Arthur C. Clarke’s tertium non datur

Saturday

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Arthur C. Clarke is best remembered for this science fiction stories, but many of his dicta and aphorisms have become common currency and are quoted and repeated to the point that their connection to their source is sometimes lost. (Clarke’s thought ranged widely and, interestingly, Clarke identified himself as a logical positivist.) Recently I quoted one of Clarke’s well-known sayings in Happy Birthday Nicolaus Copernicus!, as follows:

“Two possibilities exist: either we are alone in the Universe or we are not. Both are equally terrifying.”

quoted in Visions: How Science Will Revolutionize the Twenty-First Century (1999) by Michio Kaku, p. 295

In so saying, Clarke asserted a particular case of what is known as the logical law (or principle) of the excluded middle, which is also known as tertium non datur: the idea that, given a proposition and its negation, either one or the other of them must be true. This is also expressed in propositional logic as “P or not-P” (“P v ~P”). The principle of tertium non datur is not to be confused with the principle of non-contradiction, which can be formulated as “~(P & ~P).”

Even stating tertium non datur is controversial, because there are narrowly logical formulations as well as ontological formulations of potentially much greater breadth. This, of course, is what makes the principle fascinating and gives it its philosophical depth. Moreover, the principle of the excluded middle is subtly distinct from the principle of bivalence, though the two usually work in conjunction. Whereas the law of the excluded middle states that of a proposition and its negation, one of the other must be true, the principle of bivalence states that there are only two propositional truth values: true and false.

To get started, here is the principle of the excluded middle as formulated in The Cambridge Dictionary of Philosophy edited by Robert Audi:

principle of excluded middle, the principle that the disjunction of any (significant) statement with its negation is always true; e.g., ‘Either there is a tree over 500 feet tall or it is not the case that there is such a tree’. The principle is often confused with the principle of bivalence.

THE CAMBRIDGE DICTIONARY OF PHILOSOPHY second edition, General Editor Robert Audi, 1999, p. 738

And to continue the Oxbridge axis, here is the formulation from Simon Blackburn’s The Oxford Dictionary of Philosophy:

excluded middle, principle (or law) of The logical law asserting that either p or not-p. It excludes middle cases such as propositions being half correct or more or less right. The principle directly asserting that each proposition is either true or false is properly called the law of bivalence.

The Oxford Dictionary of Philosophy, Simon Blackburn, Oxford University Press, 1996, p. 129

For more partisan formulations, we turn to other sources. Mario Bunge formulated a narrowly syntactical conception of the law of the excluded middle in his Dictionary of Philosophy, which is intended to embody a scientistic approach to philosophy:

EXCLUDED MIDDLE A logical truth or tautology in ordinary (classical) logic: For every proposition p, p v ~p.

Dictionary of Philosophy, Mario Bunge, Prometheus Books, 1999, p. 89

By way of contrast, in D. Q. McInerny’s Being Logical: A Guide to Good Thinking we find a strikingly ontological formulation of the law of the excluded middle:

“Between being and nonbeing there is no middle state. Something either exists or it does not exist; there is no halfway point between the two.”

D. Q. McInerny, Being Logical: A Guide to Good Thinking, Part Two, The Basic Principles of Logic, 1. First Principles, p. 26

What these diverse formulations bring out for us is the difficulty of separating logical laws of how formal systems are to be constructed from ontological laws about how the world is constructed, and in so bringing out this difficulty, they show us the relation between the law of the excluded middle and the principle of bivalence, since the logical intuition that there are only two possible truth values of any one proposition — true or false — is so closely tied to our logical intuition that, of these two values, one or the other (but not both, which qualification is the principle of non-contradiction) must hold for any given (meaningful) proposition.

The powerful thing about Clarke’s observation is that it appeals to this admixture of logical intuitions and empirical intuitions, and in so doing seems to say something very compelling. Indeed, since I am myself a realist, and I think it can be shown that there is a fact of the matter that makes propositions true or false, I think that Clarke not only said something powerful, he also said something true: either there are extraterrestrial intelligences or there are not. It is humbling to contemplate either possibility: ourselves utterly alone in a vast universe with no other intelligent species or civilizations, or some other alien intelligence out there somewhere, unknown to us at present, but waiting to be discovered — or to discover us.

Although these logical intuitions are powerful, and have shaped human thought from its earliest times to the present day, the law of the excluded middle has not gone unquestioned, and indeed Clarke’s formulation gives us a wonderful opportunity to explore the consequences of the difference between constructive and non-constructive reasoning in terms of a concrete example.

To formulate the existence or non-existence of extraterrestrials in the form of a logical law like the law of the excluded middle makes the implicit realism of Clarke’s formulation obvious as soon as we think of it in these terms. In imagining the possibilities of our cosmic isolation or an unknown alien presence our terror rests on our intuitive, visceral feeling of realism, which is as immediate to us as the intuitions rooted in our own experiences as bodies.

The constructivist (at least, most species of constructivist, but not necessarily all) must deny the validity of the teritum non datur formulation of the presence of extraterrestrials, and in so doing the constructivist must pretend that our visceral feelings of realism are misleading or false, or must simply deny that these feelings exist. None of these are encouraging strategies, especially if one is committed to understanding the world by getting to the bottom of things rather than denying that they exist. Not only I am a realist, but I also believe strongly in the attempt to do justice to our intuitions, something that I have described in two related posts, Doing Justice to Our Intuitions and How to Formulate a Philosophical Argument on Gut Instinct.

In P or not-P (as well as in subsequent posts concerned with constructivism, What is the relationship between constructive and non-constructive mathematics? Intuitively Clear Slippery Concepts, and Kantian Non-constructivism) I surveyed constructivist and non-constructivist views of tertium non datur and suggested that constructivists and non-constructivists need each other, as each represents a distinct point of view on formal thought. Formal thought is enriched by these diverse perspectives.

But whereas non-constructive thought, which is largely comprised of classical realism, can accept both the constructivist and non-constructivist point of view, the many varieties of constructivism usually explicitly deny the validity of non-constructive methods and seek to systematically limit themselves to constructive methods and constructive principles. Most famously, L. E. J. Brouwer (whom I have previously discussed in Saying, Showing, Constructing and One Hundred Years of Intuitionism and Formalism) formulated the philosophy of mathematics we now know as intuitionism, which is predicated upon the explicit denial of the law of the excluded middle. Brouwer, and those following him such as Heyting, sought to formulate mathematical and logic reasoning without the use of tertium non datur.

Brouwer and the intuitionists (at least as I interpret them) were primarily concerned to combat the growing influence of Cantor and his set theory in mathematics, which seemed to them to license forms of mathematical reasoning that had gone off the rails. Cantor had gone too far, and the intuitionists wanted to reign him in. They were concerned about making judgments about infinite totalities (in this case, sets with an infinite number of members), which the law of the excluded middle, when applied to the infinite, allows one to do. This seems to give us the power to make deductions about matters we cannot either conceive or even (as it is sometimes said) survey. “Surveyability” became a buzz word in the philosophy of mathematics after Wittgenstein began using it in his posthumously published Remarks on the Foundations of Mathematics. Although Wittgenstein was not himself an intuitionist sensu stricto, his work set the tone for constructivist philosophy of mathematics.

Given the intuitionist rejection of the law of the excluded middle, it is not correct to say that there either is intelligent alien life in the universe or there is not intelligent alien life in the universe; to meaningfully make this statement, one would need to actually observe (inspect, survey) all possible locations where such alien intelligence might reside, and only after seeing it for oneself can one legitimately claim that there is or is not alien intelligence in the universe. For am example closer to home, it has been said that an intuitionist will deny the truth of the statement “either it is raining or it is not raining” without looking out the window to check and see. This can strike one as merely perverse, but we must take the position seriously, as I will try to show with the next example.

The day before the Battle of Salamis, Aristotle might have said that there would be a sea battle tomorrow or there would not be a sea battle tomorrow, and in this case the first would have been true; on other days, the second would have been true.

Already in classical antiquity, Aristotle brought out a striking feature of the law of the excluded middle, in a puzzle sometimes known as the “sea battle tomorrow.” The idea is simple: either there will be a sea battle tomorrow, or there will not be a sea battle tomorrow. We may not know anything about this battle, and as of today we do not even know if it will take place, but we can nevertheless confidently assert that either it will take place or it will not take place. This is the law of the excluded middle as applied to future contingents.

One way to think of this odd consequence of the law of the excluded middle is that when it is projected beyond the immediate circumstances of our ability to ascertain its truth by observation it becomes problematic. This is why the intuitionists reject it. Aristotle extrapolated the law of the excluded middle to the future, but we could just as well extrapolate it into the past. Historians do this all the time (either Alexander cut the Gordian Knot or Alexander did not cut the Gordian Knot), but because of our strong intuitive sense of historical realism this does not feel as odd as asserting that something that hasn’t happened yet either will happen or will not happen.

In terms of Clarke’s dichotomy, we could reformulate Aristotle’s puzzle about the sea battle tomorrow in terms of the discovery of alien intelligence tomorrow: either we will receive an alien radio broadcast tomorrow, or we will not receive an alien broadcast tomorrow. There is no third possibility. One way or another, the realist says, one of these propositions is true, and one of them is false. We do not know, today, which one of them is true and which one of them is false, but that does not mean that they do no possess definite truth values. The intuitionist says that the assertion today that we will or will not receive an alien radio broadcast is meaningless until tomorrow comes and we turn on our radio receivers to listen.

The intuitionists thus have an answer to this puzzling paradox that remains a problem for the realist. This is definitely a philosophical virtue for intuitionism, but, like all virtues, it comes at a price. It is not a price I am willing to pay. This path can also lead us to determinism — assuming that all future contingents have a definite truth value implies that they are set in stone — but I am also not a determinist (as I discussed in The Denial of Freedom as a Philosophical Problem), and so this intersection of my realism with my libertarian free willist orientation leaves me with a problem that I am not yet prepared to resolve. But that’s what makes life interesting.

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Happy Birthday Nicolaus Copernicus!

Tuesday

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Today we celebrate the 540^th anniversary of the birth of Nicolaus Copernicus. The great astronomer was born 19 February 1473 in Toruń, now part of Poland. The name of Copernicus belongs with the short list of thinkers who not only changed the direction of civilization, but also the nature and character of Western civilization. Copernicus as the distinction of having a cosmology named in his honor.

