Asymmetry in Active SETI: A case for transmissions from Earth

The Search for Extraterrestrial Intelligence (SETI) typically presupposes contact with extraterrestrial civilizations much longer lived than humanity. Many have argued that given humanity's “youth,” the burden of transmitting should be placed on the extraterrestrial civilizations, which presumably possess more advanced technologies. These assumptions have contributed to the current emphasis on Passive SETI. Complementing this existing stress on Passive SETI with an additional commitment to Active SETI, in which humankind transmits messages to other civilizations, would have several advantages, including (1) addressing the reality that regardless of whether older civilizations should be transmitting, they may not be transmitting; (2) placing the burden of decoding and interpreting messages on advanced extraterrestrials, which may facilitate mutual comprehension; and (3) signaling a move toward an intergenerational model of science with a long-term vision for benefiting other civilizations as well as future generations of humans. Technological requirements for Active SETI are considered, and a case is made for Active SETI as a means for experimentally testing variants of the Zoo Hypothesis. Recommendations are provided for sustaining Passive and Active SETI and the communities that conduct these searches.     

Efficiency in SETI

While modern SETI experiments are often highly sensitive, reaching detection limits of 10^?25 W/m² Hz in the radio, interstellar distances imply that if extraterrestrial societies are using isotropic or broad-beamed transmitters, the power requirements for their emissions are enormous. Indeed, isotropic transmissions to the entire Galaxy, sufficiently intense to be detectable by our current searches, would consume power comparable to the stellar insolation of an Earth-size planet.In this paper we consider how knowledge can be traded for power, and how, and to what degree, astronomical accuracy can reduce the energy costs of a comprehensive transmission program by putative extraterrestrials. Indeed, an exploration of how far this trade-off might be taken suggests that extraterrestrial transmitting strategies of civilizations only modestly more advanced than our own would be, as are our SETI receiving experiments, inexpensive enough to allow multiple efforts. We explore the consequences this supposition has for our SETI listening experiments.     

The art and science of interstellar message composition: a report on international workshops to encourage multidisciplinary discussion

Throughout the history of the Search for Extraterrestrial Intelligence (SETI), there has been widespread recognition of the profound societal implications of detecting intelligence beyond Earth. At the SETI Institute, interstellar message construction serves as the focus of a multidisciplinary attempt to prepare for the cultural impact of signal detection and the critical events that would follow. Interstellar message construction at the SETI Institute builds upon the recommendations of the 1991–1992 Workshops on the Cultural Aspects of SETI, while also exploring opportunities for multidisciplinary contributions on new topics. Through a series of international workshops in Toulouse, Paris, Zagreb, Washington, and Bremen, the SETI Institute and partner organizations have fostered broad-based discussion about some of the most important decisions that would follow detection of extraterrestrial intelligence, including “should we reply?” and if so, “what should we say, and how might we say it?”. Several of the themes addressed at these workshops will be highlighted, including the relationship between art and science in designing messages, the value of interactive messages, and the importance of better understanding the nature of language.     

What should we say to extraterrestrial intelligence?: An analysis of responses to “Earth Speaks”

If scientists engaged in the Search for Extraterrestrial Intelligence (SETI) detect a signal from an extraterrestrial civilization, one of the most pressing issues facing humankind will be “Should we reply, and if so, what should we say?” Building on an infrastructure that the SETI Institute used to gather over 50,000 messages from around the world to send onboard the Kepler mission, Earth Speaks invites people to submit online their text messages, pictures, and sounds, as they ponder what they would want to say to an extraterrestrial civilization. Participants for the study have been recruited from 68 nations, from all walks of life. By tracking demographic variables for each person submitting a message, we have identified commonalities and differences in message content that are related to such factors as age and gender. Similarly, by tracking the date on which messages were submitted and the location from which the message was sent, we have also identified the way in which message content is related to time and geographic location. Furthermore, when we compare previous themes derived from textual messages to our current categorical analysis of submitted images, we find our textual themes to be concurrently validated. In doing so, we find the Earth Speaks Website not only allows for the construction of interstellar messages, but also functions as a projective psychological assessment of species-level human identity. We next proceed to demonstrate the generative power of our method by showing how we can synthesize artificial messages from the Earth Speaks messages. We then discuss how these artificially generated messages can be tailored to represent both commonality and diversity in human thought as it is revealed through our data. We end by discussing our method's utility for cross-disciplinary research in the social sciences and humanities.     

