elsewhere in the universe. Note that if we are ever to be able to say anything sensible about such intelligences we need some sort of universal account—otherwise we are in the realms of science fiction. The rightness or otherwise of the account offered here is perhaps less important than the idea that some such account must be offered if we are to understand both intelligence beyond Earth, and perhaps no less useful, intelligence in all its manifestations on Earth. If it is possible to talk about intelligence in ETI then this must be because there are some General
E-mail addresses: [email protected], [email protected] 0094-5765/$ - see front matter & 2012 Elsevier Ltd. All rights reserved. doi:10.1016/j.actaastro.2011.12.001
Cognitive Principles (GCPs); it remains to be seen if the set proposed is workable. What we work with in this paper is not the specific detail of such a set of universals (for which see Ref. [7]), but rather an insight derived from them, which could have general validity irrespective of the detailed underpinnings. This insight is formulated as the functional specification of the brain. 2. Functional specification of the brain The functional specification of the brain is to serve the Sequential Imperative (SI). It is claimed here, without detailed argument, that the Sequential Imperative is the driving principle behind all behaviour in creatures (anywhere) with brains. Our purpose in this paper is to illustrate the universality claimed rather than to repeat arguments from elsewhere, and then go on to explore the consequences for SETI of working with this idea. 3. Sequential imperative The Sequential Imperative is the unavoidable and overwhelming requirement of an organism that it must overcome the temporal mismatch between the rich sequencing of experience and behaviour and the cognitive
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W. Edmondson / Acta Astronautica 78 (2012) 37–42
timelessness of thoughts, beliefs, plans, intentions, etc. The SI is also about maintenance of a being as a being (homeostasis) in the sense that any creature’s continued existence expresses a kind of stability in a sea of biochemical and physical flux. The homeostatic aspect of the SI is mentioned here for completeness, it does not form part of our deliberation in this paper (but note that it is relevant that the brain in the general sense – not just cognition – manages homeostasis). The SI is seen in operation in any creature anywhere with articulators—arms, antennae, hands, mandibles, feet, etc. These have to be controlled so as to deliver behaviours in response to plans, intentions, etc. Likewise, any organism with sensors has to process a temporally structured stream of data to yield percepts, memories, etc. The brain of the creature serves the SI by managing the processes of sequencing and desequencing, which match the atemporal ‘internal world’ to activities, and match the incessant flow of sensory stimulation to internal representations. As one reviewer acutely pointed out, whilst it is the case that the SI makes sense (in their view this is indisputable), nothing about pace or tempo is determined by the SI. This observation raises two issues, only one of which is pursued by the reviewer. The reviewer raised the question of what would happen if an intelligent life form arose in some setting where its tempo was significantly different from that of organisms around it? Would it fail to grasp the SI as a functional specification for the brain and thereby fail to develop notions of semiosis, or conceptions of intelligence and universals? Set alongside that concern is a second issue (and I had stayed my hand in the writing of the paper, but perhaps should not have done). I first encountered this second issue many decades ago, in a reprint of a short story by Eric Frank Russell [12]. The story is titled ‘‘The Waitabits’’ and concerns the unconquerability of an intelligent life form, complete with cities and solar-powered trains and video-phones, etc. The Waitabits move around very slowly—in fact they seem to do everything excruciatingly slowly. Further, their planet revolves slowly, insects move slowly, there are no birds, and so on. The essence of the story is that the pace/tempo of the world of the Waitabits renders them unknowable in any worthwhile sense. My view on the Waitabits, and thus also on the reviewer’s comment, is that in fact difference of pace/ tempo is never going to be so profound (between planets/ ecosystems) or so variable (within an ecosystem) as to cause concerns. My reason is that physical events will have tempi that provide input to an ecosystem’s workings. Gravity will produce waterfalls, rain, etc. There will be atmospheric activity, which won’t happen in ‘slo-mo’. Slick sequences of physical events will demonstrate causality, and so on and so forth. In addition, biochemistry will have its own pace governed more by energy input/ output than by organismic activity. Lastly, there is likely to be a sort of ‘devil take the hindmost’ pressure on the ability of organisms to move about, ingest prey, etc., which will surface, through evolution, in the minimisation of slothfulness as a useful trait. Indeed we see this on Earth—there are, to be sure, some slow movers. And some
so fast we can hardly keep track of them (although their predators manage this). But the variability is limited. Gravity is the interesting constraint (cf. [11])—too strong and creature movement will be very costly, too weak and the atmosphere will be too thin (and there are evolutionary issues as well as those concerning homeostasis in evolved organisms). I would also conjecture that if liquid water is a sensible habitability criterion (for the evolution of life – probably as we know it – and see [1]) then it will constrain the physical environment within which life evolves, and thus fairly directly the pace at which things happen, and the tempi of behaviours. But this is conjecture and thus a pointer to future work. 4. Embodied brains The assumption is made in this paper of a conception of ‘the brain’ as embodied; it exists within an organism, which is bounded and which has both articulators (in the general sense) and sensors. The brain’s function is to serve the SI in respect of the body within which it resides. The assumption is also made that any embodied organism must have a brain because the SI must be served in respect of that organism. We will leave to one side the issue of ‘‘how small can the organism be and still comply?’’ (as one questioner put it to me, after my presentation of the paper at the Chicheley Hall meeting). To help the reader understand the breadth of the claim being made here the answer can be ‘‘bees and anything bigger’’ although the precise lower limit is not known. The issue is not trivial and brings in factors such as ‘automatic’ behaviours (legs in millipedes) and conventional stimulus/response cycles in behaviourist models. But for now we leave those details to one side. What matters is that the creature with a brain does not have to be human, or dependent on sensors/articulators we immediately identify (bats using sonar, for example, or dolphins using sound both for communication and for echolocation). The primary reason for stressing the embodied nature of creatures with brains is that the SI is about embodiment as much as it is about brains. Something within an embodied organism would have to serve the SI; the claim is that the brain is that something. ‘‘But what about organisms which are not embodied?’’ (comes the cry from the science fiction fraternity). Show me such an organism that can evolve (for which embodiment is a core requirement), or which can smelt metals or develop language (both of which require articulators and sensors), and then we can enlarge the debate on the SI and the brain. The primary assumption we are likely to make about an ETI is that any ETI must be an embodied organism with a brain (we will consider speculations such as ‘postbiological intelligence’ below). The second point is that the functional specification of the brain of an ETI must be the same as that for any brain we encounter on Earth: it serves the SI. This is a powerful position to be in—we can reasonably claim to know something about the necessary properties of an ETI in respect of it having a body and a brain. Specifically, we can claim that its brain will exist to serve the SI. Any alternative notion ‘won’t work’ so to speak.
