In my recent post Mass Extinction in the West Asian Cluster I discussed Eric H. Cline’s book 1177 B.C.: The Year Civilization Collapsed, and in that discussion I characterized the Late Bronze Age (LBA) simultaneous collapse of many civilized societies as a “mass extinction” of civilizations. In the exposition of my argument I first formulated the following idea:

“…civilization in the region likely developed in a kind of reticulate pattern, rather than in a unitary and linear manner, so that, if we were in possession of all the evidence, we might find a series of developments took place in sequence, but not necessarily all originating in a single civilization. Developments were likely distributed across the several different civilizations, and disseminated by idea diffusion until they reached all the others. This could be called a seriation of distributed development.”

This idea, as I now see, can be understood on its own as a distinctive process of complex adaptive systems, applicable not only to civilizations, but also to a range of emergent complexities like life, consciousness, and intelligence as well.

Now I’d like to apply this idea to life, and life under the special circumstances (not presently obtaining within our own planetary system, though that may have been the case in the past) of a multi-planet ecosystem. What, then, is a multi-planet ecosystem?

When the TRAPPIST-1 planetary system was discovered, with seven smallish, rocky planets tightly orbiting a small star, the possibilities for life here were of immediate interest to astrobiologists. It has long been thought that lithopanspermia (the transfer of life between planets on rocks) may have occurred within our solar system between Venus, Earth, and Mars — all smallish, rocky planets relatively close in to the sun, and which are known to have have exchanged ejecta from collisions. With an even greater number of small rocky planets in even closer proximity, the likelihood of lithopanspermia at TRAPPIST-1 (assuming life is present in some form) would seem to be higher than in our solar system.

I already know of two papers on the possibilities of lithopanspermia in the TRAPPIST-1 system, Enhanced interplanetary panspermia in the TRAPPIST-1 system by Manasvi Lingam and Abraham Loeb, and Fast litho-panspermia in the habitable zone of the TRAPPIST-1 system, by Sebastiaan Krijt, Timothy J. Bowling, Richard J. Lyons, and Fred J. Ciesla. There is also a paper about the possibilities for botany in the system, Comparative Climates of TRAPPIST-1 planetary system: results from a simple climate-vegetation model by Tommaso Alberti, Vincenzo Carbone, Fabio Lepreti, and Antonio Vecchio.

In a couple of Tumblr posts, More is Different and Yet Another Astrobiology Thought Experiment I discussed some of these possibilities of lithopanspermia in the TRAPPIST-1 system. (And the same interesting TRAPPIST-1 system was also discussed on The Unseen Podcast Episode 69 — A Taste of TRAPPIST-1.)

In More is Different I wrote…

“It may well prove that more is different when it comes to planets, their biospheres, and ecosystems spanning multiple planets. Multi-planet ecologies (we can’t call them biospheres, because they would be constituted by multiple biospheres) may produce qualitatively distinct emergents based on the greater number of components of the ecosystem so constituted. Emergent complexities not possible in a planetary system like our own, with a single liquid-water world, may be possible where there are multiple such planets ecologically coupled through lithopanspermia, and perhaps through other vectors that we cannot now imagine.”

…and in Yet Another Astrobiology Thought Experiment I wrote…

“If life arose separately on several closely spaced planets, with slight biochemical differences between the distinct origin of life events on the several planets, and circumstances within that planetary system were conducive to lithopanspermia, this would mean that each of the planets would eventually have tinctures of life from the other planets, and if these varieties of life could live together without destroying each other, the mixed biospheres of multi-planetary habitable zones where there has been independent origins of life on multiple worlds would suggest a diversity of life not realized on Earth.”

If we combine the ideas of a multi-planetary ecosystem with the idea of reticulate distributed development (which I introduced in relation to civilizational development), we can immediately see the possibility of a multi-planetary ecosystem in which life remains in nearly continuous interaction across several different planets. In such a complex astrobiological context, the great macroevolutionary transitions would not necessarily need to occur all within a single biosphere. It would be sufficient that the macroevolutionary transition took place on at least one planet of the multi-planetary ecosystem, and was subsequently distributed to the other planets of the ecosystem by lithopanspermia. The result would be a seriation of distributed development, i.e., a series of developments taking place in sequence, but not necessarily all originating on a single planet, in a single biosphere. Is this even possible?

We know that microbial life is remarkably resilient, and could likely make the lithopanspermatic journey from one planet to another, but could anything more complex than microbial life make this journey? Recently Caleb A. Scharf in Complex Life: Wimpy or Tough? Complex life may be less resilient than microbial life by some measures, but it’s not necessarily cosmically delicate questions the received wisdom of assuming that eukaryotic multi-cellular life is too vulnerable and delicate to survive “hurdles of selection” — and certainly panspermia must be among the most vertiginous of such hurdles. What about, for example, if conditions were right to freeze complex cells into a still-liquid chamber within a rock, deep in a protected crevice, which then could travel to another planet with complex life intact? There must be similar vectors for panspermia of which we are unaware simply because our imagination fails us.

Obviously, such an occurrence would require many circumstances to occur in just the right order and in just the right way. When this happens for us, as human beings, we say that things are “just right,” and we invoke anthropic selection effects as an explanation, which in this case is simply a Kantian transcendental argument as applied to human beings. But conditions also might be “just right” for some other kind of life, and the antecedent circumstances for such life would be the transcendental conditions of that life — a selection effect of life as we do not know it. This wouldn’t be an “anthropic” explanation in the narrow sense, but if we formalized the concept of an anthropic explanation so that it applied to any being whatsoever, then what human beings call an anthropic explanation would be a special case among a class of explanations. And in this class of explanations would be the “just right” conditions that might lead to rapid and enhanced lithopanspermia among closely spaced planets, which allowed for the transfer to complex life among these planets.

The idea of panspermia has made us familiar with the possibility of life originating on one world and subsequently developing on another world. In case of enhanced and rapid lithopanspermia in an astrobiological context “just right” for such life, we might find life originating on one planet, achieving photosynthesis on another planet, becoming multi-cellular on a third planet, developing an endoskeleton on yet another planet, and so on, possibly continuing to develop into intelligent life. This is what I mean by a seriation of distributed evolutionary development.

If this is possible, if complex life can pass between planets in a multi-planetary ecosystem, I suspect that the rate of evolutionary change would be at least somewhat accelerated in this reticulate astrobiological context, much as the development of civilization was arguably accelerated in the west Asian cluster as a result of the continual interaction of the several civilizations of Mesopotamia, Anatolia, Egypt, and the eastern Mediterranean.

And as life goes, so goes civilization predicated upon life. In a multi-planetary ecosystem, a civilization that grew up on one of these worlds would evolve in a unique astrobiological context that would shape its unique development. Darwin said that, “Man still bears in his bodily frame the indelible stamp of his lowly origin.” Civilizations, too, bear the lowly stamp of their biological origins. A biocentric civilization emergent within a multi-planetary ecosystem would be distinctively shaped by the selection pressures of this ecosystem, which would not be the same as the selection pressures of a single biosphere. And a technocentric civilization arising from a biocentric civilization would continue to carry the lowly stamp of its origins into the farthest reaches of its development.

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Grand Strategy Annex

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The periodic table, color-coded by the source of the element in the solar system. By Jennifer Johnson.

Many years ago, reading a source I cannot now recall (and for which I searched unsuccessfully when I started writing this post), I came upon a passage that has stayed with me. The author was making the argument that no sciences were consistent except those that had been reduced to mere catalogs of facts, like geography and anatomy. I can’t recall the larger context in which this argument appeared, but the observation that sciences might only become fully consistent when they have matured to the point of being exhaustive but static and uninteresting catalogs of facts, implying that the field of research itself had been utterly exhausted, was something I remembered. This idea presents in miniature a developmental conception of the sciences, but I think that it is a developmental conception that is incomplete.

Thinking of this idea of an exhausted field of research, I am reminded of a discussion in Conversations on Mind, Matter, and Mathematics by Jean-Pierre Changeux and Alain Connes, in which mathematician Alain Connes distinguished between fully explored and as yet unexplored parts of mathematics:

“…the list of finite fields is relatively easy to grasp, and it’s a simple matter to prove that the list is complete. It is part of an almost completely explored mathematical reality, where few problems remain. Cultural and social circumstances clearly serve to indicate which directions need to be pursued on the fringe of current research — the conquest of the North Pole, to return again to my comparison, surely obeyed the same type of cultural and social motivations, at least for a certain time. But once exploration is finished, these cultural and social phenomena fade away, and all that’s left is a perfectly stable corpus, perfectly fitted to mathematical reality…”

Jean-Pierre Changeux and Alain Connes, Conversations on Mind, Matter, and Mathematics, Princeton: Princeton University Press, 1995, pp. 33-34

To illustrate a developmental conception of mathematics and the formal sciences would introduce additional complexities that follow from the not-yet-fully-understood relationship between the formal sciences and the empirical sciences, so I am going to focus on developmental conceptions of the empirical sciences, but I hope to return to the formal sciences in this connection.

The idea of the development of science as a two-stage process, with discovery followed by a consistent and exhaustive catalog, implies both that most sciences (and, if we decompose the individual special sciences into subdivisions, parts of most or all sciences) remain in the discovery phase, and that once the discovery phase has passed and we are in possession of an exhaustive and complete catalog of the facts discovered by a science, there is nothing more to be done in a given science. However, I can think of several historical examples in which a science seemed to be converging on a complete catalog, but this development was disrupted (one might say) by conceptual change within the field that forced the reorganization of the materials in a new way. My examples will not be perfect, and some additional scientific discovery always seems to have been involved, but I think that these examples will be at least suggestive.

