CONTACT

     By Carl Sagan

    

    

For Alexandra,

who comes of age

with the Millennium.

May we leave your generation a world

better than the one we were given.

    

    

     PART I

THE MESSAGE

    

     My heart trembles like a poor leaf.

The planets whirl in my dreams.

The stars press against my window.

I rotate in my sleep.

My bed is a warm planet.

     -MARVIN MERCER

P.S. 153, Fifth Grade, Harlem

New York City, N.Y. (1981)

    

     CHAPTER 1

Transcendental Numbers

    

Little fly,

Thy summer's play

My thoughtless hand

Has brushed away.

     Am not I

A fly like thee?

Or art not thou

A man like me?

     For I dance

And drink and sing,

Till some blind hand

Shall brush my wing.

     -WILLIAM BLAKE

Songs of Experience

"The Fly," Stanzas 1-3 (1795)

    

By human standards it could not possibly have been artificial: It was the size of a world. But it was so oddly and intricately shaped, so clearly intended for some complex purpose that it could only have been the expression of an idea. Gliding in polar orbit about the great blue-white star, it resembled some immense, imperfect polyhedron, encrusted with millions of bowl-shaped barnacles. Every bowl was aimed at a particular part of the sky. Every constellation was being attended to. The polyhedral world had been performing its enigmatic function for eons. It was very patient. It could afford to wait forever.

    

When they pulled her out, she was not crying at all. Her tiny brow was wrinkled, and then her eyes grew wide. She looked at the bright lights, the white and green-clad figures, the woman lying on the table below her. On her face was an odd expression for a newborn--puzzlement perhaps.

     *  *  *

     When she was two years old, she would lift her hands over her head and say very sweetly, "Dada, up." His friends expressed surprise. The baby was polite. "It's not politeness," her father told them. "She used to scream when she wanted to be picked up. So once I said to her, `Ellie, you don't have to scream. Just say, "Daddy, up."' Kids are smart. Right, Presh?"

     So now she was up all right, at a giddy altitude, perched on her father's shoulders and clutching his thinning hair. Life was better up here, far safer than crawling through a forest of legs. Somebody could step on you down there. You could get lost. She tightened her grip.

     Leaving the monkeys, they turned a corner and came upon a great spindly-legged, long-necked dappled beast with tiny horns on its head. I towered over them. "Their necks are so long, the talk can't get out," her father said.  she felt sorry for the poor creature, condemned to silence. But she also felt a joy in its existence, a delight that such wonders might be.

     *  *  *

     "Go ahead, Ellie," her mother gently urged her. There was a lilt in the familiar voice. "Read it." Her mother's sister had not believed that Ellie, age three, could read. The nursery stories, the aunt was convinced, had been memorized. Now they were strolling down State Street on a brisk March day and had stopped before a store window. Inside, a burgundy-red stone was glistening in the sunlight. "Jeweler," Ellie read slowly, pronouncing three syllables.

     *  *  *

     Guiltily, she let herself into the spare room. The old Motorola radio was on the shelf where she remembered it. It was very big and heavy and, hugging it to her chest, she almost dropped it. On the back were the words "Danger. Do Not Remove." But she knew that if it wasn't plugged in, there was no danger in it.  With her tongue between her lips, she removed the screws and exposed the innards. As she had suspected, there were no tiny orchestras and miniature announcers quietly living out their small lives in anticipation of the moment when the toggle switch would be clicked to "on." Instead there were beautiful glass tubes, a little like light bulbs. Some resembled the churches of Moscow she had seen pictured in a book. The prongs at their bases were perfectly designed for the receptacles they were fitted into. With the back off and the switch "on," she plugged the set into a nearby wall socket.  If she didn't touch it, if she went nowhere near it, how could it hurt her?

     After a few moments, tubes began to glow warmly, but no sound came. The radio was "broken," and had been retired some years before in favor of a more modern variety. One tube was not glowing. She unplugged the set and pried the uncooperative tube out its receptacle. There was a metallic square inside, attached to tiny wires. The electricity runs along the wires, she thought vaguely. But first it has to get into the tube. One of the prongs seemed bent, and she was able after a little work to straighten it. Reinserting the tube and plugging the set in again, she was delighted to see it begin to glow, and an ocean of static arose around her. Glancing toward the closed door with a start, she lowered the volume. She turned the dial marked "frequency," and came upon a voice talking excitedly--as far as she could understand, about a Russian machine that was in the sky, endlessly circling the Earth. Endlessly, she thought. She turned the dial again, seeking other stations. After a while, fearful of being discovered, she unplugged the set, screwed the back on loosely, and with still more difficulty lifted the radio and placed it back on the shelf.