W. Edmondson / Acta Astronautica 78 (2012) 37–42
5. Specification of behaviour—language The SI will provide some constraints on behaviours. If we consider language behaviour in humans we see these constraints in the form of the repertoire of articulations available to the human. The articulators usually deployed for language in humans are those readily identified as parts of the mouth – e.g. lips, teeth, tongue, jaw – and the larynx. The vocal apparatus is driven by air pressure from the lungs, so breathing has to be modified/deployed to suit speaking. What is important here is that the articulators provide a repertoire of articulations, which can be sequenced. In fact, in any one language the full repertoire of possible articulations is not deployed—a language specific subset (of sounds) is used to produce sequences, which are arbitrarily patterned (again in a language specific manner) to produce components we call words. We can note here the fact that for the production of some sounds different articulations might be deployed in different people—the differences are not significant linguistically although they might be visible, and even audible. What matters is that patterning of articulatory activity, in a language specific way, is multi-layered and a fascinating mix of arbitrariness and systematicity. At the level of the sounds in any one language there are sets of phones (the systematic organisation of the actual sounds) and phonemes (the cognitive precursors or specifications of the phones—also systematically organised), combined into syllables (also systematised), which may or may not be uttered with different levels of stress (systematically patterned), or perhaps tone (systematic variations in basic larynx frequency). All of these systematic patternings are arbitrary in the sense that none of them is ‘normal’ or exploits a ‘default’ set of values. What matters is that when a child learns a language they have to learn the appropriate arbitrarinesses for that language. In addition, the arbitrariness is reflected in the fact that the systematicity in the organisation of articulation at the scale of sounds is not meaningful – there is no requirement that users of a language need to learn the meanings of these individual sounds – they have no meanings. Meanings arise when sounds in combination, and/or in the context of other specific combinations, are deployed specifically to convey semiotic content—meanings. We call these combinations words (although correctly we should refer to morphemes, which frequently combine into psychologically interesting – for processing purposes – units called words), and we call their contextualising properties syntax. Other words (meanings) also contextualise—it is not just structural. Interestingly, the grammars of languages are yet more systematic arbitrariness layered onto the patterns of articulations. These syntactic patterns permit the relationships between words to be exploited in meaningful ways, additional to the meanings of the words themselves. This whole complex of linguistic activity – the multilayered structurings – is deployed by language users in settings or situations, which also contribute to the successful expression of, and understanding of, utterances as meaningful. ‘‘It’s a 144’’ takes on one set of meanings
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when uttered at a bus stop (whilst looking at an approaching bus), but quite another when uttered by a person at an instrument console reading out a fault code to a colleague. (A readable account of the systematicities can be found in [3].) Semiotics is the study of these systematicities and their deployment in linguistic activity—(a) the arbitrariness of articulations and the use of subsets in any one language; (b) to make up larger ‘units’ known as morphemes and words, which can be considered to be meaning bearing; (c) the relationships between such units of meaning (syntax); and (d) the deployment of structured combinations of structured units in situation specific ways. There are, inevitably, some systems of patterning that do not quite fit a simplistic account at some levels of detail (e.g. morphology in Semitic languages), but the overall scheme is sound: articulatory arbitrariness patterned to produce meanings, which are combined and deployed in settings. It turns out that if the use of specific sorts of articulations cannot work (deaf people cannot hear/learn the evidence of spoken articulatory activity) then other systems of articulation are deployed (signs, in signed languages). Semiotics is, in an important sense, the study of some of the outcomes forced on brainy beings by the SI—namely those outcomes deployed and exploited for communication. In short, because ETIs will come to recognise the SI and its role in shaping communication, we should conclude that they must understand semiotics if they understand anything about communication. 6. Specification of behaviour—perception and action In the foregoing account of communication behaviour – linguistic behaviour – the issue of perception is glossed over. It is assumed that the articulatory productions deployed linguistically will be perceivable, and that the producer of such articulatory behaviour will modulate their productivity to suit the listener/viewer. Superficially there is the issue that there is no point speaking too quietly, or signing whilst out of sight of the interlocutor—the user of any language will manage these factors. But additionally, of course, the articulations have to be processable and internalisable. The SI stipulates that the sensory world has to be desequenced to be internalised. For linguistic behaviour this means that the articulations have to be managed for both production and perception. Indeed, it can be argued that the whole complex of arbitrary structurings (phones, phonemes, syllables, stress patterns, morphology, syntax, pragmatics) exists to facilitate perception and internalisation; the richness of structuring provides for error correction, to put it crudely. Behaviour is not just linguistic communication behaviour. All behaviour involves activities and perceptions— and of course the opportunity to observe the behaviour of others should not be ignored, not least because such opportunities are required in situations of shared/co-operative behaviour. The SI requires of such behaviour that it be reliably produced in consequence of some internal specification (the sequencing of such a specification is required; the specification is not itself necessarily sequentially arranged). Likewise, the SI requires that perception yields
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desequenced internal representations, which can be thought of as being the specifications that would have given rise to the behaviours observed. The issue of the inevitability of idiosyncracy in such de-sequencings is important but need not detain us here (see, for example, a discussion of synaesthesia in Ref. [5]). In essence the behaviour and perception required for linguistic activity is not different from that required more generally. In communication of course the behaviours are organised to convey meaning unrelated to the behaviours (there is nothing inherently ‘dog-ish’ about the sound of the word ‘dog’, for example). But in general behaviour the meaning of the activity observed may indeed be related to the activity (sharpening a blade, putting on a coat and boots, etc.). It is significant that the behaviours of creatures (not just humans) can be ‘read’ for intention and that co-operativity exploits this ability. Two mechanics working on the engine of a car, for example, can to a significant extent ‘read’ the actions of their co-worker and respond accordingly [mechanic Fran looks up from the work in hand and glances around, and mechanic Fred sees this, and knowing what is going on is able to reach out and hand Fran the appropriate tool to finish the job]. 7. Sequential imperative and ETI If we make the safe assumption that ETIs are organisms with embodied brains – else they would not have evolved, and would not have articulators to make tools, communicate, etc. – then we can make the additional assumptions that their behaviours are constrained by the sequential imperative, that they understand semiotics, that their linguistic behaviours are as systematised and arbitrary as are those of humans, and that other behaviours are readable in ways that afford co-operation and mutual understanding of actions in relation to tasks (this is just another way of thinking about the meaning of behaviour). The detail of ETI’s circumstances, such as the number of articulators, the physical stimuli to which its sensors respond, the environment in which it exists—all these factors will be specific to each ETI. But the general operation of brained organisms within their environments, and with their physiological specific differences, will nonetheless be universally constrained by the SI. That is entailed, in a strong sense, by the fact of embodiment. We are left being able to say, with some certainty, that such an ETI will have languages conformant with the requirements of the SI in the sense of combining systematicities and arbitrarinesses at various scales of activity. What we must also say is that we will not be able to understand those languages unless we can be co-present. Indeed we may never be able to understand them if our articulatory repertoires are too different, even if we co-exist for extended periods in their environment. Anthropology, so to speak, is certainly not possible over the telephone here on Earth, and thus will not be feasible in the unlikely event of an interstellar conversation (where each turn might take 100 years). Indeed, it may never be possible in any broadened sense of the term if species differences/circumstances are too different.