We would do well to recall how radically our understanding of the world has changed in relatively recent years. Up until the advent of modern science, several ancient traditions of Western civilization had come together in a comfortingly stable picture of the world in which all of Western society was deeply invested. The Aristotelian systematization of Christian theology carried out by Thomas Aquinas was especially influential. Questioning this framework was not welcome. But science was an idea whose time had come, and, as we all know, nothing can stop the progress of an idea whose time had come.

Copernicus began questioning this cosmology by putting the sun in the center of the universe; Galileo pointed his telescope into the heavens and showed that the sun has spots, the moon has mountains, and that Jupiter had moons of its own, the center of its own miniature planetary system. Others took up the mantle and went even farther: Tycho Brahe, Johannes Kepler, and eventually Newton and then Einstein.

Copernicus was a polymath, but essentially a theoretician. One must wonder if Copernicus ever read William of Ockham, since it was Ockham along with Copernicus who initiated the unraveling of the scholastic synthesis, out of which the modern world would rise like a Phoenix from the ashes of the medieval world. Ockham provided the theoretical justification for the sweeping simplification of cosmology that Copernicus effected; it is not outside the realm of possibility that the later theoretician read the work of the earlier.

Today, when our knowledge of cosmology is expanding at breathtaking speed, Copernicus is more relevant than ever. We find ourselves forced to consider and to reconsider the central Copernican idea from every possible angle. The Fermi Paradox and the Great Filter force us to seek new insights into Copernicanism. I quite literally think about Copernicanism every day, making Copernicus a living influence on my thought.

As our civilization grows in sophistication, the question “Are we alone?” becomes more and more pressing. Arthur C. Clarke wrote, “Two possibilities exist: either we are alone in the Universe or we are not. Both are equally terrifying.” This insight is profound in its simplicity. Thus we search for peer civilizations and peer life in the universe. That is to say, we look for other civilizations like ours, and for life that resembles us.

SETI must be considered a process of elimination, which I take to already have eliminated “near by” exocivilizations, although we cannot rule out the possibility that we currency find ourselves within the “halo” of a vanished cosmological civilization.

A peer civilization only slightly advanced over our own (say 100-500 years more industrial development), if it is in fact a peer and not incomprehensibly alien, would also be asking themselves “Are we alone?” They, too, would be equally terrified at being alone in the cosmos or at having another peer civilization present. Because we know that we exist as an industrial-technological civilization, and we know the extent to which we can eliminate peer civilizations in the immediate neighborhood of our own star, we can assume that a more advanced peer civilization would have an even more extensive sphere of SETI elimination. They would home in on us as incredibly interesting, as an exception to the rule of the eerie silence, in the same way that we seek out others like ourselves. That is to say, they would have found us, not least because they would be actively seeking us. So this may be considered an alternative formulation of the Fermi paradox.

Despite the growing tally of planets discovered in the habitable zones of stars, including nearby examples at Tau Ceti which lies within our SETI exclusion zone (which excludes only civilizations producing EM spectrum signals), there is no evidence that there are other peer civilizations, and advanced peer civilizations would already have found us — and they would be as excited by discovering us as we would be excited in discovering a peer civilization. There are none close, which we know from the SETI zone of exclusion; we must look further afield. Other peer civilizations would also likely have to look further afield. In looking further afield they would find us.

I don’t believe that any of this contradicts the Copernican principle in spirit. I think it is just a matter of random chance that our civilization happens to be the first industrial-technological civilization to emerge in the Milky Way, and possibly also the first in the local cluster of galaxies. We are, after all, an accidental world. However, it will take considerable refinement of this idea to show exactly how the uniqueness of human civilization (if it is in fact locally unique) is consistent with Copernicanism — and this keeps Copernicus in my thoughts.

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The Transplanetary Perspective

Saturday

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Though I’ve already written a longish post on the relationships among earth sciences, planetary sciences, and space sciences, and I feel that a definitive formulation of this relationship continues to elude me, so I continue to write about it and think about it, in the hope that this exercise in self-clarification will eventually culminate in a more-or-less satisfying account. Or maybe not. But I will continue to think about it nonetheless, and I take a keen interest in the steady stream of new findings in planetary sciences, such as in Newborn Star Study Reveals Never-Before-Seen Stage Of Planet Birth and The Primordial Star at the Edge of the Milky Way that Shouldn’t Exist Challenges Theories of Star Formation.

Part of the difficulty is that the earth sciences, planetary sciences, and space sciences, while all having roots that go back to the very beginnings of human scientific inquiry, are relatively recent in their current incarnations, and any distinctions among them are similarly recent. Also, all sciences begin on the earth (what I will below call “earth-originating”), and all natural sciences begin, in a sense, as earth sciences, because human civilization and the science it produces originates on the earth, so that there is an inherent ambiguity once these earth-originating sciences are extrapolated beyond the earth to other celestial bodies (moons, planetesimals, etc.), other planets in our solar systems, other solar systems around other stars, other star systems in other galaxies, and so on.

What does Michel Foucault have to do with planetary science?

There is a quote from Foucault that I have cited on several occasions that is (partially) relevant here:

Each of my works is a part of my own biography. For one or another reason I had the occasion to feel and live those things. To take a simple example, I used to work in a psychiatric hospital in the 1950s. After having studied philosophy, I wanted to see what madness was: I had been mad enough to study reason; I was reasonable enough to study madness. I was free to move from the patients to the attendants, for I had no precise role. It was the time of the blooming of neurosurgery, the beginning of psychopharmacology, the reign of the traditional institution. At first I accepted things as necessary, but then after three months (I am slow-minded!), I asked, “What is the necessity of these things?” After three years I left the job and went to Sweden in great personal discomfort and started to write a history of these practices. Madness and Civilization was intended to be a first volume. I like to write first volumes, and I hate to write second ones. It was perceived as a psychiatricide, but it was a description from history. You know the difference between a real science and a pseudoscience? A real science recognizes and accepts its own history without feeling attacked. When you tell a psychiatrist his mental institution came from the lazar house, he becomes infuriated.

Truth, Power, Self: An Interview with Michel Foucault — October 25th, 1982, Martin, L. H. et al (1988) Technologies of the Self: A Seminar with Michel Foucault, London: Tavistock. pp.9-15

The portion of the above most often quoted out of context is this:

You know the difference between a real science and a pseudoscience? A real science recognizes and accepts its own history without feeling attacked.

Far from the earth sciences, planetary sciences, and space sciences (or, rather, their predecessors) constituting pseudo-sciences, they are the very standard by which we ought to judge “hard” natural sciences, but as earth-originating sciences are extrapolated beyond the earth there may be an intellectual tension (hopefully, a creative tension) between the earth-specific forms of earth-originating sciences, and the generalized forms that these sciences take when earth-originating sciences are applied to other planets. I don’t think that planetary sciences and space sciences will feel “attacked” by their earth-originating predecessors, but the tendency to specialization in the most advanced natural sciences may well lead to territoriality among disciplines. This would be regrettable.

The generalization of earth-originating sciences into non-earth-specific planetary sciences and space science will be a necessary prerequisite to the long term growth of human civilization. A future interstellar civilization will be intensely interested in where in the galaxy valuable resources are to be found, in the same way that our planetary-based (and, currently, planetary-bound) civilization is intensely interested in the distribution of mineral resources under the surface of the earth. Much of the contemporary relationship between science and industry stems from this need for resources to fuel the fires of industry. (In this connection I urge the reader to consult the excellent book by Simon Winchester, The Map That Changed the World: William Smith and the Birth of Modern Geology, which traces the development of the first geophysical map of England to the search for coal seams.)

What coal and oil have been to planetary civilization, titanium and fissionables (inter alia) will be to interplanetary and interstellar civilization; and the role that coal and petroleum geology have played in the exploitation of coal and oil for planetary civilization will have their parallel in the role that planetary sciences and space sciences will have in the exploitation of resources necessary to interplanetary and interstellar civilization. To grow as a civilization, therefore, we need to adopt a transplanetary perspective in our sciences. This is already occurring.

Planetary formation must ultimately be understood in the context of stellar formation, since stars and planets ultimately coalesce from the same disc of gas and dust, and stellar formation must ultimately be understood in the context of galactic formation, since stars coalesce from the matter that swirls together as galaxies, and galactic formation must ultimately be understood in the context of the formation of galactic clouds, clusters, and superclusters, etc. In short, the entire structure of the universe is implicated in the formation of planets, and how we are to distinguish kinds of planets or generations of planets.

Astronomers distinguish between population I stars, population II stars, and population III stars (from youngest to oldest, respectively), based on their generation of enrichment with heavier elements (called the metallicity, or Z, of a star, i.e., its composition in terms of chemical elements other than hydrogen and helium) as a result of the nucleosynthesis of earlier generations of stars. To date, population III stars, hypothetically extremely metal-poor stars from the earliest ages of the universe (coincident with the advent of the stelliferous age and the universe “lighting up” with star light), have been postulated but not observed. However, some recently reported observations (The First Stars of the Universe — Major Discovery Announced by MIT) may be of a population III star.

It is to be expected that each of these populations of stars will have planetary systems typical of for these particular stellar populations (if they have planetary systems at all). If, then, we can refine the astrophysics and cosmology of stellar and planetary formation, breaking down population I stars into a more finely-grained account, perhaps even tracing back individual stars to individual stellar nurseries, it may be possible to determine the likely composition of solar systems (and therefore their resources available for commercial and industrial exploitation) derived from a given stellar nursery. Stars and their planetary systems, where these planetary systems exist, formed from one and the same concentration of gas and dust, so that there is a systematic correlation between the chemical composition of stars and their planetary systems, both in the case of our own solar system and in other solar and planetary systems that science has only recently begun to study. While stars and planets may form at different times and from different portions of a proto-planetary disc, the whole process of stellar and planetary formation constitutes a single natural history of a solar system.

As I noted above, this kind of research is already underway. Robert McGown has directed by attention to the paper Enhanced lithium depletion in Sun-like stars with orbiting planets published in Nature, which the authors conclude with this paragraph:

“It is known that solar-type stars with high metallicity have a high probability of hosting planets. Those solar analogues with low Li content (which is extremely easy to detect with simple spectroscopy) have an even higher probability of hosting exoplanets. Understanding the long-lasting mystery of the low Li abundance in the Sun appears to require proper modelling of the impact of planetary systems on the early evolution of solar analogue stars.”