     As she left the spare room, a little out of breath, her mother came upon her and she started once more.

     "Is everything all right, Ellie?"

     "Yes, Mom."

     She affected a casual air, but her heart was beating, her palms were sweating. She settled down in a favorite spot in the small backyard and, her knees drawn up to her chin, thought about the inside of the radio. Are all those tubes really necessary? What would happen if you removed them one at a time? Her father had once called them vacuum tubes. What was happening inside a vacuum tube? Was there really no air in there? How did the music of the orchestras and the voices of the announcers get in the radio? They liked to say, "On the air." Was radio carried by the air? What happens inside the radio set when you change stations? What was "frequency"? Why do you have to plug it in for it to work? Could you make a kind of map showing how the electricity runs through the radio? Could you take it apart without hurting yourself? Could you put it back together again?

     "Ellie, what have you been up to?" asked her mother, walking by with laundry for the clothesline.

     "Nothing, Mom. Just thinking."

     *  *  *

     In her tenth summer, she was taken on vacation to visit two cousins she detested at a cluster of cabins along a lake in the Northern Peninsula of Michigan. Why people who lived on a lake in Wisconsin would spend five hours driving all the way to a lake in Michigan was beyond her. Especially to see two mean and babyish boys. Only ten and eleven. Real jerks. How could her father, so sensitive to her in other respects, want her to play day in and day out with twerps? She spent the summer avoiding them.

     One sultry moonless night after dinner she walked down alone to the wooden pier. A motorboat had just gone by, and her uncle's rowboat tethered to the dock was softly bobbing in the starlit water. Apart from distant cicadas and an almost subliminal shout echoing across the lake, it was perfectly still. She looked up at the brilliant spangled sky and found her heart racing.

     Without looking down, with only her outstretched hand to guide her, she found a soft patch of grass and laid herself down. The sky was blazing with stars. There were thousands of them, most twinkling, a few bright and steady. If you looked carefully you could see faint differences in color. That bright one there, wasn't it bluish?

     She felt again for the ground beneath her; it was solid, steady... reassuring. Cautiously she sat up and looked left and right, up and down the long reach of lakefront. She could see both sides of the water. The world only looks flat, she thought to herself. Really it's round. This is all a big ball... turning in the middle of the sky... once a day. She tried to imagine it spinning, with millions of people glued to it, talking different languages, wearing funny clothes, all stuck to the same ball.

     She stretched out again and tried to sense the spin. Maybe she could feel it just a little. Across the lake, a bright star was twinkling between the topmost branches. If you squinted your eyes you could make rays of light dance out of it. Squint a little more, and the rays would obediently change their length and shape. Was she just imagining it, or... the star was now definitely above the trees. Just a few minutes ago it had been poking in and out of the branches. Now it was higher, no doubt about it. That's what they meant when they said a star was rising, she told herself. The Earth was turning in the other direction. At one end of the sky the stars were rising. That way was called East. At the other end of the sky, behind her, the cabins, the stars were setting. That way was called West. Once every day the Earth would spin completely around, and the same stars would rise again in the same place.

     But if something as big as the Earth turned once a day, it had to be moving ridiculously fast. Everyone she knew must be whirling at an unbelievable speed. She though she could now actually feel the Earth turn--not just imagine it in her head, but really feel it in the pit of her stomach. It was like descending in a fast elevator. She craned her neck back further, so her field of view was uncontaminated by anything on Earth, until she could see nothing but black sky and bright stars. Gratifyingly, she was overtaken by the giddy sense that she had better clutch the clumps of grass on either side of her and hold on for dear life, or else fall up into the sky, her tiny tumbling body dwarfed by the huge darkened sphere below.

     She actually cried out before she managed to stifle the scream with her wrist. That was how her cousins were able to find her. Scrambling down the slope, they discovered on her face an uncommon mix of embarrassment and surprise, which they readily assimilated, eager to find some small indiscretion to carry back and offer to her parents.

     *  *  *

     The book was better than the movie. For one thing, there was a lot more in it. And some of the pictures were awfully different from the movie. But in both, Pinocchio--a life-sized wooden boy who magically is roused to life--wore a kind of halter, and there seemed to be dowels in his joints. When Geppetto is just finishing the construction of Pinocchio, he turns his back on the puppet and is promptly sent flying by a well- placed kick. At that instant the carpenter's friend arrives and asks him what he is doing sprawled on the floor. "I am teaching," Geppetto replies with dignity, "the alphabet to the ants."

     The seemed to Ellie extremely witty, and she delighted in recounting it to her friends. But each time she quoted it there was an unspoken question lingering at the edge of her consciousness: Could you teach the alphabet to the ants? And would you want to? Down there with hundreds of scurrying insects who might crawl all over your skin, or even sting you? What could ants know, anyway?