We may never really understand communicative activities in other ‘interesting’ species on Earth, such as dolphins. Understandings may be achievable in limited domains constrained by co-operative task sharing and problem solving. Here on Earth we understand such behaviour in terms of explanations involving concepts like ‘distributed cognition’, and indeed, just as we assume that ETIs must understand semiotics so too must they understand distributed cognition and the ‘reading of minds’ involved in cooperative problem solving. They would be able to appreciate such aspects of the interaction between Fran and Fred even if they had never seen a car engine. 7.1. ETI’s intelligence and the problem of SETI—I Our understanding of what is entailed by having an embodied brain leads to the following insights. Without knowing any details we can be sure that ETI’s linguistic structures will conform to certain design principles, that they will understand semiotics, that will be able to read behaviours and work with distributed cognition in cooperative endeavours—and that they will understand these things of us. All because they understand, as we do, what it means to be a species with an embodied brain. All of this means, of course, that ETI will have a view on SETI. The view they should have, so to speak, is that sending messages or attempting some sort of linguistic communication, is pointless. It is pointless because the mutual understanding of semiotics will lead to a mutual understanding of the inevitability of incomprehension and failure (mutual in the sense that we know that they know that we know that they know that ‘messaging’ won’t work). The expenditure of huge resources on an effort, when failure seems guaranteed, is likely to be judged pointless. 7.2. ETI’s intelligence and the problem of SETI—II One interesting aspect of the recognition of the SI as universal, with significant implications for understanding ETI, is that we can appreciate their appreciation of the problem we both face when trying to do SETI. If any attempt is going to be made to target a star system from another such system (for transmission and for detection) then the Intelligences in both systems must understand each other’s targeting scheme if the reciprocal ‘point at each other’ targeting is to work. This might be plausible (cf. Ref. [10]) but is something of a long shot given that the transmitting Intelligence does not know in advance that there is an Intelligence on hand to receive the signal. Additional issues such as cost, length of time for which transmissions are maintained, etc., add to the implausibility (and see also Ref. [9]). It can be argued, therefore, that because we can know something about ETI’s intelligence and its essential similarity to ours in respect especially of communication, then we can know enough to know that attempts to communicate will not be made. Communication does not look like a solution to the SETI problem to us, and likewise to ETI—and this will be recognised; thus listening for communication is not a sensible use of resources.
W. Edmondson / Acta Astronautica 78 (2012) 37–42
Communication only makes sense when you know there is intelligent life to which to send some signals; but in such circumstances the primary SETI question is already answered. This observation will not stop scientists looking for signals of one sort or another, even if it goes some way towards an explanation of why we haven’t found any thus far (that we are looking in the wrong place, and/or have not looked at enough candidates, of course figures in our failure to date). 8. Intelligence in ETI The arguments above demonstrate that it is possible to make sensible statements about what must be the case in respect of organised behaviour in any organism with a brain—an embodied brain anywhere in the universe. Understanding of behaviour – both linguistic behaviour and general behaviour – and of other aspects of cognition related to problem solving and co-operative working, shows that the sending of messages (and the search for such messages) cannot play a coherent role in SETI activities. Furthermore, discussions of developments in Artificial Intelligence, for example the concept that such developments will lead to a ‘postbiological’ form of intelligence, cannot reduce the importance of the SI. Whilst AI systems do not need to be evolved it is the case that they will be embodied, and thus constrained by the SI. It is not interesting, therefore, to speculate that ‘more advanced’ intelligences (whatever this might mean) will have found a reason or technique for sending messages— targeting remains a problem for Earthlings irrespective of the intelligence of the ETI sending signals. And energy considerations are not trivial, irrespective of intelligence. And semiotic difficulties won’t just go away because the intelligence involved is artificial. 9. ETI’s approach to SETI and CETI We should assume that ETI will not engage in ‘messaging’ as a way of answering the Are we alone? question. It will have answered that question through observation (see Refs. [8,9]). Having discerned that there is intelligent life elsewhere in the universe/galaxy – say, here on Earth – ETI may be tempted to send some sort of informative signal. We would probably need to have answered the question for ourselves before looking for signals from the identified planetary system hosting the ETI. In other words, SETI is an observational challenge, not a listening challenge. But once the big question is answered, a different question becomes important. What can we learn about the ETI we have detected? Some information might be provided observationally but for the most part we depend on transmitted signals, and likewise they will depend on transmissions from Earth to learn more about us. This is CETI—communication with ETI. But we have already seen that attempting to send linguistic signals is not worthwhile so the information in the communication has to be visual/pictorial. In a sense this simply extends the thinking behind the push for observational detection rather than messaging.