Prior to the great discoveries of cosmology in the early twentieth century, after which astronomy became indissolubly connected to astrophysics, astronomy seemed to be converging slowly upon an exhaustive catalog of all stars, with the limitation on the research being simply the resolving power of the telescopes employed to view the stars. One could imagine a counterfactual world in which technological innovations in instrumentation supplied nothing more than new telescopes able to resolve more stars, and that the task of astronomy was merely to supply an exhaustive catalog of stars, listing their position in the sky, intrinsic brightness, and a few other facts about the points of light in the sky. But the cataloging of stars itself contributed to the revolution that would follow, particularly when the period-luminosity relationship in Cepheid variable stars was discovered by Henrietta Swan Leavitt (discovered in 1908 and published in 1912). The period-luminosity relationship provided a “standard candle” for astronomy, and this standard candle began the process of constructing the cosmological distance ladder, which in turn made it possible to identify Cepheid variables in the Andromeda galaxy and thus to prove that the Andromeda galaxy was two million light years away and not contained within the Milky Way.

Once astronomy became scientifically coupled to astrophysics, and the resources of physics (both relativistic and quantum) could be brought to bear upon understanding stars, a whole new cosmos opened up. Stars, galaxies, and the universe entire were transformed from something static that might be exhaustively cataloged, to a dynamic and changing reality with a natural history as well as a future. Astronomy went from being something that we might call a Platonic science, or even a Linnaean science, to being an historical science, like geology (after Hutton and Lyell), biology (after Darwin and Wallace), and Paleontology. This coupling of the study of the stars with the study of the matter that makes up the stars has since moved in both directions, with physics driving cosmology and cosmology driving physics. One result of this interaction between astronomy and physics is the illustration above (by Jennifer Johnson) of the periodic table of elements, which prominently exhibits the origins of the elements in cosmological processes. The periodic table once seemed, like a catalog of stars, to be something static to be memorized, and divorced from natural history. This conceptualization of matter in terms of its origins puts the periodic table in a dramatically different light.

As the cosmos was once conceived in Platonic terms as fixed and eternal, to be delineated in a Linnaean science of taxonomical classification, so too the Earth was conceived in Platonic terms as fixed and eternal, to be similarly delineated in a Linnaean science of classification. The first major disruption of this conception came with geology since Hutton and Lyell, followed by plate tectonics and geomorphology in the twentieth century. Now this process has been pushed further by the idea of mineral evolution. I have been listening through for the second time to Robert Hazen’s lectures The Origin and Evolution of Earth: From the Big Bang to the Future of Human Existence, which exposition closely follow the content of his book, The Story of Earth: The First 4.5 Billion Years, from Stardust to Living Planet, in which Hazen wrote:

“The ancient discipline of mineralogy, though absolutely central to everything we know about Earth and its storied past, has been curiously static and detached from the conceptual vagaries of time. For more than two hundred years, measurements of chemical composition, density, hardness, optical properties, and crystal structure have been the meat and potatoes of the mineralogist’s livelihood. Visit any natural history museum, and you’ll see what I mean: gorgeous crustal specimens arrayed in case after glass-fronted case, with labels showing name, chemical formula, crystal system, and locality. These most treasured fragments of Earth are rich in historical context, but you will likely search in vain for any clue as to their birth ages or subsequent geological transformations. The old way all but divorces minerals from their compelling life stories.”

Robert M. Hazen, The Story of Earth: The First 4.5 Billion Years, from Stardust to Living Planet, Viking Penguin, 2012, Introduction

This illustrates, from the perspective of mineralogy, much of what I said above in relation to star charts and catalogs: mineralogy was once about cataloging minerals, and this may have been a finite undertaking once all minerals had been isolated, identified, and cataloged. Now, however, we can understand mineralogy in the context of cosmological history, and this is as revolutionary for our understanding of Earth as the periodic table understood in terms of cosmological history. It could be argued, in addition, that compiling the “particle zoo” of contemporary particle physics is also a task of cataloging the entities studied by physics, but the cataloging of particles has been attended throughout with a theory of how these particles are generated and how they fit into the larger cosmological story — what Aristotle would have called their coming to be and passing away.

The best contemporary example of a science still in its initial phases of discovery and cataloging is the relatively recent confirmation of exoplanets. On my Tumblr blog I recently posted On the Likely Existence of “Random” Planetary Systems, which tried to place our current Golden Age of Exoplanet Discovery in the context of a developing science. We find the planetary systems that we do in fact find partly as a consequence of observation selection effects, and it belongs to the later stages of the development of a science to attempt to correct for observation selection effects built into the original methods of discovery employed. The planetary science that is emerging from exoplanet discoveries, however, and like contemporary particle physics, is attended by theories of planet formation that take into account cosmological history. However, the discovery phase, in terms of exoplanets, is still underway and still very new, and we have a lot to learn. Moreover, once we learn more about the possibilities of planets in our universe, hopefully also we will learn about the varied possibilities of planetary biospheres, and given the continual interaction between biosphere, lithosphere, atmosphere, and hydrosphere, which is a central motif of Hazen’s mineral evolution, we will be able to place planets and their biospheres into a large cosmological context (perhaps even reconstructing biosphere evolution). But first we must discover them, and then we must catalog them.

These observations, I think, have consequences not only for our understanding of the universe in which we find ourselves, but also for our understanding of science. Perhaps, instead of a two-stage process of discovery and taxonomy, science involves a three-stage process of discovery, taxonomy, and natural history, in which latter the objects and facts cataloged by one of the special sciences (earlier in their development) can take their place within cosmological history. If this is the case, then big history is the master category not only of history, but also of science, as big history is the ultimate framework for all knowledge that bears the lowly stamp of its origins. This conception of the task of science, once beyond the initial stages of discovery and classification, to integrate that which was discovered and classified into the framework of big history, suggests a concrete method by which to “cash out” in a meaningful way Wilfrid Sellars’ contention that, “…the specialist must have a sense of how not only his subject matter, but also the methods and principles of his thinking about it, fit into the intellectual landscape.” (cf. Philosophy and the Scientific Image of Man) Big history is the intellectual landscape in which the sciences are located.

A developmental conception of science that recognized stages in the development of science beyond classification, taxonomy, and an exhaustive catalog (which is, in effect, the tombstone of what was a living and growing science), has consequences for the practice of science. Discovery may well be the paradigmatic form of scientific activity, but it is not the only form of scientific activity. The painstakingly detailed and disciplined work of cataloging stars or minerals is the kind of challenge that attracts a certain kind of mind with a particular interest, and the kind of individual who is attracted to this task of systematically cataloging entities and facts is distinct from the kind of individual who might be most attracted by scientific discovery, and also distinct from the kind of individual who might be attracted to fitting the discoveries of a special science into the overall story of the universe and its natural history. There may need to be a division of labor within the sciences, and this may entail an educational difference. Dividing sciences by discipline (and, now, by university departments), which involves inter-generational conflicts among sciences and the paradigm shifts that sometimes emerge as a result of these conflicts, may ultimately make less sense than dividing sciences according their stage of development. Perhaps universities, instead of having departments of chemistry, geology, and botany, should have departments of discovery, taxonomy, and epistemic integration.

Speaking from personal experience, I know that (long ago) when I was in school, I absolutely hated the cataloging approach to the sciences, and I was bored to tears by memorizing facts about minerals or stars. But the developmental science of evolution so intrigued me that I read extensively about evolution and anthropology outside and well beyond the school curriculum. If mineral evolution and the Earth sciences in their contemporary form had been known then, I might have had more of an interest in them.

What are the sciences developing into, or what are the sciences becoming? What is the end and aim of science? I previously touched on this question, a bit obliquely, in What is, or what ought to be, the relationship between science and society? though this line of inquiry is more like a thought experiment. It may be too early in the history of the sciences to say what they are becoming or what they will become. Perhaps an emergent complexity will arise out of knowledge itself, something that I first suggested in Scientific Historiography: Past, Present, and Future, in which I wrote in the final paragraph:

We cannot simply assume an unproblematic diachronic extrapolation of scientific knowledge — or, for that matter, historical knowledge — especially as big history places such great emphasis upon emergent complexity. The linear extrapolation of science eventually may trigger a qualitative change in knowledge. In other words, what will be the emergent form of scientific knowledge (the ninth threshold, perhaps?) and how will it shape our conception of scientific historiography as embodied in big history, not to mention the consequences for civilization itself? We may yet see a scientific historiography as different from big history as big history is different from Augustine’s City of God.

It is only a lack of imagination that would limit science to the three stages of development I have outlined above. There may be developments in science beyond those we can currently understand. Perhaps the qualitative emergent from the quantitative expansion of scientific knowledge will be a change in science itself — possibly a fourth stage in the development of science — that will open up to scientific knowledge aspects of experience and regions of nature currently inaccessible to science.

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Grand Strategy Annex

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A Conceptual Overview

What is the relationship between planetary endemism and the overview effect? This is the sort of question that might be given a definitive formulation, once once we have gotten sufficiently clear in our understanding of these ideas and their ramifications. I’m not yet at the point of formulating a definitive expression of this relationship, but I’m getting closer to it, so this post will be about formulating relationships among these and related concepts in a way that is hopefully clear and illuminating, while avoiding the ambiguities inherent in novel concepts.

This post is itself a kind of overview, attempting to show in brief compass how a number of interrelated concepts neatly dovetail and provide us with a rough outline of a conceptual overview for understanding the origins, development, distribution, and destiny of civilization (or some other form of emergent complexity) in the universe.


The Stelliferous Era

The Stelliferous Era is that period of cosmological history after the formation of the first stars and before the last stars burn out and leave a cold and dark universe. In the cosmological periodization formulated by Fred Adams and Greg Laughlin, the Stelliferous Era is preceded by the Primordial Era and followed by the Degenerate Era. During the Primordial Era stars have not yet formed, but matter condenses out of the primordial soup; during the Degenerate Era, the degenerate remains of stars, black holes, and some exotic cosmological objects are to the found, but the era of brightly burning stars is over.

What typifies the Stelliferous Era is its many stars, radiating light and heat, and whose nucleosynthesis and supernova explosions forge heavier forms of matter, and therefore the chemical and minerological complexity from which later generations of (high metallicity) stars and planets will form. (A Brief History of the Stelliferous Era is an older post about the Stelliferous Era that needs to be revised and updated.)