SETI in the light of cosmic convergent evolution

Theodosius Dobzhansky, one of the founding fathers of the modern evolutionary synthesis, once famously stated that “nothing makes sense in biology except in the light of evolution”. Here it will be argued that nothing in astrobiology makes sense except in the light of “Cosmic Convergent Evolution” (CCE). This view of life contends that natural selection is a universal force of nature that leads to the emergence of similarly adapted life forms in analogous planetary biospheres. Although SETI historically preceded the rise of astrobiology that we have witnessed in the recent decade, one of its main tenets from the beginning was the convergence of life on a cosmic scale toward intelligent behavior and subsequent communication via technological means. The question of cultural convergence in terms of symbolic exchange, language and scientific capabilities between advanced interstellar civilizations has been the subject of ongoing debate. However, at the core of the search for extraterrestrial intelligence lies in essence a biological problem since even post-biological extraterrestrial intelligences must have had an origin based on self-replicating biopolymers. Thus, SETI assumes a propensity of the Universe towards biogenesis in accordance with CCE, a new evolutionary concept which posits the multiple emergence of life across the Cosmos. Consequently, we have to wonder about the biophilic properties the Universe apparently exhibits, as well as to try to find an encompassing theory that is able to explain this “fine-tuning” in naturalistic terms. The aims of this paper are as follows: 1) to emphasize the importance of convergent evolution in astrobiology and ongoing SETI research; 2) to introduce novel and biology-centered cosmological ideas such as the “Selfish Biocosm Hypothesis” and the “Evo Devo Universe” as valuable arguments in theorizing about the origin and nature of extraterrestrial intelligence and 3) to synthesize these findings within an emerging post-biological paradigm on which future SETI efforts may be founded.     

Limits on interstellar messages

Despite the fact that major efforts have been expended on passive searches for extraterrestrial signals, few deliberate “transmissions” to potential alien recipients have occurred. These have generally taken the form of simple graphics depicting such things as our appearance, location, and biological construction. In this paper, we consider (a) the fundamental technical and astronomical limitations to interstellar messaging—in other words, how many “bits” could any society reasonably send, and (b) what might be a likely transmission strategy. These considerations suggest approaches for SETI programs, as well as giving insight into the types of messages we might construct for eventual replies to received signals.     

Ten thousand revolutions: conjectures about civilizations

Ten thousand years ago, no-one on Earth was living a “civilized” life. What has happened since is remarkable and impossible to fully comprehend; yet, everyone has ideas about civilization, and how the world came to be as it is. Such understandings of civilizations on Earth inevitably influence speculation about extraterrestrial civilizations, in two ways. First, sometimes a specific Earth civilization or historical experience is explicitly used as a basis for inferences about extraterrestrial civilizations. Second, more general assumptions about the development and functioning of Earth's societies shape conjectures about alien societies. This paper focuses on the latter, general assumptions, with the aim of considering how we can use multidisciplinary approaches, and our knowledge of Earth's civilizations, to our best advantage in SETI.     

