Interstellar distances seem to cry out for robotics and artificial intelligence. But as Nick Nielsen explains in the essay below, there is a compelling argument that our long-term goal should be human-crewed missions. We might ask whether the ‘overview effect’ that astronauts report from their experience of seeing the Earth from outside would have a counterpart on ever larger scales, including the galactic. In any case, what of ‘tacit knowledge,’ and that least understood faculty of human experience, consciousness? As always, Nielsen ranges widely in this piece, drawing on the philosophies of science and human experience to describe the value of an observing, embodied mind on the longest of all conceivable journeys. For more of Nick’s explorations, see his Grand Strategy: The View from Oregon and Grand Strategy Annex.
by J. N. Nielsen
0. A Scientific Argument for Human Exploration
1. The Human Condition in Outer Space
2. The Scientific Ellipsis of Tacit Knowledge
3. The Excommunication of the Eye
4. Human Experiences Intrinsic to Spacefaring Civilization
5. Upper and Lower Bounds of the Overview Experience
6. Observation and the Embodied Mind
7. The Knowledge Argument in Space Science
8. The Interstellar Imperative and the Human Imperative
0. A Scientific Argument for Human Exploration
In my essay The Moral Imperative of Human Spaceflight  I sought to construct an explicitly moral argument for human space travel. I would now like to make an explicitly scientific argument for human space travel. For those who dismiss the moral claims of human space flight, an argument from the scientific necessity of human spaceflight might possibly sound more plausible (T. E. Hulme once wrote that, “There has always been something rather unreal about ethics. In a library one’s hand glided over books on that subject instinctively.” ). Moreover, the claim is sometimes made that science inevitably favors robotic probes, which deliver “more bang for the buck”—a claim often coupled with a derisive attitude to human exploration as mere grandstanding or as a feel-good exercise.
While the moral goods and the scientific benefits of human spaceflight probably cannot be cleanly separated in practice, we can treat them according to the method of isolation and consider them individually and independently, as though the scientific benefits of human spaceflight might accrue regardless of the moral goods or evils that might result from human spaceflight, or that the moral goods of human spaceflight might accrue regardless of the scientific benefit or harm that might result from human spaceflight.
1. The Human Condition in Outer Space
Why go to the trouble of bringing the human body into extraterrestrial space? The human body requires oxygen, water, food, disposal of wastes (gaseous, liquid, and solid), a particular temperature range, and probably also gravity to remain healthy for extended periods of time. A human being additionally requires sleep, diversion (entertainment), and appropriate intellectual stimulation in order to achieve optimal performance for short periods of time.  Having evolved in a terrestrial biosphere in which all these resources are readily available (though some are at times contested and obtained only through competition), the human body is ill-adapted to the sterility of extraterrestrial space. In order to survive in space, all of these resources must be made available. In principle, this presents no essential problem, but in practical terms this means lifting all these resources out of Earth’s gravity well, until such time as there is sufficient infrastructure off the surface of Earth to provide these resources without immediate recourse to terrestrial sources—again, something that in principle presents no problems, but which in practice is a matter of great difficulty.
Because of the practical expense and difficulty of maintaining the human body in space, especially in comparison to the relative ease of operating a machine in the sterility of space, it has been argued that space science can be done most effectively and efficiently through the use of robotic probes.  With the financial resources to support a human presence in space becoming more scarce after the “space race” was won by the US, robotic probes have become the accepted method of doing science beyond Earth for the past several decades. These missions have transformed and are still transforming our knowledge of cosmology. While this strategy has been highly successful, it has given us a certain kind of science, and the science that has emerged from the use of robotic probes is not the only possible science.
2. The Scientific Ellipsis of Tacit Knowledge
The science performed by robotic probes is the result of a long process of development of the scientific method and scientific knowledge. This process had its earliest beginnings in ancient Greece, and accelerated with the scientific revolution. The technological iteration of science that has emerged since the industrial revolution has become a highly refined exercise in picking the low-hanging fruit of sensory perception. This narrow specialization, like so much in the process of industrialization, has yielded disproportionate successes, but it has yielded these gains at the expense of certain blind spots. One of these blind spots is tacit knowledge.