In comparison to the later Degenerate Era, Black Hole Era, and Dark Era of cosmological history, the Stelliferous Era is rather brief, extending from 106 to 1014 years from the origins of the universe, and almost everything that concerns us can be further reduced to the eleventh cosmological decade (from 10 billion to 100 billion years since the origin of the universe). Since this cosmological periodization is logarithmic, the later periods are even longer in duration than they initially appear to be.

Our interest in the Stelliferous Era, and, more narrowly, our interest in the eleventh decade of the Stelliferous Era, does not rule out interesting cosmological events in other eras of cosmological history, and it is possible that civilizations and other forms of emergent complexity that appear during the Stelliferous Era may be able to make the transition to survive into the Degenerate Era (cf. Addendum on Degenerate Era Civilization), but this brief period of starlight in cosmological history is the Stelliferous Era window in which it is possible for peer planetary systems, peer species, and peer civilization to exist.

planetary surfaces

Planetary Endemism

Planetary Endemism is the condition of life during the Stelliferous Era as being unique to planetary surfaces and their biospheres. Given the parameters of the Stelliferous Era — a universe with planets, stars, and galaxies, in which both water (cf. The Solar System and Beyond is Awash in Water) and carbon-based organic molecules (cf. Mixed aromatic–aliphatic organic nanoparticles as carriers of unidentified infrared emission features by Sun Kwok and Yong Zhang) are common — planetary surfaces are a “sweet spot” for emergent complexities, as it is on planetary surfaces that energy from stellar insolation can drive chemical processes on mineral- and chemical-rich surfaces. The chemical and geological complexity of the interface between atmosphere, ocean, and land surfaces provide an opportunity for further emergent complexities to arise, and so it is on planetary surfaces that life has its best opportunity during the Stelliferous Era.

Planetary endemism does not rule out exotic forms of life not derived from water and organic macro-molecules, nor does it rule out life arising in locations other than planetary surfaces, but the nature of the Stelliferous Era and the conditions of the universe we observe points to planetary surfaces being the most common locations for life during the Stelliferous Era. Also, the “planetary” in “planetary endemism” should not be construed too narrowly: moons, planetesimals, asteroids, comets and other bodies within a planetary system are also chemically complex loci where stellar insolation can drive further chemical processes, with the possibility of emergent complexities arising in these contexts as well.


The Homeworld Effect

The homeworld effect is the perspective of intelligent agents still subject to planetary endemism. When the emergent complexities fostered by planetary endemism rise to the level of biological complexity necessary to the emergence of consciousness, there are then biological beings with a point of view, i.e., there is something that it is like to be such a biological being (to draw on Nagel’s formulation from “What is it like to be a bat?”). The first being on Earth to open its eyes and look out onto the world possessed the physical and optical perspective dictated by planetary endemism. As biological beings develop in complexity, adding cognitive faculties, and eventually giving rise to further emergent complexities, such as art, technology, and civilization, embedded in these activities and institutions is a perspective rooted in the homeworld effect.

The emergent complexities arising from the action of intelligent agents are, like the biological beings who create them, derived from the biosphere in which the intelligent agent acts. Thus civilization begins as a biocentric institution, embodying the biophilia that is the cognitive expression of biocentrism, which is, in turn, an expression of planetary endemism and the nature of the intelligent agents of planetary endemism being biological beings among other biological beings.

The homeworld effect does not rule out the possibility of exotic forms of life or unusual physical dispositions for life that would not evolve with the homeworld effect as a selection pressure, but given that planetary endemism is the most likely existential condition of biological beings during the Stelliferous Era, it is to be expected that the greater part of biological beings during the Stelliferous Era are products of planetary endemism and so will be subject to the homeworld effect.


The Overview Effect

The overview effect is a consequence of transcending planetary endemism. As biocentric civilizations increase in complexity and sophistication, deriving ever more energy from their homeworld biosphere, biocentric institutions and practices begin to be incrementally replaced by technocentric institutions and practices and civilization starts to approximate a technocentric institution. The turning point in this development is the industrial revolution.

Within two hundred years of the industrial revolution, human beings had set foot on a neighboring body of our planetary system. If a civilization experiences an industrial revolution, it will do so on the basis of already advancing scientific knowledge, and within an historically short period of time that civilization will experience the overview effect. But the unfolding of the overview effect is likely to be a long-term historical process, like the scientific revolution. Transcending planetary endemism means transcending the homeworld effect, but as the homeworld effect has shaped the biology and evolutionary psychology of biological beings subject to planetary endemism, the homeworld effect cannot be transcended as easily as the homeworld itself can be transcended.

For biological beings of planetary endemism, the overview effect occurs only once, though its impact may be gradual and spread out over an extended period of time. An intelligent agent that has evolved on the surface of its homeworld leaves that homeworld only once; every subsequent world studied, explored, or appropriated (or expropriated) by such beings will be first encountered from afar, over astronomical distances, and known to be a planet among planets. A homeworld is transcended only once, and is not initially experienced as a planet among planets, but rather as the ground of all being.

The uniqueness of the overview effect to the homeworld of biological beings of planetary endemism does not rule out further overview effects that could be experienced by a spacefaring civilization, as it eventually is able to see its planetary system, its home galaxy, and its supercluster as isolated wholes. However, following the same line of argument above — stars and their planetary systems being common during the Stelliferous Era, emergent complexities appearing on planetary surfaces characterizing planetary endemism, organisms and minds evolving under the selection pressure of the homeworld effect embodying geocentrism in their sinews and their ideas — it is to be expected that the overview effect of an intelligent agent first understanding, and then actually seeing, its homeworld as a planet among other planets, is the decisive intellectual turning point.


Bifurcation of Planetary and Spacefaring Civilizations

What I have tried to explain here is the tightly-coupled nature of these concepts, each of which implicates the others. Indeed, the four concepts outlined above — the Stelliferous Era, planetary endemism, the homeworld effect, and the overview effect — could be used as the basis of a periodization that should, within certain limits, characterize the emergence of intelligence and civilization in any universe such as ours. Peer civlizations would emerge during the Stelliferous Era subject to planetary endemism, and passing from the homeworld effect to the overview effect.

If such a civilization continues to develop, fully conscious of the overview effect, it would develop as a spacefaring civilization evolving under the (intellectual) selection pressure of the overview effect, and such a civilization would birfurcate significantly from civilizations of planetary endemism still exclusively planetary and still subject to the homeworld effect. These two circumstances represent radically different selection pressures, so that we would expect spacefaring civilizations to rapidly speciate and adaptively radiate once exposed to these novel selection pressures. I have previously called this speciation and adaptive radiation the great voluntaristic divergence.

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Overview Effects

The Epistemic Overview Effect

The Overview Effect as Perspective Taking

Hegel and the Overview Effect

The Overview Effect in Formal Thought

Brief Addendum on the Overview Effect in Formal Thought

A Further Addendum on the Overview Effect in Formal Thought, in the Way of Providing a Measure of Disambiguation in Regard to the Role of Temporality

Our Knowledge of the Internal World

Personal Experience and Empirical Knowledge

The Overview Effect over the longue durée

Cognitive Astrobiology and the Overview Effect

The Scientific Imperative of Human Spaceflight

Homeworld Effects

The Homeworld Effect and the Hunter-Gatherer Weltanschauung

The Martian Standpoint

Addendum on the Martian Standpoint

Hunter-Gatherers in Outer Space

What will it be like to be a Martian?

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Grand Strategy Annex

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An Explanatory Mechanism for Aggressively Expanding Civilizations

Any emergent complexity that adds itself to the ultimate furniture of the universe can be, on the one hand, the basis of further emergent complexities, while on the other hand it can function as a selection pressure upon the other furniture of the universe, including earlier and later iterations of emergent complexity. Now, that sounds very abstract — indeed, I could express this idea even more abstractly in the language of ontology — so let me attempt to provide some illustrative examples. When biology emerged from the geochemical complexity of Earth, biology eventually gave rise to further emergent complexities (consciousness, technology, civilization), but biology also began to shape the geochemical context of its own emergence. Biochemistry emerged from geochemistry, thus biochemistry has always been, ab initio, in coevolution with the geochemistry upon which it supervenes.

Life, then, coevolved with geology, as life now coevolves with later emergent complexities, which means that, in the case of human beings, human life coevolves with the habitat it has made for itself — Earth of the anthropocene and our civilization (cf. Intellectual Niche Construction). This point has been made by Wilson and Lumsden:

“[The] high level of human mental activity creates culture, which has achieved a life of its own beyond the ordinary limits of biology. The principal habitat of the human mind is the very culture that it creates.”

Edward O. Wilson and Charles J. Lumsden, Promethean Fire: Reflections on the Origin of Mind, Cambridge and London: Harvard University Press, 1983, p.

We might distinguish between relationships of tightly-coupled coevolution and loosely-coupled coevolution, with the familiar instances of coevolution — such as pollinating bees and flowers — qualifying as tightly-coupled, while those evolutionary relationships not usually recognized as coevolutionary qualify as loosely-coupled — for example, geochemistry and biochemistry, although the scale at which we make our comparison will be crucial to determining whether the coupling is tight or loose. “Coevolution” is another way of saying that each party to the coevolutionary relationship acts as a selection pressure on the other, so we make the distinction between tightly-coupled coevolution and loosely-coupled coevolution in order to differentiate between selection pressures, some of which are immediate and enduring (tightly-coupled), and some of which are distant and only sporadically influential (loosely-coupled).

Now that civilization has established itself as an emergent complexity on Earth, civilization may serve as the springboard for further emergent complexities, but it also has emerged as a new selection pressure upon the life that gave rise to civilization, while the geology of Earth and the terrestrial biosphere are, in turn, a selection pressure on civilization. Terrestrial (planetary) civilization may come to act as a selection pressure upon other emergent complexities yet to appear, which will also act as a selection pressure on terrestrial civilization, and these emergent complexities are likely to be emergent from civilization. A spacefaring civilization that encompasses (at first) multiple worlds of a planetary system, multiple planetary systems of multiple stars, or multiple galaxies, would be one form of emergent complexity that could arise from planetary civilization.