Positive consequences of SETI before detection

Even before a signal is detected, six positive consequences will result from the scientific search for extraterrestrial intelligence, usually called SETI. (1) Humanity’s self-image: SETI has enlarged our view of ourselves and enhanced our sense of meaning. Increasingly, we feel a kinship with the civilizations whose signals we are trying to detect. (2) A fresh perspective: SETI forces us to think about how extraterrestrials might perceive us. This gives us a fresh perspective on our society’s values, priorities, laws and foibles. (3) Questions: SETI is stimulating thought and discussion about several fundamental questions. (4) Education: some broad-gage educational programs have already been centered around SETI. (5) Tangible spin-offs: in addition to providing jobs for some people, SETI provides various spin-offs, such as search methods, computer software, data, and international scientific cooperation. (6) Future scenarios: SETI will increasingly stimulate us to think carefully about possible detection scenarios and their consequences, about our reply, and generally about the role of extraterrestrial communication in our long-term future. Such thinking leads, in turn, to fresh perspectives on the SETI enterprise itself.     

MAD with aliens? Interstellar deterrence and its implications

The possibility that extraterrestrial intelligences (ETIs) could be hostile to humanity has been raised as a reason to avoid even trying to contact ETIs. However, there is a distinct shortage of analytical discussion about the risks of an attack, perhaps because of an implicit premise that we cannot analyze the decision making of an alien civilization. This paper argues that we can draw some inferences from the history of the Cold War and nuclear deterrence in order to show that at least some attack scenarios are likely to be exaggerated. In particular, it would seem to be unlikely that the humanity would be attacked simply because it might, sometime in the future, present a threat to the ETI. Even if communication proves to be difficult, rational decision-makers should avoid unprovoked attacks, because their success would be very difficult to assure. In general, it seems believable that interstellar conflicts between civilizations would remain rare. The findings advise caution for proposed interstellar missions, however, as starfaring capability itself might be seen as a threat. On the other hand, attempting to contact ETIs seems to be a relatively low-risk strategy: paranoid ETIs must also consider the possibility that the messages are a deception designed to lure out hostile civilizations and preemptively destroy them.     

Searching for alien artifacts on the moon

The Search for Extraterrestrial Intelligence (SETI) has a low probability of success, but it would have a high impact if successful. Therefore it makes sense to widen the search as much as possible within the confines of the modest budget and limited resources currently available. To date, SETI has been dominated by the paradigm of seeking deliberately beamed radio messages.However, indirect evidence for extraterrestrial intelligence could come from any incontrovertible signatures of non-human technology. Existing searchable databases from astronomy, biology, earth and planetary sciences all offer low-cost opportunities to seek a footprint of extraterrestrial technology. In this paper we take as a case study one particular new and rapidly-expanding database: the photographic mapping of the Moon's surface by the Lunar Reconnaissance Orbiter (LRO) to 0.5 m resolution. Although there is only a tiny probability that alien technology would have left traces on the moon in the form of an artifact or surface modification of lunar features, this location has the virtue of being close, and of preserving traces for an immense duration.Systematic scrutiny of the LRO photographic images is being routinely conducted anyway for planetary science purposes, and this program could readily be expanded and outsourced at little extra cost to accommodate SETI goals, after the fashion of the SETI@home and Galaxy Zoo projects.     

A SETI metapolicy: New directions towards comprehensive policies concerning the detection of extraterrestrial intelligence

At present we have only one agreed public policy for handling the detection of an extraterrestrial intelligence (ETI), the ‘First SETI Protocol’ of 1989, which guides action in the immediate aftermath of detection, even though SETI (the Search for Extraterrestrial Intelligence) constitutes an active search for such a detection. The purpose of this paper is to set out areas in which policies might fruitfully be developed, including reviewing the rationale and investment in SETI, handling ETI artefacts, and approaches to direct contact. ‘Negative’ possibilities will be examined, for example, whether an ETI artefact or data should be purposefully destroyed.     

Museums, seti and community awareness

Commentators on the social implications of detecting an extraterrestrial civilisation have stressed the need for community education and awareness during the SETI search, and for public sources of accurate, authoritative information if and when a signal is detected. Museums have a role in community education and are recognised by the community as authoritative sources of expert information. They are, therefore, well placed to be important conduits through which information on the progress of SETI programs and any signal detection can be channelled to the public. Via both exhibitions and in-house educational activities, museums are able to provide long-term community education and awareness programs and can respond quickly with detailed and accurate information in the event of a detection. This paper will consider the role of museums in educating the public about SETI. It will present suggestions for ways in which SETI researchers can develop mutually profitable relationships with museums, and also consider some of the reasons why museums might choose not to become involved with SETI, because of the wildly sensationalised and often mis-informed controversy which has surrounded it.     