We know more than we can say, more than we can explain, more than we understand how we know what we know. Much of what we know is tacit knowledge, i.e., knowledge that we possess but which we cannot explain or make explicit.  Being able to recognize the faces of those familiar to you is an instance of tacit knowledge. You immediately recognize these faces, and yet you cannot say how exactly you recognize them. We can, of course, program a computer to recognize faces, and here we can say exactly how the recognition is accomplished, but this is not how human beings recognize another human face.
Only a small fragment of our knowledge is explicitly formalized. Once we arrive at a method for formalizing knowledge (and this is one of the functions of science), the process of producing and formalizing knowledge can be rendered systematic. Once made systematic, a body of knowledge takes on a life of its own, and the growth of knowledge can be pursued often without reference to the original source of knowledge in human experience. Like the use of scientific instruments to enhance and then to far surpass human senses, the enterprise of scientific knowledge at first enhances our common sense knowledge and then surpasses it. Nevertheless, human experience remains as a potential source of knowledge not yet fully exploited by science, waiting, as it were, for the insights that will capture some heretofore unappreciated and unformalized aspect of human experience that can then, in turn, take on a life of its own that grows independently of its human source.
3. The Excommunication of the Eye
The human body is the original scientific instrument. Science began as we explored the world with the our native sensory endowment. Most scientific instruments began as instruments to augment the human senses, as in the obvious case of the microscope and the telescope, which augment the capacity of the human eye. Such instruments can grow in complexity until human senses are made irrelevant, even while the conceptual framework of the science becomes less anthropocentric by purging itself of human-specific terms and concepts (sometimes called “folk concepts”).
When Benoît Mandelbrot said that, “The eye had been banished out of science. The eye had been excommunicated,”  this can be understood both literally and metaphorically. In seeking non-anthropocentric formulations in the sciences, the human eye had indeed been banished from the sciences; the human eye was no longer needed as an instrument in science because it had been replaced by far more sensitive instruments, and in a more radical sense the eye as a contingent relic of anthropomorphic science had to be banished, along with the centrality of the other human sensory organs to scientific knowledge.
The scientific account of sight and all that sight reveals to us of the world is the most advanced instance of science not only exhausting the capabilities of the human body as a scientific instrument, but of going far beyond the capabilities of the human body. The scientific account of vision has far surpassed what the human eye can see, and has become integrated with the fundamental physics that explains the electromagnetic spectrum, of which the eye perceives only a small fraction. (The scientific account of vision has also become integrated with the biology and physiology that explains the details of how the human vision system functions.) The eye can be banished from science because the eye has been surpassed and superseded by science; the eye must be banished from science in order for science to fulfill its promise as objective, i.e., non-anthropocentric, knowledge.
Not all human senses, however, have been exhausted or exceeded by science. Our visceral sensations that reveal gravity, acceleration, and movement are less well understood, and they connect us corporeally to a different area of fundamental physics—that which falls within the purview of general relativity—which cannot yet be reconciled to the particle physics that explains the EM spectrum. Thus within our own bodies we experience the division in physics between quantum theory and general relativity—except that with our body we experience the world as a seamless whole, something we cannot yet do with physics. This is ironic, as the contemporary scientific mainstream view is that the conscious apprehension of the world is deceptive—a mere “user illusion”—and it is only (non-anthropocentric) science that can give us the correct view of the world.
4. Human Experiences Intrinsic to Spacefaring Civilization
While the human body is the original scientific instrument, in so far as we have not yet scientifically mastered all that our senses tell us about the world, the human body remains a valuable instrument for scientific research even in a time of advanced technology. The still unexplained functions of the human body that have yet to be fully exapted for science argue for the continued relevance of human beings as observers in scientific contexts, even in an advanced spacefaring civilization.
[The famous “Blue Marble” photograph of Earth taken 07 December 1972 by the crew of Apollo 17, at a distance of about 45,000 kilometers, or 28,000 miles.]