Among the immediate and enduring selection pressures on spacefaring civilizations will be the distribution of exploitable resources in space, as well as the other spacefaring civilizations with which such a civilization is in competition for these resources (these other spacefaring civilization themselves being an emergent complexity originating from other planetary civilizations derived from other biospheres). There may also be selection pressures from emergent complexities that we do not yet understand, and which we have not yet identified. These two selection pressures — distribution of resources and competition with other spacefaring civilizations — will shape (perhaps have shaped) the origins, evolution, distribution, and fate of spacefaring civilizations. Spacefaring civilizations will be in a tightly-coupled coevolutionary relationship with the cosmological distribution of resources (matter and energy) and the efforts of other spacefaring civilizations to also dominate these resources. Let us consider this more carefully.

When I wrote my post on Social Stratification and the Dominance Hierarchy I included a diagram (reproduced above; also see Group Dynamics) illustrating the selection pressures that lead to a dominance hierarchy in social animals. The diagram distinguished among scarce, limited, and abundant resources. Scarce resources lead to cooperation; sufficiently abundant resources can eliminate competition. In the case of limited resources, these resources can be scattered or concentrated. Scattered resources lead to competition in speed, while concentrated resources lead to competition in aggressiveness, and thence to a dominance hierarchy. The dominance hierarchy among human beings, which in civilization we call social stratification, implies that the resources significant to human beings have been scarce and concentrated.

If we confine our interest in human access to resources only to Earth, we can readily distinguish between regions where resources are sufficiently concentrated that they can be defended, and regions where resources are scattered, cannot be defended, and are therefore the object of competition in speed rather than aggressiveness. (We can also distinguish different social systems that have arisen shaped by the differential distribution of resources.) If we pull back from this geographical scale and consider the question from the perspective of a spacefaring civilization, the whole of Earth, our homeworld, is a concentrated and defensible locus of resources, but the cosmos on the whole represents an extreme scattering, over interstellar and intergalactic distances, of limited or scarce resources. This scattering of limited resources, in contradistinction to the concentrated and defensible resources of the homeworld of any intelligence species, ought to have the result of spacefaring civilizations defending their homeworld while competing for resources with other spacefaring civilizations, not through competition in aggressiveness, but through competition in speed.

Competition in aggressiveness for the resources of spacefaring civilization may be excluded by the scattering of these resources, so that we are not likely to see the emergence of a galactic empire, crushing under the boot heels of its storm troopers the aspirations to freedom, dignity, and equality of intelligent species throughout the galaxy. However, competition in speed for limited resources distributed on a cosmological scale may well be the primary selection pressure on spacefaring civilizations, and competition in speed ought to entail the rapid cosmological expansion of these civilizations.

Elsewhere I have mentioned the papers of S. Jay Olson (cf. Big Time, The Genesis Project as Central Project, and Second Addendum on the Genesis Project as Central Project: Invasive Species) concerning what Olson calls “aggressively expanding civilizations,” which embody rapid expansion on a cosmological scale. Here is Olson’s characterization of such as scenario:

“An ‘aggressive expansion scenario’ is a proposed cosmological phenomenon… whereby a subset of advanced life appears at random throughout the universe and expands in all directions, saturating galaxies and utilizing resources as they go… We also assume that all aggressive expanders will be of the same behaviour type, i.e. they all expand with the same velocity v in the local comoving frame, and the expanding spherical front of galaxy colonization leads to observable changes a fixed time T after the front has passed by.”

“Estimates for the number of visible galaxy-spanning civilizations and the cosmological expansion of life,” S. Jay Olson, International Journal of Astrobiology, Cambridge University Press, 2016, pp. 2-3, doi:10.1017/S1473550416000082

Competition in speed among spacefaring civilization would mean a focus on maximizing v for the expanding spherical front of galaxy colonization.

Citing Bostrom and Omohundro on the nature of superintelligent AI (presumptively the heir of our technological civilization, but see the final sentence below quoted from Olson, as he addresses this as well), Olson writes:

“From an independent field of study, it has been argued that resource acquisition is one of the ‘basic drives’ of a generic superintelligent AI. This means, in essence, that a sufficiently powerful AI will tend to use extreme expansion and resource acquisition as a means of maximizing its utility function, unless it is explicitly and carefully designed to avoid such behavior… even if advanced alien species tend to be monks who have forsaken all worldly gain, the accidents involving insufficiently careful design of an artificial superintelligence are potentially one of the largest observable phenomena in the universe, when they occur. The word ‘civilization’ is not really the best description of such a thing, but we will use it for the sake of historical continuity.”

“Long-term consequences of observing an expanding cosmological civilization”, S. Jay Olson

We can see that competition in speed for limited resources provides an explanatory mechanism for the existence and expansion of aggressively expanding civilizations. Spacefaring civilizations that successfully compete for resources on a cosmological scale endure over cosmological scales of time, and perhaps leave a legacy in the form of a universe transformed sub specie civilizationis. Spacefaring civilizations that fail to expand go extinct, and leave no observable legacy. Whether there is room for more than one aggressively expanding civilization in any one universe, or whether this expansion takes place on scale of time sufficient to foreclose the opportunity of expansion to any rival civilizations, remains an open question. Once a universe is saturated with life, no other life, and no other civilization emergent from other life, would have an opportunity to appear, unless or until a cosmological scale extinction event created such an opportunity (which could be furnished by sufficiently violent gamma ray bursts).

The above considerations pose other interesting questions that could be taken up as research questions in the study of spacefaring civilization. How are we to distinguish between scarce and limited resources on a cosmological scale? Might the closely packed stars of globular clusters and galactic centers constitute limited resources, while diffuse spiral arms and the outer portions of elliptical galaxies constitute scarce resources? At what threshold of availability should we distinguish between matter and energy being scarce or limited? This may be a problem contingently decided by the technologies of spacefaring not yet known to us. That is to say, if technologically mature civilizations find interstellar travel (or intergalactic travel) somewhat routine, then we may regard cosmological resources as scattered and limited, and more concentrated areas such as mentioned (globular clusters and galactic centers) might pass over a threshold such that they would be considered concentrated — thus there would be the possibility of galactic empires competing on aggressiveness for defensible resources. If, on the other hand, interstellar (or intergalactic) travel is always difficult, then the universe presents, at best, limited resources, and perhaps scarce resources. In the case of scarce resources, there would be a window of opportunity for cooperation among spacefaring civilization for the effective and efficient exploitation of these resources.

If, as on the surface of Earth (and relative to a planetary civilization), cosmological resources are distributed unevenly, then the distribution of civilizations will mirror the distribution of resources — not only in extent, but also in character, with concentrated regions producing civilizations competing on aggression, and diffuse regions producing civilizations competing on speed. On a sufficiently large scale, uneven distribution of cosmological resources would violate the cosmological principle, which is a cornerstone of contemporary cosmology. However, on the smaller scales (especially galactic scales) that would confront early spacefaring civilizations, the differential of resources between concentrated stellar regions and diffuse steller regions may be sufficient to differentiate regions of a galaxy given over to competition on speed for cosmological resources and regions of the same galaxy given over to competition on aggressiveness for cosmological resources. With the position of Earth in a spiral arm of the Milky Way, we inhabit a region of relatively diffuse distribution of stars, so that any nascent spacefaring civilizations with which we would be in competition would be competition in speed. It is therefore in our interest to reach the stars as soon as possible, or, by declining competition, reconcile ourselves to the existential risk of being shut out of the possibility of being a civilization relevant to the galaxy.

It may be that civilizations in regions of diffuse and therefore limited resources naturally understand their dilemma and consequently focus upon spacecraft speed (which has always been a preoccupation of those engaged in the speculative engineering of interstellar capable spacecraft), while civilizations in regions of more concentrated and therefore defensible resources intuit their relative ease of travel and focus instead on aggressive domination of their region of space, and the technology that would make such aggressive domination possible. Thus a civilization may already begin to be shaped by the selection pressures of its galactic neighborhood even as a nascent spacefaring civilization. An obvious instantiation of this phenomenon would be a single planetary system in which more than one planet produced life and civilization. These multiple civilizations expanding into a single planetary system would immediately be in conflict over the resources of that planetary system. In our exploration of our own planetary system, we have not had to compete with another civilization, and so our earliest spacecraft have gone into space without armor or armaments. We have a free hand in expanding into our planetary system; that may not be true for all nascent spacefaring civilizations, and it may not be true for us at spacefaring orders of magnitude beyond our planetary system.

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Grand Strategy Annex

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Ecological niche construction in the natural world.

Ecological niche construction in the natural world.

Recently in The Biological Conception of Civilization I defined civilization as a tightly coupled cohort of coevolving species. In proposing this definition, I openly acknowledged its limitations. This biological conception of civilization defines a biocentric civilization, and if civilization continues in its technological development, it may eventually pass from being a biocentric civilization, dependent upon intelligent organic species originating on planetary surfaces, to being a technocentric civilization, no longer dependent in this sense.

Even given these limitations of the biological conception of civilization, we need not abandon a biological framework entirely to converge upon a yet more comprehensive conception of civilization, beyond the biocentric, but still roughly characterized by conditions that we have learned from our tenure on Earth. Being ourselves an intelligent organic species existing on the surface of a planet, biological modes of thought can be made especially effective for minds such as ours, and it is in our cognitive interest to cultivate a mode of thought for which we are specially adapted.

Let us, then, go a little beyond a strictly biological conception of civilization and formulate an ecological conception of civilization. To make this conception immediately explicit, here is a first formulation…

The Ecological Conception of Civilization:

Civilization is niche construction by an intelligent species.

