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CARL SAGAN (November 9, 1934-December 20, 1996) was professor of astronomy and space sciences and director of the Laboratory for Planetary Studies at Cornell University. He played a leading role in the Mariner, Viking, and Voyager spacecraft expeditions to the planets, for which he twice received the NASA Medals for Exceptional Scientific Achievement. Dr. Sagan received the Pulitzer Prize and the highest awards of both the National Academy of Sciences and the National Science Foundation and many other awards for his contributions to science, literature, education, and the preservation of the environment. His book Cosmos (accompanying his Emmy and Peabody Award-winning television series of the same name) was the bestselling science book ever published in the English language, and his bestselling novel Contact was turned into a major motion picture.
Dr. Sagan was among the first to alert the public to the danger of global warming and the potential climatic consequences of nuclear war. In the 1980s, he initiated the campaign to forge an alliance between religion and science to protect the environment.
Jacket design: Barbara de Wilde
Jacket photograph: Spectrum of comet 2001, Q4 (NEAT), May 14, 2004
Courtesy of Gunma Astronomical Observatory, Japan
Author photograph © Andy Levin/Parade
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In The Varieties of Scientific Experience: A Personal View of the Search for God, Carl Sagan sets down his detailed thoughts on the relationship between religion and science and describes his personal search to understand the nature of the sacred in the vastness of the cosmos. In 1985, Sagan was invited to give the famous Gifford Lectures in Scotland on the grand occasion of the lectureship's centennial. The result is this delightfully intimate discussion of his views on topics ranging from the likelihood of intelligent life on other planets to the danger of nuclear annihilation of our own, on creation-ism and so-called intelligent design to a new concept of science as "informed worship" to manic depression and the possible chemical nature of transcendance. In his trademark clear and down-to-earth voice-and exhibiting a breadth of intellect nothing short of astounding- the late great astronomer and astrophysicist illuminates his conversation with examples from cosmology, physics, philosophy, literature, psychology, cultural anthropology, mythology, theology, and more. The Varieties of Scientific Experience, published now for the first time to mark the tenth anniversary of Sagan's death, has been edited and updated by his widow and longtime collaborator, Ann Druyan.
Sagan was one of the greatest scientists of our time, and his extraordinary ability to make complex scientific theory accessible and relevant has also established him as one of the most enduring and beloved communicators of science. His humorous, wise, and at times stunningly prophetic observations on some of the greatest mysteries of the cosmos have the invigorating effect of stimulating the intellect, exciting the imagination, and reawakening us to the grandeur of life in the cosmos.
A Personal View of the Search for God
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Edited by ANN DRUYAN Illustrations Editor and Scientific Consultant Steven Soter
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Frontispiece figure caption by Ann Druyan, published in What Is Enlightenment?
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LIBRARY OF CONGRESS CATALOGING IN PUBLICATION DATA
Sagan, Carl, 1934-1996. The varieties of scientific experience : a personal view of the search for God / Carl Sagan ; edited by Ann Druyan. p. cm. The author's 1985 Gifford lectures. Includes bibliographical references and index. Contents: Nature and wonder: a reconnaissance of heaven-The retreat from Copernicus-The organic universe-Extraterrestrial intelligence-Extraterrestrial folklore: implications for the evolution of religion--The God hypothesis-The religious experience-Crimes against creation-The search for who we are-Selected Q&A. ISBN 1-59420-107-2 1. Natural theology. 2. Religion and science. 3. Sagan, Carl, 1934-1996-Religion. I. Druyan, Ann, 1949- II. Title. BL183.S24 2006 215-dc22 2006044827
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Editor's Introduction ix Author's Introduction xvii
CARL SAGAN'S 1985 GIFFORD LECTURES
1. NATURE AND WONDER: A RECONNAISSANCE OF HEAVEN 1
2. THE RETREAT FROM COPERNICUS: A MODERN LOSS OF NERVE 33
5. THE ORGANIC UNIVERSE 63
4. EXTRATERRESTRIAL INTELLIGENCE 103
5. EXTRATERRESTRIAL FOLKLORE: IMPLICATIONS FOR THE EVOLUTION OF RELIGION 123
6. THE GOD HYPOTHESIS 147
7. THE RELIGIOUS EXPERIENCE 169
8. CRIMES AGAINST CREATION 191
9. THE SEARCH 213
SELECTED Q & A 223
Figure Captions 265
Carl Sagan was a scientist, but he had some qualities that I associate with the Old Testament. When he came up against a wall-the wall of jargon that mystifies science and withholds its treasures from the rest of us, for example, or the wall around our souls that keeps us from taking the revelations of science to heart-when he came up against one of those topless old walls, he would, like some latter-day Joshua, use all of his many strengths to bring it down.
As a child in Brooklyn, he had recited the Hebrew V'Ahavta prayer from Deuteronomy at temple services: "And you shall love the Lord your God with all your heart, with all your soul, with all your might." He knew it by heart, and it may have been the inspiration for him to first ask, What is love without understanding? And what greater might do we possess as human beings than our capacity to question and to learn?
The more Carl learned about nature, about the vastness of the universe and the awesome timescales of cosmic evolution, the more he was uplifted.
Another way in which he was Old Testament: He couldn't
live a compartmentalized life, operating on one set of assumptions in the laboratory and keeping another, conflicting set for the Sabbath. He took the idea of God so seriously that it had to pass the most rigorous standards of scrutiny.
How was it, he wondered, that the eternal and omniscient Creator described in the Bible could confidently assert so many fundamental misconceptions about Creation? Why would the God of the Scriptures be far less knowledgeable about nature than are we, newcomers, who have only just begun to study the universe? He could not bring himself to overlook the Bible's formulation of a flat, six-thousand-year-old earth, and he found especially tragic the notion that we had been created separately from all other living things. The discovery of our relatedness to all life was borne out by countless distinct and compelling lines of evidence. For Carl, Darwin's insight that life evolved over the eons through natural selection was not just better science than Genesis, it also afforded a deeper, more satisfying spiritual experience.
He believed that the little we do know about nature suggests that we know even less about God. We had only just managed to get an inkling of the grandeur of the cosmos and its exquisite laws that guide the evolution of trillions if not infinite numbers of worlds. This newly acquired vision made the God who created the World seem hopelessly local and dated, bound to transparently human misperceptions and conceits of the past.
This was no glib assertion on his part. He avidlyystudied the world's religions, both living and defunct, with the same hunger for learning that he brought to scientific subjects. He was enchanted by their poetry and history. When he debated religious leaders, he frequently surprised them with his ability to out-quote the sacred texts. Some of these debates led to longstanding friendships and alliances for the protection of life.
However, he never understood why anyone would want to separate science, which is just a way of searching for what is true, from what we hold sacred, which are those truths that inspire love and awe.
His argument was not with God but with those who believed that our understanding of the sacred had been completed. Science's permanently revolutionary conviction that the search for truth never ends seemed to him the only approach with sufficient humility to be worthy of the universe that it revealed. The methodology of science, with its error-correcting mechanism for keeping us honest in spite of our chronic tendencies to project, to misunderstand, to deceive ourselves and others, seemed to him the height of spiritual discipline. If you are searching for sacred knowledge and not just a palliative for your fears, then you will train yourself to be a good skeptic.
The idea that the scientific method should be applied to the deepest of questions is frequently decried as "scientism." This charge is made by those who hold that religious beliefs should be off-limits to scientific scrutiny-that beliefs (convictions without evidence that can be tested) are a sufficient way of knowing. Carl understood this feeling, but he insisted with Bertrand Russell that "what is wanted is not the will to believe, but the desire to find out, which is the exact opposite." And in all things, even when it came to facing his own cruel fate-he succumbed to pneumonia on December 20, 1996, after enduring three bone-marrow transplants-Carl didn't want just to believe: He wanted to know.
Until about five hundred years ago, there had been no such wall separating science and religion. Back then they were one and the same. It was only when a group of religious men who wished "to read God's mind" realized that science would be the most powerful means to do so that a wall was needed. These
men-among them Galileo, Kepler, Newton, and, much later, Darwin-began to articulate and internalize the scientific method. Science took off for the stars, and institutional religion, choosing to deny the new revelations, could do little more than build a protective wall around itself.
Science has carried us to the gateway to the universe. And yet our conception of our surroundings remains the disproportionate view of the still-small child. We are spiritually and culturally paralyzed, unable to face the vastness, to embrace our lack of centrality and find our actual place in the fabric of nature. We batter this planet as if we had someplace else to go. That we even do science is a hopeful glimmer of mental health. However, it's not enough merely to accept these insights intellectually while we cling to a spiritual ideology that is not only rootless in nature but also, in many ways, contemptuous of what is natural. Carl believed that our best hope of preserving the exquisite fabric of life on our world would be to take the revelations of science to heart.
And that he did. "Every one of us is, in the cosmic perspective, precious," he wrote in his book Cosmos. "If a human disagrees with you, let him live. In a hundred billion galaxies you will not find another." He lobbied NASA for years to instruct Voyager 2 to look back to Earth and take a picture of it from out by Neptune. Then he asked us to meditate on that image and see our home for what it is-just a tiny "pale blue dot" afloat in the immensity of the universe. He dreamed that we might attain a spiritual understanding of our true circumstances. Like a prophet of old, he wanted to arouse us from our stupor so that we would take action to protect our home.
Carl wanted us to see ourselves not as the failed clay of a disappointed Creator but as starstuff, made of atoms forged in the fiery hearts of distant stars. To him we were "starstuff ponder-
ing the stars; organized assemblages of 10 billion billion billion atoms considering the evolution of atoms; tracing the long journey by which, here at least, consciousness arose." For him science was, in part, a kind of "informed worship." No single step in the pursuit of enlightenment should ever be considered sacred; only the search was.
This imperative was one of the reasons he was willing to get into so much trouble with his colleagues for tearing down the walls that have excluded most of us from the insights and values of science. Another was his fear that we would be unable to keep even the limited degree of democracy we have achieved. Our society is based on science and high technology, but only a small minority among us has even a superficial understanding of how they work. How can we hope to be responsible citizens of a democratic society, informed decision makers regarding the inevitable challenges posed by these newly acquired powers?
This vision of a critically thoughtful public, awakened to science as a way of thinking, impelled him to speak at many places where scientists were not usually found: kindergartens, naturalization ceremonies, an all-black college in the segregated South of 1962, at demonstrations of nonviolent civil disobedience, on the Tonight show. And he did this while maintaining a pioneering, astonishingly productive, fearlessly interdisciplinary scientific career.
He was especially thrilled to be invited to give the Gifford Lectures on Natural Theology of 1985 at the University of Glasgow. He would be following in the footsteps of some of the greatest scientists and philosophers of the last hundred years- including James Frazer, Arthur Eddington, Werner Heisenberg, Niels Bohr, Alfred North Whitehead, Albert Schweitzer, and Hannah Arendt.
Carl saw these lectures as a chance to set down in detail his
understanding of the relationship between religion and science and something of his own search to understand the nature of the sacred. In the course of them, he touches on several themes that he had written about elsewhere; however, what follows is the definitive statement of what he took pains to stress were only his personal views on this endlessly fascinating subject.
At the beginning of each Gifford Lecture, a distinguished member of the university community would introduce Carl and marvel at the need for still more additional halls to accommodate the overflow audience. I have been careful not to change the meaning of anything Carl said, but I have taken the liberty of editing out those gracious introductory remarks as well as the hundred or more notations on the audio transcripts that merely say "[Laughter]."
I ask the reader to keep in mind at all times that any deficiencies of this book are my responsibility and not Carl's. Despite the fact that the unedited transcripts reveal a man who spoke extemporaneously in nearly perfect paragraphs, a collection of lectures is not exactly the same thing as a book. This is especially true when the Pulitzer Prize-winning author in question never published anything without combing at least twenty or twenty-five iterations of every manuscript for error or stylistic infelicity.
There was plenty of laughter during these lectures, but also the kind of pin-drop silence that comes when the audience and the speaker are united in the thrall of an idea. The extended dialogues in some of the question-and-answer periods capture a sense of what it was like to explore a question with Carl. I attended every lecture, and more than twenty years later what remains with me was his extraordinary combination of principled, crystal-clear advocacy coupled with respect and tenderness toward those who did not share his views.
The American psychologist and philosopher William James gave the Gifford Lectures in the first years of the twentieth century. He later turned them into an extraordinarily influential book entitled The Varieties of Religious Experience, which remains in print till this day. Carl admired James's definition of religion as a "feeling of being at home in the Universe," quoting it at the conclusion of Pale Blue Dot, his vision of the human future in space. The title of the book you hold in your hands is a tip of the hat to the illustrious tradition of the Gifford Lectures. My variation on James's title is intended to convey that science opens the way to levels of consciousness that are otherwise inaccessible to us; that, contrary to our cultural bias, the only gratification that science denies to us is deception. I hope it also honors the breadth of searching and the richness of insight that distinguished Carl Sagan's indivisible life and work. The varieties of his scientific experience were exemplified by oneness, humility, community, wonder, love, courage, remembrance, openness, and compassion.
In that same drawer where the transcript of these lectures was rediscovered, there was a sheaf of notes intended for a book we never had the chance to write. Its working title was Ethos, and it would have been our attempt to synthesize the spiritual perspectives we derived from the revelations of science. We collected filing cabinets' worth of notes and references on the subject. Among them was a quotation Carl had excerpted from Gottfried Wilhelm Leibniz (1646-1716), the mathematical and philosophical genius, who had invented differential and integral calculus independently of Isaac Newton. Leibniz argued that God should be the wall that stopped all further questioning, as he famously wrote in this passage from Principles of Nature and Grace:
"Why does something exist rather than nothing? For 'noth-
ing' is simpler than 'something.' Now this sufficient reason for the existence of the universe . . . which has no need of any other reason . . . must be a necessary being, else we should not have a sufficient reason with which we could stop."
And just beneath the typed quote, three small handwritten words in red pen, a message from Carl to Leibniz and to us: "So don't stop."
Ithaca, New York March 21, 2006
In these lectures I would like, following the wording of the Gifford Trust, to tell you something of my views on what at least used to be called natural theology, which, as I understand it, is everything about the world not supplied by revelation. This is a very large subject, and I will necessarily have to pick and choose topics. I want to stress that what I will be saying are my own personal views on this boundary area between science and religion. The amount that has been written on the subject is enormous, certainly more than 10 million pages, or roughly 1011 bits of information. That's a very low lower limit. And nevertheless no one can claim to have read even a tiny fraction of that body of literature or even a representative fraction. So it is only in the hope that much that has been written is unnecessary to be read that one can approach the subject at all. I'm aware of many limitations in the depth and breadth of my own understanding of both subjects, and so ask your indulgence. Fortunately, there was a question period after each of the Gifford Lectures, in which the more egregious of my errors could be pointed out, and
I was genuinely delighted by the vigorous give-and-take in those sessions.