     *  *  *

     Sometimes she would get up in the middle of the night to go to the bathroom and find her father there in his pajama bottoms, his neck craned up, a kind of patrician disdain accompanying the shaving cream on his upper lip. "Hi, Presh," he would say. It was short for "precious," and she loved him to call her that. Why was he shaving at night, when no one would know if he had a beard? "Because"--he smiled--"your mother will know." Years later, she discovered that she had understood this cheerful remark only incompletely. Her parents had been in love.

     *  *  *

     After school, she had ridden her bicycle to a little park on the lake. From a saddlebag she produced The Radio Amateur's Handbook and A Connecticut Yankee in King Arthur's Court. After a moment's consideration, she decided on the latter. Twain's hero had been conked on the head and awakened in Arthurian England. Maybe it was all a dream or a delusion. But maybe it was real. Was it possible to travel backwards in time? Her chin on her knees, she scouted for a favorite passage. It was when Twain's hero is first collected by a man dressed in armor who he takes to be an escapee from a local booby hatch. As they reach the crest of the hill they see a city laid out before them:

     "`Bridgeport?' said I...

     "`Camelot,' said he."

     She stared out into the blue lake, trying to imagine a city which could pass as both nineteenth- century Bridgeport and sixth-century Camelot, when her mother rushed up to her.

     "I've looked for you everywhere. Why aren't you where I can find you? Oh, Ellie," she whispered, "something awful's happened."

     *  *  *

     In the seventh grade they were studying "pi." It was a Greek letter that looked like the architecture at Stonehenge, in England: two vertical pillars with a crossbar at top--?. If you measured the circumference of a circle and then divided it by the diameter of the circle, that was pi. At home, Ellie took the top of a mayonnaise jar, wrapped a string around it, straightened the string out, and with a ruler measured the circle's circumference. She did the same with the diameter, and by long division divided the one number by the other. She got 3.21. That seemed simple enough.

     The next day the teacher, Mr. Weisbrod, said that ? was about 22/7, about 3.1416. But actually, if you wanted to be exact, it was a decimal that went on and on forever without repeating the pattern of numbers. Forever, Ellie thought. She raised her hand. It was the beginning of the school year and she had not asked any questions in this class.

     "How could anybody know that the decimals go on and on forever?"

     "That's just the way it is," said the teacher with some asperity.

     "But why? How do you know? How can you count decimals forever?"

     "Miss Arroway"--he was consulting his class list--"this is a stupid question. You're wasting the class's time."

     No one had ever called Ellie stupid before, and she found herself bursting into tears. Billy Horstman, who sat next to her, gently reached out and placed his hand over hers. His father had recently been indicted for tampering with the odometers on the used cars he sold, so Billy was sensitive to public humiliation. Ellie ran out of the class sobbing.

     After school she bicycled to the library at the nearby college to look through books on mathematics. As nearly as she could figure out from what she read, her question wasn't all that stupid. According to the Bible, the ancient Hebrews had apparently thought that ? was exactly equal to three. The Greeks and Romans, who knew lots of things about mathematics, had no idea that the digits in ? went on forever without repeating. It was a fact that had been discovered only about 250 years ago. How was she expected to know if she couldn't ask questions? But Mr. Weisbrod had been right about the first few digits. Pi wasn't 3.21. Maybe the mayonnaise lid had been a little squashed, not a perfect circle. Or maybe she'd been sloppy in measuring the string. Even if she'd been much more careful, though, they couldn't expect her to measure an infinite number of decimals.

     There was another possibility, though. You could calculate pi as accurately as you wanted. If you knew something called calculus, you could prove formulas for ? that would let you calculate it to as many decimals as you had time for. The book listed formulas for pi divided by four. Some of them she couldn't understand at all. But there were some that dazzled her: ?/4, the book said, was the same as 1 - 1/3 + 1/5 - 1/7..., with the fractions continuing on forever. Quickly she tried to work it out, adding and subtracting the fractions alternately. The sum would bounce from being bigger than ?/4 to being smaller than ?/4, but after a while you could see that this series of numbers was on a beeline for the right answer. You could never get there exactly, but you could get as close as you wanted if you were very patient. It seemed to her a miracle that the shape of every circle in the world was connected with this series of fractions. How could circles know about fractions? She was determined to learn calculus.