“Enhanced lithium depletion in Sun-like stars with orbiting planets,” Garik Israelian, Elisa Delgado Mena1, Nuno Santos, Sergio Sousa, Michel Mayor, Stephane Udry, Carolina Domínguez Cerdeña1, Rafael Rebolo1, & Sofia Randich, Nature 462, 189-191 (12 November 2009)

The lithium-planetary system correlation suggests a range of research questions, such as the following: Is the sun especially rich or poor in any other element that might point to the existence or composition of a proto-planetary disc during stellar or planetary formation? Does the chemical composition of the planets of our solar system stand in any systemic or predictive relationship to the chemical composition of our sun as revealed by its spectrum? Does the spectrum of a star predict not only the presence or absence of a planetary system, but also the chemical composition of any planets? Does the chemical composition of planets predict the chemical composition of the stars they orbit?

The lithium-planetary system correlation also suggests research questions bearing upon stars that have no planetary system associated with them. While the technology does not yet exist to study in detail stars without planetary systems, improved telescopy and imaging techniques may provide data for such questions in the not distant future. The most obvious hypotheses to account for stars without associated planetary systems would include isolated stars formed from a proto-stellar mass with nothing left over for planets to form, and solar systems with asteroid belts as large as an entire solar system, such the the matter for planetary formation was available but no planets formed despite the existence of a proto-planetary disc. It is an especially interesting question whether lithium had any role to play in the planetary formation or the lack thereof in either of these cases.

However, lithium-planetary system correlation relies on our very sketchy knowledge of exoplanet systems at present. All of this knowledge is strongly skewed toward large planets that tug their stars around. Astronomers have been able to figure out the planetary system around Alpha Centauri because it is close enough to detect the smaller wiggles that would betray smaller planets, but even here we don’t have any information about what surrounds the star other than a few planets. Stars without any large planets at all might have many smaller planets, or they might have a solar system sized asteroid belt. There are probably also a few stars in which all the precursor materials managed to get into the star with very little left over for planets or asteroids.

Perhaps it could be said that lithium deficiency correlates with the absence of large planets, because we have no idea what may be surrounding stars with no detectable large planets — not until we have a very large telescope in orbit or on the moon. This too suggests interesting questions. How might the formation of large planets be correlated with lithium deficiency in a star? Also, it has been theorized that large planets clear debris out of a solar system, thereby making it possible for smallish, rocky planets to exist in a more stable planetary environment, and a more stable planetary environment likely correlates with the emergence of life and eventually industrial-technological civilization. Thus lithium-planetary system correlation could extend all the way to being a predictor of industrial-technological civilizations.

It might be fruitful to compare the lithium spectra from double (and triple) star systems with known systems including hot Jupiter exoplanets (some of which are just short of being companion stars) and stars that show no evidence of large planet formation. Also, it is worth considering whether double stars or hot Jupiters play a role in the formation of other planets, e.g., such a large gravitational mass might upset the proto planetary disc just enough that the disc congeals into (large) planets, whereas the absence of such a gravitational “trigger” might result in greater uniformity in the proto-planetary disc and therefore its failure to congeal into discrete planets.

Such inquiries are now only in their infancy, and we can both expect and look forward to a flowering of knowledge in the fields of planetary science and space science as the technology to image distant stars and planetary systems rapidly improves, and as access to earth orbit becomes routine, allowing for a robust multiplicity of telescopes in earth orbit outside the atmosphere.

Not only will science on the whole be stimulated by this research, but, as I have often argued, it is the intrinsic nature of industrial-technological civilization to be spurred on by scientific innovations that result in new technologies, and new technologies are engineered into new industries that go on to create new scientific instruments that increase and improve scientific knowledge. Thus the cycle that defines and drives industrial-technological civilization escalates. This cycle is nowhere even close to being exhausted; as I have just pointed out above, instead of a handful of telescopes in orbit, the next decades may see hundreds if not thousands of telescopes in orbit, as there are now thousands of telescopes on the surface of the earth.

Civilization itself will be the beneficiary of these developments, as it continues its spiral of technological progress with its unexpected and unpredicted advantages for human life and commercial opportunity. There is also the sheer joy of better understanding the world in which we live. All of these factors will continue to fuel the growth and diversification of civilization in the future, thus at least partially mitigating against the existential risk of permanent stagnation.

The transplanetary perspective resulting from the extrapolation and generalization of earth sciences into planetary science and space sciences is to be welcomed for these far-reaching benefits both practical and intellectual.

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Carl Sagan’s Dream

Monday

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I have finally watched the whole of Carl Sagan’s Cosmos: A Personal Journey television series. I have in earlier posts expressed my admiration for Kenneth Clark’s Civilisation: A Personal View and Jacob Bronowski’s The Ascent of Man, which I have watched numerous times, but, until now, Sagan’s Cosmos had eluded me. (And I didn’t even include it in my post Documentaries Worth Watching — because I hadn’t yet watched it when I wrote that.)

While the Cosmos series is ostensibly a popular exposition of cosmology — and even, we could say, Big History before big history was known as such, since Sagan insistently places human beings in their cosmological context — the Cold War, strangely, is never far from the surface. Sagan had evidently felt so sharply the existential threat of nuclear war that he returns to this human, all-too-human theme in several places in his exposition of the grandeur of the essentially impersonal, and therefore inhuman, cosmos.

This concern for nuclear war reaches its zenith in the final episode, “Who Speaks for Earth,” when Sagan recounts the narrative of a dream of nuclear war ending our terrestrial civilization. This dream sequence does not appear in the book version of Cosmos — perhaps it was included in the television series in order to give human interest to such a difficult topic.

Sagan narrates a dream sequence of visiting a planet that is home to an alien civilization. Gazing down on the planet from space, he sees the lighted night side of the planet, but as he watches, the whole world goes dark. He checks the “Book of Worlds” — what in an earlier episode he called the Encyclopedia Galactica, which I wrote about in Cyberspace and Outer Space — and finds that the world was rated as having less than a one percent chance of survival for the next hundred years.

As the narration continues, Sagan comforts himself for this loss by listening to radio and television broadcasts from Earth. Most of the snippets of news in this aural montage feature stories of atomic weapons or political tension. As he is listening, the broadcasts from Earth are interrupted and fall silent. Disturbed by this, wondering why the broadcasts from Earth suddenly stopped, he looks up the entry for Earth in the Book of Worlds, and reviews it. He finds that Earth, too, was given a chance of survival of less than one percent over the next hundred years. “Not very good odds,” as Sagan observes. He sees that terrestrial civilization has been destroyed by a full nuclear exchange, and he then recites a melancholy litany of things that will be no more with the end of human civilization.

Sagan uses this device of his dream of terrestrial civilization extinguished by nuclear war to introduce his theme of the episode — who speaks for Earth? After the dream narrative, Sagan then describes nuclear war again, in less personal but still horrific terms, and then asks, “We know who speaks for the nations, but who speaks for the earth?” This, then, allows Sagan another summary of his history of science, this time noting the dark underside of science as a part of human civilization. Sagan returns to the Library of Alexandria, where some of the first moments of the series are set. Thus Sagan comes full circle, in a nice narrative closure.

Sagan’s final recap of the history of science in this last episode mirrors an earlier theme from episode seven, “The Backbone of Night,” in which he discussed two distinct traditions of ancient Greek civilization, one that he traces to Democritus and Aristarchus, that is about the sunny uplands of the human intellect as revealed by the best science of which human beings are capable, which is then followed by an almost malevolent account of a counter-tradition that he traces to Pythagoras and Plato, in which the pursuit of knowledge gets caught up in mysticism, obscurantism, and superstition. Even from the earliest beginnings of the Western tradition, it seems, we are dogged by the dialectic of eros and thanatos.

In episode eight, “Journeys in Space and Time,” Sagan offers us a counter-factual history in which the early beginnings of science in ancient Greek civilization develop continuously and are never interrupted and derailed by the Dark Ages. Sagan speculates that we might now be going to the stars, in spaceships emblazoned with Greek letters, if we had not experienced a thousand year hiatus in the development of science. This idea reappears in a subtle way in Sagan’s dream narrative: when describing the alien civilization that falls silent he suggests that they might have come through a similarly dark time, that they were survivors of past catastrophes, only to be later destroyed by forces they could not control — like us. For Sagan, industrial-technological civilization is its own worst enemy.

It is interesting and instructive to compare Sagan’s historical perspective to that of Kenneth Clark, who begins his Civilisation: A Personal View in the midst of the European dark ages in order to make the point that civilization made it through this period, as Clark says, by the skin of our teeth. Sagan clearly thought that we are now only making it through by the skin of our teeth. The ever-present threat of nuclear war could end our civilization at any time, and that would be it for all of us. Another way to formulate this would be to say that, for Clark, the “great filter” of human civilization was the dark ages, while for Sagan the great filter is now.

Clark’s decision to begin in the dark ages was an elegant solution to the problem of how to tell the story of Western civilization without spending all 13 episodes on the Greeks and the Romans — something I would be tempted to do. The solution was to avoid classical antiquity altogether, and to begin with the pitiful remnants of the dark ages and how these gradually grew into a new civilization. Sagan approached this differently, distributing expositions of past and possible dark ages throughout his narrative, so that it appears in the first and the last episode and several of the episodes in between — as I said above, the spirit and the existential angst of the Cold War is never far below the surface of Cosmos.

Is the history of ancient science any less essential to Western civilization than the history of ancient art? I don’t like to admit it, but I don’t think so. I think that ancient art and ancient science are equally essential and implicated in the world today — and for that reason, equally dispensable. Sagan, then, could have adopted the same “solution” as Clark: avoid classical antiquity altogether, and start with the rebuilding of Western civilization after its early medieval nadir. But Clark got the dark ages out of the way, and, once finished with them, did not return to the theme of the end of civilization. For Sagan, the potential end of civilization is an ever-present menace, so that it could not be taken up in the first episode and then forgotten.