Even if definitive statements on these subjects were possible, what follows is not such. My objective is much more modest. I hope only to trace my own thinking and understanding of the subject in the hopes that it will stimulate others to go further, and perhaps through my errors-I hope not to have made many, but it was inevitable that I would-new insights will emerge.
Carl Sagan Glasgow, Scotland October 14, 1985
THE VARIETIES of SCIENTIFIC EXPERIENCE
The truly pious must negotiate a difficult course between the precipice of godlessness and the marsh of superstition.
Certainly both extremes are to be avoided, except what are they? What is godlessness? Does not the concern to avoid the "precipice of godlessness" presuppose the very issue that we are to discuss? And what exactly is superstition? Is it just, as some have said, other people's religion? Or is there some standard by which we can detect what constitutes superstition?
For me, I would say that superstition is marked not by its pretension to a body of knowledge but by its method of seeking truth. And I would like to suggest that superstition is very simple: It is merely belief without evidence. The question of what constitutes evidence in this interesting subject, I will try to address. And I will return to this question of the nature of evidence and the need for skeptical thinking in theological inquiry. The word "religion" comes from the Latin for "binding together," to connect that which has been sundered apart. It's a very interesting concept. And in this sense of seeking the deepest interrelations among things that superficially appear to be sundered, the objectives of religion and science, I believe, are
identical or very nearly so. But the question has to do with the reliability of the truths claimed by the two fields and the methods of approach.
By far the best way I know to engage the religious sensibility, the sense of awe, is to look up on a clear night. I believe that it is very difficult to know who we are until we understand where and when we are. I think everyone in every culture has felt a sense of awe and wonder looking at the sky. This is reflected throughout the world in both science and religion. Thomas Carlyle said that wonder is the basis of worship. And Albert Einstein said, "I maintain that the cosmic religious feeling is the strongest and noblest motive for scientific research." So if both Carlyle and Einstein could agree on something, it has a modest possibility of even being right.
Here are two images of the universe. For obvious reasons they concentrate not on the spaces in which there is nothing but on the locales in which there is something. It would be very dull if I simply showed you image after image of darkness. But I stress that the universe is mainly made of nothing, that something is the exception. Nothing is the rule. That darkness is a commonplace; it is light that is the rarity. As between darkness and light, I am unhesitatingly on the side of light (especially in an illustrated book). But we must remember that the universe is an almost complete and impenetrable darkness and the sparse sources of light, the stars, are far beyond our present ability to create or control. This prevalence of darkness, both factually and metaphorically, is worth contemplating before setting out on such an exploration.
A. here are a huge number of stars. Especially in the center of the galaxy, in the direction of the constellation Sagittarius, the sky is rippling with suns, altogether a couple of hundred thousand million suns, making up the Milky Way Galaxy. As far as we can tell, the average star is in no major way different from the Sun. Or, put another way, the Sun is a reasonably typical star in the Milky Way Galaxy, nothing to call our attention to it. If you had stepped a little bit back and included the Sun in this picture, you would not be able to tell whether it was that one right there or that one right over there, maybe, in the top right-hand corner.
It would be very good to have a photograph of the Milky-Way Galaxy taken from an appropriate distance, but we have not yet sent cameras to that distance and so the best we can do for now is to show a photograph of a galaxy like our own, and this is, in fact, the nearest spiral galaxy like our own, M31 in the constellation Andromeda. And again we are looking at stars in the foreground within the Milky Way Galaxy, through which we are seeing M31 and two of its satellite galaxies.
Now, imagine that this is our galaxy. We are looking at a great concentration of stars in the center, so close together that we cannot make out individual ones. We see these spiral lanes of dark gas and dust in which star formation is mainly occurring. If this were the Milky Way Galaxy, where would the Sun be? Would it be in the center of the galaxy, where things are clearly important, or at least well lit? The answer is no. We would be somewhere out in the galactic boondocks, the extreme suburbs, where the action isn't. We are situated in a very unremarkable, unprepossessing location in this great Milky Way Galaxy. But, of course, it is not the only galaxy. There are many galaxies, a very large number of galaxies.
ing to be loved because of it. And there are other challenges to the conventional religions from even the most casual look at the sort of cosmos I have presented to you.
Let me read a passage from Thomas Paine, from The Age of Reason. Paine was an Englishman who played a major role in both the American and French revolutions. "From whence," Paine asks-"From whence, then, could arise the solitary and strange conceit that the Almighty, who had millions of worlds equally dependent on his protection, should quit the care of all the rest, and come to die in our world because, they say, one man and one woman ate an apple? And, on the other hand, are we to suppose that every world in the boundless creation had an Eve, an apple, a serpent, and a redeemer?"
Paine is saying that we have a theology that is Earth-centered and involves a tiny piece of space, and when we step back, when we attain a broader cosmic perspective, some of it seems very small in scale. And in fact a general problem with much of Western theology in my view is that the God portrayed is too small. It is a god of a tiny world and not a god of a galaxy, much less of a universe.
Now, we can say, "Well, that's just because the right words weren't available back when the first Jewish or Christian or Islamic holy books were written." But clearly that's not the problem; it is certainly possible in the beautiful metaphors in these books to describe something like the galaxy and the universe, and it isn't there. It is a god of one small world, a problem, I believe, that theologians have not adequately addressed.
I don't propose that it is a virtue to revel in our limitations. But it's important to understand how much we do not know. There is an enormous amount we do not know; there is a tiny amount that we do. But what we do understand brings us face-
to-face with an awesome cosmos that is simply different from the cosmos of our pious ancestors.
Does trying to understand the universe at all betray a lack of humility? I believe it is true that humility is the only just response in a confrontation with the universe, but not a humility that prevents us from seeking the nature of the universe we are admiring. If we seek that nature, then love can be informed by truth instead of being based on ignorance or self-deception. If a Creator God exists, would He or She or It or whatever the appropriate pronoun is, prefer a kind of sodden blockhead who worships while understanding nothing? Or would He prefer His votaries to admire the real universe in all its intricacy? I would suggest that science is, at least in part, informed worship. My deeply held belief is that if a god of anything like the traditional sort exists, then our curiosity and intelligence are provided by such a god. We would be unappreciative of those gifts if we suppressed our passion to explore the universe and ourselves. On the other hand, if such a traditional god does not exist, then our curiosity and our intelligence are the essential tools for managing our survival in an extremely dangerous time. In either case the enterprise of knowledge is consistent surely with science; it should be with religion, and it is essential for the welfare of the human species.
All of us grow up with the sense that there is some personal relationship between us, ourselves, and the universe. And there is a natural tendency to project our own knowledge, especially self-knowledge, our own feelings, on others. This is a commonplace in psychology and psychiatry. And so it is with our view of the natural world. Anthropologists and historians of religion sometimes call this animism and attribute it to so-called primitive tribes-that is, ones who have not constructed instruments of mass destruction. This is the idea that every tree and brook has a kind of actuating spirit-that, as Thales, the first scientist, said in one of the few surviving fragments of his work, "There are gods in everything." It's a natural idea. But it's not restricted to animists, of whom there are many millions on the planet today. Physicists, for example, do it all the time, except where nature does not oblige. It is the commonest thing in the world in, say, the kinetic theory of gases, to imagine each of these little molecules of air that are busily colliding in front of us as, maybe, billiard balls. Well, that's not exactly projection, since physicists are not strictly speaking of billiard balls, but it
Here's a closer view of the rings of Saturn. And you can see an enormous sequence of such rings and a gap-the so-called Cassini Division in the rings.
If you take a close-up look at this portion, you can see a succession of rings. We now know that there are many hundreds of these rings, all in a flat plane, and we now know, as both Kant and Laplace guessed, that they're made of tumbling boulders and dust particles. The rings of Saturn, by the way, are thinner compared to their lateral extent than is a piece of paper.
Kant also knew about objects that were then called nebulae. It was not clear whether they were within our Milky Way or beyond-we now know, of course, most of them are beyond. Some of the nebulae were again flattened systems made, we now know, of stars.
So Kant and Laplace, both of them explicitly mentioning the rings of Saturn, and Kant explicitly mentioning the elliptical nebulae, proposed that the solar system came from such a flattened disk and that somehow the planets condensed out of the disk. But if that's the case, the disk, after all, has some rotation. Everything that condenses out of it will be going around in the same direction. And if you think about it for a moment, you will see that as the particles come together and make larger objects, they will have a common sense of rotation as well.
What Kant and Laplace proposed is what we now call a solar nebula, or accretion disk, whose flattened form was the ancestor of the planets, and that it is perfectly easy to understand how it is that the planets are in the same plane with the same direction of revolution and the same sense of rotation.
What is more, we now know that the random orientation of the comets is not primordial and that very likely the comets began in the solar nebula, all going around the Sun in the same sense, were ejected by gravitational interactions with the major
This is just another artist's conception of an early stage in the origin of our solar system, showing some of the multitude of small objects a few kilometers across, from which the planets were formed. And that this is not solely a theoretical construct has been made clear in recent years by the discovery of a number of flattened disks around nearby stars.
This one is around the star Beta Pictoris. It's in a Southern Hemisphere constellation. But Vega, one of the brightest stars in the Northern sky, also has such a flattened disk of dust and maybe a little gas around it. And many people think that it is in the final stages of sweeping up a solar nebula, that planets have already formed there, and that if you come back in only a few tens of millions of years you will find the disk entirely dissipated and a fully formed planetary system.
So I would like now to come to what is called the anthropic principle. If you study history, it's almost irresistible to ask the question, what if something had gone in a different direction? What if George III had been a nice guy? There are many questions; that's not the deepest, but you understand what I'm saying. There are many such apparently random events that could just as easily have gone another way, and the history of the world would be significantly different. Maybe-I don't know that this is the case-but maybe Napoleon's mother sneezed and Napoleon's father said, "Gesundheit," and that's how they met. And so a single particle of dust was responsible for that deviation in human history. And you can think of still more significant possibilities. It's a natural thing to think about.
Now, here we are. We're alive; we have some modest degree of intelligence; there is a universe around us that clearly permits the evolution of life and intelligence. That's an unremarkable and, I think, as secure a remark as can be made in this subject: that the universe is consistent with the evolution of life, at least here. But what is interesting is that in a number of respects the universe is very fine-tuned, so that if things were a little different, if the laws of nature were a little different, if
the constants that determine the action of these laws of nature were a little different, then the universe might be so different as to be incompatible with life.
For example, we know that the galaxies are all running away from each other (the so-called expanding universe). We can measure the rate of expansion (it is not strictly constant with time). We can even extrapolate back and ask how long ago were all the galaxies so close that they were in effect touching. And that will surely be, if not the origin of the universe, at least an anomalous or singular circumstance from which we can begin dating. And that number varies according to a number of estimates, but it's roughly 14,000 million years.
Now, the period of time that was required for the evolution of intelligent life in the universe-if we are unique and we define ourselves immodestly as the carriers of intelligent life (a case could be made, you know, for other primates and dolphins, whales, and so on)-but for any of those cases it took something like 14,000 million years for intelligence to arrive. Well, how come? Why are those two numbers the same? Put another way: If we were at a much earlier stage or a much later stage in the expansion of the universe, would things be very different? If we were at a much earlier stage, then there would not be, according to this view, enough time for the random aspects of the evolutionary process to proceed, and so intelligent life would not be here, and so there would be nobody to make this argument or debate about it. Therefore the very fact that we can talk about this demonstrates, it is argued, that the universe must be a certain number of years old. So if only we had been wise enough to have thought of this argument before Edwin Hubble, we could have made this spectacular discovery about the expansion of the universe just by contemplating our navels.
Well, I would like to conclude, then, by just a few lines of poetry, this one from Rupert Brooke, called "Heaven."
FISH (fly-replete, in depth of June,
Dawdling away their wat'ry noon)
Ponder deep wisdom, dark or clear,
Each secret fishy hope or fear.
Fish say, they have their Stream and Pond;
But is there anything Beyond?
This life cannot be All, they swear,
For how unpleasant, if it were!
One may not doubt that, somehow, Good
Shall come of Water and of Mud;
And, sure, the reverent eye must see
A Purpose in Liquidity.
We darkly know, by Faith we cry,
The future is not Wholly Dry.
Mud unto mud!-Death eddies near-
Not here the appointed End, not here!
But somewhere, beyond Space and Time,
Is wetter water, slimier slime!
And there (they trust) there swimmeth One,
Who swam ere rivers were begun,
Immense, of fishy form and mind,
Squamous, omnipotent, and kind;
And under that Almighty Fin,
The littlest fish may enter in.
Oh! never fly conceals a hook,
Fish say, in the Eternal Brook,
But more than mundane weeds are there,
And mud, celestially fair;
Fat caterpillars drift around,
And Paradisal grubs are found;
Unfading moths, immortal flies,
And the worm that never dies.
And in that Heaven of all their wish,
There shall be no more land, say fish.
Once upon a time, the best minds of the human species believed that the planets were attached to crystal spheres, which explained their motion both daily and over longer periods of time. We now know this is not true in several ways, one of which is that the Copernican theory explains the observed motion to higher precision and with a more modest investment of assumptions. But we also know this is not true, because we have sent spacecraft to the outer solar system with acoustic micro-meteorite detectors-and there was no sound of tinkling crystal as the spacecraft passed the orbits of Mars or Jupiter or Saturn. We have direct evidence that there are no crystal spheres. Now, Copernicus did not have such evidence, of course, but nevertheless his more indirect approach has been thoroughly validated. Now, when they were believed to exist, how was it that these spheres moved? Did they move on their own? They did not. Both in classic and in medieval times, it was prominently speculated that gods or angels propelled them, gave them a twirl every now and then.
The Newtonian gravitational superstructure replaced angels with GMm/r2, which is a little more abstract. And in the course of that transformation, the gods and angels were relegated to more remote times and more distant causality skeins. The history of science in the last five centuries has done that repeatedly, a lot of walking away from divine microintervention in earthly affairs. It used to be that the flowering of every plant was due to direct intervention by the Deity. Now we understand something about plant hormones and phototropism, and virtually no one imagines that God directly commands the individual flowers to bloom.
