Faint Echoes, Distant Stars Read online

  Despite the bright hopes and hard work of the SETI researchers, dozens of radio telescope facilities working for more than four decades have found no repeated signals, no signs of intelligent life.

  Politicians found SETI an easy target, and a good way to make headlines. In the 1970s, Senator William Proxmire, of Wisconsin, postured as a guardian of the taxpayer’s purse by presenting a “Golden Fleece” award to government programs that he thought were wasting tax money. In 1978 he awarded a Golden Fleece to SETI, deriding the scientists who, his news release claimed, were searching for “Martians.”

  By 1981, when the proposed NASA budget included two million dollars to support SETI (million, not billion) Proxmire led the campaign in the Senate to forbid NASA from spending any money on SETI.

  Sagan visited Proxmire and, by showing that SETI efforts were leading to much more sophisticated electronic equipment, which would have an impact on many industries, he got Proxmire to back off somewhat. But the handwriting was on the wall. To the politicians, SETI’s lack of results meant failure. Washington’s interest in SETI shriveled like a pinpricked balloon.

  Moreover, there was a scientific counter-attack against SETI going on.

  “Where Is Everybody?”

  In 1950, at lunch with fellow scientists at the Los Alamos National Laboratory, Nobel laureate Enrico Fermi asked a simple question: If there are intelligent extraterrestrials, where is everybody? Why haven’t we seen evidence of them?

  The obvious answer was that, if they exist, the distances between their worlds and ours are so vast that the only hope we have of finding evidence for them lies in radio searches. Hence SETI.

  But by 1975, after some 15 years of radio searches, two scientists published papers that proposed something close to heresy, as far as the SETI researchers were concerned. American Michael Hart and David Viewing of Britain independently came to the conclusion that the reason no intelligent signals have been found is that there are no intelligent creatures out there. Planet Earth is so rare, they argued, that we should not expect to find a similar world, or intelligent life.

  In 1980 Tulane University mathematician Frank Tipler joined the counter-attack. Tipler is not a hidebound conservative, nor a chalkdust-dry academic. His work has included ideas on how to build time machines. Yet he concluded that there are no other intelligent species in the entire universe.

  The Milky Way galaxy is at least twice as old as our solar system, he pointed out. There are billions of stars that have existed for billions of years longer than we have. If intelligence has arisen on even a few of these ancient stars, those alien civilizations would be far older and far more knowledgeable than we. Their technological capabilities would immensely exceed our own.

  Such a civilization would be able to colonize the entire galaxy, Tipler suggested. It need not send its own people into space, it could send self-replicating machines that move from one star to another, colonizing any planets they find and using those planets’ natural resources to build more copies of themselves and move on to the next stars. In effect, such machines would be like a virus spreading from star to star, planet to planet. If their spacecraft could achieve velocities of only 10 percent of the speed of light (something that we should be able to do before this century is out), they could spread exponentially across the entire Milky Way in just about a million years.

  The fact that Earth has not been visited by these mechanical representatives of a superior civilization, Tipler concluded, is proof that no such civilizations exist.

  Howls of protest greeted Tipler’s pessimistic argument. The SETI optimists pointed out that his conclusions rest on enormous assumptions. For example: Could such ancient civilizations exist? The oldest stars are metal-poor, they might not have contained the proper elements for life, or for a technologically sophisticated civilization, to arise around them. Or, if such very old and wise civilizations do exist, perhaps they would have no interest in colonizing the galaxy.

  By the year 2000, the various arguments against the existence of intelligent aliens were summarized by paleontologist Peter D. Ward and astronomer Donald Brownlee in their book, Rare Earth. Basically, they refined the idea that complex life (meaning multicelled organisms) is so rare in the universe that we may be the only example in the galaxy. While microbial life may flourish elsewhere, intelligent life might be unique to our special planet.

  Is Intelligence Inevitable?

  Moreover, biologists were awakening to the idea that intelligence is neither a necessary nor inevitable consequence of life. Most of us still hold in our minds the concept of a Tree of Life (or perhaps a Ladder of Life) that starts with very simple organisms and culminates, at the top, with an intelligent species: Homo sapiens.

  We tacitly assume that wherever life exists, intelligence will eventually arise, given enough time. But is that true? The modern biological view of Earth’s life resembles a thick, wild bush more than a tree or a ladder. Intelligence is merely one evolutionary tactic, an adaptation that helps a species to survive, little different from developing a shaggy coat of fur, or sharp-focusing eyes, or wings or gills or any of myriads of adaptations.

  Life adapts in every way it can, and intelligence - which we regard as the high point of it all - is most likely just another adaptation that has helped our particular species to survive, but may eventually push us into extinction as our weaponry or heedlessness exceeds our ability to control our passions.

  The dinosaurs did very handsomely for nearly 200 million years without intelligence. The brainless bacteria have been around for nearly four billion years. In the entire history of Earth only genus Homo has developed unquestioned intelligence, and only one member of that genus, H. sapiens, has avoided extinction - so far. What makes us think intelligence is so lofty?

