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Applied Eschatology

Preserving Humanity’s Legacy in Spacetime

With Earth’s first Clay They did the Last Man’s knead,
And then of the Last Harvest sow’d the Seed:
Yea, the first Morning of Creation wrote
What the Last Dawn of Reckoning shall read.

—Omar Khayyám, The Rubáiyát (cca. 1100)

What’s Past Is Prologue—and It Is Very Brief

Not only all science is cosmology, as Sir Karl Popper famously pronounced, but all human culture, all human activity and the totality of human experience is indeed cosmology. Everything we have ever done is part of the overall cosmological history, theoretically discernible with infinite resolution and unlimited cognitive powers of the kind used in classical “demon” thought experiments of Laplace, Bošković or Maxwell. Of course, this is not realistic for any kind of evolved being which is a part of the physical universe under scrutiny, but it is useful as a definite baseline and groundwork. Within wider cosmological context, we encounter various events and processes as constitutive of the true cosmic evolution whose fractal structure goes as deep as the resolution of our experimental equipment, our best theories and even mental pictures. With each subsequent increment in either of those resolutions, new layers of the same underlying evolving reality are revealed.

A perspective taken in this essay is, therefore, the one of the totality of cosmic evolution. Clearly, such a viewpoint encompasses the future as well as the past, in principle at least. While we have accrued rather detailed knowledge of our cosmological past, starting at or sufficiently close to the Big Bang and going through successive epochs such as baryogenesis, nucleosynthesis, recombination and various stages of structure formation, future has mostly been neglected. In recent decades, however, science has made significant strides in understanding the future evolution of various astrophysical objects. The expression of this newly acquired knowledge is the nascent discipline of physical eschatology.

The very word (éschato = last) was used originally in an exclusively religious context, as “any system of religious doctrines concerning last or final matters, as death, judgment, or an afterlife” and “the branch of theology dealing with such matters”.[1] Sir Martin Rees first employed the word “eschatology” in an astrophysical context in the title of his pioneering article written in 1969, and Fred C. Adams and Gregory Laughlin used the term “physical eschatology” to denote the entire field in 1997.[2]

While there are many philosophical and methodological pitfalls in research comprising physical eschatology, these need not worry us unduly here. Only two basic data points are of current interest: finite future lifetimes of cosmic structures, and the limitations on our understanding imposed by currently negligible processes which will become more prominent in the limit of eschatological future. The former point includes finite future lifetimes of Earth, Solar System or the Milky Way galaxy; examples for the latter are processes such as Hawking radiation from black holes, annihilation of dark matter particles or even proton decay.

At first, it seems that perspectives are rather gloomy, since the inexorable rise of entropy may not bring about the heat death of the universe in its 19th-century rendition, but will still make the universe uninhabitable. Our Sun will enter the red giant and asymptotic giant phases, destroying the inner Solar System planets, including the Earth. Other stars will die and there will be no replacement for all of them, causing the universe to become literally darker with passage of cosmological time. All physical systems around our descendants (if any) will gradually decay, while distant galaxies will vanish beyond the cosmological event horizon, while undergoing their own causally untouchable decay. Eventually, even protons—the bulwark of all baryonic matter—will decay and the same thing will happen to even the largest supermassive black holes at inconceivably long timescales of 1080 years or more. The universe will enter the eternal “dark age” of incredibly rarefied radiation, a minuscule fraction of a kelvin above absolute zero and a bunch of surviving electrons and neutrinos separated by megaparsecs.

Faced with this dark background, we are entitled to ask about the long-term survivability of all our works and thoughts. In recent years, many philosophers have embraced a kind of cosmic pessimism or even nihilism at least partially inspired by the inexorable rise of entropy and dissipation of structures as predicted by physical eschatology.[3]

However, this is a case where judgement has, at best, been passed too early. What we first learn from physical eschatology is that the future is certainly way larger than the past. Some of the relevant future timescales are as follows:

  • Sun’s future lifetime: 7.7 × 109 yrs;
  • star-formation in the Galaxy continues for another (5–10) × 1010 yrs;
  • longest-living stars existing today will exist for another 6.5 × 1012 yrs;
  • the future lifetime of the Galaxy: cca. 1019 yrs.