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Images are the only signals that can make sense in such a circumstance, and one conception that illustrates the point quite well (irrespective of any question about its validity) is that of the tourist postcard—an image comprising 4 or 6 much smaller images each illustrating an aspect of the tourist town concerned. Postcard Earth so to speak, is a way for signalling to be managed, once we have found ETI. And I would say that ETI is likely to have thought of a similar scheme. The conception of Postcard Earth is simple enough— images in various spectral domains (ETI’s sensors will not match ours in detail), of various core themes (beings, living environments, etc.) thought likely to be both significant and too finely detailed for observational recovery, have to be sequenced for transmission (the sequential imperative again!) and in ways, which are unambiguously recoverable. These challenges for the semioticians and the technicians can be overcome, and indeed I would argue that attempting to devise Postcard Earth would be useful as the work would tell us something about what to expect should we ever – or indeed whenever – we are faced with the challenge of decoding a signal from an ETI whose existence we have observed. Of course, once we engage in depth with the cognitive and cultural challenges of devising the postcard we might realise that some other format would be more effective/valid semiotically. But that discovery/design work needs to be started—for now Postcard Earth serves as an indication of where we should be putting our intellectual resources. One reviewer of this paper reasonably points out that this is perhaps too fanciful an idea—such communication effort will fail for the reasons (and more) that photos fail to work in some cultures here on earth. And indeed our interpretative difficulties in relation, say, to ‘rock art’ artefacts suggest there could be insurmountable problems. However, as good semioticians we are aware of these issues, and we should expect the same of ETI’s semioticians. Indeed we would expect that essentially we would expect a shared solution to a shared problem (the knowing about knowing leads to expectations about expectations). But again this is a pointer to future work. Note that others are also looking more at cognitive and cultural arguments about the value of sending/expecting messages (cf. Refs. [4,13]). 10. Concluding remarks We need to build huge, really huge, telescopes to conduct observational searches for ETI. We would, en passant, become an advanced civilisation when we succeed in answering the question—Are we alone? When that is achieved we expect to send signals. But the likelihood is that at the time we discover an ETI we would also want to devise listening strategies to detect signals from them (the presence of which would indicate that they had already discovered – i.e. observed – us). In short, observational SETI should precede non-linguistic CETI. Of interest here is the realisation that worries about the inadvisability of sending messages are missing the point. In the scenario sketched above the probability is that there are ETIs ‘out there’ who already know we exist, because they
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can see evidence of our existence—or will do so as soon as recent light from Earth reaches them (if, say, they depend on being able to see our electric street lighting, or other visible signs of our behaviour). We cannot become invisible, so we will eventually be seen, irrespective of message transmission. The opening paragraphs of this paper referred to GCPs and cognitive universals. It seems clear that without some informed analysis of what it might mean to be intelligent – yet radically different in terms of evolution, culture, biology, planetary location, and the like – we should not even begin to search for ETI. The analysis offered here (and in more detail in Ref. [7]) suggests that even trying to appreciate the nature and ‘limits’ of intelligence in other species on Earth is profoundly problematic. Nonetheless, that does not mean we should not try to do these things; we are in the opening phase of the development of some understanding of cognitive universals, and thus of what it might be like to be ETI. References [1] J.A. Baross, et al., The Limits of Organic Life in Planetary Systems, National Research Council of the National Academies, Washington, 2007 (The Committee on the Limits of Organic Life in Planetary Systems).
[2] N. Chomsky, Rules and Representations, Blackwell, 1980. [3] B. Comrie, Language Universals and Linguistic Typology, Blackwell, 1989. [4] D. Dune´r, Cognitive Foundations of Interstellar Communication, in: Douglas A. Vakoch (Ed.), Commun. Extraterrestrial Intell., SUNY Press, 2011. [5] W.H. Edmondson, Synaesthesia and colour vision: the personal is ¨ philosophical, Farbige Buchstaben: Synasthesie und Sprache in Semiotik 24 (1) (2002) 51–64. In translation by Dagmar Schmauks and Roland Posner. See also /http://www.cs.bham.ac.uk/ whe/ scv.pdfS. [7] W.H. Edmondson, General cognitive principles: the structure of behaviour and the sequential imperative, Int. J. Mind Brain Cognition 1 (1) (2010) 7–40. See also /http://www.cs.bham.ac.uk/ whe/ GCPSOBSI.pdfS. [8] W.H. Edmondson, Targets and SETI: shared motivations, life signatures, and asymmetric SETI, Acta Astron. 67 (11–12) (2010) 1410–1418. [9] W.H. Edmondson, Understanding the search space for SETI, in: Douglas A. Vakoch (Ed.), Communication with Extraterrestrial Intelligence, SUNY Press, 2011. [10] W.H. Edmondson, I.R. Stevens, The utilization of pulsars as SETI beacons, Int. J. Astrobiol. 2 (4) (2003) 231–271. [11] E.R. Morey-Holton, The impact of gravity on life, in: Lynn Rothschild, Adrian Lister (Eds.), Ch. 9 of Evolution on Planet Earth: The Impact of the Physical Environment, Academic Press, 2003. [12] E.F. Russell, The Waitabits, in: John W. Campbell (Ed.), Astounding Science Fiction, Street & Smith Publications Ltd., 1955 Republished several times, for example in Best SF Six, ed. Edmund Crispin, 1966. Faber and Faber. [13] J.W. Traphagan, Culture, meaning, and interstellar message construction, in: Douglas A. Vakoch (Ed.), Communication with Extraterrestrial Intelligence, SUNY Press, 2011.
Contents lists available at SciVerse ScienceDirect
Acta Astronautica journal homepage: www.elsevier.com/locate/actaastro
The intelligence in ETI—What can we know? William Edmondson School of Computer Science, University of Birmingham, Birmingham B15 2TT, United Kingdom
a r t i c l e i n f o
abstract
Article history: Received 28 February 2011 Received in revised form 25 November 2011 Accepted 1 December 2011 Available online 4 February 2012
This paper follows a train of thought initiated in a recent paper [7]. The work sets out a theoretical perspective on the possibility of cognitive universals underpinning the behaviour of animals with brains. Consideration of what we can know of intelligence in beings elsewhere in the universe obliges us to recognise universal and local factors relevant to SETI. Linguistic communication turns out to be genuinely constrained by circumstances even though the existence of linguistic activity will be universal in intelligent beings. The implications for activity in SETI are reviewed. An alternative approach to SETI—described in a recent paper ([9], but see also [8]) is contrasted with the messaging approach, and the conclusion is drawn that an ETI would opt for the alternative. & 2012 Elsevier Ltd. All rights reserved.