Another theme that appears in a subtle way in several episodes of Sagan’s Cosmos is that of the social responsibility of scientists. Sagan does not pose this in a strong or an explicit way, but it does come up from time to time, entangled as it is with the development of science and technology. If we recall one of antiquity’s greatest scientists, Archimedes, we remember that Archimedes was known for constructing engines of war for the defense of Syracuse, and that Archimedes himself was a victim of war, struck down by a soldier because he refused to leave his mathematical work.

In episode seven, “The Backbone of Night,” mentioned above for its contrast between the traditions of Democritus on the one hand and Pythagoras on the other (i.e., the contrast between science and mysticism), Sagan discusses how many philosophers of antiquity — including the greatest among them, Plato and Aristotle — defended retrograde institutions like slavery, and how they served tyrants. (This is, in essence, a Marxist argument that Plato and Aristotle were creating an ideological superstructure to defend the economic infrastructure of the society of which they were a privileged part.) I assume that this reference to tyrants was an oblique reference to Plato’s brief foray into practical politics when he visited the tyrant Dionysius II of Syracuse (yes, the same Syracuse) in the capacity of what we would today call a political adviser. Even Plato was insufficiently brilliant to transform the dissolute Dionysius II into a philosopher king.

This unsuccessful intervention in Syracuse is recounted in Plato’s seventh letter, and in the famous seventh letter Plato made in quite clear that he was doing exactly that he presented as the duty of the philosopher in his famous allegory of the cave in Book VII of Plato’s Republic: after the philosopher has, by his own effort, raised himself out of the cave of shadows and eventually come to look at the blinding form of The Good, he has an obligation to return to the cave of shadows to try to make those still chained below understand their bondage to mere appearances. Plato wrote that he did not want to be considered a mere man of words, and so he undertook his mission to Syracuse, although he was rebuffed and unsuccessful, as most philosophers who return to the cave of shadows are rebuffed by those they seek to enlighten.

Plato, then, took the responsibilities of the philosopher seriously — so seriously that he undertook a mission likely to fail. But who most needs our intervention? Should we preach to the choir, or should we attempt to pursue our intellectual ministry among the philosophical equivalents of prostitutes, beggars, and thieves? So Plato was no stranger to the social responsibility of the intellectual, and Plato’s mentor, Socrates, took the social responsibility of the intellectual so far as to die for it. Sagan has some harsh words for Plato, and perhaps some of them are deserved, but Plato lived in a dark time, after the defeat of Athens in the Peloponnesian war, and all his efforts must be seen in this context. Could he have done more? Perhaps. Could Socrates have done more? I think not. Socrates gave all.

In the last episode of Cosmos, “Who speaks for Earth?” that includes the dream narrative recounted above, Sagan says that he really has no idea why ancient civilization failed and gave way to barbarism, but that he would make one observation: that no scientist working at the Library of Alexandria ever questioned the injustices of the society of which he was a part. This is a echo of his earlier criticisms of Plato and Aristotle for defending the institution slavery. And despite disowning knowledge of why Greek civilization failed, he adds another explanation, related to the previous: that ancient science was an elite undertaking that did not broadly involve the mass of the people of antiquity.

It was precisely Plato’s desire to initiate the masses into what he called the “dear delight” of philosophy that inspired Plato to write so beautifully in a popular style (he wrote in dialogue form), and to convey his ideas in parables and allegories that are as enchanting as stories as they are compelling as philosophical analysis. Plato did what he could, but in a society in which there was no broadly-based moral revulsion of slavery, and in which literacy was quite low compared to the level of contemporary expectations, it was inevitable that much of what Plato and Aristotle said fell on deaf ears. Bertrand Russell, in discussing Aristotle’s disproportionate influence over medieval scholasticism pointed out that this was not Aristotle’s fault, but the result of Aristotle having produced his comprehensive body of work at the end of an intellectually creative period.

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The Halos of Vanished Civilizations

Monday

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What are the consequences from a cosmological point of view when an industrial-technological civilization comes to an end, whether destroying itself or succumbing to outside forces? What kind of trace will a vanished industrial-technological civilization leave in the universe?

An industrial-technological civilization that masters electromagnetic spectrum communications — i.e., ordinary radio and television signals — generates an expanding globe of EM signals as long as it is transmitting these signals. If an industrial-technological civilization that has been transmitting EM signals comes to an end, these signals cease to be generated, and the expanding globe of EM signals tapers off to silence at the interior of this globe, which means that there will be an expanding sphere of weakening EM signals. The thickness of this three-dimensional halo in light years will correspond to the age in years of the now-vanished industrial-technological civilization.

If precise measurements of the EM halo were possible, and its exact curvature could be determined, it would be possible to extrapolate the original source of the signal. Once the curvature of the halo has been determined, and therefore also the source, the measurement of the distance from the source to the inner boundary of the halo to the source in light years will yield the number of years that have elapsed since the end of the industrial-technological civilization in question.

While such signals would be very faint, and largely lost in the background radio noise of the universe, we cannot discount the possibility that advanced detection technology of the future might reveal such EM structures. The universe might contain these ghostly structures as a sequence of overlapping bubbles of EM radiation that describe the past structure of industrial-technological civilization in the universe.

It has been said that astronomy is a form of time travel, and the farther we look from Earth, the farther back we see in time. (This is called “look back time”). Thus we can think of astronomy as a kind of luminous archaeology. Another way to think of this is that the sky reveals a kind of luminous stratigraphy. The EM halos of vanished civilizations would also admit of a certain stratigraphy, since these halos would possess a definite structure.

The outermost stratigraphic layer of an EM halo would likely consist of the simplest kind of high energy radio signals without any kind of subtle modulation of the signal — like Morse code transmitted by radio, rather than vocal modulation. This would be followed, deeper within the EM halo, by analog radio modulation corresponding to spoken language. Next within the EM halo would be analogue television signals, and then digital television signals and data signals of the sort that would be transmitted by the radio link for the internet.

This, at least, is the approximate structure of Earth’s expanding EM halo, and if our civilization destroys itself (or is destroyed) in the near future, our EM halo would be approximately 100 light years thick. The longer we last, the thicker our EM halo.

An EM halo may drop off as an industrial-technological civilization makes the transition from openly radiated EM signals to the pervasive use of fiber optic cables, but if that civilization begins to expand within its solar system, and possesses numerous settlements in EM contact with each other (as I described in Cyberspace and Outer Space), then the halo will reflect these developments — this is further historical structure layered into the EM stratigraphy of the halo.

Given that the structure of a large EM halo would consist mostly of space empty of intelligent EM signals, much of the structure of these halos would be void. It is entirely possible that Earth at present lies within the void of an EM halo that both began and ceased to transmit prior to our ability to detect such signals.

In the event of human exploration of the cosmos, as we move outward within a possible void within a halo, it is possible that our first contact with a xenomorphic exocivilization will take the form of encountering the inner boundary of an EM halo, which as we pass through it, will reveal in reverse order the development of that civilization, beginning with its destruction and ending with its emergence.

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Biology Recapitulates Cosmology

Monday

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An idea that has had a great influence despite being at very least misleading and more often completely wrong is that of recapitulation — also called embryological parallelism or the biogenetic law (the latter by Ernst Haeckel, who was also the originator of ecology). Recapitulation was most famously summed up in the phrase:

Ontogeny recapitulates phylogeny.

The idea here is that the development of the individual organism recapitulates, or reproduces in miniature, the phylogenetic history of the species to which the individual belongs. The often mistaken idea of recapitulation as it has been applied to biology, however, did have fortunate although unintended benefits, because in looking for evidence of recapitulation biologists began seriously studying developmental processes. Early on this primarily took the form of experimental embryology, but later become more sophisticated. This developmental interest eventually led to the study of evolutionary developmental biology, which is now usually referred to as evo-devo.

Quine took up the theme of recapitulation in order to cleverly skewer metaphysics in the best tradition of Post-Positivist Thought, which he formulated as follows:

Ontology recapitulates philology.

In other words, ontology, in presuming to detail the structure of reality, just gives us back again the structure of language by which we have attempted to describe the world, however imperfectly. The implied corollary here is that different languages with different philologies will yield different ontologies (an idea better known as the Sapir–Whorf hypothesis).

So what has evo-devo and Quinean post-positivism to do with biology in relation to cosmology? We can understand the traditional recapitulation idea as a variation on another ancient human idea, that of the microcosm as a mirror of the macrocosm: the development of the individual as the microcosm mirrors the development of the species as the macrocosm. Similarly, terrestrial biology, as a complex ecological system on Earth, can be understood as the microcosm of the complex ecological system of cosmology, which here becomes the macrocosm. Thus as biology is the microcosm and cosmology the macrocosm, is it the case the biology recapitulates cosmology?

But do we even know, can be even say, what biology is or what cosmology is? Is it possible to make any generalization as sweeping as this without falling into incoherency? Generalizations are made, of course, but there is a question as to the legitimacy of any such generalization. The most common generalization about the whole of biology or cosmology is that they exhibit progress. Because this is one of the most common overall interpretations, it is only the interpretation that has been most refuted and has come under the heaviest attacks.

Stephen J. Gould has most memorably be associated with a consistent refusal to see progress in the history of life, and he expressed this forcefully in one of his later books, Full House: the Spread of Excellence from Plato to Darwin, in which he returns time and again to the theme that life is overwhelmingly simple, and the human tendency (which we would now call anthropic bias, following Nick Bostrom) to see progress in this history of life is to distort the history of life by interpreting the whole of life in terms of a thin tail of complexity that emerges merely because life has a minimal bound of complexity. Since life cannot become less complex and still remain life, the essential variability of life will, with time, eventually blunder onto greater complexity because there is nowhere else for life to go. But that does not make greater complexity a trend, much less a driving force that results in ever more complex and sophisticated life forms.

