Technical Civilizations Research Articles

Biotechnology and the lifetime of technical civilizations

AbstractThe number of people able to end Earth's technical civilization has heretofore been small. Emerging dual-use technologies, such as biotechnology, may give similar power to thousands or millions of individuals. To quantitatively investigate the ramifications of such a marked shift on the survival of both terrestrial and extraterrestrial technical civilizations, this paper presents a two-parameter model for civilizational lifespans, i.e. the quantity L in Drake's equation for the number of communicating extraterrestrial civilizations. One parameter characterizes the population lethality of a civilization's biotechnology and the other characterizes the civilization's psychosociology. L is demonstrated to be less than the inverse of the product of these two parameters. Using empiric data from PubMed to inform the biotechnology parameter, the model predicts human civilization's median survival time as decades to centuries, even with optimistic psychosociological parameter values, thereby positioning biotechnology as a proximate threat to human civilization. For an ensemble of civilizations having some median calculated survival time, the model predicts that, after 80 times that duration, only one in 1024 civilizations will survive – a tempo and degree of winnowing compatible with Hanson's ‘Great Filter.’ Thus, assuming that civilizations universally develop advanced biotechnology, before they become vigorous interstellar colonizers, the model provides a resolution to the Fermi paradox.

Multiple paths to encephalization and technical civilizations.

We propose consideration of at least two possible evolutionary paths for the emergence of intelligent life with the potential for technical civilization. The first is the path via encephalization of homeothermic animals; the second is the path to swarm intelligence of so-called superorganisms, in particular the social insects. The path to each appears to be facilitated by environmental change: homeothermic animals by decreased climatic temperature and for swarm intelligence by increased oxygen levels.

The postbiological universe

The Drake Equation for the number of radio communicative technological civilizations in the Galaxy encompasses three components of cosmic evolution: astronomical, biological and cultural. Of these three, cultural evolution totally dominates in terms of the rapidity of its effects. Yet, SETI scientists do not take cultural evolution into account, perhaps for understandable reasons, since cultural evolution is not well-understood even on Earth and is unpredictable in its outcome. Thus SETI programs typically assume the existence of flesh-and-blood intelligence considerably older than our civilization, a paradigm part of what I have termed the biological universe [S.J. Dick, The Biological Universe: The Twentieth Century Extraterrestrial Life Debate and the Limits of Science, Cambridge University Press, Cambridge, 1996].Yet, the one certainty for technical civilizations billions, millions, or even thousands of years older than ours is that they will have undergone cultural evolution. Cultural evolution takes place in many directions, but in sorting priorities I adopt what I refer to as the Intelligence Principle: the maintenance, improvement and perpetuation of knowledge and intelligence is the central driving force of cultural evolution, and that to the extent intelligence can be improved, it will be improved. Applying this principle to life in the universe, extraterrestrials will have sought the best way to improve their intelligence, and may have long ago advanced beyond flesh-and-blood to artificial intelligence, constituting a postbiological universe. MacGowan and Ordway [Intelligence in the Universe, Prentice-Hall, Englewood Cliffs, NJ, 1966], Davies [Are We Alone? Philosophical Implications of the Discovery of Extraterrestrial Life, New York, Basic Books, 1995, pp. 51–55] and Shostak [Sharing the Universe: Perspectives on Extraterrestrial Life, Berkeley Hills, Berkeley, CA, 1998, pp. 103–109] have broached this subject, but it has not been given the attention it is due from its foundation in cultural evolution. Nor has the idea of a postbiological universe been carried to its logical conclusion, including a careful analysis of the implications for SETI. SETI scientists, social scientists, and experts in AI (such as Hans Moravec, who has spoken of a postbiological Earth in the next several generations) should consider the strengths and weaknesses of this new paradigm.