Keywords: Intelligence Cognitive Science Embodied Brain SETI CETI
1. Introduction In response to a seemingly casual remark in Chomsky’s Rules and Representations, [2] to the effect that cognitive universals might exist, which could account for language and other behaviours (and the learning of behaviours), a set of universals – General Cognitive Principles – has been proposed [7]. The significance of the proposals is that they frame a functional specification of the brain. In what follows we will consider this specification as the basis for reviewing what we can know of intelligence in beings elsewhere in the universe. Note that if we are ever to be able to say anything sensible about such intelligences we need some sort of universal account—otherwise we are in the realms of science fiction. The rightness or otherwise of the account offered here is perhaps less important than the idea that some such account must be offered if we are to understand both intelligence beyond Earth, and perhaps no less useful, intelligence in all its manifestations on Earth. If it is possible to talk about intelligence in ETI then this must be because there are some General
E-mail addresses: [email protected], [email protected] 0094-5765/$ - see front matter & 2012 Elsevier Ltd. All rights reserved. doi:10.1016/j.actaastro.2011.12.001
Cognitive Principles (GCPs); it remains to be seen if the set proposed is workable. What we work with in this paper is not the specific detail of such a set of universals (for which see Ref. [7]), but rather an insight derived from them, which could have general validity irrespective of the detailed underpinnings. This insight is formulated as the functional specification of the brain. 2. Functional specification of the brain The functional specification of the brain is to serve the Sequential Imperative (SI). It is claimed here, without detailed argument, that the Sequential Imperative is the driving principle behind all behaviour in creatures (anywhere) with brains. Our purpose in this paper is to illustrate the universality claimed rather than to repeat arguments from elsewhere, and then go on to explore the consequences for SETI of working with this idea. 3. Sequential imperative The Sequential Imperative is the unavoidable and overwhelming requirement of an organism that it must overcome the temporal mismatch between the rich sequencing of experience and behaviour and the cognitive
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timelessness of thoughts, beliefs, plans, intentions, etc. The SI is also about maintenance of a being as a being (homeostasis) in the sense that any creature’s continued existence expresses a kind of stability in a sea of biochemical and physical flux. The homeostatic aspect of the SI is mentioned here for completeness, it does not form part of our deliberation in this paper (but note that it is relevant that the brain in the general sense – not just cognition – manages homeostasis). The SI is seen in operation in any creature anywhere with articulators—arms, antennae, hands, mandibles, feet, etc. These have to be controlled so as to deliver behaviours in response to plans, intentions, etc. Likewise, any organism with sensors has to process a temporally structured stream of data to yield percepts, memories, etc. The brain of the creature serves the SI by managing the processes of sequencing and desequencing, which match the atemporal ‘internal world’ to activities, and match the incessant flow of sensory stimulation to internal representations. As one reviewer acutely pointed out, whilst it is the case that the SI makes sense (in their view this is indisputable), nothing about pace or tempo is determined by the SI. This observation raises two issues, only one of which is pursued by the reviewer. The reviewer raised the question of what would happen if an intelligent life form arose in some setting where its tempo was significantly different from that of organisms around it? Would it fail to grasp the SI as a functional specification for the brain and thereby fail to develop notions of semiosis, or conceptions of intelligence and universals? Set alongside that concern is a second issue (and I had stayed my hand in the writing of the paper, but perhaps should not have done). I first encountered this second issue many decades ago, in a reprint of a short story by Eric Frank Russell [12]. The story is titled ‘‘The Waitabits’’ and concerns the unconquerability of an intelligent life form, complete with cities and solar-powered trains and video-phones, etc. The Waitabits move around very slowly—in fact they seem to do everything excruciatingly slowly. Further, their planet revolves slowly, insects move slowly, there are no birds, and so on. The essence of the story is that the pace/tempo of the world of the Waitabits renders them unknowable in any worthwhile sense. My view on the Waitabits, and thus also on the reviewer’s comment, is that in fact difference of pace/ tempo is never going to be so profound (between planets/ ecosystems) or so variable (within an ecosystem) as to cause concerns. My reason is that physical events will have tempi that provide input to an ecosystem’s workings. Gravity will produce waterfalls, rain, etc. There will be atmospheric activity, which won’t happen in ‘slo-mo’. Slick sequences of physical events will demonstrate causality, and so on and so forth. In addition, biochemistry will have its own pace governed more by energy input/ output than by organismic activity. Lastly, there is likely to be a sort of ‘devil take the hindmost’ pressure on the ability of organisms to move about, ingest prey, etc., which will surface, through evolution, in the minimisation of slothfulness as a useful trait. Indeed we see this on Earth—there are, to be sure, some slow movers. And some
so fast we can hardly keep track of them (although their predators manage this). But the variability is limited. Gravity is the interesting constraint (cf. [11])—too strong and creature movement will be very costly, too weak and the atmosphere will be too thin (and there are evolutionary issues as well as those concerning homeostasis in evolved organisms). I would also conjecture that if liquid water is a sensible habitability criterion (for the evolution of life – probably as we know it – and see [1]) then it will constrain the physical environment within which life evolves, and thus fairly directly the pace at which things happen, and the tempi of behaviours. But this is conjecture and thus a pointer to future work. 4. Embodied brains The assumption is made in this paper of a conception of ‘the brain’ as embodied; it exists within an organism, which is bounded and which has both articulators (in the general sense) and sensors. The brain’s function is to serve the SI in respect of the body within which it resides. The assumption is also made that any embodied organism must have a brain because the SI must be served in respect of that organism. We will leave to one side the issue of ‘‘how small can the organism be and still comply?’’ (as one questioner put it to me, after my presentation of the paper at the Chicheley Hall meeting). To help the reader understand the breadth of the claim being made here the answer can be ‘‘bees and anything bigger’’ although the precise lower limit is not known. The issue is not trivial and brings in factors such as ‘automatic’ behaviours (legs in millipedes) and conventional stimulus/response cycles in behaviourist models. But for now we leave those details to one side. What matters is that the creature with a brain does not have to be human, or dependent on sensors/articulators we immediately identify (bats using sonar, for example, or dolphins using sound both for communication and for echolocation). The primary reason for stressing the embodied nature of creatures with brains is that the SI is about embodiment as much as it is about brains. Something within an embodied organism would have to serve the SI; the claim is that the brain is that something. ‘‘But what about organisms which are not embodied?’’ (comes the cry from the science fiction fraternity). Show me such an organism that can evolve (for which embodiment is a core requirement), or which can smelt metals or develop language (both of which require articulators and sensors), and then we can enlarge the debate on the SI and the brain. The primary assumption we are likely to make about an ETI is that any ETI must be an embodied organism with a brain (we will consider speculations such as ‘postbiological intelligence’ below). The second point is that the functional specification of the brain of an ETI must be the same as that for any brain we encounter on Earth: it serves the SI. This is a powerful position to be in—we can reasonably claim to know something about the necessary properties of an ETI in respect of it having a body and a brain. Specifically, we can claim that its brain will exist to serve the SI. Any alternative notion ‘won’t work’ so to speak.