This formulation of the ecological conception of civilization could be amended to read, “by an intelligent species or by several intelligent species,” in order to anticipate the possibility of intelligence-rich biospheres that give rise to civilizations constituted by multiple intelligent species.

What is niche construction? Here is a sketch of the idea from a book on niche construction:

“…organisms… interact with environments, take energy and resources from environments, make micro- and macrohabitat choices with respect to environments, construct artifacts, emit detritus and die in environments, and by doing all these things, modify at least some of the natural selection pressures present in their own, and in each other’s, local environments.”

Niche Construction: The Neglected Process in Evolution, F. John Odling-Smee, Kevin N. Laland, and Marcus W. Feldman, Monographs in Population Biology 37, Princeton University Press, 2003, p. 1

The authors go on to say:

“All living creatures, through their metabolism, their activities, and their choices, partly create and partly destroy their own niches, on scales ranging from the extremely local to the global.”


Human interaction with the terrestrial environment is an obvious example of taking energy and resources from the environment on a global scale, altering the selection pressures on our own evolution as a species by both creating and destroying a niche for ourselves. We are not the first terrestrial organisms to act upon the planet globally; when stromatolites (microbial mats composed of cyanobacteria) were the dominant life form on Earth, their photosynthetic processes ultimately produced the Great Oxygenation Event and catastrophically changed the biosphere. Had it not been for that global catastrophic change of the biosphere, oxygen-breathing organisms such as ourselves could not have evolved.

'The Great Oxygenation Event (GOE), also called the Oxygen Catastrophe, Oxygen Crisis, Oxygen Holocaust, Oxygen Revolution, or Great Oxidation, was the biologically induced appearance of dioxygen in Earth's atmosphere.'  from Wikipedia (

‘The Great Oxygenation Event (GOE), also called the Oxygen Catastrophe, Oxygen Crisis, Oxygen Holocaust, Oxygen Revolution, or Great Oxidation, was the biologically induced appearance of dioxygen in Earth’s atmosphere.’ from Wikipedia (

Though we are not the first terrestrial organism to shape the biosphere entire, we are the first intelligent terrestrial agents to shape the biosphere, and it has been the application of human intelligence to the problem of human survival that has resulted in human beings adapting their activity to every terrestrial biome and so eventually constructing civilization. At the stage of the initial emergence of civilization, the biological and ecological conceptions of civilizations coincide, as niche construction takes the form of engineering a coevolving cohort of species beneficial to the intelligent agent intervening in the biosphere. In later stages in the development of civilization, the ecological conception is shown to be more comprehensive than the biological conception of civilization, and subsumes the biological conception of civilization.

Not any cohort of coevolving species constitutes a civilization. Pollinating insects (bees) and flowers are involved in what might be called a tightly-coupled cohort of coevolving species, but we could not call bees and flowers together a civilization. Perhaps on other worlds the distinction between what we call civilization and coevolution in the natural world would not be so evident, and we could not as confidently make the distinction. For us, however, this distinction seems obvious. Why? At least one difference between civilization and naturally occurring coevolution is that the tightly-coupled cohort of coevolving species that we call civilization has been purposefully engineered for the benefit of the intelligent species that has demonstrated its agency through this engineering of a niche for itself. Moreover, the engineered niche is entirely dependent upon ongoing intervention to maintain this engineered niche. In the absence of civilization, the tightly-coupled cohort(s) of coveolving species would unravel, while naturally occurring instances of coevolution would continue unchanged, i.e., they would continue to coevolve. (I leave it as an exercise to the reader to compare this observation to Schrödinger’s definition of life in thermodynamic terms.)

The necessary role of an intelligent agent in maintaining a coevolutionary cohort of species points beyond the biological conception of civilization to the ecological conception of civilization, which in term points beyond civilizations constructed by biological agents to the possibility of niches constructed by any intelligent agent whatsoever. This makes the ecological conception of civilization more comprehensive than the biological conception of civilization, as the intelligent agents involved in niche construction need not be biological beings. However, biological beings are likely to be the intelligent agents with which civilization begins.

In the kind of universe we inhabit, during the Stelliferous Era biology represents the first possible emergence of intelligent agency, hence the first possibility of intelligent niche construction. (I could hedge a bit on this and instead assert that biological agents are the first likely emergence of intelligent agents, as Abraham Loeb has posited the possibility of life in the very early universe — cf. “The Habitable Epoch of the Early Universe” — but I consider this scenario to be unlikely, and the possibility of such life yielding civilization even less likely.) This biocentric possibility of intelligent niche construction can later be supplemented or replaced by later forms of emergent complexity consistent with intelligent agency and capable of niche construction (which latter could involve either building on existing forms of intelligent niche construction or innovating new forms of intelligent niche construction transcending what we today understand as civilization).

The biological conception of civilization — an engineered coevolving cohort of species — constitutes one possible form of niche construction. That is to say, in managing an ecosystem so that it produces a disproportionate number of the plants and animals consumed as food or other products for the use of the directing intelligent agent (human beings in our case), human beings have attained the first possible stage of intelligent niche construction, which is essentially a delineation of biocentric civilization, but the ecological conception of civilization can be adapted to the understanding of non-biocentric civilizations, as, for example, in the case the technocentric civilizations. The various kinds of civilization that we have seen on Earth — including but not limited to agrarian-ecclesiastical civilization and industrial-technological civilization — represent distinct forms of intelligent niche construction, and therefore all fall within the ecological conception of civilization. Civilizations constructed by post-biological agents in the form of technological beings may build upon these constructed niches or construct niches more distinctly adapted to post-biological agents (which may be technological agents).

The ecological conception of civilization lends itself to technocentric extrapolation in so far as the ecological recognition of the biology of planetary endemism being dependent on solar flux is readily adapted to conceptions of civilization that have emerged from the work of Dyson and Kardashev. Dyson famously imagined stars so surrounded by the productions of a technological civilization that only the waste heat of these civilizations would be visible to us in the infrared spectrum, and Kardashev equally famously translated this idea into a formalism representing civilization types in terms of total energy resources commanded by a civilization. Even these distant extrapolations of the possibility of our technological civilization are still recognizably dependent upon stellar flux, no less than the biomass of our terrestrial environment is dependent upon solar flux, as stellar flux represents the primary source of readily available energy during the Stelliferous Era. In this way, even technocentric civilizations constructed by post-biological intelligent agents are continuous with the civilizations of planetary endemism emerging from the biology of planetary surfaces, and both are describable in ecological terms.

ecological relationships

It could be said that the ecological conception of civilization presupposes the biological conception, because ecological systems supervene on biological systems (or, at least, ecological systems have supervened upon biological systems to date, but this is not a necessary relationship and may be superseded in the fullness of time), and an ecological perspective provides a conceptual framework placing civilization in the context of the natural world from which it emerged and upon which it depends, as well as placing any given civilization in the context of other civilizations. This latter function — providing a systematic framework for the interaction of civilizations — ultimately may be the most valuable aspect of the ecological conception of civilization, but one that can only be suggested at present. The ecological relationships familiar to us from the study of living organisms — mutualism (or symbiosis), commensalism, predation, and parasitism — may hold for civilizations also, but this kind of parallelism cannot be assumed. The ecological relationships among civilizations — i.e., among intelligent species that have engaged in niche construction — may well be more complex than the ecological relationships among organisms, but this is a matter for further study that I will not attempt to elaborate at present.

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Niche construction by intelligent agents.

Niche construction by intelligent agents.

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Grand Strategy Annex

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There are a lot of Earth-like planets out there, and they vary from Earth according to physical gradients.

There are a lot of Earth-like planets out there, and they vary from Earth according to physical gradients.

In my previous posts on planetary endemism (see links below) I started to explore the ideas of how civilization is shaped by the planet upon which a given civilization arises. I began to sketch a taxonomy based on developmental factors arising from planetary endemism, but I have realized the inadequacy of this. As I have no systematic idea for a taxonomy based on a more comprehensive understanding of planetary types, I must undertake a series of thought experiments to explore the relevant ideas in more detail. This I intend to do.

I should point out that taxonomy I began to sketch in my 2015 Starship Congress talk, “What kind of civilizations build starships?” — a taxonomy employing a binomial nomenclature based on a distinction between economic infrastructure and intellectual superstructure — still remains valid to make fine-grained distinctions among terrestrial civilizations, or indeed within the history of any civilization of planetary endemism. What I am seeking to do now to arrive at a more comprehensive taxonomy under which this more fine-grained taxonomy can be subsumed, and which, as a large-scale conception of civilization, is consistent with and integrated into our knowledge of cosmology and planetology.

While I have no systematic idea of taxonomy at present taking account of types of planets, I think I can identify a crucial question for this inquiry, and it is this:

What physical gradient is, or would be, correlated with the greatest qualitative gradient in the civilization supervening upon that physical gradient?

In other words, if we could experiment with civilization under controlled condition, systematically substituting different valuables for a given variable while holding all over variables constant, and these variables are the physical conditions to which a given planetary civilization is subject, which one of these variables when its value is changed would produce the greatest variation on the supervening civilization? A qualitative change in civilization yields another kind of civilization, so that if varying a physical condition produces a range of different kinds of civilizations, this is the variable to which we would want to pay the greatest attention in formulating a taxonomy of civilizations that takes into account the kind of planet on which a civilization arises. Understood in this way, civilization, or at least the kind of civilization, can be seen as an emergent property with the physical condition given a varying value as the substructure upon which emergent civilization supervenes.

Some gradients of physical conditions will be closely correlated: planet size correlates with surface area, surface gravity, and atmospheric density. These multiple physical conditions are in turn correlated with multiple constraints upon civilization. With the single variable of planet size correlated to so many different conditions and constraints upon civilization, planet size will probably figure prominently in a taxonomy of civilizations based on homeworld conditions. Large planets and small planets both have advantages and disadvantages for supervening civilizations. Large planets have a large surface area, but the higher gravity may pose an insuperable challenge for the emergence of spacefaring civilization. Small planets would pose less of a barrier to a spacefaring breakout, but they also have less surface area and probably a thinner atmosphere, possibly limiting the size of organisms that could survive in its biosphere. Also, there may be a point at which the surface area on a small planet falls below the minimum threshold necessary for the unimpeded development of civilization.