  Gould put it this way: “Humans [and intelligence] are here by the luck of the draw, not the inevitability of life’s direction or evolution’s mechanism.”

  In other words, it is not inevitable that there are other intelligent species out there to communicate with us. We may indeed be alone.

  Congress Strikes Again

  Scientists argued these points back and forth. The politicians in Washington acted on them. In 1992 Congress again forbade NASA from spending a penny on SETI. Proxmire was long gone from the Senate, but Sen. Richard Bryan of Nevada echoed his sentiments:

  The Great Martian Chase has finally come to an end. As of today, millions have been spent and we have yet to bag a single little green fellow. Not a single martian has said take me to your leader, and not a single flying saucer has applied for FAA approval.

  Notwithstanding the fact that SETI had nothing to do with Mars or UFOs, NASA was prohibited from working on SETI.

  Is Anybody Out There?

  The hell of it is, those know-nothing politicians may be right.

  Enthusiasts such as Zubrin may write, “Our galaxy is almost certainly currently inhabited by large numbers of starfaring species.” But that is a statement of belief, not fact. It is based on that tacit assumption that life anywhere will inevitably lead to intelligence.

  All the supporting arguments that Zubrin, and Drake, and Sagan, and everyone else have used to “prove” the existence of extraterrestrial intelligence are nothing more than sheer numerology. They all rest on that assumption that intelligence is a natural culmination of life.

  I don’t mean to pick on Zubrin especially. He possesses a sharp, original mind, and his proposals for exploring Mars at a fraction of the “official” price NASA has hung on human missions to the red planet are wonderful examples of clear thinking and bold vision.

  Yet when he writes about “Galactic Society” it seems to me that he is allowing his enthusiasm to run far ahead of the evidence.

  “But if [intelligence] could have happened on Earth,” Zubrin says, “then it could happen on other planets. And there are likely billions of other planets where it could have happened first, and therefore, in all probability, did.”

  See h
ow the assumption colors the attitude? Zubrin goes on to draw up a table showing the probable numbers of extraterrestrial civilizations. Then he writes, “So even in most cases where the galaxy is only partially settled, the Earth should have drifted through somebody’s interstellar empire at some time in its history.”

  Then he goes on to offer explanations for why there’s no evidence of our being visited by these hypothetical extraterrestrial imperialists.

  The simplest answer is that they don’t exist. Occam’s Razor can cut painfully through our most cherished dreams, but the simplest answer is usually the closest to the truth.

  There are no interstellar empires. There are no intelligent extraterrestrials. There is very likely a lot of life out among the stars. The universe may very well be teeming with life. But the chances are overwhelming that it is primarily microbial. Even on worlds where multicelled creatures have evolved, intelligence is no more inevitable than any other trait a species might develop in its struggle for survival.

  I wish it were otherwise. I wish Zubrin and all the other “pro-intelligence” thinkers were absolutely right, and we live in a galaxy that abounds with intelligent species. But the evidence points against it.

  Where does that leave us? With an enormous opportunity. And an enormous responsibility.

  The human race can expand through interstellar space, unchallenged by alien and possibly hostile intelligent species. This places the stewardship of life squarely on our shoulders. We must revere life, wherever we find it. We must protect life while we expand our own habitat across the starry heavens.

  For some day the galaxy will be filled with intelligent civilizations: the children of Earth. We owe it to our descendants to keep the living universe a fit place for them to grow in.

  We should strive to make Isaac proud of us.

  This article was derived from Ben Bova’s book, The Living Universe.

  Copyright © 2003 by Ben Bova

  Prologue

  Author to Reader

  Astrobiology is the scientific study of the origin, distribution, evolution, and future of life in the universe.

  —Astrobiology Roadmap WorkshopAmes Research Center, July 1998

  THIS BOOK IS ABOUT ASTROBIOLOGY, a field of scientific research that didn’t exist ten years ago. Astrobiology is the study of the living universe. Astrobiologists seek the answers to three fundamental questions:

  What is the history of life?

  Are we alone in the universe?

  What is the future of life?

  The men and women involved in astrobiology come from many different scientific disciplines, including astronomy, biology, the geophysical sciences, computer sciences, and many more. They are probing the farthest reaches of space and time, from the distant origins of life on Earth to the future epochs when humans may live on other worlds, far from our planet of origin.

  Scientists are like explorers, constantly heading into unknown territory. To understand what it is like to be a scientist working on the frontier of existing knowledge, imagine yourself a scout in uncharted terrain. No one has reached this far before, no one has ever seen the pristine vista that your eyes now behold.

  Just ahead of you lies a deep, rugged canyon, a rift in the ground with walls so steep you have no hope of climbing down them. This chasm is deep, too; its bottom is hazy with mist. The canyon is so wide that its far rim is barely distinguishable, wavering in the heat haze of the bright afternoon. You can make out the dim and distant shapes of what might be low hills and huge boulders, but even in the binoculars you have carried with you those distant shapes remain blurry, indistinct.