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5. Specification of behaviour—language The SI will provide some constraints on behaviours. If we consider language behaviour in humans we see these constraints in the form of the repertoire of articulations available to the human. The articulators usually deployed for language in humans are those readily identified as parts of the mouth – e.g. lips, teeth, tongue, jaw – and the larynx. The vocal apparatus is driven by air pressure from the lungs, so breathing has to be modified/deployed to suit speaking. What is important here is that the articulators provide a repertoire of articulations, which can be sequenced. In fact, in any one language the full repertoire of possible articulations is not deployed—a language specific subset (of sounds) is used to produce sequences, which are arbitrarily patterned (again in a language specific manner) to produce components we call words. We can note here the fact that for the production of some sounds different articulations might be deployed in different people—the differences are not significant linguistically although they might be visible, and even audible. What matters is that patterning of articulatory activity, in a language specific way, is multi-layered and a fascinating mix of arbitrariness and systematicity. At the level of the sounds in any one language there are sets of phones (the systematic organisation of the actual sounds) and phonemes (the cognitive precursors or specifications of the phones—also systematically organised), combined into syllables (also systematised), which may or may not be uttered with different levels of stress (systematically patterned), or perhaps tone (systematic variations in basic larynx frequency). All of these systematic patternings are arbitrary in the sense that none of them is ‘normal’ or exploits a ‘default’ set of values. What matters is that when a child learns a language they have to learn the appropriate arbitrarinesses for that language. In addition, the arbitrariness is reflected in the fact that the systematicity in the organisation of articulation at the scale of sounds is not meaningful – there is no requirement that users of a language need to learn the meanings of these individual sounds – they have no meanings. Meanings arise when sounds in combination, and/or in the context of other specific combinations, are deployed specifically to convey semiotic content—meanings. We call these combinations words (although correctly we should refer to morphemes, which frequently combine into psychologically interesting – for processing purposes – units called words), and we call their contextualising properties syntax. Other words (meanings) also contextualise—it is not just structural. Interestingly, the grammars of languages are yet more systematic arbitrariness layered onto the patterns of articulations. These syntactic patterns permit the relationships between words to be exploited in meaningful ways, additional to the meanings of the words themselves. This whole complex of linguistic activity – the multilayered structurings – is deployed by language users in settings or situations, which also contribute to the successful expression of, and understanding of, utterances as meaningful. ‘‘It’s a 144’’ takes on one set of meanings
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when uttered at a bus stop (whilst looking at an approaching bus), but quite another when uttered by a person at an instrument console reading out a fault code to a colleague. (A readable account of the systematicities can be found in [3].) Semiotics is the study of these systematicities and their deployment in linguistic activity—(a) the arbitrariness of articulations and the use of subsets in any one language; (b) to make up larger ‘units’ known as morphemes and words, which can be considered to be meaning bearing; (c) the relationships between such units of meaning (syntax); and (d) the deployment of structured combinations of structured units in situation specific ways. There are, inevitably, some systems of patterning that do not quite fit a simplistic account at some levels of detail (e.g. morphology in Semitic languages), but the overall scheme is sound: articulatory arbitrariness patterned to produce meanings, which are combined and deployed in settings. It turns out that if the use of specific sorts of articulations cannot work (deaf people cannot hear/learn the evidence of spoken articulatory activity) then other systems of articulation are deployed (signs, in signed languages). Semiotics is, in an important sense, the study of some of the outcomes forced on brainy beings by the SI—namely those outcomes deployed and exploited for communication. In short, because ETIs will come to recognise the SI and its role in shaping communication, we should conclude that they must understand semiotics if they understand anything about communication. 6. Specification of behaviour—perception and action In the foregoing account of communication behaviour – linguistic behaviour – the issue of perception is glossed over. It is assumed that the articulatory productions deployed linguistically will be perceivable, and that the producer of such articulatory behaviour will modulate their productivity to suit the listener/viewer. Superficially there is the issue that there is no point speaking too quietly, or signing whilst out of sight of the interlocutor—the user of any language will manage these factors. But additionally, of course, the articulations have to be processable and internalisable. The SI stipulates that the sensory world has to be desequenced to be internalised. For linguistic behaviour this means that the articulations have to be managed for both production and perception. Indeed, it can be argued that the whole complex of arbitrary structurings (phones, phonemes, syllables, stress patterns, morphology, syntax, pragmatics) exists to facilitate perception and internalisation; the richness of structuring provides for error correction, to put it crudely. Behaviour is not just linguistic communication behaviour. All behaviour involves activities and perceptions— and of course the opportunity to observe the behaviour of others should not be ignored, not least because such opportunities are required in situations of shared/co-operative behaviour. The SI requires of such behaviour that it be reliably produced in consequence of some internal specification (the sequencing of such a specification is required; the specification is not itself necessarily sequentially arranged). Likewise, the SI requires that perception yields
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desequenced internal representations, which can be thought of as being the specifications that would have given rise to the behaviours observed. The issue of the inevitability of idiosyncracy in such de-sequencings is important but need not detain us here (see, for example, a discussion of synaesthesia in Ref. [5]). In essence the behaviour and perception required for linguistic activity is not different from that required more generally. In communication of course the behaviours are organised to convey meaning unrelated to the behaviours (there is nothing inherently ‘dog-ish’ about the sound of the word ‘dog’, for example). But in general behaviour the meaning of the activity observed may indeed be related to the activity (sharpening a blade, putting on a coat and boots, etc.). It is significant that the behaviours of creatures (not just humans) can be ‘read’ for intention and that co-operativity exploits this ability. Two mechanics working on the engine of a car, for example, can to a significant extent ‘read’ the actions of their co-worker and respond accordingly [mechanic Fran looks up from the work in hand and glances around, and mechanic Fred sees this, and knowing what is going on is able to reach out and hand Fran the appropriate tool to finish the job]. 