Gould wrote:

“…I can marshal an impressive array of arguments, both theoretical (the nature of the Darwinian mechanism) and factual (the overwhelming predominance of bacteria among living creatures), for denying that progress characterizes the history of life as a whole, or even represents an orienting force in evolution at all…”

Stephen J. Gould, Full House: the Spread of Excellence from Plato to Darwin

Gould writes a bit like Darwin, who called his own Origin of Species “one long argument,” so it can be difficult to get just the right quote from Gould to illustrate his argument and his point of view, so the quote above should not be considered definitive. Thus the following quote also cannot be called definitive, but it does give a sense of Gould’s “big picture” conception of his work, and even suggests an approach to cosmology consistent with Gould’s ideas:

“…this book does have broader ambitions, for the central argument of Full House does make a claim about the nature of reality… I am making my plea by gentle example, rather than by tendentious frontal assault in the empyrean realm of philosophical abstraction (the usual way to attack the nature of reality, and to guarantee limited attention for want of anchoring). I am asking my readers finally and truly to cash out the deepest meaning of the Darwinian revolution and to view natural reality as composed of varying individuals in populations — that is, to understand variation itself as irreducible, as ‘real’ in the sense of ‘what the world is made of.’ To do this, we must abandon a habit of thought as old as Plato and recognize the central fallacy in our tendency to depict populations either as average values (usually conceived as ‘typical’ and therefore representing the abstract essence or type of the system) or as extreme examples…”

Stephen J. Gould, Full House: the Spread of Excellence from Plato to Darwin

Gould, as the great enemy of progressivism (and, as we see in the above passage, a passionate advocate of nominalism), may be contrasted with Kevin Kelly’s explicit defense of progress in his recent book What Technology Wants (which I have written about in Civilization and the Technium and The Genealogy of the Technium). In Chapter 5 of his book, “Deep Progress,” Kelly takes the bull by the horns and against much recent thought and much well-justified cynicism, argues that progress is real. Aware of the difficulties his argument faces, Kelly states up from the expected objections:

“Any claim for progressive change over time must be viewed against the realities of inequality for billions, deteriorating regional environments, local war, genocide, and poverty. Nor can any rational person ignore the steady stream of new ills bred by our inventions and activities, including new problems generated by our well-intentioned attempts to heal old problems. The steady destruction of good things and people seems relentless. And it is.”

Kevin Kelly, What Technology Wants, Chapter 5

Despite these difficulties, Kelly soldiers on finishes his chapter on progress as follows:

“…there will be problems tomorrow because progress is not Utopia. It is easy to mistake progressivism as utopianism because where else does increasing and everlasting improvement point to except Utopia? Sadly, that confuses a direction with a destination. The future as unsoiled technological perfection is unattainable; the future as a territory of continuously expanding possibilities is not only attainable but also exactly the road we are on now.”

Kevin Kelly, What Technology Wants, Chapter 5

It is admirable that Kelly makes a distinction between progress as a direction of development and progress as an end or aim. What Kelly is doing here is to posit non-teleological progress, and this is an idea that deserves attention. Non-teleological progress only partially blunts the force of Gould’s determined opposition to finding progress in history, because Gould often assumes without stating that progress implies a goal toward which a progress of development is developing, but whether or not it answers all of Gould’s objections, it deserves attention if for no other reason than that it confounds expectations and assumptions about historical thought.

Kelly, in arguing for increasing complexity against a tradition denying historical progress or trends as anthropocentric, is himself part of another emerging tradition, that is the growing discipline of Big History. In the works of David Christian, Cynthia Stokes Brown, and Fred Spier, inter alia, the central theme of history conceived as a whole from the big bang to the present day is the theme of increasing complexity.

Does the universe, on the whole, exhibit increasing complexity? We could bring to cosmology essentially the same arguments that Gould used in biology, especially since Gould wrote that he had wider ambitions for his ideas. It would be easy to argue that the universe is overwhelmingly composed of hydrogen and helium, in the same way that life is overwhelmingly composed of bacteria. Just as life has a minimal bound of complexity, and only blunders into higher complexity because it has nowhere else to go, so too matter has a lower bound of complexity — ordinary baryonic matter composed of protons, neutrons, and electrons doesn’t get any simpler than hydrogen — and it could be said that it is only with accidental variation over time that complexity emerges in the universe because matter has nowhere else to go except in the direction of greater complexity.

Thus we can admit the existence of greater complexity in biology or cosmology, but it would be a mistake to argue that this complexity is the telos of the whole, or that it is a trend, or that it is even predominant. In fact, we know that bacteria predominate in life and that hydrogen predominates in cosmology. The later emergence of complexity does not alter the overwhelming predominance of the simple, and to judge of the whole by a long and very narrow tail of complexity is to allow the tail to wag the dog.

Between the inner intimacies of biology that transpire unnoticed within our bodies, and the distant and impersonal life cycles of stars and galaxies and the cosmos, unnoticed by us because it is too large and too slow to play a role in human perception, there lies the broad ground of human history. Even if biology and cosmology can be interpreted in terms of overwhelming simplicity and the absence of any trend or progress, does this have any relevance for human affairs?

It should be evident that human history, the macroscopic doings of human beings on a human scale of time, can be interpreted either according to the Gould model or according to the model of progress that one finds in Kevin Kelly and Big History.

I have mentioned in an earlier post, Taking Responsibility for Our Interpretations, how I came to realize that history can be a powerful method of conveying an interpretation, and it is wrong to understand history in the sense of a list of names, dates, and places in the spirit of what might be called histoire vérité.

This is a sense of historiography most famously attributed to Leopold van Ranke, who wrote:

“History has had assigned to it the office of judging the past and of instructing the account for the benefit of future ages. To show high offices the present work does not presume; it seeks only to show what actually happened [wie es eigentlich gewesen].”

Later historians have endlessly debated what exactly Ranke had in mind when he mentioned showing that actually happened; even if Ranke thought (as he is usually interpreted) that there is a single unique and correct account of history, there is no single and unique account of Ranke.

There is an Hegelian interpretation of Ranke’s much-discussed aside on showing what actually happened (“wie es eigentlich gewesen,” which has, of course, been translated in varying ways), according to which “gewesen” must be understood in an essentialist sense, so that to say what really happened is to give the essence of what happened — and this, I hope you will agree, can be very different from giving “the facts, just the facts.”

This Hegelian-essentialist interpretation of Ranke is illuminated by a famous aphorism of Hegel’s such that, “The real is the rational and the rational is the real.” When this is read through contemporary spectacles it doesn’t make any sense at all, because we tend to think of the “real” as that which really is or really happened, and we know very well that the world as it is has no end of irrationality in it, so that to say that for Hegel to say that the real is the rational makes Hegel look like a fool or worse. If, however, we understand the “real” to be the essentially true, or even the genuine — so that Hegel’s aphorism can be rendered, “The genuine is the rational and the rational is the genuine” — it suddenly becomes clear how the real and the rational might be systematically interrelated.

Here we encounter the deeper ontological substratum of these divergent interpretations of history, whether natural, human, or cosmological. The difference between the orientation of Gould and the orientation of Kelly and others is the difference between nominalism and essentialism. Nominalist historiography can give us all the facts, but ultimately cannot do anything more than sum up the facts. If you sum up the totality of life or the totality of matter in the universe, you are forced to acknowledge that life is overwhelmingly bacteriological in nature, and the universe is overwhelmingly composed of hydrogen and helium.

There is, for the nominalist, nothing to say beyond this. The essentialist, however, finds a narrative buried within the mountain of facts, but there are many essentialists, and they all have their own narratives. And essentialism is weakened by the one thing that can never touch nominalism: underdetermination. All essentialist accounts are underdetermined by the evidence. Nominalist accounts on principle never go beyond the evidence, and for that reason they are not underdetermined by the evidence, but they are also unable to say anything relevant about the meanings and values that constitute the daily bread and butter of human life. And so our strict conscience may suggest to us that we ought to stop with nominalism, but our less-than-strict human conscience suggests to us that there is something more than an undifferentiated mountain of facts.

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The Visibility Presumption

Friday

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SETI visibility

How “visible” is any given industrial-technological civilization from the perspective of interstellar distances? In this context, “visible” means some technological sign that can be detected by technological means. Most obviously this includes any electromagnetic spectrum emissions, but might also include large scale engineering and industrial projects that could be discerned at interstellar distances.

SETI is based upon what we will here call the visibility presumption. SETI can’t really operate in any other way; if you’re going to conduct a search at the present, there are only so many things you can do with current technology at interstellar distances.

In the future (and not all that long from now — in the next ten to twenty years), as I have mentioned in other posts, we will be able to take the spectrum of the atmospheres of exoplanets and from this information we will be able to conduct a genuine Search for Extra-Terrestrial Life (SETL, presumably) by identifying biochemistry in exoplanet atmospheres. Such techniques might also reveal the activities of a civilization prior to the kind of electromechanical technologies that typify industrial-technological civilization and imply the mastery of electromagnetic spectrum emissions.

For the time being, such investigations are just beyond present technology and, as a result, extraterrestrial life that falls below the threshold of industrial-technological civilization with a mastery of electromagnetic technologies is “invisible” to us. In other words, such sub-technological civilizations, or life without civilization, lacks SETI visibility.

Many have commented that, in light of SETI visibility, what we call the search for extraterrestrial intelligence ought to be called something like the search for extraterrestrial technology or the search for advanced extraterrestrial civilizations — but we can keep the familiar SETI acronym by thinking of it as the Search for Extra-Terrestrial Industrialization.

Employing our technology to search for signs of an alien technology is essentially to search for a peer civilization, i.e., another industrial-technological civilization: we are staring into the heavens and trying to find ourselves in the mirror. Not exactly ourselves, but something that would identifiable as life, as intelligence, as rationality, as civilization, and as technology. The visibility presumption implicitly incorporates all of these variables and assumes that the parameters of each variable will be just enough to challenge our assumptions without being so profoundly alien as to be unidentifiable by us as species of a familiar genus.

Recent thought concerning the emergence of a post-human future in the wake of a technological singularity has given a great impetus to the discussion of beings or institutions so changed by rapidly evolving technology that either we would not be able to recognize them, or they would not find us sufficiently interesting to communicate with us. In other words, the technological singularity could make xenocivilization invisible to us or make us essentially invisible (in the sense of being beneath notice) to a xenocivilization, thus posing a challenge to the assumptions of the visibility presumption that another industrial-technological civilization in the galaxy would be a peer civilization and visible to us.

Since I have posted quite a bit recently about the Fermi paradox, I have taken the trouble to look up one of the more thorough books on the topic, If the universe is teeming with aliens… where is everybody?: fifty solutions to the Fermi paradox and the problem of extraterrestrial life by Stephen Webb. The author divides up the solutions according to three broad categories, “They Are Here,” “They Exist But Have Not Yet Communicated,” and “They Do Not Exist.” The Wikipedia entry on the Fermi paradox also incorporates a long list of possible responses to the silentium universi.