One of the consequences of knowing more than we can say, i.e., one of the consequences of possessing tacit knowledge, is that we occasionally have experiences that affect us in unpredictable and unprecedented ways. One of these experiences that has emerged from technologies that have expanded the range of human experiences is known as the overview effect.  Individuals who have traveled into space and have seen our planet whole from above report an experience of great personal relevance. All of us have had an attenuated experience of the same through the “blue marble” photographs that have show us the vision of Earth from space. This experience has not yet been fully explicated and remains at the level of a profound feeling because we do not yet have a theoretical framework sufficient to clarify and formalize the experience and thus to assimilate it to scientific knowledge. 
The overview effect may be understood as an experience intrinsic to spacefaring civilization, and in Cognitive Astrobiology and the Overview Effect I suggested that the overview effect as we know it, the view of our planet entire from space, is one among a class of experiences to be studied by what David Dunér has called, “astrocognitive epistemology, what we can learn through extraterrestrial explorations, interactions and encounters.”  Further experiences of this class are to be expected as our spacefaring capacity grows in sophistication.
Our natural sensory endowment allows for an overview of Earth, and, if we could place ourselves in space outside our galaxy, we would have a breathtaking overview of the Milky Way—an overview effect that our technology does not yet afford us. What would the rest of the sky beyond the Milky Way look like? Probably we would see the other galaxies of the local group: the Magellanic Clouds and the Helmi Stream would be obvious, and the Andromeda and Triangulum galaxies would be visible. Probably other galaxies would be visible as well, and some large scale structure unobscured by the many stars that populate any vision of the universe as viewed from within the Milky Way. We would not, however, see with our natural sensory endowment the faint galaxies captured in deep field images of the universe beyond our galaxy.  There are limits to the knowledge yielded by personal experience, just as there are limits to the kind of knowledge derived from robotic probes, so that these approaches to science are complementary.
5. Upper and Lower Bounds of the Overview Effect
The kind of personal knowledge represented by the overview effect, involving human experiences intrinsic to spacefaring civilization, has been limited by the limits of our sensory organs and the limits of our conscious apprehension in understanding our observations. Technological instrumentation expands the range of observation, and may someday also expand the range of conscious apprehension as well. The spacecraft we have constructed to date can be understood as scientific instruments that have enabled the observations that have made the overview effect possible. We cannot yet build the scientific instruments (spacecraft) that would enable the overview of the Milky Way described in the previous section, though we may someday be able to do so, and, if we do, we can predict what we will see. We cannot, however, predict how we will understand and interpret what we see.
With a starship as a scientific instrument, one might employ the time dilation of relativistic travel to arrive at an overview of our galaxy when the Milky Way and Andromeda were colliding. Relativistic travel could be the ultimate time lapse observation tool, allowing us to see and to personally experience scales of time far in excess of ordinary human perception, like the temporal inverse of employing high speed cameras to see phenomena that occur far too rapidly to be observed by ordinary means. Science on a far larger scale than any “big science” to date would be enabled by the use of a starship as a scientific instrument.
We can distinguish between the kind of scientific instruments that enable novel observations. Firstly, a rough distinction can be made between observations that can be made with the unaided eye and observations only possible with instrumentation, with the former giving us direct, personal, immediate, and visceral experience, and the latter providing us with a derivative experience of varying degrees of immediacy. The distinction is rough because it is difficult to say at what point experiences cease to possess the immediate and visceral qualities of personal experience. Watching an event through binoculars seems more immediate than watching on a television screen, and watching an event live on a television screen seems more immediate than watching a recording after the fact on a screen. Thus the immediacy of a personal experience is subject to a certain degree of ambiguity between mediated and unmediated experience.
A further distinction can be made between scientific instruments that register certain readings of phenomena not accessible to human beings without instrumentation, and scientific instruments that place the human observer within a context that allows novel observations to be made. There are, then, at least two ways in which technology can be used to augment our natural sensory endowment: through improvements in the resolution of a particular sense or senses, or through placing the entire observer into a context in which it is possible to observe that which could not be previously observed. The starship as a scientific instrument belongs in the second class of technological augmentations of human experience.
