Cosmos - Carl Sagan (1980)


The time will come when diligent research over long periods will bring to light things which now lie hidden. A single lifetime, even though entirely devoted to the sky, would not be enough for the investigation of so vast a subject … And so this knowledge will be unfolded only through long successive ages. There will come a time when our descendants will be amazed that we did not know things that are so plain to them … Many discoveries are reserved for ages still to come, when memory of us will have been effaced. Our universe is a sorry little affair unless it has in it something for every age to investigate … Nature does not reveal her mysteries once and for all.

—Seneca, Natural Questions,
Book 7, first century

In ancient times, in everyday speech and custom, the most mundane happenings were connected with the grandest cosmic events. A charming example is an incantation against the worm which the Assyrians of 1000 B.C. imagined to cause toothaches. It begins with the origin of the universe and ends with a cure for toothache:

After Anu had created the heaven,

And the heaven had created the earth,

And the earth had created the rivers,

And the rivers had created the canals,

And the canals had created the morass,

And the morass had created the worm,

The worm went before Shamash, weeping,

His tears flowing before Ea:

“What wilt thou give me for my food,

What wilt thou give me for my drink?”

“I will give thee the dried fig

And the apricot.”

“What are these to me? The dried fig

And the apricot!

Lift me up, and among the teeth

And the gums let me dwell!…”

Because thou hast said this, O worm,

May Ea smite thee with the might of

His hand!

(Incantation against toothache.)

Its treatment: Second-grade beer … and oil thou shalt mix together;

The incantation thou shalt recite three times thereon and shalt put the medicine upon the tooth.

Our ancestors were eager to understand the world but had not quite stumbled upon the method. They imagined a small, quaint, tidy universe in which the dominant forces were gods like Anu, Ea, and Shamash. In that universe humans played an important if not a central role. We were intimately bound up with the rest of nature. The treatment of toothache with second-rate beer was tied to the deepest cosmological mysteries.

Today we have discovered a powerful and elegant way to understand the universe, a method called science; it has revealed to us a universe so ancient and so vast that human affairs seem at first sight to be of little consequence. We have grown distant from the Cosmos. It has seemed remote and irrelevant to everyday concerns. But science has found not only that the universe has a reeling and ecstatic grandeur, not only that it is accessible to human understanding, but also that we are, in a very real and profound sense, a part of that Cosmos, born from it, our fate deeply connected with it. The most basic human events and the most trivial trace back to the universe and its origins. This book is devoted to the exploration of that cosmic perspective.

In the summer and fall of 1976, as a member of the Viking Lander Imaging Flight Team, I was engaged, with a hundred of my scientific colleagues, in the exploration of the planet Mars. For the first time in human history we had landed two space vehicles on the surface of another world. The results, described more fully in Chapter 5, were spectacular, the historical significance of the mission utterly apparent. And yet the general public was learning almost nothing of these great happenings. The press was largely inattentive; television ignored the mission almost altogether. When it became clear that a definitive answer on whether there is life on Mars would not be forthcoming, interest dwindled still further. There was little tolerance for ambiguity. When we found the sky of Mars to be a kind of pinkish-yellow rather than the blue which had erroneously first been reported, the announcement was greeted by a chorus of good-natured boos from the assembled reporters—they wanted Mars to be, even in this respect, like the Earth. They believed that their audiences would be progressively disinterested as Mars was revealed to be less and less like the Earth. And yet the Martian landscapes are staggering, the vistas breathtaking. I was positive from my own experience that an enormous global interest exists in the exploration of the planets and in many kindred scientific topics—the origin of life, the Earth, and the Cosmos, the search for extraterrestrial intelligence, our connection with the universe. And I was certain that this interest could be excited through that most powerful communications medium, television.