Solution No. 28 in Webb’s book, and also mentioned on Wikipedia entry, is that xenocivilizations experience a technological singularity and therefore engage in the cosmic equivalent of Tune in, Turn on, Drop out. Here is what Webb writes:

“Vinge argues that if the Singularity is possible, then it will happen. It has something of the character of a universal law: it will occur whenever intelligent computers learn how to produce even more intelligent computers. If ETCs develop computers — since we routinely assume they will develop radio telescopes, we should assume they will develop computers — then the Singularity will happen to them, too. This, then, is Vinge’s explanation of the Fermi paradox: alien civilizations hit the Singularity and become super-intelligent, transcendent, unknowable beings.”

Stephen Webb, If the universe is teeming with aliens… where is everybody?: fifty solutions to the Fermi paradox and the problem of extraterrestrial life, New York: Praxis Publishing Ltd, 2002, p. 135

This is in itself a complex response to the Fermi paradox, because different people understand different things by the “technological singularity,” and it could just as plausibly be argued that a species experiencing a technological singularity would have its ability to communicate within the known universe exponentially increased and improved, which in turn poses the Fermi paradox in an even stronger form: if alien technological intelligence is so advanced, and has so many technological and intellectual resources at its command, why is it still unable to communicate across interstellar distances? (The protean character of the singularity thesis — anyone seems to be able to make of it what they will — is one reason that I have characterized it as a quasi-theological belief.)

Once the Fermi paradox is posed again in a stronger form, we must have recourse to other familiar responses, such as the singularity makes them lose interest in the outside world, or the technological singularity destroys the civilization in question, and so forth.

Does the idea of a technological singularity or a post-biological future (for ourselves or for some other xenobiological species) fundamentally challenge the visibility presumption?

Recently in Cyberspace and Outer Space I suggested that any civilization expanding beyond its native planet (or other naturally occurring celestial body that is the home of life elsewhere) would almost certainly have some kind of pervasively present radio or EM spectrum communication system — an internet for the solar system, which Heath Rezabek has called a solarnet — and such a network would be highly visible, and perhaps even unintentionally visible, even at interstellar distances.

This can be formulated in even a stronger form: because civilizations that remain exclusively based on their native planets are highly vulnerable to natural disasters, and therefore potentially vulnerable to natural disasters of sufficient scope and scale to result in extinction, such civilizations could be expected to have shorter lifespans and to therefore be less represented in the universe. In other words, exclusively planetary civilizations would be disproportionately selected for extinction.

What we would expect to find in our survey of the cosmos are those long-lived civilizations with the most robust survival mechanisms — redundancy, dispersion, diversity — and robust survival mechanisms of redundancy and dispersion will mean communication between dispersed centers of the civilization in question, and this communication would likely have a high visibility profile — although it could be argued that one survival mechanism would be to go to ground and remain silent so as not to be exterminated by hostile civilizations.

The same considerations of survivability would apply to any civilization that experienced a technological singularity and had subsequently made the transition to post-biological being. While it is fun to imagine mega-engineering projects like a matrioshka brain, a ringworld, an Alderson disk or a Dyson sphere, such massive projects would be very vulnerable, even for an advanced civilization. Horace said that you can drive out Nature with a pitchfork, but she keeps on coming back, and this remains true even at cosmological scales.

One of the arguments made for the Matrioshka brain scenario is that of keeping the whole structure of a massive super-intelligent entity compact in order to reduce communication times between its parts (the speed of light would be where the shoe pinches for a Matrioshka brain), but no super-intelligent entity, biological, post-biological, or non-biological, would put all its eggs in one basket unless its technological hubris had reached the point of considering itself invulnerable. Such hubris would eventually be punished and the brain would go extinct in one fell swoop. Natural selection does not and would not spare technological entities, though it would operate on a cosmological scale rather than at the familiar scale of planetary niches.

It would make much more sense to make the same effort to construct many different megastructures that remain structurally independent but in continuous communication with each other. Since electrical or fiber optic cables strung in space would be even more vulnerable than structures, these independent megastructures would be hard-pressed to find any more robust and survivable form of communication than good old EM spectrum communications, and if multiple megastructures employing massive energy levels were in continuously in communication with each other by way of EM spectrum communication, such a xenocivilization would have a very high visibility profile unless it made a conscious effort to suppress its visibility — which latter is a distinct response to the Fermi paradox.

The technological singularity or post-biological beings do not, in and of themselves, apart from distinct assumptions, argue against the visibility presumption.

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Earth Science, Planetary Science, Space Science

Wednesday

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Earth and the moon in one frame as seen from the Galileo spacecraft 6.2 million kilometers away. (from Picture of Earth from Space by Fraser Cain)

It is ironic, though not particularly paradoxical, that the earth sciences as we known them today only came into being as the result of the emergence of space science, and space science was a consequence of the advent of the Space Age. We had to leave the Earth and travel into space in order to see the Earth for what it is. Why was this the case, and what do I mean by this?

It has often been commented that we had to go into space in order to discover the earth, which is to say, to understand that the earth is a blue oasis in the blackness of space. The early images of the space program had a profound effect on human self-understanding. Photographs (as much or more than any theory) provided the theoretical context that allowed us to have a unified perspective on the Earth as part of a system of worlds in space. Once we saw the Earth for what it was, What Carl Sagan called a “pale blue dot” in the blackness of space, drove home a new perspective on the human condition that could not be forgotten once it had been glimpsed.

To learn that our sun was a star among stars, and that the stars were suns in their own right, that the Earth is a planet among planets, and perhaps other planets are other Earths, has been a long epistemic struggle for humanity. That the Milky Way is a galaxy among galaxies, a point that has been particularly driven home by recent observational cosmology as with the Hubble Ultra-Deep Field (UDF) image (and now the Hubble eXtreme-Deep Field (XDF) image), is an idea that we still today struggle to comprehend. The planethood of the Earth, the stellarhood of the sun, the galaxyhood of the Milky Way are all exercises in contextualizing our place in the universe, and therefore an exercise in Copernicanism.

But I am getting ahead of myself. I wanted to discuss the earth sciences, and to try to understand what they are and how they have become what they are. What are the Earth sciences? The Biology Online website has this brief and concise definition of the earth sciences:

The Earth Sciences, investigating the way our planet works and the mechanisms of nature that drive it.

The geology.com website has a more detailed definition of the earth sciences that already hints at their relation to the space sciences:

Earth Science is the study of the Earth and its neighbors in space… Many different sciences are used to learn about the earth, however, the four basic areas of Earth science study are: geology, meteorology, oceanography and astronomy.

For a more detailed overview of the earth sciences, the Earth Science Literacy Initiative (ESLI), funded by the National Science Foundation, has formulated nine “big ideas” of earth science that it has published in its pamphlet Earth Science Literacy Principles. Here are the nine big ideas taken from their pamphlet:

1. Earth scientists use repeatable observations and testable ideas to understand and explain our planet.

2. Earth is 4.6 billion years old.

3. Earth is a complex system of interacting rock, water, air, and life.

4. Earth is continuously changing.

5. Earth is the water planet.

6. Life evolves on a dynamic Earth and continuously modifies Earth.

7. Humans depend on Earth for resources.

8. Natural hazards pose risks to humans.

9. Humans significantly alter the Earth.

Each of these “big ideas” is further elaborated in subheadings that frequently bring out the planethood of the Earth. For example, section 2.2 reads:

Our Solar System formed from a vast cloud of gas and dust 4.6 billion years ago. Some of this gas and dust was the remains of the supernova explosion of a previous star; our bodies are therefore made of “stardust.” This age of 4.6 billion years is well established from the decay rates of radioactive elements found in meteorites and rocks from the Moon.

Intuitively, we would say that the earth sciences are those sciences that study the Earth and its natural processes, but the rapid expansion of scientific knowledge has made us realize that the Earth is not a closed system that can be studied in isolation. The Earth is part of a system — the solar system, and beyond that a galactic system, etc. — and must be studied as part of this system. But we didn’t always know this, and this comprehensive conception of earth science is still in the process of formulation.

The realization that the processes of the Earth and the sciences that study these processes must ultimately be placed in a cosmological context means that contemporary earth science is now, like astrobiology, which seeks to place biology in a cosmological context, a fully Copernican science, though not perhaps quite as explicitly as in the case of astrobiology. The very idea of Earth science as it is understood today, like planetary science and space science, is essentially Copernican; Copernicanism is now the telos of all the sciences. Copernican civilization needs Copernican sciences. As I said in my presentation to this year’s 100YSS symposium, the scope of an industrial-technological civilization corresponds to the scope of the science that enables this civilization.

What this means is that the sciences that generations of Earth-bound scientists have labored to create in order to describe the planet upon which they have lived, which was the only planet that they could know prior to the advent of space science, are all planetary sciences in embryo — all potentially Copernican sciences that can be extended beyond the Earth that was their inspiration and origin. Before space science, all science was geocentric and therefore essentially Ptolemaic. Space science changed that, and now all the sciences are gradually becoming Copernican.

In the case of earth science, this is a powerful scientific model because the earth sciences have been, by definition, geocentric. That even geocentric sciences can become Copernican is a powerful lesson and provides a model for other sciences to follow. I have often quoted Foucault as saying that “A real science recognizes and accepts its own history without feeling attacked.” I think it can be honestly said that the geosciences recognize and accept their history as geocentric sciences and this in no way inhibits their ability to transcend their geocentric origins and become Copernican sciences no longer exclusively tied to the Earth. I find this rather hopeful for the future of science.

Another way to conceptualize earth science is to think of the earth sciences as those sciences that have come to recognize the planethood of the Earth. This places the Earth in its planetary context among other planets of our solar system, and it also places these planets (as well as the growing roster of exoplanets) in the context of planetary history that we have learned first-hand from the Earth.