So as science advances, there seems to be less and less for God to do. It's a big universe, of course, so He, She, or It could be profitably employed in many places. But what has clearly been happening is that evolving before our eyes has been a God of the Gaps; that is, whatever it is we cannot explain lately is attributed to God. And then after a while, we explain it, and so that's no longer God's realm. The theologians give that one up, and it walks over onto the science side of the duty roster.
We've seen this happen repeatedly. And so what has happened is that God is moving-if there is a real God of the Western sort, I am, of course, speaking only metaphorically- God has been evolving toward what the French call un roi faineant-a do-nothing king-who gets the universe going, establishes the laws of nature, and then retires or goes somewhere else. This is not far at all from the Aristotelian view of the unmoved prime mover, except that Aristotle had several dozen unmoved prime movers, and he felt that this was an argument for polytheism, something that is often overlooked today.
Well, I want to describe one of the most major gaps that is in the course of being filled in. (We cannot surely say it is fully filled in yet.) And that has to do with the origin of life.
at least it's not immediately obvious, which organic molecules we see on the Earth are here because of life and which would be here even if there had not been life. And virtually all the organic molecules that we see in our everyday lives are of biological origin. If you want to know something about organic chemistry on the Earth prior to the origin of life, it is a good idea to look elsewhere.
The idea of extraterrestrial organic matter is important not just for this reason but also because it tells us something relevant at least about the likelihood of extraterrestrial life. If it turns out that there is no sign of organic molecules elsewhere, or they're extremely rare, that might lead you to conclude that life elsewhere was extremely rare. If you found the universe burgeoning and overflowing with organic matter, then at least that prerequisite for extraterrestrial life would be satisfied. So it's an important issue. It's an issue where remarkable progress has been made since the early 1950s, and it speaks to us, I believe, if not centrally at least tangentially, about our origins.
The astronomer Sir William Huggins frightened the world in 1910. He was minding his own business, doing astronomy, but as a result of his astronomy (the work I'm talking about was done in the last third of the nineteenth century) there were national panics in Japan, in Russia, in much of the southern and midwestern United States. A hundred thousand people in their pajamas emerged onto the roofs of Constantinople. The pope issued a statement condemning the hoarding of cylinders of oxygen in Rome. And there were people all over the world who committed suicide. All because of Sir William Huggins's work. Very few scientists can make similar claims. At least until the invention of nuclear weapons. What exactly did he do? Well, Huggins was one of the first astronomical spectroscopists.
This image of four spectra is taken from one of Huggins's publications. These are wavelengths of light in the visible part of the spectrum to which the eye is sensitive. At the bottom is the spectrum of an 1868 comet called Brorsen. Above that is the spectrum of another 1868 comet called Winnecke II. And at the top is the spectrum of olive oil.
You can see that Comet Winnecke resembles olive oil more than it does Comet Brorsen. However, nobody deduced the existence of olive oil on the comets. (It would be an important discovery if it could be made.) But instead what this similarity shows is that a molecular fragment, diatomic carbon or C2-two carbon atoms attached together-is present when you look at the spectrum of the comets and also when you look at natural gas and the vapor from heated olive oil. This is the discovery of an organic molecule, not one very familiar on Earth because of its instability when it collides with other molecules. It requires something close to a high vacuum, which does not naturally occur on the surface of the Earth. In the vicinity of a cometary coma, there is a high vacuum sufficient for C2 not to be destroyed, and so here it is-the first discovery of an extraterrestrial organic molecule. And it turns out not to be one with which we have great familiarity.
vapor and carbon dioxide. Air, as you know, is mainly oxygen and nitrogen. Now, if you take some air and cool it, you will progressively condense out the various molecules. Water will condense out first, carbon dioxide next, oxygen and nitrogen much later; that is, at much lower temperatures.
Let's consider the condensation of the water molecule. When condensation happens, it's not just that the water molecules drop out of the air helter-skelter. In fact they form a lovely hexagonal crystal lattice, which stretches off as far as the ice crystal or snowflake or whatever it is goes. Other molecules condense out at much higher temperatures, like silica, for example (silicon dioxide), which also forms a crystal lattice.
Let's go back to the solar nebula from which, as we said earlier, the solar system almost surely formed, with a protosun in the center and the temperature declining the farther we get from the Sun. Now we must imagine this as a mix of cosmically abundant materials, including water (H2O, which we know through spectroscopic analysis of astronomical images is very abundant), methane (CH4; we know that's very abundant), silica (SiO2; we know that's very abundant), and what happens is that at different distances from the Sun, different materials will condense out, because they have different vapor pressures or different melting points. And what we see is (guess what?), water condenses out roughly at the vicinity of the Earth, whereas silicates condense out closer to the Sun, so liquid silicates or gaseous silicates are not to be expected under ordinary planetary conditions, even at the orbit of Mercury. Whereas you have to go out to somewhere near the present distance of Saturn before methane condenses. Now, methane is probably the chief carbon-containing molecule in the cosmos, and what this says is that in the early stages of the formation of the solar nebula there should have been a preferential condensation of methane in the
And I should mention that Mars itself, around which Phobos and Deimos are orbiting (all that rocky stuff is Mars, and the foreground instrumentation is the Viking 1 Lander), at least in the two places that we landed with Viking 1 and Viking 2, shows not a hint of organic matter. I will return to Martian exploration later, but I want to stress that the limits to the presence of organic matter on Mars are very low. There is not one part in a million of simple organic molecules and not one part in a billion of complex organic molecules. Mars is very dry, denuded in organic matter, and yet there are these two moons that may be made entirely of organic matter orbiting it. It's an interesting dilemma. These are two trenches that were dug by this sample arm in the Martian soil. So we gathered material from the subsurface and withdrew it back into the spacecraft and examined it with a gas chromatograph/mass spectrometer for organic matter, of which there was none.
I want to continue the story about organic matter in the outer solar system. And the best story by far, the one that we have the most information on, although it is still quite limited, is for Titan. Titan is the largest moon in the Saturn system. It is remarkable for many reasons, the most striking of which is that it is the only moon in the solar system with a significant atmosphere. The surface pressure on Titan (we know from Voyager 1) is about 1.6 bars, that is, about 1.6 times what it is in the room I am in as I write this. Since the acceleration due to gravity is about one-sixth on Titan what it is here on Earth, there is ten times more gas in the Titanian atmosphere than in the terrestrial atmosphere, which is a substantial atmosphere.
The organic molecules found in the gas phase in the atmosphere of Titan by the Voyager 1 and 2 spacecraft include hydrogen cyanide (HCN, which we've talked about before), cyanoacetylene, butadiene, cyanogen (which is two CNs glued together), propylene, propane (which we know), acetylene, ethane, ethylene (these are all components of natural gas). Methane, likewise. And the principal constituent of the atmosphere, there as here, is molecular nitrogen.
It is, I think, very interesting that we have a world in the outer solar system that is loaded with the stuff of life. And we can calculate, at the present rate at which these materials are being formed on Titan, how much of this stuff has accumulated during the history of the solar system. The answer is the equivalent of a layer at least hundreds of meters thick all over Titan, and possibly kilometers thick. The difference depends on how long a wavelength of ultraviolet light can be used for such synthetic experiments. And, incidentally, there is also a range of entertaining evidence that there is a surface ocean of liquid
digenous organic matter. The amount of organic matter that could have been produced in the first few hundred million years of Earth history was sufficient to have produced in the present ocean a several-percent solution of organic matter. That is just about the dilution of Knorr's chicken soup, and not all that different from the composition either. And chicken soup is widely known to be good for life. In fact, it is just this warm, dilute soup, in the words of J. B. S. Haldane, who was one of the first two people to realize that this sequence of events was likely, in which the standard scenario for the origin of life occurs.
In the laboratory we can take molecules of water, ammonia, and methane-rather like the ones we've been talking about for Titan-and dissociate them by ultraviolet light. The fragments make a set of precursor molecules, including hydrogen cyanide, which then combine and, in water, form the amino acids. In such experiments not just the building blocks of the proteins but the building blocks of the nucleic acids are routinely produced. There is a range of subsequent experiments, in which the smaller molecular building blocks join together to form large and complex molecules.
If we look at the fossil record, we find that there is a range of evidence for microfossils dating back not just to the beginning of the Cambrian but dating back to as much as 3,500 million years ago.
Now, just think about these numbers. The Earth itself forms about 4,600 million years ago. Because of the final stages of accretion, we know that the Earth environment was not suitable for the origin of life back then. From studies of the late cratering on the Moon, it looks-since the Earth and the Moon were presumably in the same part of the solar system then as now- as if the Earth was not in a suitable state for the origin of life until perhaps 4,000 million years ago. So if the Earth is not ap-
when a whirlwind passed over a junkyard. That's a vivid image. It's also a very useful image, because, of course, the Boeing 747 did not spring full-blown into the world of aviation; it is the end product of a long evolutionary sequence, which, as you know, goes back to the DC-3 and so on until you get to the Wright biplane. Now, the Wright biplane does look as if it were spontaneously assembled by a whirlwind in a junkyard. And while I don't mean to criticize the brilliant achievement of the Wright brothers, as long as you remember that there is this evolutionary history, it's a lot easier to understand the origin of the first example.
I want to close on a beautiful little piece of poetry written by a woman in rural Arkansas. Her name is Lillie Emery, and she is not a professional poet, but she writes for herself and she has written to me. And one of her poems has the following lines in it:
My kind didn't really slither out of a tidal pool, did we? God, I need to believe you created me:
we are so small down here.
I think there is a very general truth that Lillie Emery expresses in this poem. I believe everyone on some level recognizes that feeling. And yet, and yet, if we are merely matter intricately assembled, is this really demeaning? If there's nothing in here but atoms, does that make us less or does that make matter more?
There was a time when angels walked the Earth
Now they cannot even be found in Heaven.
If there is as a continuum from self-reproducing molecules, such as DNA, to microbes, and an evolutionary sequence continuum from microbes to humans, why should we imagine that continuum to stop at humans? Why should there be an open-ended gap in the spectrum of beings? And isn't it a little suspicious that the gap would begin with us?
It's of interest to me that our language has not really any appropriate terms for such beings. The theological languages have terms like angels and demigods and seraphim and so on. Even here it's interesting that the theological expectations of beings superior to humans generally represent a hierarchy of power but not of intelligence. And here again I think it is clear that we have imposed human values onto the universe. Certainly on this planet it is not apparent that there are beings more intelligent than humans, although a case can be made for dolphins and whales, and in fact if humans succeed in destroying themselves with nuclear weapons, a case could be made that all the other animals are smarter than humans.
I would like to describe a famous case of the search for extraterrestrial intelligence-the search for beings more advanced than we-a case that failed. I want to explore why it failed, what lessons we can learn from this failure, and then move on to the modern search for extraterrestrial intelligence. I hope to stress where we have to be extremely careful, where we must demand the most stringent and rigorous standards of evidence precisely because we have profound emotional investments in the answer. Later I will attempt to use those skeptical strictures to apply more directly to the more conventional God hypothesis.
I suppose an equally good epigram for this subject is the following sentence said by John Adams, second president of the United States, but long before he was that. As a lawyer and advocate, he argued in defense of the British soldiers who were being tried at the Boston Massacre trials in December 1770. And he did this not because he was in favor of the British cause. He wasn't. He defended those he opposed because he believed that the truth should be pursued above all other considerations. He said, "Facts are stubborn things; and whatever may be our wishes, our inclinations, or the dictates of our passions, they cannot alter the state of facts and evidence." Well, sometimes they can, but we hope they can't.
The year is 1877, let us imagine. The motion of the Earth around the Sun and Mars around the Sun has brought Mars and the Earth close together, as they tend to be at intervals of roughly seventeen years.
An Italian astronomer named Giovanni Schiaparelli, looking through a newly completed and fairly large aperture telescope in Italy, was glancing at Mars and suddenly saw the surface
you do to search for extraterrestrial intelligence, it is going to cost some money. You want a plausibility argument first that it makes at least a little sense. Clearly, were we to find extraterrestrial intelligence, this would be a discovery of enormous importance scientifically, philosophically, and, I maintain, theologically. But you'd want to have some expectation of success, some argument to counter skeptics who might say, "There is no evidence that we have been visited; therefore it is a waste of time."
So what we would really like to know is how many sites of intelligent beings, more intelligent than we, there are in, say, the Milky Way Galaxy? And how far is it from here to the nearest one? If it turns out that the nearest one is some immense distance away-let's say, at the center of the Milky Way Galaxy, 30,000 light-years-then we might conclude that the prospects of contact are small. On the other hand, if it turns out that the nearest such civilization is relatively nearby-let's say, a few tens or even a few hundreds of light-years-then it might make sense in some way, which I'll go into, to try to search for it.
Now, a convenient approach to this issue (it is hardly precise) is what is called the Drake equation, after the astronomer Frank Drake, who has been a pioneer in the scientific approach to this question. And it goes roughly like this: There is a number, call it N, of technical civilizations in the Galaxy, civilizations with the technology to permit interstellar contact (that technology essentially is radio astronomy). That number is
N = R x fp x np x fl x fi x fc x L
the product of a set of factors, each of which I will define. (All that is involved in this equation is the idea that a collective probability is the product of the individual probabilities, quite like
what we were talking about earlier on the probability that the right amino acid is in the first slot in the protein, and in the second slot, and in the third slot, and then you multiply those probabilities. The chance that you'll get heads in the first coin toss is one-half, the chance that you'll get heads in the second toss is one-half, the chance that you will get two consecutive heads is a quarter, three consecutive heads is an eighth, and so on.)
So the number of such civilizations depends on the rate of star formation, which we call R. The more stars that are formed, the more potential abodes for life there will be if they have planetary systems. That seems clear. Multiply that figure times fp, the fraction of stars that have planetary systems. But it's not good enough just to have planets; they have to be suitable for life. So multiply by np, the number of planets in an average system that are ecologically suitable for the origin of life, then times fl, the fraction of such worlds in which life actually arises, times fi, the fraction of such worlds in which over their lifetime intelligent life evolves, times fc, the fraction of such worlds in which the intelligent life develops a technical communicative capability, times L, the lifetimes of the technical civilization, because clearly if civilizations destroy themselves as soon as they are formed, everything else may go swimmingly well and yet there would be nobody for us to talk to.