(This is valid provided that the conventional picture of dark energy as cosmological constant, or even quintessence, holds, in which case the future is formally open t → +∞; if dark energy is in fact what cosmologists call phantom energy, the Big Rip catastrophe looms at a finite future epoch. But even that would take much longer in realistic cases than most of the timescales listed above.)[4] I shall use the last datum as a convenient placeholder and I shall call the last timescale τMW ≈ 1019 yrs. If Adams and Laughlin’s estimate is correct—and at present there is no clear astrophysical reason why it should not be—we are living in the first millionth of the first percent of our stellar system history! Even if future research reduces the future lifetime of the Galaxy, this is unlikely to be for an amount that is significant for the kind of point I wish to make about limitations of all our historical (i.e., cosmological + geological + evolutionary + cultural) experience in discussing the future.

As Shakespeare noticed, what’s past is prologue—although in the cosmological case the prologue is very brief indeed. The fact that we are living so early in the course of the universal evolution—again, the first 0.000001%—of the lifetime of our stellar system, should make us pause for breath and perhaps instill some humility regarding our temporal position and epistemic pretensions. Plus, it should arguably motivate us to reassess our research priorities, which have thus far been extremely, staggeringly, flabbergastingly past-oriented rather than future-oriented.[5]

It is incredibly presumptuous and hubristic to assume that even our conceptualization of what is and what is not possible under the laws of nature will survive long enough to be considered by our future descendants, even a century or a millennium down the line, let alone all the way to the vast timescale of physical eschatology. It makes sense to be at least agnostic toward the very distinction of possible vs. impossible when everything not directly contradicting the laws of nature is concerned; and even if something does seem to contradict those laws, we are still entitled to be healthily optimistic since the timescales of possible progress are so vast that even a tiny probability that we do not understand the laws correctly at present actually works in our favour. If there is a possible loophole, it is virtually certain to be found and exploited in the course of future eons. This should be kept in mind at all times, especially when short-sighted and hubristic pessimism is advertised as the “sure thing”. Extinction is unavoidable! No, it is not. No traces of our works will survive—full expunction! No evidence for that. Eschatological extinction makes our efforts pointless! Well, this one deserves a special name, let us call it the Alvy Singer fallacy; the reference is to Woody Allen’s famous 1977 movie Annie Hall where Allen’s alter ego Alvy claims that doing homework makes no point because science tells us that the universe is expanding. As his cosmology-savvy mother correctly notices, Brooklyn (where they live) is not expanding, in contrast to the universe. And in contrast to modern “humanist” philosophers invoking the Alvy Singer fallacy, the protagonist is nine years old at the time.

The fact that the infantile Alvy Singer fallacy is often taken seriously by high-brow philosophers should give us pause. There is a powerful conceptual obstacle to the open-mindedness about the Big Future that physical eschatology suggests we have. While the extinction of each individual habitat may seem unavoidable, there is no reason for the general pessimism about preserving some form of (post)humanity as long as some entropy gradient exists in this universe (or any other topologically connected within the multiverse). In the rest of this essay, I shall outline some of the arguments that those doors are wide open, or at least ajar. I shall first consider the long-term prospects, before moving on with somewhat more confidence on comparatively short-term issues.

Survival at the End of Time < Long Run >

To preserve something, even a legacy, one has to understand what its vital ingredients are, what is important and what is not in its material and causal composition. In simplified terms, modern science tells us that what is vitally important is information and the abstract structure of its flow—what can be captured intuitively by the concept of algorithm. Hence, I adopt what is usually called the information paradigm: life and mind are structures ultimately reducible to patterns of information and information flows/algorithms, at least potentially independent of any specific material substrate as such. The information paradigm has proved to be extraordinarily useful in myriad different fields, most notably in numerical simulations of cosmology, applied physics or molecular biology. However, a further ingredient one needs is something akin to ontic structural realism: the view that structure is not only everything we can know, it is also everything there is.[6]

This type of ontology may not appeal to everyone, but there is no doubt it is a highly plausible philosophical position with much to offer in multiple areas, including the futures studies. In particular, it offers legitimacy to speculation about the distant future in which the purely material basis of many processes will be utterly transformed by long-term phenomena such as proton decay. In this context, switching to a radically new substrate is not only a possibility but a kind of expected major evolutionary transition, if not necessity.