My feelings were shared by B. Gentry Lee, the Viking Data Analysis and Mission Planning Director. We decided, gamely, to do something about the problem ourselves. Lee proposed that we form a production company devoted to the communication of science in an engaging and accessible way. In the following months we were approached on a number of projects. But by far the most interesting was an inquiry tendered by KCET, the Public Broadcasting Service’s outlet in Los Angeles. Eventually, we jointly agreed to produce a thirteen-part television series oriented toward astronomy but with a very broad human perspective. It was to be aimed at popular audiences, to be visually and musically stunning, and to engage the heart as well as the mind. We talked with underwriters, hired an executive producer, and found ourselves embarked on a three-year project called Cosmos. At this writing it has an estimated worldwide viewing audience of over 200 million people, or almost 5 percent of the human population of the planet Earth. It is dedicated to the proposition that the public is far more intelligent than it has generally been given credit for; that the deepest scientific questions on the nature and origin of the world excite the interests and passions of enormous numbers of people. The present epoch is a major crossroads for our civilization and perhaps for our species. Whatever road we take, our fate is indissolubly bound up with science. It is essential as a matter of simple survival for us to understand science. In addition, science is a delight; evolution has arranged that we take pleasure in understanding—those who understand are more likely to survive. The Cosmos television series and this book represent a hopeful experiment in communicating some of the ideas, methods and joys of science.

The book and the television series evolved together. In some sense each is based on the other. Many illustrations in this book are based on the striking visuals prepared for the television series. But books and television series have somewhat different audiences and admit differing approaches. One of the great virtues of a book is that it is possible for the reader to return repeatedly to obscure or difficult passages; this is only beginning to become possible, with the development of videotape and video-disc technology, for television. There is much more freedom for the author in choosing the range and depth of topics for a chapter in a book than for the procrustean fifty-eight minutes, thirty seconds of a noncommercial television program. This book goes more deeply into many topics than does the television series. There are topics discussed in the book which are not treated in the television series and vice versa. For example, explicit representations of the Cosmic Calendar, featured in the television series, do not appear here—in part because the Cosmic Calendar is discussed in my book The Dragons of Eden; likewise, I do not here discuss the life of Robert Goddard in much detail, because there is a chapter in Broca’s Brain devoted to him. But each episode of the television series follows fairly closely the corresponding chapter of this book; and I like to think that the pleasure of each will be enhanced by reference to the other. Only a few of the more than 250 full-color illustrations in the hardbound and trade paperback editions of Cosmos could be accommodated in this edition, but all illustrations necessary to understand the text are included.

For clarity, I have in a number of cases introduced an idea more than once—the first time lightly, and with deeper passes on subsequent appearances. This occurs, for example, in the introduction to cosmic objects in Chapter 1, which are examined in greater detail later on; or in the discussion of mutations, enzymes and nucleic acids in Chapter 2. In a few cases, concepts are presented out of historical order. For example, the ideas of the ancient Greek scientists are presented in Chapter 7, well after the discussion of Johannes Kepler in Chapter 3. But I believe an appreciation of the Greeks can best be provided after we see what they barely missed achieving.

Because science is inseparable from the rest of the human endeavor, it cannot be discussed without making contact, sometimes glancing, sometimes head-on, with a number of social, political, religious and philosophical issues. Even in the filming of a television series on science, the worldwide devotion to military activities becomes intrusive. Simulating the exploration of Mars in the Mohave Desert with a full-scale version of the Viking Lander, we were repeatedly interrupted by the United States Air Force, performing bombing runs in a nearby test range. In Alexandria, Egypt, from nine to eleven A.M. every morning, our hotel was the subject of practice strafing runs by the Egyptian Air Force. In Samos, Greece, permission to film anywhere was withheld until the very last moment because of NATO maneuvers and what was clearly the construction of a warren of underground and hillside emplacements for artillery and tanks. In Czechoslovakia the use of walkie-talkies for organizing the filming logistics on a rural road attracted the attention of a Czech Air Force fighter, which circled overhead until reassured in Czech that no threat to national security was being perpetrated. In Greece, Egypt and Czechoslovakia our film crews were accompanied everywhere by agents of the state security apparatus. Preliminary inquiries about filming in Kaluga, U.S.S.R., for a proposed discussion of the life of the Russian pioneer of astronautics Konstantin Tsiolkovsky were discouraged—because, as we later discovered, trials of dissidents were to be conducted there. Our camera crews met innumerable kindnesses in every country we visited; but the global military presence, the fear in the hearts of the nations, was everywhere. The experience confirmed my resolve to treat, when relevant, social questions both in the series and in the book.

Science is an ongoing process. It never ends. There is no single ultimate truth to be achieved, after which all the scientists can retire. And because this is so, the world is far more interesting, both for the scientists and for the millions of people in every nation who, while not professional scientists, are deeply interested in the methods and findings of science. So, while there is little in the Cosmos book that has become obsolete since its first publication, there have been many significant new findings.