So let me give my wild guesses about what these numbers are. I stress that we don't know these numbers very well, that our uncertainty progressively increases as we go from the leftmost to the rightmost factor. And that the largest uncertainty by far is in L, the lifetime of a technical civilization.
There are some hundred thousand million stars in the Milky Way Galaxy.
The lifetime of the Milky Way Galaxy is something like ten
program going on at Harvard, in Massachusetts, a cooperative project with Harvard University and the Planetary Society, a hundred-thousand-member worldwide organization, and it is remarkable that dues and contributions to a private organization are able to maintain by far the most sophisticated search for extraterrestrial intelligence yet attempted.*
*In 2006 the Planetary Society and Harvard University inaugurated the SETI Optical Telescope, the first-ever optical observatory dedicated to the search for intelligent extraterrestrial signals. For the history of the Planetary Society and SETI, see www.planetary.org, and for the thrill of actually participating in the search, go to www.setiathome.ssl.berkeley.edu/.
This illustration might convey a sense of how a success would be noted. The slanting line indicates a very weak signal from an extraterrestrial source. You listen at many frequencies for a while and see if there's anything happening. The Planetary Society system was recently upgraded, so that 8.4 million separate channels are being listened to simultaneously. The antenna points to some part of the sky. And some places have peaks. They may be due to radio interference on the Earth, satellites in Earth orbit, automobile ignitions, diathermy machines. But each of those has a particular kind of signature, and it is possible to imagine signals that don't look like any of those things, which the computer immediately would cull out of the noise, leaving no doubt that this was an artificial signal of extraterrestrial origin, even if we had no opportunity, no ability, to understand what it meant.
Now, as I said, the expectation is that they send and we, newly emerged, the youngest communicative civilization in the Galaxy, we listen. Not the other way around.
Let me stress that this is the one respect in which our civilization is probably unique in the Galaxy. No one even slightly more ignorant can communicate at all. Let me say this in a better way: A civilization only a few decades behind us would not have radio astronomy and therefore could not tumble to this technique. Or maybe they could tumble to it, but they couldn't manifest it. And anyone, therefore, whom we hear from is likely to be ahead of us, because if they're even a little bit behind us, they can't communicate at all.
So the most likely situation is communications from beings vastly more advanced than us. And this therefore raises the ques-
branch. Very good to have four limbs that can hold on to trees. We just happened to have the toes in this particular transitional moment. Big toe is good for balance; little toe is not good for very much at all. It's just an evolutionary accident. Vermiform appendix? Likewise good for nothing. It's just on its way out.
Arthur Clarke has said that Christian orthodoxy is too narrow and timid for what is likely to be found in the search for extraterrestrial intelligence. He has said that the doctrine of man made in the image of God is ticking like a time bomb at Christianity's base, set to explode if other intelligent creatures are discovered. I don't in the least agree. I think that the only sense that can be put on the phrase "made in God's image" is that there is a sense of intellectual affinity between us and higher organisms, if such there be.
The same laws of physics apply everywhere. If we imagine those extraterrestrial beings sending us radio messages, we and they have something in common. We must. The very act of receiving the message means that we have radio technology in common. We have quantum mechanics. We have atomic physics. We have Newtonian gravitation. We can see that those laws of nature apply everywhere in the universe. It's not a question of what your biology is like. It's not a question of the sequence of events that led to you getting a technical civilization. The mere fact that you have a technical civilization means that you have come to grips to some extent with the universe as it really is. And so it is in that sense and in that sense alone, I believe, that it makes sense to talk about such an affinity between advanced beings and ourselves.
I consider the idea of extraterrestrial intelligence a subject of philosophical, scientific, and even historical importance. If we were so lucky as to receive some sign of extraterrestrial intelligence, I think there is little doubt that it would be an extremely significant historical event. And if, on the other hand, we were to make a detailed and comprehensive search to no avail, that would also be something worth knowing. It would say something about the rarity and preciousness of intelligent life and again, I believe, would have extremely important and beneficial social consequences. Therefore the search for extraterrestrial life is one of those few circumstances where both a success and a failure would be a success by all standards.
So I am hardly opposed to the idea of extraterrestrials visiting us. If we ourselves are poking around our solar system, if we are capable, as we are, of sending our own spacecraft not just to the other planets in our solar system but beyond our solar system to the stars, then surely other civilizations, if they exist, thousands or millions of years more advanced than ours, ought
to be able to achieve interstellar spaceflight much more readily, much more swiftly.
And I don't for a moment deny this as a possibility. I would stress that the economy of effort is far greater for radio communication than direct communication by interstellar spacecraft. I would argue that you can broadcast to millions or thousands of millions of worlds simultaneously, speedily, inexpensively, in a way that even for a very advanced civilization would be much more difficult and costly to do via interstellar spacecraft. However, I certainly could not exclude the possibility that the Earth is now or once was visited. But precisely because the stakes in the answer are high, precisely because this is an issue that engages powerful emotions, we would in this case demand only the most scrupulous standards of evidence.
I want tonight to discuss two modern hypotheses that I think are proper to call folklore, the ancient astronaut hypothesis and the UFO or unidentified flying object hypothesis, and then attempt to connect them with the history of slightly more conventional religions.
The ancient astronaut hypothesis was popularized most effectively by a Swiss hotelier named Erich von Däniken. And his works, the first of which was called Chariots of the Gods? (the question mark becoming suppressed in subsequent printings), were huge bestsellers in the late 1960s, early 1970s, selling worldwide tens of millions of copies, an enormously successful set of books.
The fundamental hypothesis of von Däniken was that there is impressed in the archaeology and folklore and myth of many civilizations on Earth certain indications of past contact with the Earth by extraterrestrial beings. This is not an absurd proposition on the face of it, but how acceptable the hypothesis is depends on how good the evidence is. And, unfortunately, the
willingly detect the cheat in order to undeceive the deluded multitudes, the season is now past and the records and witnesses which might clear up the matter have perished beyond recovery.
Well, it seems to me that there is only one conceivable approach to these matters. If we have such an emotional stake in the answers, if we want badly to believe, and if it is important to know the truth, then nothing other than a committed, skeptical scrutiny is required. It is not very different from buying a used car. When you buy a used car, it is insufficient to remember that you badly need a car. After all, it has to work. It is insufficient to say that the used-car salesman is a friendly fellow. What you generally do is you kick the tires, you look at the odometer, you open up the hood. If you do not feel yourself expert in automobile engines, you bring a friend who is. And you do this for something as unimportant as an automobile. But on issues of the transcendent, of ethics and morals, of the origin of the world, of the nature of human beings, on those issues should we not insist upon at least equally skeptical scrutiny?
The Gifford Lectures are supposed to be on the topic of natural theology. Natural theology has long been understood to mean theological knowledge that can be established by reason and experience and experiment alone. Not by revelation, not by mystical experience, but by reason. And this is, in the long, historical sweep of the human species, a reasonably novel view. For example, we might look at the following sentence written by Leonardo da Vinci. In his notebooks he says, "Whoever in discussion adduces authority uses not intellect but rather memory."
This was an extremely heterodox remark for the early sixteenth century, when most knowledge was derived from authority. Leonardo himself had many clashes of this sort. During a trip to an Apennine mountaintop, he had discovered the fossilized remains of shellfish that ordinarily lived on the ocean floor. How did this come about? The conventional theological wisdom was that the Great Flood of Noah had inundated the mountain-tops and carried the clams and oysters with it. Leonardo, remembering that the Bible says that the flood lasted only forty days, attempted to calculate whether this would be sufficient time to carry the shellfish with them, even if the mountaintops
were inundated. During what state in the life cycle of the shellfish had they been deposited?-and so on. He came to the conclusion this didn't work, and proposed a quite daring alternative; namely, that over immense vistas of geological time the mountaintops had pushed up through the oceans. And that posed all sorts of theological difficulties. But it is the correct answer, as I think it's fair to say it has been definitively established in our time.
If we are to discuss the idea of God and be restricted to rational arguments, then it is probably useful to know what we are talking about when we say "God." This turns out not to be easy. The Romans called the Christians atheists. Why? Well, the Christians had a god of sorts, but it wasn't a real god. They didn't believe in the divinity of apotheosized emperors or Olympian gods. They had a peculiar, different kind of god. So it was very easy to call people who believed in a different kind of god atheists. And that general sense that an atheist is anybody who doesn't believe exactly as I do prevails in our own time.
Now, there is a constellation of properties that we generally think of when we in the West, or more generally in the Judeo-Christian-Islamic tradition, think of God. The fundamental differences among Judaism, Christianity, and Islam are trivial compared to their similarities. We think of some being who is omnipotent, omniscient, compassionate, who created the universe, is responsive to prayer, intervenes in human affairs, and so on.
But suppose there were definitive proof of some being who had some but not all of these properties. Suppose somehow it were demonstrated that there was a being who originated the universe but is indifferent to prayer. . . . Or, worse, a god who was oblivious to the existence of humans. That's very much like Aristotle's god. Would that be God or not? Suppose it were
down, and then later, sure enough, it's Maxwell's laws or the Schrödinger equation. Anything like that would have been possible had God existed and had God wanted us to have evidence of His existence. Or in biology. How about, "Two strands entwined is the secret of life"? You may say that the Greeks were onto that because of the caduceus. You know, in the American army all the physicians wore the caduceus on their lapels, and various medical insurance schemes also use it. And it is connected with, if not the existence of life, at least saving it. But there are very few people who use this to say that the correct religion is the religion of the ancient Greeks, because they had the one symbol that survives critical scrutiny later on.
This business of proofs of God, had God wished to give us some, need not be restricted to this somewhat questionable method of making enigmatic statements to ancient sages and hoping they would survive. God could have engraved the Ten Commandments on the Moon. Large. Ten kilometers across per commandment. And nobody could see it from the Earth but then one day large telescopes would be invented or spacecraft would approach the Moon, and there it would be, engraved on the lunar surface. People would say, "How could that have gotten there?" And then there would be various hypotheses, most of which would be extremely interesting.
Or why not a hundred-kilometer crucifix in Earth orbit? God could certainly do that. Right? Certainly, create the universe? A simple thing like putting a crucifix in Earth orbit? Perfectly possible. Why didn't God do things of that sort? Or, put another way, why should God be so clear in the Bible and so obscure in the world?
I think this is a serious issue. If we believe, as most of the great theologians hold, that religious truth occurs only when
there is a convergence between our knowledge of the natural world and revelation, why is it that this convergence is so feeble when it could easily have been so robust?
So, to conclude, I would like to quote from Protagoras in the fifth century B.C., the opening lines of his Essay on the Gods:
About the gods I have no means of knowing either that they exist or that they do not exist or what they are to look at. Many things prevent my knowing. Among others, the fact that they are never seen.
Cast your mind back some hundreds of thousands of years. Those who can do that readily will have demonstrated some of the issues that I considered dubious earlier, but apart from reincarnation let's try to think about what were the circumstances of the greater part of the tenure of the human species on Earth. That surely is relevant to any attempt to understand our present circumstances.
The human family is some millions of years old, the human species perhaps one million, with some uncertainty. For the greater part of that period by far, we did not have anything like present technology, present social organization, or present religions. And yet our emotional predispositions were powerfully set in those times. Whatever our feelings and thoughts and approaches to the world were then, they must have been selectively advantageous, because we have done rather well. On this planet we are certainly the dominant organism of some fair size. An argument could be made for beetles or bacteria at smaller scales as being the dominant organism on the planet, but at least on our scale we have done quite well.
Now, what were those characteristics, and how would we know what they are? Well, one way we can know is by examining the groups of hunter-gatherers that are still tenuously alive on the planet today. These are small groups of people whose way of life predates the invention of agriculture. The fact that we know them means they must have made some contact with our present global civilization-and that immediately implies that their way of life is in its last days. They are the essence of humans. They have been studied by dedicated anthropologists who have lived with them, learned their languages, been adopted into the group in those cases that permit outsiders to have such an experience, and we can learn something about them. They are by no means all the same. This is a large topic, called cultural anthropology. I do not pretend to be expert in it, but I have had the benefit of spending a fair amount of time with some of the anthropologists who have been at the forefront of studying some of these groups. And I think it's relevant to the task before us.
There are, as I say, different kinds of groups, including some that we might consider absolutely horrendous and some that we might consider astonishingly benign, and I'll try to give a sense of each.
For the latter let me say just a few words about the !Kung people in the Kalahari Desert in the Republic of Botswana. These are a people who now have been drafted into the army of apartheid South Africa, and their culture has been irrevocably abused. But up until some twenty years ago, they had been well studied. We know something about them.
They are hunter-gatherers, which mainly means that the men hunt and the women gather. There is a kind of sexual division of labor, but there is very little in the way of social hier-
archy. There is not a significant male dominance of women. In fact, there's very little in the way of social hierarchy at all. There is specialization of labor. That's different from social hierarchy. Children are treated with tenderness and understanding. And there is very little in the way of warfare, although occasionally they run into difficulties because of misunderstandings.
For example, there was a famous case, sometime ago, in which a hunting party came back and said that there was the most astonishing good fortune-a completely new creature had been discovered, and you could actually creep up to it with your bow and arrow and get within a meter of it, and it would not run away. And then you could shoot it dead. And here it is. And it was a cow. The neighboring Herero people protested, and this conflict between two groups, one that had not yet left the hunter-gatherer stage and the other that had domesticated animals, then had to be settled.
Another interesting question has to do with the hunt. Who owns the prey that is killed? It turns out it is not the hunter who killed the animal, it is the artisan who made the arrow. It is his kill. But this is merely a matter of bookkeeping, because everyone gets part of the kill, except that the arrowsmith has a right to a favored part. In fact, there is very little in the way of property. They are a nomadic people and can own only what they can carry with them-except for pots and some pieces of clothing and hunting apparatus and things of that sort. And even some of that (there is no personal property) is community property. There is no head man or head woman per se. And there is a cosmology, there is a kind of religion, there is the active encouragement of the religious experience which is obtained, as in many cultures-in fact, all cultures as far as I know-partly by the use of chemical hallucinogens and partly
I wish to propose for the reader's favorable consideration a doctrine which may, I fear, appear wildly paradoxical and subversive. The doctrine in question is this: that it is undesirable to believe a proposition when there is no ground whatever for supposing it true. I must of course admit that if such an opinion became common it would completely transform our social life and our political system. Since both are at present faultless this must weigh against it.