The transcension hypothesis: Sufficiently advanced civilizations invariably leave our universe,and implications for METI and SETI

The emerging science of evolutionary developmental (“evo devo”) biology can aid us in thinking about our universe as both an evolutionary system, where most processes are unpredictable and creative, and a developmental system, where a special few processes are predictable and constrained to produce far-future-specific emergent order, just as we see in the common developmental processes in two stars of an identical population type, or in two genetically identical twins in biology. The transcension hypothesis proposes that a universal process of evolutionary development guides all sufficiently advanced civilizations into what may be called "inner space," a computationally optimal domain of increasingly dense, productive, miniaturized, and efficient scales of space, time, energy, and matter, and eventually, to a black-hole-like destination. Transcension as a developmental destiny might also contribute to the solution to the Fermi paradox, the question of why we have not seen evidence of or received beacons from intelligent civilizations. A few potential evolutionary, developmental, and information theoretic reasons, mechanisms, and models for constrained transcension of advanced intelligence are briefly considered. In particular, we introduce arguments that black holes may be a developmental destiny and standard attractor for all higher intelligence, as they appear to some to be ideal computing, learning, forward time travel, energy harvesting, civilization merger, natural selection, and universe replication devices. In the transcension hypothesis, simpler civilizations that succeed in resisting transcension by staying in outer (normal) space would be developmental failures, which are statistically very rare late in the life cycle of any biological developing system. If transcension is a developmental process, we may expect brief broadcasts or subtle forms of galactic engineering to occur in small portions of a few galaxies, the handiwork of young and immature civilizations, but constrained transcension should be by far the norm for all mature civilizations.The transcension hypothesis has significant and testable implications for our current and future METI and SETI agendas. If all universal intelligence eventually transcends to black-hole-like environments, after which some form of merger and selection occurs, and if two-way messaging (a send–receive cycle) is severely limited by the great distances between neighboring and rapidly transcending civilizations, then sending one-way METI or probes prior to transcension becomes the only real communication option. But one-way messaging or probes may provably reduce the evolutionary diversity in all civilizations receiving the message, as they would then arrive at their local transcensions in a much more homogenous fashion. If true, an ethical injunction against one-way messaging or probes might emerge in the morality and sustainability systems of all sufficiently advanced civilizations, an argument known as the Zoo hypothesis in Fermi paradox literature, if all higher intelligences are subject to an evolutionary attractor to maximize their local diversity, and a developmental attractor to merge and advance universal intelligence. In any such environment, the evolutionary value of sending any interstellar message or probe may simply not be worth the cost, if transcension is an inevitable, accelerative, and testable developmental process, one that eventually will be discovered and quantitatively described by future physics. Fortunately, transcension processes may be measurable today even without good physical theory, and radio and optical SETI may each provide empirical tests. If transcension is a universal developmental constraint, then without exception all early and low-power electromagnetic leakage signals (radar, radio, television), and later, optical evidence of the exoplanets and their atmospheres should reliably cease as each civilization enters its own technological singularities (emergence of postbiological intelligence and life forms) and recognizes that they are on an optimal and accelerating path to a black-hole-like environment. Furthermore, optical SETI may soon allow us to map an expanding area of the galactic habitable zone we may call the galactic transcension zone, an inner ring that contains older transcended civilizations, and a missing planets problem as we discover that planets with life signatures occur at a much lower frequencies in this inner ring than in the remainder of the habitable zone.     