Planets too large or too small may be inhabitable, in terms of possessing a biosphere, but may be too challenging for a civilization to arise. Any intelligent being on a planet too large or too small would be faced with challenges too great to overcome, resulting in what Toynbee called an arrested civilization. But how large is too large, and how small is too small? We don’t have an answer for these questions yet, but to formulate the question explicitly provides a research agenda.

Other important physical gradients are likely to be temperature (or insolation, which largely determines the temperature of a planet), which can result in planets too hot (Venus) or too cold (Mars), and the amount of water present, which could mean a world too wet or too dry. A planet with a higher temperature would probably have a higher proportion of its surface as desert biomes, and possibly also a greater variety of desert biomes than we find on Earth, while a planet with a lower temperature would probably possess a more extensive cryosphere and a large proportion of it surface in arctic biomes. And a planet mostly ocean (i.e., too wet), with extensive island archipelagos, might foster the emergence of a vigorous seafaring civilization, or it might result in the civilizational equivalent of insular dwarfism. Again, we don’t yet know the parameters the values of these variables can take and still be consistent with the emergence of civilization, but to formulate the question is to contribute to the research agenda.

I think it is likely that we will someday be able to reduce to most significant variables to a small number — perhaps two, size and insolation, much as the two crucial variables for determining a biome are temperature and rainfall — and a variety of qualitatively distinct civilizations will be seen to emerge from variations to these variables — again, as in a wide variety of biomes that emerge from changes in temperature and rainfall. And, again, like ecology, we will probably begin with a haphazard system of taxonomy, as today we have several different taxonomies of biomes.

Civilizations (i.e., civilizations of planetary endemism during the Stelliferous Era) supervene upon biospheres, and a biosphere is a biome writ large. We can study the many terrestrial biomes found in the terrestrial biosphere, but we do not yet have a variety of biospheres to study. When we are able to study a variety of distinct biospheres, we will, of course, in the spirit of science, want to produce a taxonomy of biospheres. With a taxonomy of biospheres, we will be more than half way to a taxonomy of civilizations, and in this way astrobiology is immediately relevant to the study of civilization.

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Planetary Endemism

● Civilizations of Planetary Endemism: Introduction (forthcoming)

Civilizations of Planetary Endemism: Part I

Civilizations of Planetary Endemism: Part II

● Civilizations of Planetary Endemism: Part III

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Grand Strategy Annex

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three peaks 3

This post is intended as a quick addendum to my post The Apotheosis of Emergent Complexity, in which I considered, in turn, the respective peaks of star formation, life, and civilization during the Stelliferous Era, as exemplifying significant forms of emergent complexity in the universe.

peak 5

The apotheosis of emergent complexity recognized in that earlier post — when stars, life, and civilization are all represented — can be further narrowed in scope beyond the parameters I previously set. With the sole examples of ourselves as representing life and civilization, we can acknowledge a minimal form of the apotheosis of emergent complexity already extant, and as long as our civilization endures and continues in development it retains the possibility of seeing further emergent complexities arise. Among the further emergent complexities that could arise from terrestrial life and civilization is the possibility of this life and civilization expanding to other worlds. A simple expansion would represent the spatial and temporal extension of emergent complexity, but life and civilization almost certainly will be changed by their adaptation to other worlds, and this adaptive radiation on a cosmological scale may involve the emergence of further emergent complexity (in which case a fourth peak would need to be defined beyond stars, life, and civilization).

peak 6

An expansion of terrestrial life and civilization into the universe that constitutes an adaptive radiation on a cosmological scale, is an event that I have called the Great Voluntaristic Divergence (in Transhumanism and Adaptive Radiation) — “great” because it takes place on a cosmological scale that dwarfs known adaptive radiations on Earth by many orders of magnitude, “voluntaristic” because both the direction and the nature of the radiation and the adaptation will be a function of conscious and intelligent choice, and “divergence” because different choices will lead to the realization of diverse forms of life and civilization not existing, and not possible, on Earth alone. We can think of the Great Voluntaristic Divergence as a “forcing” event for the principle of plenitude. I have noted previously that cosmology is the principle of plenitude teaching by example. When the principle of plenitude works at the scale of the cosmos and at the level of complexity of civilization, further emergent complexity may yet transform the universe.

peak 7

If we take the peak of emergent complexity as beginning with the Great Voluntaristic Divergence, this peak of emergent complexity so conceived will end with the End Stelliferous Mass Extinction Event (which I first formulated in my Centauri Dreams post Who will read the Encyclopedia Galactica?). Once star formation ceases, the remaining stars will burn out one by one, and, as they wink out, the planetary surfaces on which they have been incubating life and civilizations will go dark. Any life or civilization that survives the coming darkness of the Degenerate Era, the Black Hole Era, and the Dark Era, will have to derive its energy flows from some source other than stellar energy flux concentrated on planetary surfaces, which I noted in my previous post, Civilizations of Planetary Endemism, typify the origins of civilizations during the Stelliferous Era.

peak 8

If life and civilization endure for so long as to confront the end of the Stelliferous Era, there will be plenty of time to prepare for alternative methods of harnessing energy flows. Moreover, I strongly suspect that the developmental course of advanced civilizations — the only kind of civilizations that could so endure — will experience demographic changes that will bring populations into equilibrium with their energy environment, much as we have seen birth rates plummet in advanced industrialized civilizations where scientific medicine reduces infant mortality, lengthens life, and increases the costs of child-rearing. When the End Stelliferous Mass Extinction Event is visited upon our distant descendants and their successor institution to civilization, their horizons will already have been altered to accommodate the change.

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Grand Strategy Annex

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David Christian and Stephen Jay Gould on Complexity

The development of the universe as we have been able to discern its course by means of science reveals a growth of emergent complexity against a background of virtually unchanging homogeneity. Some accounts of the universe emphasize the emergent complexity, while other accounts emphasize the virtually unchanging homogeneity. The school of historiography we now call Big History focuses on the emergent complexity. Indeed, Big Historians, most famously David Christian, employ a schematic hierarchy of emergent complexity for a periodization of the history of the universe entire.

David Christian, the best known figure in Big History, emphasizes emergent complexity over cosmological scales of time.

David Christian, the best known figure in Big History, emphasizes emergent complexity over cosmological scales of time.

In contradistinction to the narrative of emergent complexity, Stephen Jay Gould frequently emphasized the virtually unchanging homogeneity of the world. Gould argued that complexity is marginal, perhaps not even statistically significant. Life is dominated by the simplest forms of life, from its earliest emergence to the present day. Complexity has arisen as an inevitable byproduct of the fact that the only possible development away from the most rudimentary simplicity is toward greater complexity, but complexity in life remains marginal compared to the overwhelming rule of simplicity.

When we have the ability to pursue biology beyond Earth, to de-provincialize biology, as Carl Sagan put it, this judgment of Gould is likely to be affirmed and reaffirmed repeatedly, as we will likely find simple life to be relatively common in the universe, but complexity will be rare, and the more life we discover, the less that complex life will represent of the overall picture of life in the universe. And what Gould said of life we can generalize to all forms of emergent complexity; in a universe dominated by hydrogen and helium, as it was when it began with the big bang, the existence of stars, galaxies, and planets scarcely registers, and 13.7 billion years later the universe is still dominated by hydrogen and helium.

Stephen Jay Gould characterized emergent complexity as the 'long tail' of a right-skewed distribution that distracts us from the vast bulk of simple life.

Stephen Jay Gould characterized emergent complexity as the ‘long tail’ of a right-skewed distribution that distracts us from the vast bulk of simple life.

Here is how Gould characterized the place of biological complexity in Full House, his book devoted to an exposition of life shorn of any idea of a trend toward progress:

“I do not deny the phenomenon of increased complexity in life’s history — but I subject this conclusion to two restrictions that undermine its traditional hegemony as evolution’s defining feature. First, the phenomenon exists only in the pitifully limited and restricted sense of a few species extending the small right tail of a bell curve with an ever-constant mode at bacterial complexity — and not as a pervasive feature in the history of most lineages. Second, this restricted phenomenon arises as an incidental consequence — an ‘effect,’ in the terminology of Williams (1966) and Vrba (1980), rather than an intended result — of causes that include no mechanism for progress or increasing complexity in their main actions.”

Stephen Jay Gould, Full House: The Spread of Excellence from Plato to Darwin, 1996, p. 197

And Gould further explained the different motivations and central ideas of two of his most influential books:

Wonderful Life asserts the unpredictability and contingency of any particular event in evolution and emphasizes that the origin of Homo sapiens must be viewed as such an unrepeatable particular, not an expected consequence. Full House presents the general argument for denying that progress defines the history of life or even exists as a general trend at all. Within such a view of life-as-a-whole, humans can occupy no preferred status as a pinnacle or culmination. Life has always been dominated by its bacterial mode.”

Stephen Jay Gould, Full House: The Spread of Excellence from Plato to Darwin, 1996, p. 4

Gould’s work is through-and-through permeated by the Copernican principle, taken seriously and applied systematically to biology, paleontology, and anthropology. Gould not only denies the centrality of human beings to any narrative of life, he also denies any mechanism that would culminate in some future progress of complexity that would be definitive of life. Gould conceived a biological Copernicanism more radical than anything imagined by Copernicus or his successors in cosmology.

emergent complexity 0

Emergent Complexity during the Stelliferous Era

How are we to understand the cohort of emergent complexities of which we are a part and a representative, and therefore also possess a vested interest in magnifying the cosmic significance of this cohort? Our reflections on emergent complexity are reflexive (as we are, ourselves, an emergent complexity) and thus are non-constructive in the sense of being impredicative. Perhaps the question for us ought to be, how can we avoid misunderstanding emergent complexity? How are we to circumvent our cognitive biases, which, when projected on a cosmological scale, result in errors of a cosmological magnitude?