Tradition is a precious thing, a kind of distillation of tens or hundreds of thousands of generations of humans. It is a gift from our ancestors. But it is essential to remember that tradition is invented by human beings and for perfectly pragmatic purposes. If instead you believe that the traditions are from an exhortatory god and hold that the traditional wisdom is handed down directly from a deity, then we are much scandalized at the idea of challenging the conventions. But when the world is changing very fast, I suggest survival may depend precisely on our ability to change rapidly in the face of changing conditions. We live in precisely such a time.
Consider our past circumstances. Imagine our ancestors, a small, itinerant, nomadic group of hunter-gatherer people. Surely there was change in their lives. The last ice age must have been quite a challenge some ten to twenty thousand years ago. There must have been droughts and new animals suddenly migrating into their area. Of course there is change. But by and large the change is extraordinarily slow. The same traditions for chipping stone to make spears and arrowheads, for example,
continues in the East African paleoanthropological sites for tens or hundreds of thousands of years.
In such a society, the external change was slow compared to the human generation time. Back then traditional wisdom, parental prescriptions, were perfectly valid and appropriate for generations. Children growing up of course paid the closest attention to these traditions, because they represented a kind of elixir of the wisdom of previous generations; it was constantly tested, and it constantly worked. It is not for nothing that ancestors were venerated. They were heroes to subsequent generations, because they passed on wisdom that could preserve lives and save them.
Now compare that with another reality, one in which the external changes, social or biological or climatic or whatever we wish, are rapid compared to a human generation time. Then parental wisdom may not be relevant to present circumstances. Then what we ourselves were taught and learned as youngsters may have dubious relevance to the circumstances of the day. Then there is a kind of intergenerational conflict, and that conflict is not restricted to intergenerational but is also intragenerational, internally, because the part of us that was trained twenty years ago, let's say, must be in some conflict with the part of us that is trying to deal with the difficulties of today. So I claim that there are very different ways of thinking for these two circumstances: when change is slow compared to a generation time and when change is fast compared to a generation time. There are different survival strategies. And I would also like to suggest that there has never been a moment in the history of the human species in which so much change has happened as in our time. In fact, it can be argued that in many respects there never will be a time when the change can be so rapid as it has been in our generation.
mutually dependent. It's like living in a lifeboat. We breathe the air that Russians have breathed, and Zambians and Tasmanians and people all over the planet. Whatever the causes that divide us, as I said before, it is clear that the Earth will be here a thousand or a million years from now. The question, the key question, the central question-in a certain sense the only question-is, will we?
Without knowing what I am and why I am here, life is impossible.
Leo Tolstoy, Anna Karenina
If we don't find life literally impossible without answering that question, at least its difficulties increase. It is very reasonable for humans to want to understand something of our context in a broader universe, awesome and vast. It is also reasonable for us to want to understand something about ourselves. Since we have powerful unconscious processes, this means that there are parts of our selves that are hidden from us. And this two-pronged investigation into the nature of the world and the nature of our selves is, to a very major degree, I believe, what the human enterprise is about.
Our success as a species is surely due to our intelligence, not primarily to our emotions, because many, many different species of animals surely have emotions. Many, many different species of animals also have varying degrees of intelligence. But it is our intelligence-our interest in figuring things out, our ability to do so, coupled with our manipulative abilities, our engineering talents-that is responsible for our success. Because surely we are not faster than all other species, or better camouflaged, or
better diggers or swimmers or fliers. We are only smarter. And, at least until the invention of weapons of mass destruction, this intelligence has led to the steady-in fact exponential-increase in our numbers. And in the last few thousand years, our numbers on this planet have increased by much more than a factor of a hundred. There are human outposts not just everywhere on the planet, including Antarctica, but in the ocean depths and in near-Earth orbit. And it is clear that if we do not destroy ourselves, we will continue this progressive, outward movement until there will be human settlements on neighboring worlds.
It seems to me also clear that historians of a thousand years from now, if there are any, will look back on our time as being absolutely critical, a turning point, a branch point in human history. Because if we survive, then this time will be remembered as the time when we could have destroyed ourselves and came to our senses and did not. It will also be the time in which the planet was bound up. And it will also be remembered as the time when, slowly, tentatively, haltingly, we first sent our robot emissaries and then ourselves to neighboring worlds.
Now, all of these are extraordinary and unprecedented activities. Never before have we had the capability of destroying ourselves, and therefore never before have we had the ethical and moral responsibility not to do so. A way of looking at the time we happen to inhabit is as follows: We started hundreds of thousands to millions of years ago as itinerant tribespersons, in which the fundamental loyalty was to a very small group, by contemporary standards. Typical hunter-gatherer groups are maybe a hundred people, so the typical person on the planet had an allegiance to a group of no more than a hundred or a few hundred people.
The names that many of these tribes give to themselves are
Nahuatl-you will be fundamentally limited in your ability to generate a broad, interdisciplinary, predictive theory of language. How could you be expected to do very well if you knew only one language? If Newton were restricted, in working through the theory of gravitation, to apples and forbidden to look at the motion of the Moon or the Earth, it is clear he would not have made much progress. It is precisely being able to look at the effects down here, look at the effects up there, comparing the two, which permits, encourages, the development of a broad and general theory. If we are stuck on one planet, if we know only this planet, then we are extremely limited in our understanding even of this planet. If we know only one kind of life, we are extremely limited in our understanding even of that kind of life. If we know only one kind of intelligence, we are extremely limited in knowing even that kind of intelligence. But seeking out our counterparts elsewhere, broadening our perspective, even if we do not find what we are looking for, gives us a framework in which to understand ourselves far better.
I think if we ever reach the point where we think we thoroughly understand who we are and where we came from, we will have failed. I think this search does not lead to a complacent satisfaction that we know the answer, not an arrogant sense that the answer is before us and we need do only one more experiment to find it out. It goes with a courageous intent to greet the universe as it really is, not to foist our emotional predispositions on it but to courageously accept what our explorations tell us.
After each lecture there was a lively question-and-answer period. Unfortunately, the transcripts report that in some cases the audience was not provided with working microphones. These are the fragments of the sessions that survive.
Questioner: When will we be likely to make contact with another intelligence?
CS: Prophecy, is a lost art. But what I would say is that it's clear that if we don't try to seek such intelligence, it will be more difficult to find it. And it is remarkable that we live in a time when the technology permits us, at least in a halting way, to seek such intelligences, mainly by constructing large radio telescopes to listen for signals being sent to us-radio signals- by civilizations on planets of other stars.
Questioner: Considering the accomplishments of scientists like Newton and Kepler, is it likely that science will one day come upon a demonstration of the existence of God?
CS: The answer depends very much on what we mean by God. The word "god" is used to cover a vast multitude of mutually exclusive ideas. And the distinctions are, I believe in some cases, intentionally fuzzed so that no one will be offended that people are not talking about their god.
But let me give a sense of two poles of the definition of God. One is the view of, say, Spinoza or Einstein, which is more or less God as the sum total of the laws of physics. Now, it would be foolish to deny that there are laws of physics. If that's what we mean by God, then surely God exists. All we have to do is watch the apples drop.
Newtonian gravitation works throughout the entire universe. We could have imagined a universe in which the laws of nature were restricted to only a small portion of space or time. That does not seem to be the case. And Newtonian gravitation is one example, but quantum mechanics is another. We can look at the spectra of distant galaxies and see that the same laws of quantum mechanics apply there as here. So that is itself a deep and extraordinary fact: that the laws of nature exist and that they are the same everywhere. So if that is what you mean by God, then I would say that we already have excellent evidence that God exists.
But now take the opposite pole: the concept of God as an outsize male with a long white beard, sitting in a throne in the sky and tallying the fall of every sparrow. Now, for that kind of god I maintain there is no evidence. And while I'm open to suggestions of evidence for that kind of god, I personally am dubious that there will be powerful evidence for such a god not only in the near future but even in the distant future. And the two examples I've given you are hardly the full range of ideas that people mean when they use the word "god."
CS: The questioner asked whether I was familiar with Democritus, bearing in mind my suggestion that we now know things that were not known in the past. Democritus is one of my heroes. I think I know more than Democritus. Now, I don't claim to be smarter than Democritus, but I have the advantage that Democritus did not of having twenty-five hundred years of scientists between him and me. So, for example, I'll give you a few things that I know and that Democritus did not know. Democritus proposed that the Milky Way Galaxy was composed of stars. Far ahead of his time. He did not know that there were other galaxies. We know that.
We know of the existence of many more planets than he did. We have examined them close up. We know what their physical natures are. He did not, although he speculated that they were at least made of matter. We have an idea of how many stars there are in the Milky Way Galaxy.
Democritus was an atomist. You will not exceed me in your admiration for Democritus. And were the vision of Democritus to have been adopted by Western civilization, instead of being cast aside for the pale views of Plato and Aristotle, we would be vastly further ahead today, in my personal view.
CS: The questioner asks have I not perhaps been looking through the wrong end of the telescope; that is, is not the proper province of religion the human heart and mind and ethical questions and so on, and not the universe?
Well, I couldn't agree with you more, except that it is striking how many religions have felt that astronomy is their province and have made confident statements about matters astronomical. It is possible to design religions that are incapable of disproof. All they have to do is to make statements that cannot be validated or falsified. And some religions have very neatly posi-
tioned themselves in that respect. Now, that means that you cannot make any statements on how old the world is; you cannot make any statements about evolution; you cannot make any statements about the shape of the Earth (the Bible is quite clear about the Earth being flat, for example), and so on. And then you have religions that are making statements on human behavior, where religions have, in my view, made significant contributions. But it is a very rare religion that avoids the temptation to make pronouncements on matters astronomical and physical and biological.
Questioner: Do you think humans at this time could cope with us finding extraterrestrial intelligence?
CS: Sure. Why not? Well, there's no question that the discovery of something very different will worry people precisely because it's different. Look at the degree of xenophobia in human cultures in which it is other humans, trivially different from us, who are the object of great fear and concern and violence and aggression and murder and terrible crimes. So there's no question that were we to receive a signal, much less come face-to-face, or whatever the appropriate bodily part is, with another intelligent being, there would be a sense of fear, horror, loathing, avoidance, and so on.
But the receipt of a message is a very different story. You are not even obligated to decode. If you find it offensive, you can ignore it. And there is a kind of providential quarantine between the stars, with very long transit times even at the speed of light, that I think obviates, if not altogether eliminates, this difficulty.
CS: The questioner asks that is not one central goal of religions the idea of a personal god, of a purpose for individuals and for the species as a whole, and is that not one of the reasons for
This does remind me, though, that I forgot to say something. Very nearby civilizations can detect our presence, and that is because television gets out. Not just television but radar. Radar and television get out. Most of AM radio, for example, doesn't. So let's just look at the television for a moment. Large-scale commercial television broadcasting on Earth begins when? In the late 1940s, mainly in the United States.
So forty years ago there's a spherical wave of radio signals that spreads out at the speed of light, getting bigger and bigger as time goes on. Every year later it's an additional light-year away from the Earth. Now, let's say it's forty years later, so that expanding spherical wave front is forty light-years from the Earth, containing the harbingers of a civilization newly arrived in the galaxy. And I don't know if you know about 1940s television in the United States, but it would contain Howdy Doody and Milton Berle and the Army-McCarthy Hearings and other signs of high intelligence on the planet Earth. So I'm sometimes asked, if there are so many intelligent beings in space, why haven't they come here? Now you know. It's a sign of their intelligence that they haven't come. (I'm just joking.) But it's a sobering fact that our mainly mindless television transmissions are our principal emissaries to the stars. There is an aspect of self-knowledge that this implies that I think would be very good for us to come to grips with.
Questioner: How do you recognize the truth when it is upon us?
CS: A simple question: How can we recognize the truth? It is, of course, difficult. But there are a few simple rules. The truth ought to be logically consistent. It should not contradict it-
self; that is, there are some logical criteria. It ought to be consistent with what else we know. That is an additional way in which miracles run into trouble. We know a great many things-a tiny fraction, to be sure, of the universe, a pitifully tiny fraction. But nevertheless some things we know with quite high reliability. So where we are asking about the truth, we ought to be sure that it's not inconsistent with what else we know. We should also pay attention to how badly we want to believe a given contention. The more badly we want to believe it, the more skeptical we have to be. It involves a kind of courageous self-discipline. Nobody says it's easy. I think those three principles at least will winnow out a fair amount of chaff. It doesn't guarantee that what remains will be true, but at least it will significantly diminish the field of discourse.
Questioner: Have you any comments to make on the Shroud of Turin?
CS: The Shroud of Turin is almost certainly a pious hoax; that is, not a contemporary hoax but a hoax from the fourteenth century, when there was significant traffic in pious hoaxes. And my technical knowledge of the Shroud of Turin comes from Dr. [Walter] McCrone of Chicago, who has worked on it for some years. He found the "blood" to be iron oxide pigments, and there is nothing that cannot be explained by the technology available in the fourteenth century. By the way, there is no provenance of the Shroud of Turin earlier than the fourteenth century* So I'm sorry that my knowledge is secondhand on this issue, and I know that there are people who believe, for reasons
*In 1988 the Vatican allowed samples of the original shroud material to be dated by the radiocarbon method. Three laboratories (in Arizona, Oxford, and Zurich) independently determined that the fabric dates from the period A.D. 1260 to 1390.
change from the usual sorts of cases they have to deal with) go in a small railroad car along every inch of the thousand miles, and there isn't any rotor sitting by the side of the railway bed. So it has disappeared. Supernatural. And insurance companies are involved because it's expensive, so there's a second search. They can't find it. Nobody on the train saw anything amiss.
Twenty years pass, and then about three miles from the railway track a swamp is drained for a housing project, and there, at the bottom of the swamp, is this rotor, which must have broken its moorings and rolled three miles to the swamp. Can you imagine being out for a midnight walk and seeing this apparition rolling by? If anyone had seen it, it surely would have been an impetus to found a new religion.
Questioner: Well, I'd just like to ask you about your closing remarks. You were talking about possible proofs that God could have left us of His own existence. You don't think that you're making a rather arrogant assumption in that you are assuming that, for example, it could be possible that He has . . . that God has left in these religious writings the types of statements that you are suggesting, but it was simply that we ourselves have not got to that stage of development. For example, if He'd made statements about special relativity, a hundred years ago those would have been still meaningless. Could there not now be statements that in a hundred years would make sense to us that would not make sense to us now? Secondly, a more specific example, some people at the Hebrew University at Tel Aviv claim that there are in the Torah in Hebrew various words or messages in which were concealed the names of some thirty trees in Hebrew, with the letters of each tree equally spaced within the
there's no completely satisfactory proof that everyone in this room exists. I don't know if you know of one. I think it comes down in the end to belief of one sort or another that people in this room exist, and putting the proofs about God's existence in that context, we're demanding a lot more in proving God's existence than we are in proving our own existence.