As described in the previous section (and as I noted in Cognitive Astrobiology and the Overview Effect), one could never experience, with one’s native sensory endowment, the view provided by the Hubble Space Telescope’s deep field image when this scientific instrument focused on a very small portion of the sky for a long period of time, but if one’s mind and senses were augmented by the technologies of transhumanism—i.e., if the limits of our sensory organs and our consciousness were mitigated or eliminated—it might well become possible to personally observe a deep field view of the cosmos. One might be enhanced so that one could in fact focus on a miniscule portion of the sky for days at a time—something not possible with one’s native cognitive endowment—or consciousness might be directly interfaced with the instrumentation that would make this possible. In an example such as this, technologies of sensory enhancement coincide with technologies that place the observer in a context that enables novel observations.
Why should we be concerned with a personal experience of something like a deep field image of the cosmos? Given a mind shaped by the evolutionary psychology of our particular embodiment and history—and given that this is what makes us human, and is therefore something we are likely to want to retain as our identity—the most powerful (if not transformative) epistemic experiences are those that follow from the use of technology to place a human observer entire into a context that allows immediate personal experience of a phenomenon. A high speed camera is a marvelous scientific instrument, but better still (from an epistemic point of view) would be the technology to speed up the consciousness and sensory capabilities until it were possible to observe high speed phenomena with one’s own eyes.
It is not only our sensory organs that allow us to observe the world. Consciousness, too, is an aspect of the human condition that can be understood as a scientific instrument that gives us a unique and indeed uniquely intimate way of perceiving the world. Consciousness makes it possible for us to “observe” time. This is the scientific instrument least understood among all the faculties of the human condition, and the least integrated into science, even as it is pervasively present. Contemporary science cannot explain what an observer is, or how an observer observes, but it recognizes that an observer is crucial for all science, which must often correct for the perspective and the biases of the observer.
Technologies that could enhance consciousness in the way that we have used technology to enhance our senses are not yet on the horizon, partly because we have no science of consciousness that could be technologically implemented, and partly because of moral objections to the enhancement of consciousness. The efficacy of consciousness enhancing drugs is questionable at this time, while social disapproval and legal penalties stymie systematic research into the enhancement of consciousness. Since consciousness is coupled to all human observations, the only kind of scientific instrumentation that can expand the range of observation, where “observation” is understood in terms of personal experience, are those that place the observer within a context in which novel observations are possible. This is the kind of science that has not been possible with robotic probes.
The transformative nature of observational experiences in which the individual is present as an individual, and observes with his or her own body, is almost certainly a function of several factors, including a reflexive self-awareness of being present as well as those subtle aspects of observation not yet mastered by science. Gestalt experiences that involve the entire body are only possible when the entire body is present in for the experience in question.
We can hold out hope for such transformative observational scientific experiences (i.e., further instances of the class of experiences including the overview experience) wherever physical symmetries hold. It seems unlikely that we could shrink ourselves down in size to be able to observe what electron microscope allows us to see (since symmetries of scale do not hold), but symmetries of space and time imply the possibility of personal knowledge of here or there, now or then, even on a cosmic scale. From this it is obvious that the overview effect is a special case—a limiting case, if you will (following Einstein, who wrote that, “No fairer destiny could be allotted to any physical theory, than that it should of itself point out the way to the introduction of a more comprehensive theory, in which it lives on as a limiting case.” )—of these possibilities of personal observation. The overview effect known to date is, as it were, the lower bound of astrocognitive epistemology. The upper bound of astrocognitive epistemology would be approached by a deep field overview.
6. Observation and the Embodied Mind
The presence of the whole person in making an observation matters because the human mind is, as we now say, embodied; the human body is the corporeal context of the human mind—and one might say with equal justification that the human mind is the cognitive context of the human body. One of the most significant developments in the philosophy of mind over the past several decades has been a rejection of Cartesian dualism and a recognition of and engagement with the “embodied” nature of the mind.
The embodied mind is embodied in a body with an evolutionary history, and the mind no less than the body has been selected for its evolutionary fitness (which does not always entail logical rigor). For some, this is a problem. Daniel Dennett opened his book Darwin’s Dangerous Idea with this observation:
“Darwin’s theory of evolution by natural selection has always fascinated me, but over the years I have found a surprising variety of thinkers who cannot conceal their discomfort with his great idea, ranging from nagging skepticism to outright hostility. I have found not just lay people and religious thinkers, but secular philosophers, psychologists, physicists, and even biologists who would prefer, it seems, that Darwin were wrong. This book is about why Darwin’s idea is so powerful, and why it promises—not threatens—to put our most cherished visions of life on a new foundation.” 