Thus, the preservation of minds—posthuman or other—at the very longest timescales will require a kind of divorce from the baryonic matter substrate we are so accustomed to that we usually take it entirely for granted. Some physicists, perhaps surprisingly, have been thinking about the issue.[7] To survive beyond the end of the stelliferous era, beyond proton decay and other aspects of the heat death, we need a manner of encoding the relevant information in structures of progressively longer and longer duration.

While it is impossible (of course!) to offer a specific engineering idea or a proof-of-concept for such an extremely long-term endeavour, it is entirely possible to speculate upon the series of steps to be undertaken in order to increase the durability and robustness of any such encoding. Plasma-based life, sometimes invoked as a prototype of non-chemical-based life, relies on stable solitons in astrophysical plasmas.[8] In a sense, this is a revival of the ancient speculation of William Hershel that even the Sun and other stars are inhabited by some forms of life. Sir Fred Hoyle’s famous Black Cloud belongs to the same category, being based on electromagnetic interactions within an interstellar gaseous cloud.[9] Transitioning to plasma-based life may be an appealing suggestion for advanced intelligences in the vast period between the end of the stelliferous era and the dissipation of galactic structures in around τMW. How efficient this may be will depend on the “resolution” of mental structures which can be encoded in collective interaction in plasma. How fine that resolution might be is unclear at present. Even if this is inefficient or unfeasible as a way of encoding entire minds, it is clear that some of the relevant informational content of an advanced technological civilization could be encoded in this manner.

For even more long-term and radical substrates, we need to go beyond classical physics/astrophysics and appeal to quantum physics. It is at the quantum level where true limits of the laws of nature are manifested. Moreover, novel fields of quantum information theory and quantum computing—celebrated these days by the Nobel Prize in physics for 2022, inter alia[10]—rely exactly on those properties of nature which have no classical macroscopic analogs, such as quantum entanglement.

Per analogy with previous historical pathways, a true breakthrough could be expected in the course of the shift from encoding in (quantum) mechanical objects to encoding in (quantum) field objects. Stable field configurations are less intuitive to us, present-day humans, because both our evolution and our everyday routines are not conducive to acquiring experience with fields: we have senses with which we perceive mechanical objects, such as touch or hearing, but no senses for perceiving fields—in contrast to, for example, magnetotactic bacteria[11] or many species of birds and fishes. (It is entirely conceivable that, for example, radio-communicating animals might have evolved on other planets, as suggested by the great paleontologist David Raup.)[12]

In contrast, posthumans are likely to develop capacities for manipulating quantum fields with extreme precision, equal or superior to our present capacity for manipulating electromagnetic fields on the classical level; the latter is responsible for all the successes of modern electronics, radio technology and some stunning interactive exhibits at museums of science around the world. In the course of the immense duration of eschatological time, it is likely that the various field solitons (stable wave packets) and their complex aggregates will gradually replace “normal” matter configurations. We have so far only scratched the surface of possibilities with all skyrmions, vector solitons, BIons (Born-Infeld solitons), EBIons (Einstein-BIons) etc. The generalization to quantum fields, especially cosmological fields such as inflationary scalar fields (likely to be many, according to our best models of cosmological inflation), the Higgs field and others—including those associated with exotic matter—will provide a convenient substrate for a wild variety of practical purposes, most of which are, naturally and expectably, inconceivable at present.