CS: But the burden . . . the burden of proof is on those who claim that God exists. Or do you think not?
Questioner: I think you say that. I don't think that, in fact.
CS: You think the burden of proof is on those who say that God does not exist?
Questioner: An equal burden of proof, I would say. I don't see why it should be put to those who say that He exists.
CS: But would you say that, no matter what contention is made, that the burden of proving or disproving it falls equally on those who agree and those who disagree?
Questioner: I would say that.
CS: Have you thought of the political applications of this?
Questioner: Well, it's not a political issue, I don't think.
CS: No, but I thought it was a general proposition you were proposing.
Questioner: If you take a physical proposition, would you say you know that in every case the burden of proof rests to prove one type of case or the other type of case?
CS: The burden of proof always falls on those who make the contention.
Questioner: Well, all right. Yes. But only in the sense that it's disproving the other contention.
CS: No, no. It can be in an area where no one has any other contentions.
Questioner: Yes, well. . .
CS: It is-and it seems to me quite proper. Because otherwise opinions would be launched very casually if those who proposed them did not have the burden of demonstrating their truth. Here is a set of thirty-one proposals that I make, and good-bye. I mean, you would be left with a chaotic circumstance.
Questioner: Yes, all right. Yes, I see. I see your point. Yes.
CS: The audience is laughing. May I say I think these are . . . some of these are very good points, and this sense of dialogue I welcome and find delightful.
Questioner: I didn't agree with the way you presented some of the proofs for the existence of God. There was one other proof that I would like to give. I wouldn't call it a proof. I'd call it an argument, because I don't believe that you can prove in absolute logical terms the existence of God.
CS: So we are in agreement.
Questioner: There was an eminent scientist called Sir James Jeans, a Fellow of our Royal Society in the 1930s, who published a book called The Mysterious Universe, in which he went into great detail discussing the new discoveries of physics. And he presented a rather elegant argument concerning the existence of God, which was based on a very simple, almost unspoken law, the law being that if any two things interact, they
CS: Why? Why? Why can't natural selection accommodate large numbers of unrelated organisms to the same laws of nature?
CS: I have a letter that I was sent that concluded by saying, "I have at times found your views somewhat naive and immature but hope for better things this week." I hope I have not disappointed. Let me read one remark of this deeply concerned person, who requested anonymity. He says, "On several occasions it has seemed to me that you try to quantify what is a qualitative experience. There is a spiritual and psychical world superimposed, as it were, on the physical. Worlds within worlds. Man is not just a physical being but a spiritual and a psychic entity, too."
Well, my only response is that this is a claim that, from my point of view, remains to be proved. I would have to ask, "What is the evidence that we are more than material beings?" I don't think anyone would doubt that matter is a part of our makeup. And the question is, what is the compelling evidence that it is not all?
Questioner: Sir, I have a feeling that we have a lot of growing to do. The scientist doesn't perhaps know yet how to bring a greater being into the picture, and suddenly there are psychic things that are spiritual. You're taking the wrong set of faculties to disprove the psychic element. You must use the similar faculty. So it will be hundreds of years before scientists can ever prove the psychic part of life.
CS: Would you grant the possibility that there is no psychic part of life?
Now, surely that in itself is a proposition. What grounds would you have for believing that proposition?
CS: Yes. That's a very good question that leads to an infinite regress. And notice that Russell said he would merely propose for our consideration this proposition. Russell was, in his mathematician incarnation, the author of precisely such logical paradoxes as the one you just suggested. So if you wish to have the statement justified in internal logic-that is, a self-consistent closed system-obviously it cannot, because it leads to an infinite regress. But as I was saying, it seems to me that the approach of skeptical scrutiny commends itself to our attention because it has worked so well in the past. So many findings-I tried to give some simple physical and astronomical ones in the earlier lectures-were made possible by science not accepting the conventional wisdom, not taking on blind faith what was taught in the religious and secular schools, that everybody knew-the teachings of Aristotle on physics and astronomy, for example-but instead by asking, "Is there really evidence for it?" It is the method of science. And at every step along the way, it has produced some agonizing reappraisals and some powerful emotions that don't like it. And I understand that very well. But it seems to me that if we are not dedicated to the truth in this sense of truth, then we are in very bad shape.
Questioner: How serious do you think the problem is with the creationists that are in the States?
CS: Well, different people will have a different answer. Some fundamentalist Christians believe that it is without any doubt that the world will end shortly, that the signs, especially
the formation in 1948 of the state of Israel, are clear; that is, there are many fundamentalist Christians, at least in the United States-I don't know about elsewhere in the world-who deeply believe that this is true. And there will be a tribulation and a rapture, and there's an entire mythology about the events that will happen. We are even told by the Reverend Mr. Falwell that believing Christians, when the trumpet is sounded, will be taken bodily to heaven. And if they are driving a car or flying an airplane at that moment, then the car and airplane containing its nonbelieving passengers are in some difficulty. The conclusion of which would seem to be that there has to be a test of faith before issuing a license.
Questioner: You seem to think that in the event of a nuclear war, all human beings may become extinct. I put the question on the grounds of two things that you didn't bring up at all in your talk: One, nuclear power stations will be damaged in a nuclear war, and that will leak radiation that will be dangerous for thousands of years, and two, we don't know the effects of ultraviolet light that may come through to Earth after a nuclear war.
CS: Right. So the questioner says, is it clear that other forms of life would survive bearing in mind the enhanced ultraviolet flux from the destruction of the ozone layer and the radioactive fallout, especially if nuclear power plants are targeted. I chose grasses and cockroaches because of their high radiation resistance. And if you check it out, you find that they are several orders of magnitude more resistant than humans are. A typical dose of radiation to kill a human being is a few hundred rads. There are organisms that are not killed until a few million rads. Also, the sulfur-eating marine worms that I mentioned, they were not selected randomly either. They live entirely at the ocean bottom where no ultraviolet light can get and where they
CS: There was one question that was sent to me in a letter to my hotel, which was signed, "God Almighty." Probably just to attract my attention. It said that the writer's definition of a miracle would be if I would answer the letter. So to show that miracles can happen, I thought I would answer the question. The question was a straightforward and important one, often asked: "If the universe is expanding, what's it expanding into? Something that isn't the universe?"
Well, the way to think of this is to remember that we are trapped in three dimensions, which constrains our perspective (although there's not much we can do about being trapped in three dimensions). But let us imagine that we were two-dimensional beings. Absolutely flat. So we know about left/ right and we know about forward/back, but we've never heard of up/down. It is an absolutely incoherent idea. Just nonsense syllables. And now imagine that we live on the surface of a
tain that everyone in the room has felt compassion. Everyone in the room has felt love. Everyone in the room has felt kindness. And so we have two warring principles in the human heart, both of which must have evolved by natural selection, and it's not hard to understand the selective advantage of both of them. And so the issue has to do with which is in the preponderance. And here it is the use of our intellect that is central. Because we're talking about adjudicating between conflicting emotions. And you can't have an adjudication between emotions by an emotion. It must be done by our perceptive intellectual ability. And this is the place where Einstein said something very perceptive. In response-this is post-nuclear war, post-1945-in response to precisely the question you have just formulated, in which Einstein was saying that we must give the dominance to our compassionate side, he said, "What is the alternative?" That is, if we do not, if we cannot manage it, it is clear that we are gone. We're doomed. And therefore we have no alternative. Certainly untrammeled, continuing aggression in an age of nuclear weapons is a prescription for disaster. So either get rid of the nuclear weapons or change what passes for social relations among humans.
But even getting rid of nuclear weapons altogether will not solve this problem. There will be new technical advances. And already there are chemical and biological weapons that could perhaps rival some of the effects of nuclear war. So this is a very key aspect of what I was thinking when I said we are at a branch point in our history, in the sense of who we are. I maintain it's not a question of sudden change, that we have been compassionate for a million years, and it's a question of which part of the human psyche the governments-and the media, and the churches, and the schools-give precedence to. Which one do they teach?
Which one do they encourage? And all I'm saying is that it is within our capability to survive. I don't guarantee it. Prophecy is a lost art. And I don't know what the probabilities are that we will go one way or another. And no one says it's easy. But it is clear, as Einstein said, that if we do not make a change in our way of thinking, all is lost.
Editing these lectures afforded me, for precious moments at a time, the happy delusion that I was working with Carl once again. The words he spoke in these lectures would sound in my head and it felt wonderfully as if we had somehow been transported back to the two heavenly decades when we thought and wrote together.
We had the pleasure of writing several of our projects, the Cosmos television series among them, with the astronomer Steven Soter, our dear friend. Since Carl's death Steve and I wrote the first two planetarium shows for the magnificent Rose Center at the American Museum of Natural History in New York City. Once I had turned Carl's Gifford Lectures into a book, I invited Steve to join me in editing the final drafts. We felt sure that Carl would not have wanted us to use the 1985 slides from the lectures. Astronomers have seen farther and more clearly since then. Steve found the gorgeous images that replace them. He also wrote the scientific updates that appear in the footnotes. I am grateful to him for his many editorial contributions to this book.
Ann Godoff has been our editor ever since Shadows of Forgotten Ancestors, Carl's favorite among all the books he and we ever wrote. She also edited Carl's Pale Blue Dot, The Demon-Haunted World, and Billions & Billions. It was her recognition that the Gifford Lectures should become a book that made The Varieties of Scientific Experience possible. Her imagination and wit made the process of that transformation a pleasure. I thank her colleagues at the Penguin Press, art director Claire Vaccaro, and Ann's assistant Liza Darnton for all they did for the book and for me. I am grateful to Maureen Sugden for her meticulous and thoughtful copyediting.
Jonathan Cott has always been a North Star to me, guiding me to every possible kind of great cultural experience. I am further indebted to him for the valuable editorial comments and suggestions he gave me for this book.
I thank Sloan Harris of ICM, for his excellent representation and his consistent commitment to my work, and Katharine Cluverius, in his office, for her kind assistance.
Kristin Albro and Pam Abbey in my office at Cosmos Studios have provided valuable administrative support, and Janet Rice helped in a host of ways, making it possible for me to focus on this work.
I wish to acknowledge the encouragement and loving kindness of Harry Druyan, Cari Sagan Greene, Les Druyan and Viky Rojas-Druyan, Nick and Clinnette Minnis Sagan, Sasha Sagan, Sam Sagan, Kathy Crane-Trentalancia, and Nancy Palmer.
Carl's Gifford Lectures were expertly transcribed from audiotapes long ago by Shirley Arden, his executive assistant at the time. As I read the transcripts, which were done without the text-processing magic of today's computer technology, I felt a renewed sense of respect for her consistently meticulous work.
I would also like to thank the organizers of the Gifford Lec-
tures and the University of Glasgow for their kind invitation to Carl and their hospitality to us during our time in Scotland.
In the ten years since Carl's death, these lectures sat in one of the thousand drawers of his vast archives. For some reason the Gifford Lectures were never logged into the archives' otherwise reliably comprehensive index. In the midst of a worldwide pandemic of extreme fundamentalist violence and during a time in the United States when phony piety in public life reached a new low and the critical separation of church and state and public classroom were dangerously eroded, I felt that Carl's perspective on these questions was needed more than ever. I searched in vain for the transcripts. Our friend, who wishes to remain anonymous, succeeded where I had failed. My gratitude to him for this, and much else, is profound.
Ithaca, New York March 21, 2006
A 2004 image of Comet NEAT made by the Gunma Observatory of Japan. Every little red/green/blue dash is the spectral trace of a star.
Frontispiece: Hubble Ultra-Deep Field
In 2004 the Hubble Space Telescope looked at a small piece of sky (a tenth the size of the full Moon) for eleven days to make this image of nearly ten thousand galaxies. Light from the most distant galaxies took almost thirteen billion years to travel the distance to Hubble's lens. Each galaxy contains many billions of stars, each star a potential sun to perhaps a dozen worlds.
Science lifts the curtain on a tiny piece of night and finds ten thousand galaxies hidden there. How many stories, how many ways of being in the universe are contained therein? All residing in what, to us, had been just a little patch of empty sky.
Figure 1. Eagle Nebula
A stellar nursery located about 6,500 light-years away from us. Through a window in a dark enveloping shell of interstellar dust, we
see a cluster of brilliant newborn stars. Their intense blue light has sculpted filaments and walls of gas and dust, clearing and illuminating a cavity in a cloud about 20 light-years across.
Figure 2. Crab Nebula
This is the remnant of the same exploded star, or supernova, that Chinese and Native American Anasazi astronomers observed in the constellation Taurus in A.D. 1054. They recorded the sudden appearance of a brilliant new star that then slowly faded from view. The filaments are the unraveling debris of the star, enriched in heavy elements produced by the explosion.
Figure 3. Sun and Planets
Here in their order and relative sizes are the Sun (at left), the four terrestrial planets (Mercury, Venus, Earth, Mars), the four gas giant planets (Jupiter, Saturn, Uranus, Neptune), and Pluto (far right).
Figure 4. Wright Solar System and Sirius
The top shows to scale the Sun (left) and the orbit of Mercury (right). The middle shows the entire solar system with the orbit of Saturn (S) and several elliptical comet orbits (left) and the system of the bright star Sirius (right). The bottom shows from left to right the orbits of Saturn, Jupiter, Mars, Earth, Venus, Mercury, and the Sun.
Figure 5. Solar System Scales
Upper left: The orbits of the inner planets Mercury, Venus, Earth, and Mars, the asteroid belt, and the orbit of Jupiter.
Upper right The scale increases tenfold to encompass the larger orbits of all the gas giant planets Jupiter, Saturn, Uranus, and Neptune, and the elliptical orbit of Pluto.
Lower right: A further scale change compresses the orbits of all the planets into the box at one end of the highly elliptical orbit of a comet.
Lower left: The scale increases again so that the cometary orbit is now in the tiny box at the center and we see the inner portion of the Oort Cloud of comets.
Figure 6. OORT CLOUD
Schematic view shows the vast spherical cloud of perhaps a trillion comets, weakly bound by the gravity of the Sun (center). It was named after the Dutch astronomer Jan Oort, who correctly hypothesized its existence in 1950.