To a certain extent, earth science and planetary science (or planetology) are convertible: each is increasingly formulated and refined in reference to the other. What is planetary science? Here is the Wikipedia definition of planetary science:

Planetary science (rarely planetology) is the scientific study of planets (including Earth), moons, and planetary systems, in particular those of the Solar System and the processes that form them. It studies objects ranging in size from micrometeoroids to gas giants, aiming to determine their composition, dynamics, formation, interrelations and history. It is a strongly interdisciplinary field, originally growing from astronomy and earth science, but which now incorporates many disciplines, including planetary astronomy, planetary geology (together with geochemistry and geophysics), atmospheric science, oceanography, hydrology, theoretical planetary science, glaciology, and the study of extrasolar planets.[1] Allied disciplines include space physics, when concerned with the effects of the Sun on the bodies of the Solar System, and astrobiology.

The Division for Planetary Sciences of the American Astronomical Society doesn’t give us the convenience of a definition for planetary science, but in its offerings on A Planet Orbiting Two Suns, A Thousand New Planets, Buried Mars Carbonates, The Lunar Core, Propeller Moons of Saturn, A Six-Planet System, Carbon Dioxide Gullies on Mars, and many others, give us concrete examples of planetary science which examples may, in certain ways, be more helpful than an explicit definition.

Jupiter’s moon Europa may have liquid water beneath its icy surface, kept warm inside by the enormous gravitational forces of Jupiter. Planet science is endlessly fascinating, and we learn new things about planetology almost every day.

The “aims and scope” of the journal Earth and Planetary Science Letters also give something of a sense of what planetary science is:

Earth and Planetary Science Letters (EPSL) is the journal for researchers, policymakers and practitioners from the broad Earth and planetary sciences community. It publishes concise, highly cited articles (“Letters”) focusing on physical, chemical and mechanical processes as well as general properties of the Earth and planets — from their deep interiors to their atmospheres. Extensive data sets are included as electronic supplements and contribute to the short publication times. EPSL also includes a Frontiers section, featuring high-profile synthesis articles by leading experts to bring cutting-edge topics to the broader community.

A recent (2006) controversy over the status of Pluto as a planet led to an attempt by The International Astronomical Union (IAU) to formulate a more precise definition of what a planet is. The definition upon which they settled demoted Pluto from being a planet to being a dwarf planet. While this decision does not have complete unanimity, it is gaining ground in the literature. Here is the IAU of planets, dwarf planets, and small solar system bodies:

(1) A planet is a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and (c) has cleared the neighbourhood around its orbit.
(2) A “dwarf planet” is a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, (c) has not cleared the neighbourhood around its orbit, and (d) is not a satellite.
(3) All other objects, except satellites, orbiting the Sun shall be referred to collectively as “Small Solar System Bodies.”

With this greater precision of definition than had previously been the case in regard to planets, we could easily define planetary science as the study of celestial bodies that (a) are in orbit around the Sun, (b) have sufficient mass for their self-gravity to overcome rigid body forces so that they assume a hydrostatic equilibrium (nearly round) shape, and (c) have cleared the neighbourhood around their orbits. Of course, this ultimately won’t do, because a comprehensive planetary science will want to study all three classes of celestial bodies detailed above, and will especially want to study the mechanisms of planet formation, dwarf planet formation, and small object formation for the light that each shines on the other. Like the Earth, that is part of a larger system, all the planets are also part of a larger system, and how they relate to that system will have much to teach us about solar system formation.

This more comprehensive perspective brings us to the space sciences. What is space science? The Wikipedia entry on space sciences characterizes them in this way:

The term space science may mean:

●The study of issues specifically related to space travel and space exploration, including space medicine.

●Science performed in outer space (see space research).

●The study of everything in outer space; this is sometimes called astronomy, but more recently astronomy can also be regarded as a division of broader space science, which has grown to include other related fields.

It is interesting that this definition of space science does not mention cosmology, which is more and more coming to assume the role of the master category of the sciences, since it is ultimately cosmology that is the context for everything else, but we could easily modify that last of the above three stipulations to read “cosmology” in place of “astronomy.” As the definition notes, the space sciences have grown to include other related fields, and in the future it may well be that the space sciences become the most comprehensive scientific category, providing the conceptual infrastructure in which all other scientific enterprises must be contextualized.

Since the Earth is a planet, and planets are to be found in space, one might readily assume that the Earth sciences, planetary sciences, and space sciences might be arranged in a nested hierarchy as follows:

Conceptually this is correct, but genetically, i.e., in terms of historical descent, it is obvious that the sciences that we have created to study our home planet are the sciences that, when generalized and applied beyond the surface of the Earth, are the sciences that become planetary science and space science.

Before space science and planetary science, there were of course the familiar sciences of geology (later geomorphology), atmospheric science or meteorology (later climatology), oceanography, paleontology, and so forth, but it was only when the emergence of space science and planetary science placed these terrestrial sciences into a cosmological context that we came to see that our sciences that study the planet that we call our home together constitute the Earth sciences in contrast to, and really in the context of, space science and planetary science. Great strides have been made in this direction, but further work remains to be done.

Geologic timescales for Earth and Mars with rocks plotted at the age of their emplacement. The age of soil samples analyzed by landed missions to Mars are too uncertain to plot on Fig. 4, and since no rocks were analyzed at the Viking 1 landing site in Chryse Planitia, that site is not shown. Martian geologic timescale of Hartmann and Neukum (2001), with subdivisions indicating the early, middle, and late Noachian, early and late Hesperian, and early, middle, and late Amazonian.

We know that the Earth and its solar system is about 4.6 billion years old, and most recent estimates for the age of the known universe put it at about 13.7 billion years. This means that the Earth has been around for almost exactly a third of age of the entire universe, which is not an inconsiderable length of time. Our sun and its solar system stands in relation to other stars of a similar age, and these stars and solar systems with significant traces of heavier elements stand in certain relationships to earlier populations of stars. The whole history of the universe is present in the rocks of the Earth, and we have to keep this in mind in the expanding knowledge base of the earth sciences.

While geological time scales are essentially geocentric, it would be possible to formulate an astrogeography and an astrogeographical time scale, extrapolating earth science to planetary science and thence to space science, that not only placed Earth’s geological history into cosmological context but also placed all planetary bodies and planetary systems and their geology in a cosmological context. For such an undertaking the generations of stars and planetary formation would be of central concern, and we could expect to see patterns across stars and solar systems of the same generations, and across planets within a given solar system.

This work has already begun, as can be seen in the above table laying out the geological histories of the Earth, the Moon, and Mars in parallel. Since one of the major theories for the formation of the Moon is that most of its substance was ripped out of the Earth by an enormous collision, the geological histories of the Earth and the Moon may ultimately be shown to coincide.

Stars and planets formed from the same dust and debris clouds filled with the remnants of the nucleosynthesis of earlier poulations of stars. This is now familiar to everyone. Galaxies, in turn, formed from stars, and thus also reflect a generational index reflecting a galaxy’s position in the natural history of the universe.

Since we now also believe that all or almost all spiral galaxies (and perhaps also other non-spiral or irregular galaxies) have a supermassive black hole at their centers, I have lately come of think of entire galaxies as the vast “solar systems” of supermassive black holes. In other words, a supermassive black hole is to a galaxy as a star is to a solar system. As planetary systems formed around newly born stars, galaxies formed around newly born black holes (if their gravity was sufficiently strong to form such a system). This way of thinking about galaxies introduces another parallelism between the microcosm of the solar system and the macrocosm of the universe at large, the structure of which is defined by galaxies, clusters of galaxies, and super clusters.

All of this falls within a single natural history of which we are a part.

Our history and the history of the universe are one and the same.

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The Terrestrial Eocivilization Thesis

Wednesday

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A Thesis in the Theory of Civilization

Not long ago in Eo-, Eso-, Exo-, Astro- I discussed how Joshua Lederberg’s distinctions between eobiology, esobiology, and exobiology can be used as a model for the concepts of eocivilization, esocivilization, and exocivilization, all of which are anterior to the more comprehensive conception of astrocivilization (like the more comprehensive conception of astrobiology).

My post on Eo-, Eso-, Exo-, Astro- was in part a correction to my earlier post Eo-, Eso-, Astro-, in which I had contrasted eobiology to exobiology, when I should have been contrasting esobiology to exobiology.

I had derived the contrast of eobiology and exobiology from Steven J. Dick and James E. Strick’s excellent book The Living Universe: NASA and the Development of Astrobiology, in which they cite Lederberg’s contrast of these terms. I had initially drawn the wrong contrast between the two concepts. When I started to read Lederberg’s writings, I realized that Lederberg was making a dramatic contrast between the scientific study of origins and the scientific study of destiny, rather than the contrast I expected. However, the contrast I originally drew remains a valid schema for understanding the comprehensive conception of astrobiology — and, by extension, the comprehensive conception of astrocivilization.

Astrobiology may be understood as the integration of esobiology — our biology, terrestrial biology — and exobiology — biology not of the Earth — into a comprehensive whole that places life in a cosmological context. Parallel to this, I define astrocivilization as the integration of esocivilization — our civilization, terrestrial civilization — and exocivilization — civilization not of the Earth — into a comprehensive whole that places civilization in a cosmological context. These concepts are not merely parallel, but the parallel between concepts of biology and concepts of civilization follows from a naturalistic conception of civilization as an extension of biology.

Civilization can be understood as a greatly elaborated result of behavioral adaptation. Just as evolutionary gradualism takes us imperceptibly over countless generations from the simple origins of life to the complexity of life we know today, so too evolutionary gradualism in the development of civilization takes us imperceptibly over countless generations from the simplest behavioral adaptations to the complexity of behavioral adaptation that culminates in civilization — and which may well culminate in some further post-civilizational social institution. (We must add this last proviso so as not to be mistaken for advocating some kind of teleological conception of civilization, as one might expect, for example, from strong formulations of the anthropic cosmological principle.)

In reformulating my contrast of eocivilization and exocivilization as the contrast between esocivilization and exocivilization, the term “eocivilization” is freed up to assume its more etymologically accurate meaning, which properly should be “early civilization” (“eo-” coming from the Greek means “early”). This turns out to be a very useful concept, but it always points to an additional thesis in the theory of civilization.

As in astrobiology, in which we study life on Earth as a clue to life in the cosmos, so too in astrocivilization we study civilization on Earth as a clue to civilization in the universe. Life on Earth is the only life that we know of, and civilization on the Earth is the only civilization that we know of, but in so far as we approach life and civilization from the scientific perspective of methodological naturalism, we do not assume that these are necessarily the only instances of life or of civilization in the cosmos. There may be other instances of life and civilization of which we simply know nothing.