Emergent complexities represent the “middle ages” of the cosmos, which first comes out of great simplicity, and which will, in the fullness of time, return to great simplicity. In the meantime, the chaotic intermixing of the elements and parts of the universe can temporarily give rise to complexity. Emergent complexity does not appear in spite of entropy, but rather because of entropy. It is the entropic course of events that brings about the temporary admixture that is the world we know and love. And entropy will, in the same course of events, eventually bring about the dissolution of the temporary admixture that is emergent complexity. In this sense, and as against Gould, emergent complexity is a trend of cosmological history, but it is a trend that will be eventually reversed. Once reversed, once the universe enters well and truly upon its dissolution, emergent complexities will disappear one-by-one, and the trend will be toward simplicity.

We can't simply take the thresholds of emergent complexity recognized in Big History and reverse them in order to obtain the future history of the universe.

We can’t simply take the thresholds of emergent complexity recognized in Big History and reverse them in order to obtain the future history of the universe.

One could, on this basis, complete the sequence of emergent complexity employed in Big History by projecting its mirror image into the future, allowing for further emergent complexities prior to the onset of entropy-driven dissolution, except that the undoing of the world will not follow the same sequence of steps in reverse. If the evolution of the universe were phrased in sufficiently general terms, then certainly we could contrast the formation of matter in the past with the dissolution of matter in the future, but matter will not be undone by the reversal of stellar nucleosynthesis.

The Structure of Emergent Complexity

Among the emergent complexities are phenomena like the formation of stars and galaxies, and nucleosynthesis making chemical elements and minerals possible. But as human beings the emergent complexities that interest us the most, perhaps for purely anthropocentric reasons, are life and civilization. We are alive, and we have built a civilization for ourselves, and in life and civilization we see our origins and our end; they are the mirror of human life and ambition. If we were to find life and civilization elsewhere in the universe, we would find a mirror of ourselves which, no matter how alien, we could see some semblance of a reflection of our origins and our end.

Recognizable life would be life as we know it, as recognizable civilization would be civilization as we know it, presumably following from life as we know it. Life, i.e., life as we know it, is predicated upon planetary systems warmed by stars. Thus it might be tempting to say that the life-bearing period of the cosmos is entirely contained within the stelliferous, but that wouldn’t be exactly right. Even after star formation ceases entirely, planetary systems could continue to support life for billions of years yet. And, similarly, even after life has faded from the universe, civilization might continue for billions of years yet. But each development of a new level of emergent complexity must await the prior development of the emergent complexity upon which it is initially contingent, even if, once established in the universe, the later emergent complexity can outlive the specific conditions of its emergence. This results in the structure of emergent complexities not as a nested series wholly contained within more comprehensive conditions of possibility, but as overlapping peaks in which the conditio sine qua non of the later emergent may already be in decline when the next level of complexity appears.

The Ages of Cosmic History

In several posts — Who will read the Encyclopedia Galactica? and A Brief History of the Stelliferous Era — I have adopted the periodization of cosmic history formulated by Adams and Greg Laughlin, which distinguishes between the Primordial Era, the Stelliferous Era, the Degenerate Era, the Black Hole Era, and the Dark Era. The scale of time involved in this periodization is so vast that the “eras” might be said to embody both emergent complexity and unchanging homogeneity, without favoring either one.

The Primordial Era is the period of time between the big bang and when the first stars light up; the Stelliferous Era is dominated by stars and galaxies; during the Degenerate Era it is the degenerate remains of stars that dominate; after even degenerate remains of stars have dissipated only massive black holes remain in the Black Hole Era; after even the black holes dissipate, it is the Dark Era, when the universe quietly converges upon heat death. All of these ages of the universe, except perhaps the last, exhibit emergent complexity, and embrace a range of astrophysical processes, but adopting such sweeping periodizations the homogeneity of each era is made clear.

Big History’s first threshold of emergent complexity corresponds to the Primordial Era, but the remainder of its periodizations of emergent complexity are all entirely contained within the Stelliferous Era. I am not aware of any big history periodization that projects the far future as embraced by Adams and Laughlin’s five ages periodization. Big history looks forward to the ninth threshold, which comprises some unnamed, unknown emergent complexity, but it usually does not look as far into the future as the heat death of the universe. (The idea of the “ninth threshold” is a non-constructive concept, I will note — the idea that there will be some threshold and some new emergent complexity, but even as we acknowledge this, we also acknowledge that we do not know what this threshold will be, nor do we known anything of the emergent complexity that will characterize it). Another periodization of comparable scale, Eric Chaisson’s decomposition of cosmic history into the Energy Era, the Matter Era, and the Life Era, cut across Adams and Laughlin’s five ages of the universe, with the distinction between the Energy Era and the Matter Era decomposing the early history of the universe a little differently than the distinction between the Primordial Era and the Stelliferous Era.

peak 1

Peak Stelliferous

The “peak Stelliferous Era,” understood as the period of peak star formation during the Stelliferous Era, has already passed. The universe as defined by stars and galaxies is already in decline — terminal decline that will end in new stars ceasing the form, and then the stars that have formed up to that time eventually burning out, one by one, until none are left. First the bright blue stars will burn out, then the sun-like stars, and the dwarf stars will outlast them all, slowly burning their fuel for billions of years to come. That is still a long time in the future for us, but the end of the peak stelliferous is already a long time in the past for us.

In the paper The Complete Star Formation History of the Universe, by Alan Heavens, Benjamin Panter, Raul Jimenez, and James Dunlop, the authors note that the stellar birthrate peaked between five and eight billion years ago (with the authors of the paper arguing for the more recent peak). Both dates are near to being half the age of the universe, and our star and planetary system were only getting their start after the peak stelliferous had passed. Since the peak, star formation has fallen by an order of magnitude.


The paper cited above was from 2004. Since then, a detailed study star formation rates was widely reported in 2012, which located the peak of stellar birthrates about 11 billion years ago, or 2.7 billion years after the big bang, in which case the greater part of the Stelliferous Era that has elapsed to date has been after the peak of star formation. An even more recent paper, Cosmic Star Formation History, by Piero Madau and Mark Dickinson, argues for peak star formation about 3.5 billion years after the big bang. What all of these studies have in common is finding peak stellar birthrates billions years in the past, placing the present universe well after the peak stelliferous.

peak 2

Peak Life

A recent paper that was widely noted and discussed, On The History and Future of Cosmic Planet Formation by Peter Behroozi and Molly Peeples, argued that, “…the Universe will form over 10 times more planets than currently exist.” (Also cf. Most Earth-Like Worlds Have Yet to Be Born, According to Theoretical Study) Thus even though we have passed the peak of the Stelliferous in terms of star formation, we may not yet have reached the peak of the formation of habitable planets, and population of habitable planets must peak before planets actually inhabited by life as we know it can peak, thereby achieving peak life in the universe.

The Behroozi ane Peeples paper states:

“…we note that only 8% of the currently available gas around galaxies (i.e., within dark matter haloes) had been converted into stars at the Earth’s formation time (Behroozi et al. 2013c). Even discounting any future gas accretion onto haloes, continued cooling of the existing gas would result in Earth having formed earlier than at least 92% of other similar planets. For giant planets, which are more frequent around more metal-rich stars, we note that galaxy metallicities rise with both increasing cosmic time and stellar mass (Maiolino et al. 2008), so that future galaxies’ star formation will always take place at higher metallicities than past galaxies’ star formation. As a result, Jupiter would also have formed earlier than at least ~90% of all past and future giant planets.”

We do not know the large scale structure of life in the cosmos, whether in terms of space or time, so that we are not at present in a position to measure or determine peak life, in the way that contemporary science can at least approach an estimate of peak stelliferous. However, we can at least formulate the scientific resources that would be necessary to such a determination. The ability to take spectroscopic readings of exoplanet atmospheres, in the way that we can now employ powerful telescopes to see stars throughout the universe, would probably be sufficient to make an estimate of life throughout the universe. This is a distant but still an entirely conceivable technology, so that an understanding of the large scale structure of life in space and time need not elude us perpetually.

Even if life exclusively originated on Earth, the technological agency of civilization may engineer a period of peak life that follows long after the possibility of continued life on Earth has passed. Life in possession of technological agency can spread itself throughout the worlds of our galaxy, and then through the galaxies of the universe. But peak life, in so far as we limit ourselves to life as we know it, must taper off and come to an end with the end of the Stelliferous Era. Life in some form may continue on, but peak life, in the sense of an abundance of populated worlds of high biodiversity, is a function of a large number of worlds warmed by countless stars throughout our universe. As these stars slowly use up their fuel and no new stars form, there will be fewer and fewer worlds warmed by these stars. As stars go cold, worlds will go cold, one by one, throughout the universe, and life, even if it survives in some other, altered form, will occupy fewer and fewer worlds until no “worlds” in this sense remain at all. This inevitable decline of life, however abundantly or sparingly distributed throughout the cosmos, eventually ending in the extinction of life as we know it, I have called the End Stelliferous Mass Extinction Event (ESMEE).

peak 3

Peak Civilization

If we do not know when our universe will arrive at a period of peak life, even less do we know the period of peak civilization — whether it has already happened, whether it is right now, right here (if we are the only civilization the universe, and all that will ever be, then civilization Earth right now represents peak civilization), or whether peak civilization is still to come. We can, however, set parameters on peak civilization as we can set parameters on peak star formation of the Stelliferous Era and peak life.

The origins of civilization as we know it are contingent upon life as we known it, and life as we known it, as we have seen, is a function of the Stelliferous Era cosmos. However, civilization may be defined (among many other possible definitions) as life in possession of technological agency, and once life possesses technological agency it need not remain contingent upon the conditions of its origins. Some time ago in Human Beings: A Solar Species I addressed the idea that humanity is a solar species. Descriptively this is true at present, but it would be a logical fallacy to conflate the “is” of this present descriptive reality with an “ought” that prescribes out dependence upon our star, or even upon the system of stars that is the Stelliferous Era.