Seti target selection

The NASA High Resolution Microwave Survey consists of two complementary elements: a Sky Survey of the entire sky to a moderate level of sensitivity; and a Targeted Search of nearby stars, one at a time, to a much deeper level of sensitivity. In this paper we propose strategies for target selection. We have two goals: to improve the chances of successful detection of signals from technical civilizations that inhabit planets around solar-type stars, and to minimize the chances of missing signals from unexpected sites. For the main Targeted Search survey of approximately 1000 nearby solar-type stars, we argue that the selection criteria should be heavily biased by what we know about the origin and evolution of life here on Earth. We propose that observations of stars with stellar companions orbiting near the habitable zone should be de-emphasized, because such companions would prevent the formation of habitable planets. We also propose that observations of stars younger than about three billion years should be de-emphasized in favor of older stars, because our own technical civilization took longer than three billion years to evolve here on Earth. To provide the information needed for the preparation of specific target lists, we have undertaken an inventory of a large sample of solar-type stars out to a distance of 60 pc, with the goal of characterizing the relevant astrophysical properties of these stars, especially their ages and companionship. To complement the main survey, we propose that a modest sample of the nearest stars should be observed without any selection biases whatsoever. Finally, we argue that efforts to identify stars with planetary systems should be expanded. If found, such systems should receive intensive scrutiny.

CETI. Metaphor and universal language

Are we alone in the Universe or are we but one of many advanced technical civilizations? Assuming that we are not alone and wished to make contact with our galactic neighbours how could we do so? When humans communicate, meaning comes from written and verbal language embedded in metaphor. However, the public nature of metaphoric language reduces the personal essence of individual experience during translation into words. The delusion of shared metaphor being obtained through written and verbal language distorts our views of reality, it impairs our ability to empathise with others, and it disharmonizes our attempts to attune to any invariants and affordances of universal language. This paper attempts to identify some of the elements of universal language and probes the limitations of the communication metaphor as a way of empathising between humans and other intelligent life. Our investigation suggests that if Communication with Extraterrestrial Intelligence (CETI) is to become realised then a new paradigm...

Galactic Colonization and Competition in a Young Galactic Disk

Even if long-lived advanced technical civilizations arise very frequently and interstellar colonization is possible and common among them, it is argued that this colonization process is unlikely to fully occupy the Galaxy (i.e., saturate it) due to interactions between the colonizing civilizations. This argument is supported by the analysis of population dynamics equations based upon those of theoretical ecology which are believed to be applicable to an extremely wide range of behavior patterns. It is also pointed out that recent astronomical evidence suggests that the disk of our Galaxy may be substantially younger than previously thought, thus making a non-saturated colonization model more plausible.

A Milky Way Search Strategy for Extraterrestrial Intelligence

We assume that the density of sites of technical civilizations emitting suitable signals (whether purposeful or unintentional) is proportional to the stellar density at any location in our Galaxy, as modelled by Bahcall and Soneira (1980). A wide variety of possible radio luminosity functions Ø(L) for these civilizations is then assumed and for each the number of detectable signals per square degree over the sky is calculated. We find that most detectable signals occur at galactic latitudes of 10° or less and longitudes within 90° of the galactic center, a region which covers only 9 per cent of the entire sky. This result holds for a wide range of Ø(L) types, including Gaussian distributions and power law functions with slopes less than 2.5, or any combination of these. The Milky Way is much less preferred, but still advantageous, for cases of steep power law functions (slopes greater than 2.5) or Gaussian functions with mean luminosities so low that any existing civilizations can only be detected at distances less than 0.5 kpc. The only cases where low galactic latitudes are not advantageous are (1) for frequencies of operation less than 600 MHz where the deleterious effects on signal-to-noise ratios of the natural galactic background emission become dominant, and (2) in searches for narrowband (⩽ 1 Hz) signals at frequencies less than 2 GHz where significant interstellar broadening of signals occurs over distances of ≳10 kpc. Furthermore, all of the above results have broader applicability: they are equally valid for searches for any type of natural radio phenomenon if its probability of occurrence is proportional to stellar density.