Figure 7. Wright: Other Systems
Wright imagined that our own solar system was but one of a countless number of similar systems in the Milky Way, each perhaps containing a star surrounded by its own retinue of planets and comets.
Figure 8. The Pleiades Star Cluster
The bright stars in this cluster illuminate the faint remnants of the interstellar cloud from which they formed. This star cluster, a naked eye object in the constellation Taurus, is about 13 light-years across.
Figure 9. Orion Nebula
A vast cloud of glowing interstellar gas and opaque dust, which is giving birth to dozens of new stars. The nebula is about 40 light-years across and 1,500 light-years away. If you look up at the constellation Orion on a winter night, this stellar nursery appears as the hazy central "star" in his sword.
Figure 10. Eskimo Nebula
Ten thousand years ago this halo of gas and dust was part of the central star. The aging star then expelled its outer layers into space in successive bursts, forming what astronomers call a planetary nebula. All ordinary stars like the Sun will eventually meet a similar fate.
Figure 11. Veil Nebula
These glowing filaments trace a portion of the expanding remnants of a supernova, a star that exploded about five thousand years ago in the constellation Cygnus.
Figure 12. SAGITTARIUS STAR CLOUD
A relatively crowded region of old stars in the direction of the center of the Milky Way Galaxy.
Figure 13. Andromeda Galaxy, M31
This large spiral galaxy is only about 2 million light-years away, making it the closest one to our own Milky Way. The flattened rotating disk of stars and clouds of gas and dust is about 200,000 light-years across and contains several hundred billion solar systems.
Figure 14. Hercules Cluster
Most of the objects in this image are entire galaxies, like our own Milky Way, each containing many billions of stars. Many of the galaxies of the Hercules Cluster are interacting, with some of them actually colliding and merging. This rich cluster is about 650 million light-years away.
Figure 15. Saturn Wide Shot
A stunning array of orbiting rings encircles the gas giant planet Saturn, which casts its shadow on them. The Cassini Division is the most prominent of many gaps in the ring system. It is named after the seventeenth-century Italian-French astronomer Giovanni Domenico Cassini who made many important discoveries about our solar system. His namesake spacecraft, the one that took this picture, has now done the same.
Figure 16. Close-up of Saturn's Rings
In this back-lit image from the Cassini spacecraft, the Sun illuminates Saturn's rings from behind, revealing the fine structure of multiple thin rings.
Figure 17. Solar Nebula
A chaotic cloud of interstellar gas and dust collapses under its own gravity (A). Most of the mass falls to the center to form and ignite the Sun, but the residual spin of the cloud prevents it from collapsing in one direction, resulting in a flat rotating disk (B). The particles in the disk coagulate to form larger objects, and the largest ones sweep out clear lanes from the debris disk (C). This process continues as the colliding particles become larger and fewer (D), eventually leaving the solar system in its present form (E).
Figure 18. Planetesimals
In this stage of formation of a planetary system, colliding asteroid-size bodies orbit around the central star.
Figure 19. Beta Pictoris
This 1997 false-color image shows a debris disk seen edge on in orbit around the star Beta Pictoris, which some twenty years earlier had provided the first evidence of planetary formation around a star outside our solar system. The telescope has blocked out the direct light from the star to reveal the fainter light reflected from the disk. The inner gap in the disk suggests that planets are forming there. Most young stars have such orbiting disks.
Figure 20. Comet Machholz
The extended atmosphere, or coma, of the comet blows away from the Sun to form faint tails of dust and ionized gas.
Figure 21. Olive Oil and Comets
English astronomer William Huggins compared the spectra of vaporized olive oil and ethylene (olefiant gas) with the spectra of two comets, which he observed in 1868. He correctly deduced that comets contain carbon-bearing substances.
Figure 22. Comet NEAT Spectrum
The light of Comet NEAT (shown on the jacket of this book) is spread out into its constituent rainbow of colors (bottom), revealing the presence of different molecules at particular wavelengths (middle).
Figure 23. End of the World
An illustration by R. Jerome Hill, published in Harper's Weekly, May 14, 1910, depicting the romantic fatalism inspired by the coming of the "cyanide laden" Halley's Comet.
Figure 24. Iapetus
The surface of this mysterious satellite of Saturn has two distinct zones, one icy and very bright, the other covered by a very dark red material of unknown composition. This bimodal distribution of brightness is unique in the solar system, as is the ridge around the satellite's equator.
Figure 25. Saturn Small Moons
The satellites shown here range in size from about 20 to 200 kilometers. They lack sufficient gravity to enforce a spherical shape.
Figure 26. Uranus Rings
This infrared image, taken at a wavelength of 2.2 microns, reveals several distinct rings encircling the planet. The isolated bright spot is the moon called Miranda.
Figure 27. PHOBOS
This curiously potatolike cratered inner moon of Mars has an average diameter of 22 kilometers and an orbit period of about eight hours.
Figure 28. Deimos
The outer moon of Mars has an average diameter of 15 kilometers and an orbit period of thirty hours.
Figure 29. Mars Surface by Viking 1
The view from the Viking 1 Lander on the surface of Mars, in 1977, shows a rocky landscape and a ruddy sky. The lander in the foreground has its meteorology arm extended.
Figure 30. Titan Disk
The largest moon of Saturn, with its intriguing features photographed by the Cassini orbiting space probe in 2005.
Figure 31. Titan Coast
Showing icy highlands with dry rivers and what appears to be the shoreline of a vanished sea, as seen by the Huygens descent probe from an altitude of about 10 kilometers in 2005.
Figure 32. Sagittarius Stars
The Spitzer Space Telescope turned its gaze toward the constellation Sagittarius. Its infrared camera was able to penetrate the obscuring curtains of gas and dust for a thrilling look at the crowded center of the Milky Way Galaxy.
Figure 33. SETI Spectrum
A graph of the natural radio background noise over a wide range of frequencies. At lower frequencies (left), charged particles in our
galaxy emit increasing noise. At higher frequencies (right), the intrinsic quantum noise of any radio receiver increases. Between them is a relatively quiet "window," where interstellar hydrogen (H) and hydroxyl (OH) emit radio energy at discrete frequencies. This plot does not include radio emission from molecules in the Earth's atmosphere.
Figure 34. Simulated SETI Signal
The search for extraterrestrial intelligence includes the monitoring of stars at many radio frequencies simultaneously over time. A successful detection might resemble this signal, which actually came from the Pioneer 10 spacecraft in the outer solar system. The drift in frequency over time shows that the source is not rotating with the Earth, but is of extraterrestrial origin.
Figure 35. The Cretaceous-Tertiary Record in the Rocks at Gubbio
The evidence for the event that caused the extinction of the dinosaurs sixty-five million years ago was discovered in this sequence of sedimentary strata from Gubbio, northern Italy. The pale limestone layers at the lower right were deposited in the Cretaceous period, when dinosaurs ruled the Earth. The darker limestone layers at the upper left are from the subsequent Tertiary period, when they had become extinct. In between, the diagonal layer of black clay contains the worldwide iridium-rich fallout of debris from the crater excavated by the collision of an asteroid or comet. This layer is found everywhere on Earth where rocks of this age are exposed. The edge of a coin at the top is for scale.
Figure 36. Cretaceous-Tertiary Impact
Don Davis, one of the greatest painters of science-based art, takes us to the panicky last second of the age of the dinosaurs. An asteroid
or comet some 10 kilometers in diameter plunged through the shallow ocean near what is now Yucatan in Mexico, igniting global wildfires and producing a dense cloud of smoke and dust that darkened and froze the surface of the Earth.
Page numbers in italics are for illustrations,
Adams, John, 104
Adamski, George, 152-35
alternate universes, 58-59
amino acids, 75, 98
ammonia, 75, 98
ancient astronauts, 108, 126-29
angels, 65-64, 103, 143
animal sacrifice, 175
animism, 33-34, 174
Anselm, Saint, 160
anthropic principle, 43, 53-59, 158, 232
apartheid, South Africa, 186-87
apocalyptic visions of the future, 219
Aquinas, Thomas, 37, 155
arguments for the existence of God. See proofs of the existence of God
Democritus contrasted with, 225
on first cause, 155, 158
on God as oblivious to humans, 148
on nothing changing in the heavens, 58
one-way communication from, 115
on planetary motion, 35-56, 37
on prime mover, 64
on slavery, 219
astronomical unit, 8
atheism, 148, 150
atoms, stability of, 56-57
automatic writing, 139-40
awe, 2, 184
Barrow, J. D., 57
base-ten number system, 121-22
Bermuda Triangle, 232-34
Beta Pictoris, 52, 53
birth control, 183, 193
Brahe, Tycho, 38-39
Bronowski, Jacob, 128
Brooke, Rupert, 60-61
Brorsen, Comet, 72, 73
Burroughs, Edgar Rice, 107
canals on Mars, 104-8
Carlyle, Thomas, 2
Cassiopeia supernova explosion, 38
causality, 153, 154-55
change, tradition and, 191-94
Chariots of the Gods? (von Däniken), 126
apparitions of Virgin Mary, 152
as atheism to the Romans, 148
fundamentalism, 207, 249-50
historicity of Jesus, 237
Judeo-Christian-Islamic tradition, 148, 156, 175, 256
and nuclear war, 207, 208-10
Clarion religion, 139-42
Clarke, Arthur, 123
Brorsen, 72, 73
cause of random orientation of, 47-48
Comet of 1577,38-39
Machholz, 70, 71
NEAT, 74, 75
Newton on orbits of, 43-44
Oort Cloud, 8,10, 11
organic molecules in, 72, 73, 74, 75, 76
spectroscopic study of, 71
Winnecke II, 72, 73
communication, advances in, 193
compassion, 148, 153, 163-64
condensation of molecules from air, 78
conformity, social, 184-88
consciousness, argument from, 160-62
conversion, religious, 152-53
Copernicus, Nicolaus, 36-38, 63
cosmological argument, 154-58
Crab Nebula, 3
creationism, 39, 249-50
Cretaceous-Tertiary catastrophe, 112, 196-200, 204, 251
crimes against Creation, 205
cyanide, 75, 76
Darwin, Charles, x, 40, 42, 158
Deimos, 88, 89
democracy, xiii, 174, 257, 258
design, argument from, 41-42, 158-59
devil's advocate, 137-38
dinosaurs, extinction of, 112, 198, 200
divine right of kings, 219, 220
dominance hierarchies, 172-74, 179, 184-85
Dostoyevsky, Fyodor, 179, 185
Drake equation, 109-15, 227-28
Drake, Frank, 109
Druyan, Ann, 29
Eagle Nebula, 3 Earth
age of, 39, 42, 98
Aristotle on motion of, 35-36
Copernicus degrading status of, 36-38
in modern depictions of solar system, 8, 9
national boundaries as artificial, 210-11
origin of life on, 96-102
relative sizes of planets, 4, 5
religion as Earth centered, 30
seen from space, 210
when Sun becomes red giant, 20
Wright on insignificance of, 27-28
in Wright's depiction of solar system, 6,7
Easter Island, 128
ecliptic (zodiacal) plane, 43
Egyptian pyramids, 127
Einstein, Albert, 2, 34, 40-41, 149, 224, 239-40, 256, 259
elements, four, 36
Emery, Lillie, 102
chemical effects on, 179-84
intellect for adjudicating between
predispositions formed early, 169
projecting human feelings into science, 33-36, 59
endorphins, 181, 183
enkephalins, 181, 183
enzymes, 67-68, 99-101
Eskimo Nebula, 18
evil, problem of, 163-64
argument from design and, 42
evidence for, 65-66
Genesis and, x
human uniqueness disproved by, 39-40, 65
natural selection, 42, 50, 68, 100, 159, 182,244,259
time required for intelligent life, 54
argument from, 162-63
religious, 162-63, 183-84
experiments, 156, 232
extinction, 66, 112, 196-200, 204, 250-51
extraterrestrial intelligence, 103-23
ancient astronauts, 108, 126-29
approaches to, 108
canals on Mars attributed to, 104-8
Drake equation, 109-15, 227-28
folklore about visits by, 125-45
humans coping with finding, 226
human uniqueness threatened by, 41
in other galaxies, 228
seeking required for finding, 223
television and radar reaching, 229
unidentified flying objects, 129-42
why haven't they made their existence obvious, 238-39
Festinger, Leon, 139, 142
fight-or-flight syndrome, 181-82
first cause, 155, 158
flying saucers. See unidentified flying objects (UFOs)
fossil record, 65-66, 98-99, 147-48, 196-200
four essences, 36
Frazer, Sir James, 174
free will, 238
frequencies, radio, 116, 117
Freud, Sigmund, 178, 179, 247
number of, 27
searching for life in other, 228
See also Milky Way Galaxy
Galileo, 37-38 Galton, Sir Francis, 176-77
animism, 33-34, 174
conceptions of, 148-53, 224
curiosity and intelligence provided by, 31
as father, 178
of the Gaps, 64
humans as made in image of, 122-23
immortality attributed to, 29-30
intervention in human affairs, 148, 165, 256
Judeo-Christian-Islamic conception of, 148
knowledge of nature and knowledge of, x
as love, 236
naive Western view of, 149, 224
planetary motion attributed to, 63-64