Civilization need not suffer from the End Stelliferous Mass Extinction Event as life must inevitably and eventually suffer. It could be argued that civilization as we know it (and, moreover, as defined above as “life in possession of technological agency”) is as contingent upon the conditions of the Stelliferous Era as is life as we known it. If we focus on the technological agency rather than upon life as we known it, even the far future of the universe offers amazing opportunities for civilization. The energy that we now derive from our star and from fossil fuels (itself a form of stored solar energy) we can derive on a far greater scale from angular momentum of rotating black holes (not mention other exotic forms of energy available to supercivilizations), and black holes and their resources will be available to civilizations even beyond the Degenerate Era following the Stelliferous Era, throughout the Black Hole Era.

Fred Adams and Greg Laughlin's five ages of the universe.

Fred Adams and Greg Laughlin’s five ages of the universe.

In Addendum on Degenerate Era Civilization and Cosmology is the Principle of Plenitude teaching by Example I considered some of the interesting possibilities remaining for civilization during the Degenerate Era, and I pushed this perspective even further in my long Centauri Dreams post Who will read the Encyclopedia Galactica?

It is not until the Dark Era that the universe leaves civilization with no extractable energy resources, so that, if we have not by that time found our way to another, younger universe, it is the end of the Black Hole Era, and not the end of the Stelliferous Era, that will spell the doom of civilization. As black holes fade into nothingness one by one, much like stars at the end of the Stelliferous Era, the civilizations dependent upon them will wink out of existence, and this will be the End Civilization Mass Extinction Event (ECMEE) — but only if there is a mass of civilizations at this time to go extinct. This would mark the end of the apotheosis of emergent complexity.

peak 4

The Apotheosis of Emergent Complexity

We can identify a period of time for our universe that we may call the apotheosis of emergent complexity, when stars are still forming, though on the decline, civilizations are only beginning to establish themselves in the cosmos, and life in the universe is at its peak. During this period, all of the forms of emergent complexity of which we are aware are simultaneously present, and the ecologies of galaxies, biospheres, and civilizations are all enmeshed each in the other.

It remains a possibility, perhaps even a likelihood, that further, unsuspected emergent complexities will grace the universe before its final dissolution in a heat death when the universe will be reduced to the thermodynamic equilibrium, which is the lowest common denominator of existence as we know it. Further forms of emergent complexity would require that we extend the framework I have suggested here, but, short of a robust and testable theory of the multiverse, which would extend the emergent complexity of stars, life, and civilizations to universes other than our own, the basic structure of the apotheosis of emergent complexity should remain as outlined above, even if extended by new forms.

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filter layers

In my recent post Is encephalization the Great Filter? I quoted Robin Hansen’s paper that gave the original formulation of the Great Filter. Again, Hanson wrote:

“Consider our best-guess evolutionary path to an explosion which leads to visible colonization of most of the visible universe… The Great Silence implies that one or more of these steps are very improbable; there is a ‘Great Filter’ along the path between simple dead stuff and explosive life. The vast vast majority of stuff that starts along this path never makes it. In fact, so far nothing among the billion trillion stars in our whole past universe has made it all the way along this path. (There may of course be such explosions outside our past light cone [Wesson 90].)”

Robin Hanson, The Great Filter — Are We Almost Past It? 15 Sept. 1998

In filtration technology, the “steps” between the input and the output of a filter are called “elements,” “layers,” or “media.” I will here speak of “elements” of the Great Filter, and I will here take seriously the idea that, “…one or more of these [elements] are very improbable.” In other words, the Great Filter may be one or many, and we do not yet know which one of these alternatives is the case. Most formulations of the Great Filter reduce it to a single factor, but I want to here explicitly consider the Great Filter as many.

What is the Great Filter filtering? Presumably, the higher forms of complexity that are represented by the successive terms of the Drake equation, and which Big History recognizes (according to a slightly different schema) as levels of emergent complexity. The highest forms of complexity of which we are aware seem to be very rare in the universe, whereas the relatively low level of complexity — like hydrogen atoms — seems to be very common in the universe. Somewhere between plentiful hydrogen atoms and scarce civilizations the Great Filter interposes. And there may yet be forms of complexity not yet emergent, and therefore a filter through which we have not yet passed.

Hanson mentions visible colonization of the visible universe — this is a different and a much stronger standard to overcome than that of mere intelligence or civilization. Our own civilization does not constitute visible colonization of the universe, in so far as visible colonization means the consequences of intelligent colonization of the universe are obvious in the visible spectrum, but there is a sense in which we are highly visible in the EM spectrum. Thus the scope of the “visibility” of a civilization can be construed narrowly or broadly.

Construed broadly, the “visible” colonization of the universe would mean that the effects of colonization of the universe would be somewhere obvious along some portion of the EM spectrum. We can imagine several such scenarios. It might have been that, as soon as human beings put up the first radio telescope, we would have immediately detected a universe crowded with intelligent radio signals. We might have rapidly come to a science of analyzing the classifying the variety of signals and signatures of exocivilizations in the way that we now routinely classify kinds of stars and galaxies and now, increasingly, exoplanets. Or it might have been that, as soon as we thought to look for the infrared signatures of Dyson civilizations, we would have found many of these signatures. Neither of these things did, in fact, happen, but we can entertain them as counterfactuals and we easily visualize how either could have been the case.

The difference between a universe that is visibly colonized and one that is not is like the difference between coming over the ridge of hill and seeing a vast forest spread out below — i.e., a natural landscape that came about without the intervention of intelligence — and coming over the ridge of a hill and seeing an equally vast landscape of a city spread out below, with roads and building and lights and so on — i.e., an obvious built environment that did not come about naturally — out of reach from a distance, but no less obvious for being out of reach. At present, when we look out into the cosmos we see the cosmological equivalent of the forest primeval — call it the cosmos primeval, if you will (with a nod to Longfellow’s Evangeline).

In the illustration below the Great Filter is everything that stands between an empty universe and a universe filled with visible colonization by intelligent agents and their civilization. The Great Filter is then broken down into seven (7) diminutive filters, each a filter “element” of the Great Filter, which correspond to the terms of the Drake Equation. We could choose other elements for the Great Filter than the terms of the Drake equation, but this is a familiar and accessible formalism so I will employ it without insisting that it is exhaustive or even the best breakdown of the elements of the Great Filter. The reader is free to substitute any other appropriate formalism as an expression of the Great Filter, with any number of elements.

drake equation 1

In this illustration the lower case letters along the left margin that correspond to arrows each stopped by an element of the Great Filter are to be understood as follows:

a – failure of stars to form

b – failure of planets to form

c – failure of planets to be consistent with the emergence of a biosphere

d – failure of planets consistent with the emergence of a biosphere to produce a biosphere

e – failure of a biosphere to produce intelligent life and civilization

f – failure of a civilization to produce technically detectable signatures

g – failure of a technologically detectable civilization to survive a period of time sufficient to communicate

h – a civilization on a trajectory toward visible colonization of the universe

Given a Great Filter constructed from a series of lesser filters, relations between the elements of the Great Filter (the individual lesser filters) describe possible permutations in the overall structure of the Great Filter, as I have attempted to illustrate in the image below.

great filter elements

In this illustration the pathways marked by arrows are to be understood as curves, the X axis of which is the difficulty of passing through an element of the Great Filter, and the Y axis of which marks the gradual emergence of complexity strung out in time, as follows:

A – An inverse logarithmic Great Filter in which successive elements of the filter are easier to pass through by an order of magnitude with each element

B – An inverse linear gradient Great Filter in which successive elements of the filter are easier to pass through by degrees defined by the gradient

C – A constant Great Filter in which each element is equally easy, or equally difficult, to pass

D – A linear gradient Great Filter in which successive elements of the filter are progressively more difficult to pass through, with the change in the degree of difficulty between any two elements defined by the gradient (call it Δe, for change in difficulty of passage through an element)

E – A logarithmic Great Filter in which successive elements of the filter are each progressively more difficult to pass through by an order of magnitude for each element (my drawings are, or course, inexact, so I appeal to the leniency of the reader to get my general drift).

In the case of a Great Filter of an inverse logarithmic scale, the first filter element is by far the most difficult to pass through, and every subsequent element is an order of magnitude easier to pass. Once given the universe, then, intelligence and civilization are nearly inevitable. While such a filter seems counter-intuitive (most filters begin with coarse filtration elements and proceed in steps to finer filtration elements), something like may be unconsciously in mind in the accounts of the universe as a place teaming not only with life, but with civilizations — what I have elsewhere called an intelligence-rich galactic habitable zone (IRGHZ) — and I note that such visions of an IRGHZ often invoke the idea of inevitability in relation to life and intelligence.

However, this is not the problem that the universe presents to us. We do not find ourselves in the position of having to explain the prolixity of civilization in the universe; rather, we find ourselves in the predicament of having to explain the silentium universi.

The above analysis ought to make it clear that, not only do we not know what the Great Filter is — i.e., we do not know if there is one factor, one element among others, that is the stumbling block to the broadly-based emergence of higher complexity — but also that we do not know the overall structure of the Great Filter. Even if I am right that encephalization could be singled out at the Great Filter (as I postulated in Is encephalization the Great Filter?), and the one especially difficult element of the Great Filter to pass beyond, there are still further filters that could prevent our civilization from developing into the kind of civilization that Hanson describes as visibly colonizing the universe, that is to say, a cosmologically visible civilization.

encephalization filter

We can easily project a universe with a spacefaring civilization so pervasive that the stars in their courses are diverted from any trajectory that would be based on natural forces, that the constellations would have an obviously artificial character, and that use of energy on a cosmological scale leaves unambiguous infrared traces due to waste heat. A universe that was home to such a civilization would have passed beyond a filtration element that we have not yet passed beyond.

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