From the viewpoint of the present essay, however, the important speculation is that in the very long run (and I mean very long!), various stable quantum fields’ configurations, such as systems of field solitons, are the best hope of preserving at least some of the information content created by humanity. In the best-case scenario, our distant descendants will learn how to encode themselves and their superior minds into such field configurations and thus achieve the old cliché of “transcending matter”. While the cliché is ridiculous and betrays common ignorance of modern physics (fields are matter = energy), this form of naturalistic “transcendence” would offer great benefits far before the eschatological concerns about the heat death. In the sufficiently long run, this may offer the only chance of even attenuated survival into the incredibly distant future dominated by black holes and their Hawking radiation. In the worst-case scenario, some of the databases of our descendants could persist in such a format, even if their own indefinite survival turns out to be impossible, thus creating the most durable imaginable monuments of mind at the inexorable winding down of the universe.

Comet-Riding and Hyperbolic Library of Babel < Short Run >

If one worries about going too far into the eschatological future, here are some less disturbing and more immediately practical ideas for, say, the next couple of centuries or a millennium. If we are looking for a stable environment on the timescales comparable to the Main Sequence lifetime of the Sun (5 × 109 years as a placeholder), we need not go far beyond the physics known in Newton’s or at worst Laplace’s time. So, no ultraspeculative fancy physics of the previous section; consider instead simple celestial mechanics.

Intuitively, stable orbits around large celestial bodies in our vicinity, like the Sun and planets, seem like an excellent bet for preserving the records of humanity. In contrast to any terrestrial time capsule, erosion by air, water, acidity or tectonic motions is irrelevant for satellites in stable orbits. They are subject only to erosion by micrometeorites and cosmic-ray particles. Both these processes are extremely slow, although orders of magnitude quicker than the blink of an eye when compared to the timescales of physical eschatology such as τMW. In addition to being slow, both these kinds of erosion are not difficult to protect against, even by a primitive civilization such as the present-day or near-future humans. The most relevant protection measure is (as evolution teaches us) massive redundancy.

It is in fact rather easy and cheap to safeguard the records of humanity. Even hardcore pessimists like Robert Klee admit that our space probes in the interstellar space, such as the Pioneers and the Voyagers, will survive into the physical eschatological future, eons beyond the end of Solar evolution. Therefore, what needs to be done is to launch more such probes, acting as time capsules, using technologies such as quantum lithography to inscribe maximal amount of information on their payload. This amount of information is indeed huge.[13] (Theoretical limits stemming from quantum-gravitational considerations, such as the holographic limit on the amount of information which could be encoded per unit mass, are much larger still, but they are of dubious practical value, at least for the kind of futures considered in this section.)

The interstellar space is arguably the most stable environment for presenting information about human civilization for the benefit of either our human or posthuman descendants or possible extraterrestrial intelligent beings. Therefore, I wish to argue that a desirable course of action in the near future will be launching a large number of small inscribed-matter packages on hyperbolic orbits, serving as detailed cosmic time capsules preserving information about human civilization on eschatological timescales. The rationale for such a course of action goes far beyond usual space science, and even astrobiology research—instead, it touches upon some of the deepest beliefs about the place of consciousness in the universe and ethical attitudes toward the future. In an epoch characterized by enhanced awareness of the global risk landscape provoked, among other things, by the ongoing COVID-19 pandemic, the general theme of persistence with cosmic time gains additional importance and freshness.

As mentioned above, the information paradigm suggests that human cultural artefacts which can be encoded in language (natural or mathematical, including simulations of material structures down to the quantum level) can nowadays be efficiently digitalized and, at least in principle, copied. The exponential advances of information technologies could soon enable the manufacture of many copies of all or most of the key achievements of humanity at a minor or modest cost. It is highly desirable to do so anyway, even from a pessimistic perspective. In ethical terms, one can also argue that it is our moral duty to do so, thus enabling the preservation of humanity’s legacy even if our species goes extinct.