The contemporary iteration of this range of Darwinian rejectionism from nagging skepticism to outright hostility is the controversy over evolutionary psychology, which is sometimes dismissed as unfalsifiable, as indeed Popper once held that the whole of Darwinism was unfalsifiable and therefore unscientific.  Moreover, evolutionary psychology is distasteful because it forces us to recognize some unflattering aspects of human nature. In other words, evolutionary psychology is a Copernican punishment of pride of the human intellect. But it doesn’t, or need not, stop there.
The embodied mind cuts both ways: there are reductionist consequences for consciousness, but there are also anti-reductionist consequences for the body (and especially for the central nervous system, which is integrated both into the body and into the world). But the idea of anti-reductionism is so unfamiliar to us that we don’t have the terminology or the concepts to explain it. We can, however, begin to glimpse that evolutionary psychology has edifying as well as humbling implications—a duality that has long been recognized as a consequence of other aspects of the Copernican revolution. We are not the center of the universe, or even the center of our own solar system, but we are part of something that possesses an ineffable grandeur, and our minds are part of this also. Indeed, it is our minds that grasp their own derivation from the cosmos. 
7. The Knowledge Argument in Space Science
When the embodied mind is placed in a position to personally observe experiences intrinsic to spacefaring civilization, new forms of knowledge intrinsic to spacefaring civilization may result, and new forms of consciousness may emerge, shaped by the knowledge. This perfectly exemplifies Frank White’s description of the overview effect as, “…the predicted experience of astronauts and space settlers, who would have a different philosophical point of view as a result of having a different physical perspective.” (cf. note )
One might hold that nothing new is learned by the personal observation of such experiences. There is, appropriately, a philosophical thought experiment that addresses exactly this question. Known as “Mary’s room” or as the knowledge argument, the thought experiment was originally formulated by Frank Jackson in this way:
“Mary is a brilliant scientist who is, for whatever reason, forced to investigate the world from a black and white room via a black and white television monitor. She specializes in the neurophysiology of vision and acquires, let us suppose, all the physical information there is to obtain about what goes on when we see ripe tomatoes, or the sky, and use terms like ‘red’, ‘blue’, and so on. She discovers, for example, just which wavelength combinations from the sky stimulate the retina, and exactly how this produces via the central nervous system the contraction of the vocal cords and expulsion of air from the lungs that results in the uttering of the sentence ‘The sky is blue’. […] What will happen when Mary is released from her black and white room or is given a color television monitor? Will she learn anything or not?” 
An individual might master what I above called, “the fundamental physics that explains the electromagnetic spectrum… [and] the biology and physiology that explains the details of how the human vision system functions,” while never having had personal experience of them. The “Mary’s room” thought experiment is intended to force the question of whether anything is learned when personal experience of a given phenomenon is added to scientific knowledge of the same phenomenon. There is, as yet, no consensus on the question; philosophers disagree on whether Mary learns anything upon leaving Mary’s room.
As a thought experiment, “Mary’s room” it is intended not to give us a definitive answer to a circumstance that is never likely to occur in fact, but to sharpen our intuitions and refine our formulations. The same could be done for the overview effect. We could easily formulate a parallel circumstance to the knowledge argument that addresses the class of astrocognitive epistemological experiences to which the overview effect belongs, according to which some individual has studied scientifically everything there is to know about space travel and human perception in extraterrestrial space, and then the same individual travels into space and experiences this personally. Does the individual learn anything from the personal experience of space travel?
Astronauts and cosmonaut themselves, who have personally experienced this transition from scientific knowledge of what they expect to see, to the actual first person experience, have testified to the impact of the personal experience. Alan B. Shepard, Jr. said, “…no one could be briefed well enough to be completely prepared for the astonishing view that I got.”  Robert Cenker said, “Of all the people I’ve spoken to about the experience of space, only those closest to me can begin to understand. My wife knows what I mean by the tone of my voice. My children know what I mean by the look in my eye. My parents know what I mean because they watched me grow up with it. Unless you actually go and experience it yourself you will never really know.” 