The Voyager 1 and 2 spacecraft encountered the Saturn system and uncovered a host of wonders concerning the planet, its intricate ring system, and its swarm of attendant satellites. Perhaps most interesting of these is Titan, which is now known to have an atmosphere rather like that of the primitive Earth, a dense haze layer composed of complex organic molecules, and perhaps a surface ocean of liquid hydrocarbons. A range of observations have recently been made of rings of debris surrounding young stars. These rings may be in the process of coagulating into new planetary systems, and suggest that planets may be overwhelmingly abundant among the stars of the Milky Way galaxy. Life has been found unexpectedly nibbling on sulfur compounds in very high temperature vents on the Earth’s ocean floor. New evidence has accumulated suggesting that comets are periodically sprayed into the inner solar system, triggering the extinction of many species on Earth. Great regions of intergalactic space have been uncovered that seemingly are depleted in galaxies. New and important components of the universe bearing on the question of its ultimate fate have been suggested.

And the pace of discovery continues. Spacecraft of Japan, of the European Space Agency, and of the Soviet Union are scheduled to intercept Halley’s Comet in 1986. The U.S. Space Telescope, the largest orbiting observatory ever attempted, is scheduled to be launched before the end of the decade. Important opportunities for spacecraft missions to Mars, to other comets, to asteroids, and to Titan are emerging. The U.S. Galileo spacecraft, scheduled to arrive in the Jupiter system in 1988, is designed to drop the first entry probe into the atmosphere of one of the giant planets. And there is a somber side to the pace of scientific discovery as well: recent work suggests that in the aftermath of a nuclear war the resulting soot and dust lofted high into the atmosphere would darken and freeze the Earth, producing an unprecedented catastrophe even for nations on which not a single bomb has fallen. Our technology is increasingly permitting us to explore the wonders of the Cosmos and to reduce the Earth to chaos. We are privileged to live in, and if we are lucky to influence, one of the most critical epochs in the history of the human species.

On a project of this magnitude it is impossible to thank everyone who has made a contribution. However, I would like to acknowledge, especially, B. Gentry Lee; the Cosmos production staff, including the senior producers Geoffrey Haines-Stiles and David Kennard and the executive producer Adrian Malone; the artists Jon Lomberg (who played a critical role in the original design and organization of the Cosmosvisuals), John Allison, Adolf Schaller, Rick Sternbach, Don Davis, Brown, and Anne Norcia; consultants Donald Goldsmith, Owen Gingerich, Paul Fox, and Diane Ackerman; Cameron Beck; the KCET management, particularly Greg Andorfer, who first carried KCET’s proposal to us, Chuck Allen, William Lamb, and James Loper; and the underwriters and co-producers of the Cosmos television series, including the Atlantic Richfield Company, the Corporation for Public Broadcasting, the Arthur Vining Davis Foundations, the Alfred P. Sloan Foundation, the British Broadcasting Corporation, and Polytel International. Others who helped in clarifying matters of fact or approach are listed at the back of the book. The final responsibility for the content of the book is, however, of course mine. I thank the staff at Random House, particularly my editor, Anne Freedgood, for their capable work and their patience when the deadlines for the television series and the book seemed to be in conflict. I owe a special debt of gratitude to Shirley Arden, my Executive Assistant, for typing the early drafts of this book and ushering the later drafts through all stages of production with her usual cheerful competence. This is only one of many ways in which the Cosmos project is deeply indebted to her. I am more grateful than I can say to the administration of Cornell University for granting me a two-year leave of absence to pursue this project, to my colleagues and students there, and to my colleagues at NASA, JPL and on the Voyager Imaging Team.

My greatest debt for the writing of Cosmos is owed to Ann Druyan and Steven Soter, my co-writers in the television series. They made fundamental and frequent contributions to the basic ideas and their connections, to the overall intellectual structure of the episodes, and to the felicity of style. I am deeply grateful for their vigorous critical readings of early versions of this book, their constructive and creative suggestions for revision through many drafts, and their major contributions to the television script which in many ways influenced the content of this book. The delight I found in our many discussions is one of my chief rewards from the Cosmos project.

Ithaca and Los Angeles
May 1980
and July 1984