Security considerations in signal detection

This paper maintains that international security considerations are likely to present major problems to the community of scientists who first confirm the existence of an extraterrestrial technology. The discussion focuses on those activities that will affect the SETI community should a detection be made. It is probable that security agencies will require official debriefings, signal monitoring, some forms of information management, and a voice in science policy with regard to reply. The SETI community has, in the past, underestimated the constraints that are likely to be placed upon them in the post-detection environment. Such constraints present major problems for the scientific community. Response to these constraints should be discussed prior to detection.     

The benefits and harm of transmitting into space

Deliberate and unintentional radio transmissions from Earth propagate into space. These transmissions could be detected by extraterrestrial watchers over interstellar distances. This article analyzes the harm and benefits of deliberate and unintentional transmissions relevant to Earth and humanity. Comparing the magnitude of deliberate radio broadcasts intended for messaging to extraterrestrial intelligence (METI) with the background radio spectrum of Earth, we find that METI attempts to date have much lower detectability than emissions from current radio communication technologies on Earth. METI broadcasts are usually transient and several orders of magnitude less powerful than other terrestrial sources, such as astronomical and military radars, which provide the strongest detectable signals. The benefits of radio communication on Earth most probably outweigh the potential harm of detection by extraterrestrial watchers; however, the uncertainty regarding the outcome of contact with extraterrestrial beings creates difficulty in assessing whether or not to engage in long-term and large-scale METI.     

Being technological

SETI's essential premises involve evolution in multiple domains: cosmology, biology, culture and technology. Comparatively little has been written about the last of these, technology, in relation to SETI's targets, but it is a crucial variable and well worth deep examination. In particular, it would seem prudent to consider carefully our assumptions about hypothetical extraterrestrial societies which have developed technology that SETI could detect, or which could detect, at interstellar distances, the existence of intelligent life on Earth. This paper contributes to that effort by reflecting upon our habits of projecting terracentric assumptions onto hypothetical worlds, exploring dominant narratives about technological development and presenting varied philosophical theories about the nature of technology. It highlights the cultural aspects of technology here on Earth, particularly their role in the development of radio technology. In the end, it is clear that technology need not develop along a prescribed, linear path; projections about extraterrestrial societies which rely on this assumption need to be reconsidered.     

Invited Pesek lecture: Exploration rather than speculation–assembling the puzzle of potential life beyond Earth

Speculations about the existence of life beyond Earth are probably as old as mankind itself, but still there is no evidence – neither for its presence nor for its absence. Moreover, we neither know the necessary nor the sufficient conditions for life to emerge, sustain or evolve. The Drake equation famously quantifies our ignorance by writing the number of detectable civilizations as product of factors that get increasingly uncertain the further one goes to the right. As a result, the predictive power is poor, and it ultimately depends on the most uncertain factor. However, if we were able to derive a reasonable estimate, we would not need SETI experiments to tell us whether we are alone or not. What has changed substantially over human history is our ability to explore the Universe. Most significantly, radio transmission technology gives us the opportunity to communicate over interstellar distances, and we are now able to not only determine the population statistics of planets within the Milky Way, but even in principle to find biosignatures in their atmospheres. By finding life beyond Earth, we will learn how frequently it emerges. By finding signals from intelligent extra-terrestrial civilizations, we will get unprecedented insight into our biological, technological, and societal evolution. The Drake equation is not such a useful means for assessing the chances of success of SETI, but instead it provides the framework for using observational data in advancing towards understanding the origins of our existence and our role in the cosmos, and maybe to get a glimpse of our future.     

Reply policy and signal type: assumptions drawn from minimal source information

A scenario is developed under which a discovery of extraterrestrial technology is made by one of the World’s search for exterrestial intelligence (SETI) programs. The nature of the signal received gives an absolute minimum of information as to the nature of the senders. Current SETI detection and reply policy is examined under these assumptions. Current policy calls for prompt and public release of signal information and stellar coordinates upon announcement of a discovery. The SETI protocol calls for no reply until authorized by international consultations. It is argued that changes are needed in these policies to guard against the possibility of unauthorized replies that could severely complicate long-term interstellar communication.