In light of the possibility of life and civilization elsewhere in the universe, but our only knowledge of civilization being terrestrial civilization, I will call the terrestrial eocivilization thesis the position that identifies early civilization, i.e., eocivilization, with terrestrial civilization. In other words, our terrestrial civilization is the earliest civilization to emerge in the cosmos. Thus the terrestrial eocivilization thesis is the civilizational parallel to the rare earth hypothesis, which maintains, contrary to the Copernican principle, that life on earth is rare. I could call it the “rare civilization hypothesis” but I prefer “terrestrial eocivilization thesis.”

It is possible to further distinguish between the position that terrestrial civilization is the first and earliest civilization in the cosmos, and the position that terrestrial civilization is unique and the sole source of civilization in the cosmos. There may be exocivilizations that have and will emerge after terrestrial civilization, meaning that there are several sources of civilization in the cosmos, but that terrestrial civilization is the earliest to emerge. Thus the terrestrial eocivilization thesis can be distinguished from the uniqueness of terrestrial civilization. We might call the non-uniqueness of industrial-technological civilization on the Earth the “multi-regional hypothesis” in astrocivilization (to borrow a term from hominid evolutionary biology), but I would prefer to simply call it the “Non-Uniqueness Thesis.”

In the event that human civilization expands cosmologically and is ultimately the source of civilization on exoplanets that are part of other solar systems and perhaps even other galaxies, the terrestrial eocivilization thesis will have more substantive content than it does now at present, when (if the thesis is true) eocivilization is simply identical to all civilization in the cosmos. All we can say at present, however, is that terrestrial civilization is identical to all known civilization in the cosmos. To assert more than this is to assert the terrestrial eocivilization thesis, which is underdetermined and goes well beyond available evidence.

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The Law of Trichotomy for Exocivilizations

Wednesday

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The Search for Extra-Terrestrial Industrialization

In the Past, Present, and Future

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In several posts I have discussed the Fermi Paradox, which, stated in its simplest form, is this: if the universe if full of life and full of technological civilizations, then where are the aliens? My posts on the Fermi Paradox include:

● Silent Worlds, Empty Worlds

● Methodological Naturalism and the Eerie Silence

● Why the Fermi paradox must be taken seriously

● Addendum on the Fermi Paradox

I have also, in a number of posts, reflected on how the progress of scientific knowledge in cosmology has continued to affirm and to follow a Copernican trajectory, consistently demonstrating to us that the cosmological context of the earth is not unique and not even especially rare. These posts have included:

● Other Worlds

● Twenty Years of the Hubble Space Telescope

● More Evidence for the Copernican Principle

Given the success in extrapolating the Copernican principle, and knowing that small, rocky planets with an atmosphere circling sun-like stars in their habitable zones are not rare, the same Copernican principle ought to allow us to posit the non-rarity of life, of sentience, of civilization, and of technology. If this is the case, why are we not hearing the EM (electro-magnetic spectrum) broadcasts of other industrial-technological civilizations in our neck of the woods, galactically speaking?

It was my point in SETI as a Process of Elimination that the attempts to detect the EM signatures of alien civilizations, while very limited in extent to date, would have told us by now if there had been an advanced industrial-technological civilization on a planet orbiting, say, Tau Ceti or Epsilon Eridani. If there were such a civilization “close by,” say, within 25 light years of us, you would probably be able to listen to their radio broadcasts or watch their television shows with an especially sensitive receiver. Thus we can eliminate the possibility of an advanced technological civilization that is “close” to us in galactic terms.

We cannot, at least not yet, rule out peer industrial-technological civilizations farther afield in the Milky Way, much less in other peer galaxies throughout the universe. We can, however, say a few things about the possibility that remains of contacting other industrial-technological civilizations.

I have come to realize that the Fermi paradox can be expressed according to a law of trichotomy of exocivilizations. Taking our terrestrial industrial-technological civilization as the base line (not because we should count it a privileged civilization, but only because it is the one civilization of which we know something, and whose time and place of origin we can definitely assert), any other industrial-technological civilization would have to have appeared either…

1. …prior to the appearance of terrestrial industrial-technological civilization…

2. …at roughly the same time as the appearance of terrestrial industrial-technological civilization… or…

3. …after the appearance of terrestrial industrial-technological civilization…

Here we must carefully define the time-frames we will be discussing, because without being careful about the time-frame of the trichotomy we will quickly descend into incoherence.

In terms of the individual human life, civilization is very old; in cosmological terms, civilization is very young, and its few thousand years of development on the earth is nothing but the blink of an eye in the cosmic scale of things. Taking this cosmic perspective, the few thousand years it takes a species to go from essentially nothing to industrial-technological civilization is negligible. This is one of the sources of the Fermi paradox, because it is sometimes asserted that earlier civilizations could have or even should have emerged and colonized the galaxy before us.

Recent cosmological thought, however, with a greater appreciation for the natural history of the universe, has come to realize that an industrial-technological civilization cannot emerge until the heavier elements that fuel such a civilization are available, and these heavier elements can only come about through several generations of stellar nucleosynthesis, meaning that several generations of stars must be formed and then scatter their substance through going supernova before the heavier elements are available in sufficient amount to create both life as we know it and industrial-technological civilization as we know it.

This point has been made in relation to the anthropic cosmological principle. I haven’t yet taken the time to write in any detail about the anthropic cosmological principle, but I have mentioned on several occasions that, while I consider strong formulations of the anthropic principle to be seriously wrong, weak formulations of the anthropic principle seem to me to be tautologically true: only a universe consistent with the existence of observers can be observed. Here is how Barrow and Tipler formulate a weak version of the anthropic principle as it relates to the age and size of the universe:

“…for there to be enough time to construct the constituents of living beings the Universe must be at least ten billion years old and therefore, as a consequence of its expansion, at least ten billion light years in extent. We should not be surprised to observe the the Universe is so large. No astronomer could exist in one that was significantly smaller. The Universe needs to be as big as it is in order to evolve just a single carbon-based life-form.”

John S. Barrow, and Frank J. Tipler, The Anthropic Cosmological Principle, Oxford: Clarendon Press, 1986, p. 3

What this means is that we cannot simply extrapolate backward in time and assert that an industrial-technological civilization might have emerged at any time in the history of the universe. The universe has to be approximately as old as old as it is now — old enough to produce our sun and our planets with their relatively plentiful mineral resources — for a civilization to emerge with a technological infrastructure capable to creating radio transmitters and receivers.

This argument — it could be called an anthropic argument, but I would call it the argument from natural history — can be extended to the appearance of terrestrial civilization, which, since the industrial revolution that made contemporary technology possible, has been powered by fossil fuels. A civilization that exploits fossil fuels to bootstrap itself to rapidly achieve high technology cannot come about until these fossil fuels have been laid down and fossilized. So no more than the age of the universe being arbitrary is the age of the earth arbitrary when it comes to the production of industrial-technological civilization.

It would certainly be possible to have a technological civilization without fossil fuels, but there is still a temporal constraint on the emergence of a sufficiently sophisticated biological infrastructure to support a brain of sufficient complexity for sentience, consciousness, and instrumental intelligence to emerge.

Thus in terms of the first division of the trichotomy of exocivilizations, industrial-technological civilizations would be limited to the recent past, with “recent” understood on a biological time scale. It would be unlikely that another industrial-technological civilization would have emerged in the Milky Way, or in another galaxy of approximately the same age as the Milky Way, beyond, say, 10-20 million years ago. This still means that there could be a civilization in the Milky Way millions of years old, which would seriously out-class our terrestrial civilization. The point here is that we don’t have a past of 13.7 billion years (the current estimate for the age of the universe) possibly filled with civilizations.

In terms of the second division of the trichotomy of exocivilizations, industrial-technological civilizations roughly contemporaneous with our own — and here I place the emphasis on roughly — would presumably be of a roughly similar character to our own, having emerged in a similar cosmological context and at a similar age of the universe. Seeing civilization in its cosmological context, like seeing biology in its cosmological context as I wrote about yesterday in Eo-, Eso-, Exo-, Astro-, means that we understand exocivilization to have been constrained by the same physical laws and material resources as our own civilization, i.e., esocivilization (which I now realize might also be called endocivilization).

Once an industrial-technological civilization emerges, it progresses rapidly (as I discussed in The Industrial-Technological Thesis), so that an industrial-technological civilization a mere few thousand years more mature than our own — a very real possibility in cosmological and biological terms — would possess a significant technological advantage over terrestrial civilization. However, as contemporary civilizations on a cosmological time scale, we must think of exocivilizations a few thousand years older or younger than terrestrial civilization as near-peer civilizations.

Because of the size the universe, and the great gulf between galaxies, between galactic clusters, and between super-clusters, and because of the constraints placed on communication and transportation by relativistic physics, it may be that near-peer civilizations are prevented from talking to each other for all practical purposes by virtue of the light cone in which each civilization finds itself embedded. The light cone not only describes the propagation of light but of EM radiation, including radio signals.

The third division of the trichotomy of exocivilizations, regarding exocivilizations that emerge after our terrestrial esocivilziation, would involve different consequences for the possibilities open to the development of contemporary industrial-technological civilization, which would include:

● After end of terrestrial esocivilization, precluding the possibility of communication

● After the end of terrestrial industrial-technological civilization, which is to say, a stagnant successor to contemporary terrestrial civilization, capable of being “discovered” in its dotage (imagine all of human civilization as a terrestrial India, with ancient and venerable traditions but a marginal role)

● During the existence of an intact terrestrial industrial-technological civilization, which implies a spatially expanding terrestrial esocivilization, and therefore exocivilizations subordinate to, and perhaps even subject to, human civilization

Once one begins thinking about the possibilities there are two many to list, and providing some kind of typology of the interrelationship of civilizations would require a significant investment of time. For example, an expansionary exocivilization might exapt terrestrial civilization, expanding through and around and on top of that which came before, as later cities have exapted earlier cities and grown through them. The effort to formulate the interrelationships of esocivilization and exocivilizations would be the project of astrocivilization, i.e., the totality of civilization in the universe.

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