7. Sequential imperative and ETI If we make the safe assumption that ETIs are organisms with embodied brains – else they would not have evolved, and would not have articulators to make tools, communicate, etc. – then we can make the additional assumptions that their behaviours are constrained by the sequential imperative, that they understand semiotics, that their linguistic behaviours are as systematised and arbitrary as are those of humans, and that other behaviours are readable in ways that afford co-operation and mutual understanding of actions in relation to tasks (this is just another way of thinking about the meaning of behaviour). The detail of ETI’s circumstances, such as the number of articulators, the physical stimuli to which its sensors respond, the environment in which it exists—all these factors will be specific to each ETI. But the general operation of brained organisms within their environments, and with their physiological specific differences, will nonetheless be universally constrained by the SI. That is entailed, in a strong sense, by the fact of embodiment. We are left being able to say, with some certainty, that such an ETI will have languages conformant with the requirements of the SI in the sense of combining systematicities and arbitrarinesses at various scales of activity. What we must also say is that we will not be able to understand those languages unless we can be co-present. Indeed we may never be able to understand them if our articulatory repertoires are too different, even if we co-exist for extended periods in their environment. Anthropology, so to speak, is certainly not possible over the telephone here on Earth, and thus will not be feasible in the unlikely event of an interstellar conversation (where each turn might take 100 years). Indeed, it may never be possible in any broadened sense of the term if species differences/circumstances are too different.
We may never really understand communicative activities in other ‘interesting’ species on Earth, such as dolphins. Understandings may be achievable in limited domains constrained by co-operative task sharing and problem solving. Here on Earth we understand such behaviour in terms of explanations involving concepts like ‘distributed cognition’, and indeed, just as we assume that ETIs must understand semiotics so too must they understand distributed cognition and the ‘reading of minds’ involved in cooperative problem solving. They would be able to appreciate such aspects of the interaction between Fran and Fred even if they had never seen a car engine. 7.1. ETI’s intelligence and the problem of SETI—I Our understanding of what is entailed by having an embodied brain leads to the following insights. Without knowing any details we can be sure that ETI’s linguistic structures will conform to certain design principles, that they will understand semiotics, that will be able to read behaviours and work with distributed cognition in cooperative endeavours—and that they will understand these things of us. All because they understand, as we do, what it means to be a species with an embodied brain. All of this means, of course, that ETI will have a view on SETI. The view they should have, so to speak, is that sending messages or attempting some sort of linguistic communication, is pointless. It is pointless because the mutual understanding of semiotics will lead to a mutual understanding of the inevitability of incomprehension and failure (mutual in the sense that we know that they know that we know that they know that ‘messaging’ won’t work). The expenditure of huge resources on an effort, when failure seems guaranteed, is likely to be judged pointless. 7.2. ETI’s intelligence and the problem of SETI—II One interesting aspect of the recognition of the SI as universal, with significant implications for understanding ETI, is that we can appreciate their appreciation of the problem we both face when trying to do SETI. If any attempt is going to be made to target a star system from another such system (for transmission and for detection) then the Intelligences in both systems must understand each other’s targeting scheme if the reciprocal ‘point at each other’ targeting is to work. This might be plausible (cf. Ref. [10]) but is something of a long shot given that the transmitting Intelligence does not know in advance that there is an Intelligence on hand to receive the signal. Additional issues such as cost, length of time for which transmissions are maintained, etc., add to the implausibility (and see also Ref. [9]). It can be argued, therefore, that because we can know something about ETI’s intelligence and its essential similarity to ours in respect especially of communication, then we can know enough to know that attempts to communicate will not be made. Communication does not look like a solution to the SETI problem to us, and likewise to ETI—and this will be recognised; thus listening for communication is not a sensible use of resources.
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Communication only makes sense when you know there is intelligent life to which to send some signals; but in such circumstances the primary SETI question is already answered. This observation will not stop scientists looking for signals of one sort or another, even if it goes some way towards an explanation of why we haven’t found any thus far (that we are looking in the wrong place, and/or have not looked at enough candidates, of course figures in our failure to date). 8. Intelligence in ETI The arguments above demonstrate that it is possible to make sensible statements about what must be the case in respect of organised behaviour in any organism with a brain—an embodied brain anywhere in the universe. Understanding of behaviour – both linguistic behaviour and general behaviour – and of other aspects of cognition related to problem solving and co-operative working, shows that the sending of messages (and the search for such messages) cannot play a coherent role in SETI activities. Furthermore, discussions of developments in Artificial Intelligence, for example the concept that such developments will lead to a ‘postbiological’ form of intelligence, cannot reduce the importance of the SI. Whilst AI systems do not need to be evolved it is the case that they will be embodied, and thus constrained by the SI. It is not interesting, therefore, to speculate that ‘more advanced’ intelligences (whatever this might mean) will have found a reason or technique for sending messages— targeting remains a problem for Earthlings irrespective of the intelligence of the ETI sending signals. And energy considerations are not trivial, irrespective of intelligence. And semiotic difficulties won’t just go away because the intelligence involved is artificial. 9. ETI’s approach to SETI and CETI We should assume that ETI will not engage in ‘messaging’ as a way of answering the Are we alone? question. It will have answered that question through observation (see Refs. [8,9]). Having discerned that there is intelligent life elsewhere in the universe/galaxy – say, here on Earth – ETI may be tempted to send some sort of informative signal. We would probably need to have answered the question for ourselves before looking for signals from the identified planetary system hosting the ETI. In other words, SETI is an observational challenge, not a listening challenge. But once the big question is answered, a different question becomes important. What can we learn about the ETI we have detected? Some information might be provided observationally but for the most part we depend on transmitted signals, and likewise they will depend on transmissions from Earth to learn more about us. This is CETI—communication with ETI. But we have already seen that attempting to send linguistic signals is not worthwhile so the information in the communication has to be visual/pictorial. In a sense this simply extends the thinking behind the push for observational detection rather than messaging.