Like the dandelion seed, which is produced in copious amounts in order to ensure the preservation of relevant (genetic) information in a compact and dispersed form, technological evolution enables an advanced culture to at least partially self-reproduce. In the deep time of cosmology/physical eschatology, one can regard such self-reproduction as a new kind of ecology and new level of evolution. One can even go farther and argue that simple evolutionary stable strategies, such as r/K strategies, would be applicable.[14] Dandelion seeds are a prototype of the r-strategy, in which a large number of copies are spread around without much resource investment, relying on the probability that some seeds will be lucky. This could be a fine metaphor for what the proposed cosmic time capsules could represent from a long-term perspective.

Such inscribed-matter information storages could be placed all around and about the Solar System.[15] The best value durability-wise could be achieved in either stable circumplanetary orbits, at the cold outskirts of the Kuiper Belt and Oort’s cometary cloud, or by launching them along hyperbolic orbits calculated to slowly disperse the “posthuman information cloud” all around the Galaxy. The accent here is on “slowly”; there will be no real hurry—which in any case is undesirable wherever engineering eschatological futurity is concerned. Moreover, while the hyperbolic orbits will eventually succumb to even purely Newtonian deterministic chaos, they will be broadly predictable for millions or even billions of years to come. It could be important to keep track of their trajectories, since those will be analogs to “treasure maps” for multiple possible species or cultures to come after us; considering how huge the future is according to physical eschatology, there will be more than enough time for countless empires to be born and fade.

As far as the time capsules are concerned, since they could be quite small, it is not prohibitively expensive to launch them onto the hyperbolic trajectory even today, and it will be ridiculously cheap to do so in the near future. Breakthrough Starshot’s StarChip probes are to weigh in grams and to be mass-produced for the Proxima mission; even 2.75 tons projected for the Project Dragonfly[16] is lightweight for the present and especially near-future launching systems.

Their mass production could serve both as a testing opportunity for various advanced manufacturing and launch systems, and as a further artistic expression of (post)human creative spirit; I shall return to this point in the concluding section. In essence, even a small number of such cosmic time capsules will serve an important philosophical purpose: namely to clearly demonstrate that, contra extreme versions of pessimism such as Klee’s, we can safeguard at least against “expunction”: complete loss of all traces of our existence and action. With massive redundancy easily enabled by utilization of in situ resources, we can hope to achieve that our artefacts will co-exist with the Galaxy itself.

Such resources are already available in objects on the outskirts of the Solar System. Of special interest are objects like the comet C/2017 U7 (PanSTARRS), which originated in our Solar System but is now observed on hyperbolic orbits, leaving our planetary system. C/2017 U7 has been effectively ejected from the Solar System before our eyes, having originated in an Oort-Cloud-like orbit with the aphelion at 16,000 ± 1,000 AU (for comparison, our farthest current interstellar artefact, the Voyager 1 probe, is currently about 158 AU distant[17]). This cometary object is not only huge for the world of Solar System small bodies, being tens of kilometers in size, it also has anomalous colours and spectra indicating presence of many organic compounds, notably aliphatic-rich hydrocarbons.[18] In other words, it is a truly useful kind of natural interstellar traveller, choke-full of resources which could serve as a producing hub for time capsules to be then dispersed in its wake.

Coda: Legends of the Long-Lost Earth

We see why pessimism regarding the future of mind in the universe, and more specifically the future of posthuman minds, is at best premature and at worst both dumb and immoral. Most of its proponents are victims of the Alvy Singer fallacy, using their outdated and unimaginative thinking as an excuse to evade doing their homework. In particular, the lack of imagination becomes an epistemological fault in taking the long-term perspective (and the perspective of physical eschatology is much longer still than the conventionally discussed issues related to longtermism). Now we should add some speculations about the local implications and feedbacks of attempts to preserve our legacy into the eschatological future.

The question of weighing the relative importance of various long-term scenarios plays the key role in countering the Alvy Singer fallacy. In particular, an approach to watch for is the infinite ethics[19] motivated by the cosmological conjecture that at least some chunks of the multiverse could contain an infinite number of intelligent observers. Posthuman capacities for producing “baby universes” or large-scale simulations of intelligent observers will require us to account for possible infinities, paralyzing conventional ethical calculus. This is relevant even under the moderate longtermism, but is certainly exacerbated in the physical eschatological limit. Facing infinities in this context is perhaps the major cognitive task for human/posthuman minds in the years to come.