If our scientific knowledge of space travel is incomplete, then it is difficult to avoid the conclusion that one learns something from personal experience of a phenomenon incompletely described by science. Indeed, there is an interesting interplay between the problem of tacit knowledge and the knowledge argument. The knowledge argument might be revised so that the situation it describes only holds for mature sciences from which all tacit, folk, and anthropocentric concepts have been purged.  Therefore a poorly understood experience such as the overview effect, which has not been fully assimilated to science, might be epistemically augmented by personal experience, but if we possessed an exhaustive account in the context of a mature science, the epistemic augmentation of personal experience would disappear.
The pursuit of mature and definitive formulations of science is as unending as the universe. We might arrive at the mature formulation of a given science, but in so doing new questions will be posed, and we will want to push the frontiers of knowledge further outward, so that there will always be an unknown epistemic margin where personal experiences may epistemically augment our account of the world where no science as yet exists to fully explain what we see. For example, a galactic overview such as described earlier would take place in the context of the continuing expansion of scientific knowledge, and seeing this for ourselves may still contribute to scientific knowledge in unexpected and unanticipated ways. Much is likely to change in ourselves and our civilization by the time we can achieve a galactic overview, so that we cannot predict what we will learn, or even what our science will be like at that time; we can only postulate the possibility of a particular kind of experience, anticipating but not knowing its content.
8. The Interstellar Imperative and the Human Imperative
In a previous Centauri Dreams post, The Interstellar Imperative, I argued that the starship will become the ultimate scientific instrument, “…constituting both a demanding engineering challenge to build and offering the possibility of greatly expanding the scope of scientific knowledge by studying up close the stars and worlds of our universe, as well as any life and civilization these worlds may comprise.” Our future starships could take the form of robotic probes , but given what I have written here about the human body as a scientific instrument, and the as-yet-unrealized scientific potential of human experience, the starship as a scientific instrument could only be fully exploited for the purposes of scientific knowledge when coupled with a human presence. Putting human beings in starships and sending them to other words is an indispensible condition of the continued advancement of science and scientific civilization.
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 This essay was the basis of my presentation at the 2011 100YSS symposium.
 T. E. Hulme, Speculations, New York: Harcourt Brace and Company, 1924, p. 257. And, again, in Hulme’s Further Speculations: “It must be very difficult for the writers on ethics (who seem to be more happily endowed than most of us) to realise how excessively difficult it is for the ordinary modern to realise that there is any real subject ‘Ethics’ which can be at all compared with ‘Logic’ or even with ‘Aesthetic.’ It seems almost impossible for us to look on it as anything objective; everything seems to us arbitrary and human, and we should at a certain age no more think of reading a book on ethics than we should reading one on manners or astrology. There may even seem something ridiculous about the word ‘Virtue’.” (p. 203)
 These lists of bodily and intellectual needs are not intended to be exhaustive, but are presented here only to give a sense of the challenges of supporting human life in space.
 As a survey of some of these robotic probes, cf., e.g., Great robotic missions to explore space by Pallab Ghosh.
 The term “tacit knowledge” is due to Michel Polanyi, whose book The Tacit Dimension is an exposition of tacit knowledge. The idea is developed throughout Polanyi’s works.
 From an interview with Benoît Mandelbrot in the NOVA documentary Fractals: Hunting the Hidden Dimension.
 The “overview effect” is a term due to Frank White, describing the experience of astronauts and cosmonauts who have seen the Earth whole from orbit or beyond, given exposition in his book The Overview Effect: Space Exploration and Human Evolution. White summarizes the overview effect as, “…the predicted experience of astronauts and space settlers, who would have a different philosophical point of view as a result of having a different physical perspective.” (Frank White, The Overview Effect, Boston: Houghton Mifflin Company, 1987, p. 4) My posts on the overview effect include The Epistemic Overview Effect, The Overview Effect as Perspective Taking, Hegel and the Overview Effect, The Overview Effect in Formal Thought, Our Knowledge of the Internal World, Personal Experience and Empirical Knowledge, and Cognitive Astrobiology and the Overview Effect.
 On the difference between profundity and clarity cf. The Study of Civilization as Rigorous Science and Addendum on the Study of Civilization as Rigorous Science.