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Images are the only signals that can make sense in such a circumstance, and one conception that illustrates the point quite well (irrespective of any question about its validity) is that of the tourist postcard—an image comprising 4 or 6 much smaller images each illustrating an aspect of the tourist town concerned. Postcard Earth so to speak, is a way for signalling to be managed, once we have found ETI. And I would say that ETI is likely to have thought of a similar scheme. The conception of Postcard Earth is simple enough— images in various spectral domains (ETI’s sensors will not match ours in detail), of various core themes (beings, living environments, etc.) thought likely to be both significant and too finely detailed for observational recovery, have to be sequenced for transmission (the sequential imperative again!) and in ways, which are unambiguously recoverable. These challenges for the semioticians and the technicians can be overcome, and indeed I would argue that attempting to devise Postcard Earth would be useful as the work would tell us something about what to expect should we ever – or indeed whenever – we are faced with the challenge of decoding a signal from an ETI whose existence we have observed. Of course, once we engage in depth with the cognitive and cultural challenges of devising the postcard we might realise that some other format would be more effective/valid semiotically. But that discovery/design work needs to be started—for now Postcard Earth serves as an indication of where we should be putting our intellectual resources. One reviewer of this paper reasonably points out that this is perhaps too fanciful an idea—such communication effort will fail for the reasons (and more) that photos fail to work in some cultures here on earth. And indeed our interpretative difficulties in relation, say, to ‘rock art’ artefacts suggest there could be insurmountable problems. However, as good semioticians we are aware of these issues, and we should expect the same of ETI’s semioticians. Indeed we would expect that essentially we would expect a shared solution to a shared problem (the knowing about knowing leads to expectations about expectations). But again this is a pointer to future work. Note that others are also looking more at cognitive and cultural arguments about the value of sending/expecting messages (cf. Refs. [4,13]). 10. Concluding remarks We need to build huge, really huge, telescopes to conduct observational searches for ETI. We would, en passant, become an advanced civilisation when we succeed in answering the question—Are we alone? When that is achieved we expect to send signals. But the likelihood is that at the time we discover an ETI we would also want to devise listening strategies to detect signals from them (the presence of which would indicate that they had already discovered – i.e. observed – us). In short, observational SETI should precede non-linguistic CETI. Of interest here is the realisation that worries about the inadvisability of sending messages are missing the point. In the scenario sketched above the probability is that there are ETIs ‘out there’ who already know we exist, because they
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can see evidence of our existence—or will do so as soon as recent light from Earth reaches them (if, say, they depend on being able to see our electric street lighting, or other visible signs of our behaviour). We cannot become invisible, so we will eventually be seen, irrespective of message transmission. The opening paragraphs of this paper referred to GCPs and cognitive universals. It seems clear that without some informed analysis of what it might mean to be intelligent – yet radically different in terms of evolution, culture, biology, planetary location, and the like – we should not even begin to search for ETI. The analysis offered here (and in more detail in Ref. [7]) suggests that even trying to appreciate the nature and ‘limits’ of intelligence in other species on Earth is profoundly problematic. Nonetheless, that does not mean we should not try to do these things; we are in the opening phase of the development of some understanding of cognitive universals, and thus of what it might be like to be ETI. References [1] J.A. Baross, et al., The Limits of Organic Life in Planetary Systems, National Research Council of the National Academies, Washington, 2007 (The Committee on the Limits of Organic Life in Planetary Systems).
[2] N. Chomsky, Rules and Representations, Blackwell, 1980. [3] B. Comrie, Language Universals and Linguistic Typology, Blackwell, 1989. [4] D. Dune´r, Cognitive Foundations of Interstellar Communication, in: Douglas A. Vakoch (Ed.), Commun. Extraterrestrial Intell., SUNY Press, 2011. [5] W.H. Edmondson, Synaesthesia and colour vision: the personal is ¨ philosophical, Farbige Buchstaben: Synasthesie und Sprache in Semiotik 24 (1) (2002) 51–64. In translation by Dagmar Schmauks and Roland Posner. See also /http://www.cs.bham.ac.uk/ whe/ scv.pdfS. [7] W.H. Edmondson, General cognitive principles: the structure of behaviour and the sequential imperative, Int. J. Mind Brain Cognition 1 (1) (2010) 7–40. See also /http://www.cs.bham.ac.uk/ whe/ GCPSOBSI.pdfS. [8] W.H. Edmondson, Targets and SETI: shared motivations, life signatures, and asymmetric SETI, Acta Astron. 67 (11–12) (2010) 1410–1418. [9] W.H. Edmondson, Understanding the search space for SETI, in: Douglas A. Vakoch (Ed.), Communication with Extraterrestrial Intelligence, SUNY Press, 2011. [10] W.H. Edmondson, I.R. Stevens, The utilization of pulsars as SETI beacons, Int. J. Astrobiol. 2 (4) (2003) 231–271. [11] E.R. Morey-Holton, The impact of gravity on life, in: Lynn Rothschild, Adrian Lister (Eds.), Ch. 9 of Evolution on Planet Earth: The Impact of the Physical Environment, Academic Press, 2003. [12] E.F. Russell, The Waitabits, in: John W. Campbell (Ed.), Astounding Science Fiction, Street & Smith Publications Ltd., 1955 Republished several times, for example in Best SF Six, ed. Edmund Crispin, 1966. Faber and Faber. [13] J.W. Traphagan, Culture, meaning, and interstellar message construction, in: Douglas A. Vakoch (Ed.), Communication with Extraterrestrial Intelligence, SUNY Press, 2011.