While science in the eschatological context becomes somewhat indistinguishable from engineering (Armstrong and Sandberg’s “exploratory engineering”, Stephen Wolfram’s “something computationally sophisticated” or Stanisław Lem’s “a new cosmogony”), the question of cultural and societal motivation remains. Judging by our experience thus far, it seems unlikely or impossible to make human beings interested, not to mention involved and invested, in eschatological future on the basis of cosmological calculations alone. This is a sweeping statement on a par with statements such as “Joe cleared snow off his car” which we use instead of statements such as “Joe cleared 98.5408% of snow off his car”. The latter may capture objective reality better, but clearly obstructs efficient communication, to say the least. Therefore, both the advent of posthuman minds and the search for other manners of formulating the issue, including extra-scientific ones, should be warmly welcomed.

Suppose a call for proposals is issued asking for a list of “canonical” achievements to be included in such cosmic time capsules to be scattered throughout the Galaxy. It is easy to be cynical about the outcome of such a call for proposals, considering all the deep divisions of today’s world, often sowed on purpose by crazy ideologues and fostered by unscrupulous political and media figures. We should be realistic and discount all utopian yearnings and focus on what could reasonably be achieved: not any kind of political consensus, but an outline of cultural unity. Herein lies a potential goldmine for artistic expression to be created in the course of crafting our collective legacy. New and potentially revolutionary artforms, employing new technologies and corresponding to the truly cosmic perspective of survival in eschatological time, will emerge and further demonstrate our creative and transformative potential as a species.

As argued by some of the spaceflight pioneers like Tsiolkovsky or O’Neill, the project of space settlement is likely to produce entirely new ways of creative expression, including new artistic genres, media and forms. These prospects for currently inconceivable artistic and playful expressions offer synergistic reasons for optimism about creative dialogue between science and the arts capable of encoding our long-term legacy. This is something one should prepare long in advance; and I do think long here, for instance—right now! We have, as a civilization, been woefully unprepared to express ourselves thus far. Even a simple increase in the visibility of our physical eschatological prospects would be a wonderful and adventurous giant step forward. There is a widely open space—and perhaps a deep need—for such a new cultural front. If a lack of imagination is a fault, a natural question arises: how to correct it? Well, we have some inkling about that. In a quasi-Haeckelian recapitulation spirit, we may claim that those challenges to imagination facing an individual are the very same we need to spread around any cultural constructs: notably arts and games. We should hope this will usher a new era of cosmic art and wider intercultural dialogue prefiguring the Wellsian shape of things to come—in the epochs when the Sun turns into cinder and the Earth is nothing bar a long-lost faint memory.

Should we do it? This is a deeper enigma, one that cannot be so readily addressed here. While ethics has its theories and its scholarship and its learned journals, it still all too often fumbles in the dark even when contemporary issues are concerned, much less those of the deep future. Perhaps this is the true test of our mettle, the true measurement of our worth and maturity as a species—and as tiny specks in the grandiose mosaic of cosmic evolution. It could and should be the work of love, as much as that of reason. And it is perhaps on those dealing with matters of the heart, poets, artists, even preachers, to take over that particular burden from the shoulders of scientists/technologies and give it a form—if not exactly immortal, then at least a form memorable for the aeons to come.

  • 1

    Random House Webster’s Unabridged Dictionary, Random House, 1966.

  • 2

    REES, Martin J., “The collapse of the universe: an eschatological study”, in: Observatory, 89, 1969, pp. 193–198; ADAMS, F. C. & LAUGHLIN, G., “A dying universe: the long-term fate and evolution of astrophysical objects”, in: Reviews of Modern Physics, 69, 1997, pp. 337–372.