 David Dunér, “Astrocognition: Prolegomena to a future cognitive history of exploration,” in Humans in Outer Space – Interdisciplinary Perspectives, edited by Ulrike Landfester, Nina-Louisa Remuss, Kai-Uwe Schrogl, and Jean-Claude Worms, Springer, 2011, p. 119. I prefer Pauli Laine’s term “cognitive astrobiology” to Dunér’s “astrocognition,” though Dunér’s analysis of the forms of astrocognition is a helpful framework.
 There have been three such “deep field” images from the Hubble Space Telescope, of increasing resolution, the Hubble Deep Field (HDF), the Hubble Ultra Deep Field, (HUDF), and the Hubble eXtreme Deep Field (XDF). There is also the Subaru Deep Field (SDF) image.
 Albert Einstein, Relativity: The Special and General Theory, New York: Plume, 2006, pp. 98-99.
 Daniel C. Dennett, Darwin’s Dangerous Idea: Evolution and the Meanings of Life, Penguin Books, 1995, Preface, p. 11.
 Popper changed his opinion on the scientificity of Darwinism over the course of his career. Popper, famous for his definition of scientificity in terms of falsifiability, wrote in his Unended Quest: An Intellectual Autobiology (1974, section 37), “I have come to the conclusion that Darwinism is not a testable scientific theory, but a metaphysical research programme—a possible framework for testable scientific theories.” Not many years later in “Natural Selection and the Emergence of Mind” a lecture delivered at Darwin College, Cambridge, 08 November 1977 (also Chapter VI in Evolutionary Epistemology, Rationality, and the Sociology of Knowledge, by Gerard Radnitzky, William Warren Bartley, Karl Raimund Popper), Popper said, “…I have changed my mind about the testability and the logical status of the theory of natural selection; and I am glad to have an opportunity to make a recantation. My recantation may, I hope, contribute a little to the understanding of the status of natural selection.”
 Evolutionary psychology places the human mind in the context of cognitive astrobiology, because evolutionary psychology itself must eventually be placed in the context of astrobiology, which is the more comprehensive discipline. The human mind placed in the context of cognitive astrobiology, i.e., the embodiment of mind in nature and history, means that, in Carl Sagan’s terms, our minds are star stuff too: “…if you are bothered by the disturbing vision that evolutionary psychology paints of the human mind, take heart, because it also implies this edifying corollary, that the mind is as much of the stars as it is of the earth, as much of the universe at large as of nature, red in tooth and claw.” (Cf. also The Mind as Star Stuff) In this astrocognitive context, the human being has a crucial role to play as an observer in science, and especially in those sciences that will emerge from the comparative study of other worlds, other life, and hopefully also other civilizations.
 Frank Jackson, “Epiphenomenal Qualia,” 1982, Philosophical Quarterly 32: 127–136. I have previously written about the “Mary’s room” thought experiment in Computational Omniscience and Colonia del Sacramento and the Knowledge Argument.
 Quoted in Frank White, The Overview Effect: Space Exploration and Human Evolution, Boston: Houghton Mifflin Company, 1987, p. 197.
 Quoted in Kevin W. Kelley, editor, The Home Planet, Reading, et al.: Addison-Wesley, 1988, p. 142. These astronaut and cosmonaut experiences might be interpreted as experiments that verify the epistemic role of personal experience explored by the knowledge argument.
 Cf. Folk Concepts and Scientific Progress
 Interstellar probes without a live crew are sometimes referred to as “Bracewell probes,” following the work of Ronald Bracewell, whose papers “Communications from Superior Galactic Communities” and “Interstellar Probes” proposed interstellar probes as a medium for communication among civilizations, as an alternative to the SETI paradigm of radio or optical communication. Cf. Bracewell, R. N. (1960), “Communications from Superior Galactic Communities,” Nature 186 (4726): 670–671, reprinted in A. G. Cameron, ed., Interstellar Communication, New York: W. A. Benjamin, 1963, pp. 243–248, and Bracewell, R. N., “Interstellar Probes,” in A.G.W. Cameron and Cyril Ponnamperuma, eds., Interstellar Communcation: Scientific Perspectives, Boston: Houghton-Mifflin, 1974, pp. 102-117.