A milky way search strategy for extraterrestial intelligence

It is assumed that the density of sites of technical civilizations emitting suitable signals (whether purposeful or unintentional) is proportional to the stellar density at any location in our Galaxy, as modeled by Bahcall and Soneira (1980, Astrophys. J. Suppl. Ser.44, 73–110). A wide variety of possible radio luminosity functionsφ(L)for these civilizations is then assumed and for each the number of detectable signals per square degree over the sky is calculated. It has been found that most detectable signals occur at galactic latitudes of 10° or less and longitudes within 90° of the galactic center, a region which covers only 9% of the entire sky. This result holds for a wide range ofφ(L) types, including Gaussian distributions and power law functions with slopes less than 2.5, or any combination of these. The Milky Way is much less preffered, but still advantageous, for cases of steep power law functions (slopes greater than 2.5) or Gaussian functions with mean luminosities so low that any existing civilizations can only be detected at small distances(<0.5 kpc). The only cases where low galactic latitudes are not advantageous are (1) for frequencies of operation less than 600 MHz where the deleterious effects on signal-to-noise ratios of the natural galactic background emission become dominant, and (2) in searches for narrowband(<1 Hz) signals at frequencies less than 2 GHz where significant interstellar broadening of signals occurs over distances of≳ 10 kpc. Furthermore, all of the above results have broader applicability: they are equally valid for searches for any type of natural radio phenomenon if its probability of occurence is proportional to stellar density. Therefore, for a nontargeted search, a Milky Way strategy which concentrates on the inner galactic plane is preferred. The factor of 10 in time saved over an all-sky survey can then be used for, say, increased sensitivity or a survey of nearby galaxies. For a targeted search, rather than searching the nearestn solar-like stars, time is more profitably spent, for example, on the very nearest0.1n stars plus the next nearest0.9n stars which are also within 10° of the galactic plane. This picks up the Milky Way background while only sacrificing a factor of 2 in the average distance to the target stars.

Eavesdropping: The Radio Signature of the Earth

In addition to searches for purposeful signals, those attempting interstellar communication should also consider the possibility of eavesdropping on radio emissions inadvertently "leaking" from other technical civilizations. To understand better the information which might be derivable from radio leakage, the case of planet earth is considered. The most detectable and useful escaping signal arise in a few BMEWS-type radar systems and in normal television broadcasting. A model including over 2000 television transmitters is used to demonstrate the wealth of astronomical and cultural information available from a distant observer's careful monitoring of frequency and intensity variations in individual video carriers (program materials is not taken to be detectable).

Interstellar archaeology and the prevalence of intelligence

Simple calculations indicate that the spatial density in the galaxy of extinct civilizations, and of planets inhabited by intelligent creatures who do not have technical civilizations, may be quite large.

On the detectivity of advanced galactic civilizations

Even with slow rates of technological advance, extraterrestrial civilizations substantially in our future will have technologies and laws of nature currently inaccessible to us, and will probably have minimal interest in communicating with us. If this communication horizon is ∼10 3 years in our future, other crude estimates previously published imply that only ∼10 −4 of the technical civilizations in the Galaxy are accessible to us. The mean distance to the nearest such society is then ∼10 4 light years. Radio detection of extraterrestrial intelligence seems to imply either (1) much larger telescopes or antenna arrays for the detection of civilizations within our Galaxy than now exist; or (2) attention to the nearer extragalactic systems, with smaller radio telescopes, to detect the very small fraction of very advanced societies which may choose to make their presence known to emerging civilizations via antique communication modes.

Direct contact among galactic civilizations by relativistic interstellar spaceflight

An estimate of the number of advanced technical civilizations on planets of other stars depends on our knowledge of the rate of star formation; the frequency of favorably situated planets ; the probabilities of the origins of life, of intelligence and of technical civilization ; and the lifetimes of technical civilizations. These parameters are poorly known. The estimates of the present paper lead to ∼10 6 extant advanced technical civilizations in our Galaxy. The most probable distance to the nearest such community is then several hundred light years. Interstellar spaceflight at relativistic velocities has several obvious advantages over electromagnetic communication among these civilizations. One striking feature is that with uniform acceleration of 1 g to the midpoint of the journey, and uniform deceleration thereafter, all points in the Galaxy are accessible within the lifetime of a human crew, due to relativistic time dilation. Some of the technical problems in the construction of starships capable of relativistic velocities are discussed. It is concluded that with nuclear staging, fusion reactors, and the Bussard interstellar ramjet, no fundamental energetic problems exist for relativistic interstellar spaceflight. We assume that there exists in the Galaxy a loosely integrated community of diverse civilizations, cooperating in the exploration and sampling of astronomical objects and their inhabitants. If each such advanced civilization launches one interstellar vehicle per year, the mean time interval between samplings of an average star would be 10 5 years, that between samplings of a planetary system with intelligent life would be 10 4 years, and that between sampling of another advanced civilization would be 10 3 years. It follows that there is the statistical likelihood that Earth was visited by an advanced extraterrestrial civilization at least once during historical times. There are serious difficulties in demonstrating such a contact by ancient writings and iconography alone. Nevertheless, there are legends which might profitably be studied in this context. Bases or other artifacts of interstellar spacefaring civilizations might also exist elsewhere in the solar system. The conclusions of the present paper are clearly provisional.