as portrayed too small, 28, 30
prayer to, 175-78
problem of evil, 163-64
as promoting well-being of creation, 29
scientific advances leaving less room for, 64
as sum total of laws of physics, 149-50, 224, 239-40
as supernatural, 149
See also proofs of the existence of God
Golden Rule, 208-9 gravitation, Newtonian, 55-56, 57, 64, 221, 224
Great Flood, 147-48
greenhouse effect, 58
Gubbio (Italy), 196-98
Halley's Comet, 76
hallucinogens, 162-63, 171, 180, 183
Hammurabi, code of, 186
Harvard University, 117
"Heaven" (Brooke), 60-61
Hercules Cluster, 26, 27
Herodotus, 127, 172
Heyerdahl, Thor, 128
Hillel, Rabbi, 209
Hinduism, 153, 156
Hiroshima, 200, 201
history, rewriting of, 143-44, 237
Hobbes, Thomas, 215, 219
Hoyle, Fred, 101
Hubble, Edwin, 54
Huggins, Sir William, 69-72, 76
anthropic principle, 53-59
biochemical similarity to other organisms, 66
as at branch point in our history, 214, 259
chemical effects on emotions, 179-84
contrasting principles in, 258-60
dependence on nonhuman species, 205-6
dominance hierarchies in, 172-74
emotional predispositions formed early, 169
evolution disproving uniqueness of, 39-40, 65
extraterrestrials conceived as similar to, 121-22
hunter-gatherers, 151, 170-73, 191-92, 214-15
instinctive aspects of, 40
intelligence in success of, 213-14
as made in God's image, 122-23
nuclear war, 200-210, 250-51
population growth of, 214
psychic dimension attributed to, 244-47
relativity disproving privileged position of, 40-41
search for meaning by, 213-21
as small and mortal in Western religion, 29-30
human sacrifice, 175
Hume, David, 136, 144-45
hunter-gatherers, 151, 170-73, 191-92, 214-15
Huxley, Aldous, 183
hydrogen cyanide, 76, 92, 98
Iapetus, 80, 81
infant mortality, 193
for adjudicating between conflicting
in Drake equation, 110, 112-13
in humans' success, 213-14
selective advantage of, 112
time required for evolution of, 54
See also extraterrestrial intelligence
international organizations, 215-16
interstellar spaceflight, 126
intervention in human affairs, 148, 165, 256
inverse square law, 55-56
iridium anomaly, 198
Islam, 148, 156, 175, 256
James, William, xv
Jeans, Sir James, 242-44
Jesus Christ, 237
Jivaro people, 172
Judeo-Christian-Islamic tradition, 148, 156, 175,256
Jupiter, 6, 7, 79
Kant, Immanuel, 44, 47, 159
!Kung people, 170-72
Laplace, Pierre-Simon, marquis de, 44, 47, 188
Lecompte du Nouy, Pierre, 99
Leibniz, Gottfried Wilhelm, xv-xvi
Leonardo da Vinci, 147-48
anthropic principle and existence of, 53-59
extinction, 66, 112, 196-200,204, 250-51
fossil record, 65-66, 98-99, 147-48, 196-200
as improbable, 195-96 number of planets suitable for origin of, 111
only one kind of, 67
origin of terrestrial, 96-102
prevailing scientific view on origin of, 218
probability of spontaneous origin of, 101-2
source of organic molecules for, 67-96
See also evolution; humans; intelligence light, speed of, 34, 166, 193
Lowell, Percival, 105-7
Machholz, Comet, 70,71
Madonna, weeping, 138
manic-depressive syndrome, 179-80
many universes idea, 58-59
canals on, 104-8
Deimos, 88, 89
exploration of, 194, 195
as lifeless, 195
organic molecules rare on, 91
Phobos, 86, 87
as suitable for origin of life, 111
in Wright's depiction of solar system, 6, 7
Maxwell, James Clerk, 44
meaning, human search for, 213-21
medicine, advances in, 193, 220
mediocrity, principle of, 41
Mercury, 6, 20, 78
meteorites, carbonaceous, 80
methane, 78-79, 92, 95, 98
microintervention, 148, 165, 256
Milky Way Galaxy, 22
Democritus on composition of, 225
distance to closest technical civilization, 109, 115
explosions from center of, 28
lifetime of, 110-11
M31 as similar to, 24, 25
number of stars in, 12, 23, 110
number of technical civilizations in, 109-15
Sun's location in, 24, 37
Wright's conception of, 12
See also solar system, the
miracles, 136-38, 144, 175,251
Moon, the, 194, 195
moral argument for existence of God, 159-60
religion endorsing conventional, 186-88
religion and moral courage, 206
M31 Galaxy, 24, 25
Nagasaki, 200, 201
Nagel, Ernest, 160
natural selection, 42, 50, 68, 100, 159, 182, 244, 259
natural theology, xvii, 147, 152-53
anthropic principle and laws of, 55-59
God seen as sum total of laws of, 149-50, 224, 239-40
knowledge of God and knowledge of, x
religion not encouraging understanding of, 218
and wonder, 1-31
Nazca, plains of, 128
NEAT, Comet, 74, 75
solar, 47-53, 49, 52, 78, 111
Veil, 20, 21
Neptune, 58, 79
Newton, Isaac, 42-44, 48, 55-56, 64, 221, 224,231,232
nonviolence, political, 209 nuclear war, 200-210, 220, 250-51, 252-56, 258-59
nuclear winter, 203
nucleic acids, 67-68, 98
Old Testament, ix-x, 150-51, 256
olive oil, 72, 73
omnipotence, 148-49, 153, 163-64, 236 omniscience, 148-49, 153, 163-64, 236, 237
ontological argument, 160
Oort Cloud, 8, 10, 11
organic molecules, 67-96
biological origin of terrestrial, 69
in comets, 72, 73, 74, 75, 76
on early Earth, 98
in outer solar system, 79-94
probability of producing the first time, 99-101
Orion Nebula, 17
Osiander, Andreas, 36
Paine, Thomas, 30, 136-37
peyote cult, 163
Phobos, 86, 87
fundamental difference between
religion and, 231-32
God seen as sum total of laws of, 149-50, 224, 239-40
laws applying everywhere, 123, 231
projecting human feelings into, 33-34, 59
quantum mechanics, 34-35, 239-40
relativity, 34, 40-41
Second Law of Thermodynamics, 157-58
Planetary Society, 117, 118
Aristotle on motion of, 35-36
Copernicus on motion of, 36-38, 63
Democritus on composition of, 225
in Drake equation, 110, 111-12
evolution of, 28
inverse square law and orbits of, 55
Newton on motion of, 42-44, 64
solar nebula in formation of, 47-53, 48, 51
total number in universe, 11
See also Earth; Mars; Saturn; and others by name
Pleiades, 14, 15
Prescott, James, 172-73
prime mover, 64
prime numbers, 120
privilege, 35-36, 40-41
problem of evil, 163-64
proofs of the existence of God, 153-65
anthropic principle, 43, 53-59, 158, 232
argument from consciousness, 160-62
argument from design, 41-42, 158-59
argument from experience, 162-63
burden of proof in, 241-42
proofs of the existence of God (cont) compared with other existence proofs, 240-41
cosmological argument, 154-58
deduced from probability of producing
organic molecules, 100-101
God leaving clear evidence of His existence, 165-68, 234-36, 237-39
Jeans's interaction argument, 242-44
moral argument, 159-60
no new proof in centuries, 232
as not compelling, 163, 165
ontological argument, 160
science possibly discovering, 223-24
of Udayana, 153-54
propitiation, 174-75, 178
proteins, 67-68, 98
psychic dimension of human life, 244-47
pyramids of Egypt, 127
quantum mechanics, 34-35, 239-40
quasars, 28 quintessence, 36
radioactive fallout, 203-4, 250
radio communication, 115-21, 126
radio frequencies, 116,117
radio telescopes, 109, 115, 114, 118, 223
red dwarf stars, 56, 57
relativity, 34, 40-41
adapting beliefs to the future, 256
awe in, 2
belief in face of contradictory evidence, 141-45
conventional morality endorsed by, 186-88
culture as determining belief, 152
early function and origins of, 174-79
as Earth centered, 30
etymology of word, 1
extraterrestrial intelligence and, 122-23
fundamental difference between science and, 231-32
inconsistency of different religions, 150-51
interrelationships sought by, 1-2
James's definition of, xv
making people contented with their lot, 185-86
miracles, 136-38, 144, 175, 251
natural theology as boundary area
between science and, xvii
and nuclear war, 205-10
purpose provided by, 226-27
restricting to human behavior, 225-26
scale of universe ignored in, 27
science separated from, xi-xii, 247-48
social conformity enjoined by, 184-88
understanding of nature not encouraged by, 218
See also God/gods
religious experience, 162-63, 183-84
revelation, xvii, 147, 152
rewriting history, 143-44, 237
Russell, Bertrand, xi, 160, 188-89, 248-49
sacred, the, believing our understanding of is complete, xi
Sagittarius, 22, 23, 96, 97
Iapetus, 80, 81
methane on, 78, 79
rings of, 44, 45, 46, 47
small moons of, 82, 83
Titan, 92, 93, 94, 95, 96, 111, 196
in Wright's depiction of solar system, 6,7
Schiaparelli, Giovanni, 104-5, 106
advances leaving less room for God, 64
contradictory impulses in, 248
and democracy, xiii
error-correcting methodology of, xi, 231-32
fundamental difference between religion and, 231-32
as informed worship, xiii, 31
interrelationships sought by, 1-2
natural theology as boundary area between religion and, xvii
of Old Testament, 256
possibly proving existence of God, 223-24
projecting human feelings into, 33-36, 59
religion separated from, xi-xii, 247-48
"why" questions avoided in, 232
See also physics
Second Law of Thermodynamics, 157-58
sex hormones, 182-83
Shroud of Turin, 230-31
skepticism, 145, 231, 248-49
slavery, 206, 219-20
social conformity, 184-88
solar system, the
Copernicus on planetary motion, 36-38, 63
exploration of, 194-95
inverse square law and planetary orbits, 55
as lifeless except on Earth, 195-96
location in Milky Way Galaxy, 24, 37
modern depictions of, 8, 9
Newton on order within, 42-44, 64
relative sizes of objects in, 4, 5
solar nebula in formation of, 47-53, 48, 78
Sun becoming red giant, 20
Wright's depiction of, 6, 7
See also comets; Earth; Mars; Saturn; and other planets by name
South Africa, 186-87
space exploration, 194
spaceflight, interstellar, 126
spectroscopy, astronomical, 69-72
Spinoza, Baruch, 149, 224
spiritual dimension of human life, 244-47
in Copernican system, 37
in Drake equation, 110-11
dying, 18, 19
Hercules Cluster, 26, 27
late stages of evolution of, 20, 28
number of, 12, 27
number with planetary systems, 111
red dwarfs, 56, 57
supernova explosions, 20, 21, 28, 38
See also Sun
Star Wars (Strategic Defense Initiative), 252-56
strong nuclear force coupling constant, 56-57
becoming red giant, 20
location in Milky Way Galaxy, 24, 37
in modern depictions of solar system, 8,9
as typical star, 23
in Wright's depiction of solar system, 6, 7
See also solar system, the supernatural beings
angels, 63-64, 103, 143
Tillich on God as, 149
See also God/gods
supernova explosions, 20, 21, 28, 38
distance to closest, 109, 115
lifetime of, 110, 114-15
number in Milky Way Galaxy, 109-15
proportion of intelligent beings developing, 113
Tennyson, Alfred, Lord, 29
Textor, Robert, 172-73
tidal locking, 56, 57-58
Tillich, Paul, 149
Titan, 92, 93, 94, 95, 96, 111, 196
Tolstoy, Leo, 213
tradition, change and, 191-94
transportation, advances in, 193
Trotsky, Leon, 144, 237
conflict over different conceptions of, 216-17
Turgenev, Ivan, 175
unidentified flying objects (UFOs), 129-42
as approach to extraterrestrial intelligence, 108
in Clarion religion, 139-42
humans taken aboard, 133
photographs of, 132-33
physical evidence lacking for, 133-34
postjudice in claims of, 135-36
religious experience compared with, 162
silo taken for, 134-35
standard mythos of, 130
things mistaken for, 131-32
age of, 54
chaos in, 158-59
creation of, 155-56, 218
darkness as the rule in, 2
as evolving, 40
expansion of, 54, 155-56, 251-52
massive destruction in, 28-29
no such thing as center of, 37
scale of, 27-28
understanding as betraying lack of humility, 31
See also galaxies; nebulae; planets (worlds); s
Uranus, 79, 84, 85
Ussher, James, 151
Veil Nebula, 20, 21
Venus, 6,20, 135, 194, 195
Virgin Mary, apparitions of, 152
von Däniken, Erich, 126-29
water, 56, 78, 96, 98
weeping Madonna, 138
Welles, Orson, 107
Wells, H.G, 107
When Prophecy Fails (Festinger et al.), 139-42
Wickramasinghe, N. G, 101
Winnecke II, Comet, 72, 73
Carlyle on worship and, 2
nature and, 1-31
Wright, Thomas, 6, 12, 27-28
Wright, W. H., 106
Young, Edward, 28
zodiacal (ecliptic) plane, 43
zoo hypothesis, 238
fronds NASA, ESA, S. Beckwith (STScI) and the HUDF Team
1 T. A. Rector and B. A. Wolpa, NOAO, AURA
2 FORS Team, 8.2-meter VLT, ESO
4 Thomas Wright, 1750, An Original Theory or New Hypothesis of the Universe
5 NASA/JPL-Caltech/R. Hurt (SSC-Caltech)
6 © 1999,. Calvin Hamilton
7 Thomas Wright, 1750, An Original Theory or New Hypothesis of the Universe
8 © Matthew T. Russell
9 © Stefan Seip
10 Andrew Fruchter (STScI) et al., WFPC2, HST, NASA
11 © Steve Mandel, Hidden Valley Observatory
12 Hubble Heritage Team (AURA/STScI/NASA)
13 © Robert Gendler
14 © Jim Misti (Misti Mountain Observatory)
15 Cassini Imaging Team, SSI, JPL, ESA, NASA
16 Cassini Imaging Team, SSI, JPL, ESA, NASA
17 Tasa Portfolio, Volume One, © 2002 Tasa Graphic Arts, Inc., courtesy of Dennis Tasa
18 NASA/JPL-Caltech/T. Pyle (SSC)
19 J.-L. Beuzit et al. (Grenoble Observatory), ESO
20 Adam Block (NOAO), AURA, NSF
21 Philosophical Transactions Royal Society of London, vol. 168
22 Gunma Astronomical Observatory, 6860-86 Nakayama Takayama-mura Agatsuma-gun Gunma-ken, Japan
23 Harper's Weekly, May 14, 1910
24 Cassini Imaging Team, SSI, JPL, ESA, NASA
25 NASA Voyager 1
26 Heidi Hammel, Space Science Institute, Boulder, CO/Imke de Pater, University of California at Berkeley/W. M. Keck Observatory
27 Viking Project, JPL, NASA; image mosaic by Edwin V. Bell II (NSSDC/Raytheon ITSS)
28 Viking Project, JPL, NASA
29 NASA Viking 1, image 77-HC-62
30 NASA/JPL/Space Science Institute
31 ESA/NASA/JPL/University of Arizona
32 Susan Stolovy (SSC/Caltech) et al., JPL-Caltech, NASA
33 Steven Soter, adapted from Barney Oliver
34 Steven Soter
35 Walter Alvarez, University of California at Berkeley
36 Don Davis (NASA)
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