  Then something catches your eye. Movement! Something moved on that distant edge of the canyon. Was it dust blown by the wind or some animal stalking its prey? Might it have been a person, a human being from some unknown tribe who lives in that undiscovered country?

  Scientists are like that scout, probing into the unknown, searching, seeking, stretching our knowledge and our capabilities to their uttermost—and beyond.

  The men and women who work in this new and exciting field of astrobiology are trying to understand whether life is a normal part of the universe or whether our Earth is the only world that harbors living creatures.

  This means that they must learn how life on Earth got started. After all, our planet is the only place that we know of where life exists. Can there be life on other worlds? Are there other intelligent creatures out among the stars? If there are, are they superior to us?

  The astrobiologists are in the same predicament as that scout at the canyon’s rim. They are searching through new territory, regions never before seen by human eyes. They are at the edge of the known world, peering into the unknown. Even with the best instruments and tools that human ingenuity can devise, they cannot get a clear view of what lies on the far rim of the chasm.

  They are working hard to get a sharper, more distinct view and to find ways to bridge that chasm so that they—and we—can cross the abyss of ignorance that now separates us from the knowledge we seek.

  You and I are going to journey with them on this thrilling quest. We are going to discover what is known about life here on Earth and in the wide and starry universe, why many hard-headed thinkers fully believe that life exists beyond the limits of our planet Earth. In fact, some of them believe that we have already discovered firm evidence of extraterrestrial life.

  Astrobiology is a new field of research, born hardly ten years ago. It has been a tumultuous decade filled with startling discoveries in astronomy, biology, and many other sciences. It has also been a decade of political struggle, for science and politics are intimately intertwined in modern societies, and there is political infighting among the scientists themselves.

  All the discoveries, all the struggles, have led most astrobiologists to believe that life is an integral part of the universe, as much a part of the cosmic whole as the stars and planets. They are seeking evidence for life on Mars and on the moons of the giant planets Jupiter and Saturn.

  Within the next decade or two they very well may find unequivocal proof that life exists beyond our Earth. Whether that discovery is made in ten years or twenty depends more on political decisions than scientific ones. The astrobiologists know where to look, and they know how. All that they lack is the firm commitment of funding to build the necessary instruments and the spacecraft to carry them.

  Moreover, in their quest to understand life’s role in the universe, it is equally likely that scientists will create forms of life in their laboratories. Not Frankenstein monsters, but microscopic cellular living creatures will be created out of nonliving chemicals. The first steps have already been taken. The fundamental processes that started life on Earth are being simulated in laboratories, where biologists and computer scientists are striving to determine if life can begin anywhere that the proper environmental conditions exist.

  The discovery of extraterrestrial life and the creation of life in the laboratory are two parts of the same quest for understanding how life arose and how it has affected the universe. These discoveries will rock human consciousness as nothing else has rattled us for thousands of years.

  Once we find life on other worlds, no matter whether it is a bacterium or a whale, the search for intelligent life will intensify. Once we know that Earth is not the only place in the universe where life exists, we will face the question of whether or not ours is the only world where intelligence reigns.

  That is the great unknown. We tacitly assume that intelligence is a natural outcome of life; after all, life on Earth has led to an intelligent species: Homo sapiens. But is intelligence an inevitable outcome of life, or is it just a useful trait that living creatures might or might not adopt, like wings or gills or tails?

  Will we at last find other intelligences somewhere in the vast universe and end our long loneliness? Whether we do or not, the search itself will expand our consciousness as never before.

  This is the ultimate quest, and the astrobiologis
ts have already embarked upon it.

  Section I

  The

  Path

  to

  Astrobiology

  1

  Are We Alone?

  It goes against nature in a large field to grow only one shaft of wheat, and in an infinite universe to have only one living world.

  —Metrodorus of Chios

  Circa 400 B.C.

  WHAT IS THE HISTORY of life?

  Are we alone in the universe?

  What is the future of life?

  Is life a normal part of the universe, or is our Earth the only world that harbors living creatures?

  Children ask, “Where did I come from?” Stargazers wonder if there is life on any of the fiery specks that dot the night sky. Philosophers ponder the meaning of life and seek to understand our place in the greater universe that surrounds us.

  These questions haunt our consciousness today, as they have for countless millennia. Human beings have always wondered about how life began and whether life exists beyond the Earth. The quest for life elsewhere in the universe is far older than written history.

  THE ALIENS AMONG US

  Since the beginning of human existence our ancestors have populated the world with powerful supernatural creatures. The earliest writings we know of deal with gods and goddesses who are obviously much more powerful than mere mortals and who inhabit realms far beyond this mundane world in which you and I live.

  Try to see the world as our prehistoric Ice Age ancestors did. Living in small tribes of hunters and gatherers, following the game herds across the land, they faced a world of terrifying dangers. Powerful lions and leopards stalked the night. When they sought shelter in caves, often as not a ferocious cave bear would mangle them with its sharp claws and powerful, crushing teeth. Hunger was a constant threat; wildfires, bewildering attacks of disease, a broken bone, even childbirth was dangerous.