  • 3

    E.g., BRASSIER, Ray, Nihil Unbound, Palgrave Macmillan, 2007; THACKER, E., After Life, University of Chicago Press, 2010; KAHANE, G., “Our Cosmic Insignificance”, in: Nous, 48, 2014, pp. 745–772; KLEE, R., “Human expunction”, in: International Journal of Astrobiology, 16, 2017, pp. 379–388.

  • 4

    E.g., CALDWELL, Robert R., “A phantom menace? Cosmological consequences of a dark energy component with super-negative equation of state”, in: Physics Letters B, 545, 2002, pp. 23–29.

  • 5

    For an uplifting counterexample, see ORD, Toby, The Precipice: Existential Risk and the Future of Humanity, Bloomsbury Publishing: London, 2020.

  • 6

    LADYMAN, James & ROSS, Don, Every Thing Must Go: Metaphysics Naturalised, Oxford University Press: Oxford, 2007.

  • 7

    Cf. LINDE, Andrei. D., “Life after inflation”, in: Physics Letters B, 211, 1988, pp. 29–31; GARRIGA, Jaume, MUKHANOV, Viatcheslav F., OLUM, Ken D. & VILENKIN, Alexander, “Eternal inflation, black holes, and the future of civilizations”, in: International Journal of Theoretical Physics, 39, 2000, pp. 1887–1900; ĆIRKOVIĆ, Milan M., “Forecast for the Next Eon: Applied Cosmology and the Long-Term Fate of Intelligent Beings”, in: Foundations of Physics, 34, 2004, pp. 239–261.

  • 8

    See, for instance, TSYTOVICH, Vadim N. et al., “From plasma crystals and helical structures towards inorganic living matter”, in: New Journal of Physics, 9, 2007, p. 263; ANCHORDOQUI, Luis A. & CHUDNOVSKY, Eugene M., “Can self-replicating species flourish in the interior of a star?”, in: Letters in High Energy Physics, 166, 2020.

  • 9

    HOYLE, Fred, The Black Cloud, William Heinemann Ltd: London, 1957.

  • 10

  • 11

    BLAKEMORE, Richard P., “Magnetotactic bacteria”, in: Annual Reviews in Microbiology, 36, 1982, pp. 217–238.

  • 12

    RAUP, David M., “Nonconscious Intelligence in the Universe”, in: Acta Astronautica, 26, 1992, pp. 257–261.

  • 13

    ROSE, Christopher & WRIGHT, Gregory, “Inscribed matter as an energy-efficient means of communications with an extraterrestrial civilization”, in: Nature, 431, 2004, pp. 47–49.

  • 14

    E.g., REZNICK, David, BRYANT, Michael J. & BASHEY, Farrah, “r-and K-selection revisited: the role of population regulation in life-history evolution”, in: Ecology, 83, 2002, pp. 1509–1520.

  • 15

    See also GUZMAN, Melissa, HEIN, Andreas M. & WELCH, Chris, “Extremely long-duration storage concepts for space”, in: Acta Astronautica, 130, 2017, pp. 128–136.

  • 16

    HÄFNER, Tobias, KUSHWAHA, Manisha, CELIK, Onur & BELLIZZI, Filippo, “Project Dragonfly: Sail to the stars”, in: Acta Astronautica, 154, 2019, pp. 311–319.

  • 17

  • 18

    EVANGELISTA-SANTANA, Marçal et al., “Physical and dynamical characterization of hyperbolic comet C/2017 U7 (PANSTARRS)”, in: Icarus, 377, 2022, 114834.

  • 19

    E.g., BOSTROM, Nick, “Infinite Ethics”, in: Analysis and Metaphysics, 10, 2011, pp. 9–59.

Milan M. Ćirković

Milan M. Ćirković is a Research Professor at the Astronomical Observatory of Belgrade and a Research Associate of the Future of Humanity Institute at Oxford University. He is a member of the Belgrade based Center for the Study of Bioethics. His primary research interests are in the fields of astrobiology, risk analysis, and philosophy of science.