     The book said something else: ? was called a "transcendental" number. There was no equation with ordinary numbers in it that could give you ? unless it was infinitely long. She had already taught herself a little algebra and understood what this meant. And ? wasn't the only transcendental number. In fact there was an infinity of transcendental numbers. More than that, there were infinitely more transcendental numbers than ordinary numbers, even though ? was the only one of them she had ever heard of. In more ways than one, ? was tied to infinity.

     She had caught a glimpse of something majestic. Hiding between all the ordinary numbers was an infinity of transcendental numbers whose presence you would never have guessed unless you looked deeply into mathematics. Every now and then one of them, like ?, would pop up unexpectedly in everyday life. But most of them--an infinite number of them, she reminded herself--were hiding, minding their own business, almost certainly unglimpsed by the irritable Mr. Weisbrod.

     *  *  *

     She saw through John Staughton from the first. How her mother could ever contemplate marrying him-- never mind that it was only two years after her father's death--was an impenetrable mystery. He was nice enough looking, and he could pretend, when he put his mind to it, that he really cared about you. But he was a martinet. He made students come over weekends to weed and garden at the new house they had moved into, and then made fun of them after they left. He told Ellie that she was just beginning high school and was not to look twice at any of his bright young men. He was puffed up with imaginary self-importance. She was sure that as a professor he secretly despised her dead father, who had been only a shopkeeper. Staughton had made it clear that an interest in radio and electronics was unseemly for a girl, that it would not catch her a husband, that understanding physics was for her a foolish and aberrational notion. "Pretentious," he called it. She just didn't have the ability. This was an objective fact that she might as well get used to. He was telling her this for her own good. She'd thank him for it in later life. He was, after all, an associate professor of physics. He knew what it took. These homilies would always infuriate her, even though she had never before--despite Staughton's refusal to believe it--considered a career in science.

     He was not a gentle man, as her father had been, and he had no idea what a sense of humor was. When anyone assumed that she was Staughton's daughter, she would be outraged. Her mother and stepfather never suggested that she change her name to Staughton; they knew what her response would be.

     Occasionally there was a little warmth in the man, as when, in her hospital room just after her tonsillectomy, he had brought her a splendid kaleidoscope.

     "When are they going to do the operation," she had asked, a little sleepily.

     "They've already done it," Staughton had answered. "You're going to be fine." She found it disquieting that whole blocks of time could be stolen without her knowledge, and blamed him. She knew at the time it was childish.

     That her mother could truly love him was inconceivable. She must have remarried out of loneliness, out of weakness. She needed someone to take care of her. Ellie vowed she would never accept a position of dependence. Ellie's father had died, her mother had grown distant, and Ellie felt herself exiled to the house of a tyrant. There was no one to call her Presh anymore.

     She longed to escape.

     "`Bridgeport?' said I.

     "`Camelot,' said he."

    

     CHAPTER 2

Coherent Light

    

Since I first gained the use of reason my inclination toward learning has been so violent and strong that neither the scoldings of other people... nor my own reflections... have been able to stop me from following this natural impulse that God gave me. He alone must know why; and He knows too that I have begged Him to take the light of my understanding, leaving only enough for me to keep His law, for anything else is excessive in a woman, according to some people. And others say it is even harmful.

     -JUANA INES DE LA CRUZ

Reply to the Bishop of Puebla (1691), who had attacked her scholarly work as inappropriate for her sex

     I wish to propose for the reader's favourable 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.

     -BERTRAND RUSSELL

Skeptical Essays, I (1928)

    

Surrounding the blue-white star in its equatorial plane was a vast ring of orbiting debris--rocks and ice, metals and organics--reddish at the periphery and bluish closer to the star. The world- sized polyhedron plummeted through a gap in the rings and emerged out the other side. In the ring plane, it had been intermittently shadowed by icy boulders and tumbling mountains. But now, carried along its trajectory toward a point above the opposite pole of the star, the sunlight gleamed off its millions of bowl-shaped appendages. If you looked very carefully you might have seen one of them make a slight pointing adjustment. You would not have seen the burst of radio waves washing out from it into the depths of space.

    

For all the tenure of humans on Earth, the night sky had been a companion and an inspiration. The stars were comforting. They seemed to demonstrate that the heavens were created for the benefit and instruction of humans. This pathetic conceit became the conventional wisdom worldwide. No culture was free of it. Some people found in the skies an aperture to the religious sensibility. Many were awestruck and humbled by the glory and scale of the cosmos. Others were stimulated to the most extravagant flights of fancy.

 

At the very moment that humans discovered the scale of the universe and found that their most unconstrained fancies were in fact dwarfed by the true dimensions of even the Milky Way Galaxy, they took steps that ensured that their descendants would be unable to see the stars at all. For a million years humans had grown up with a personal daily knowledge of the vault of heaven. I the last few thousand years they began building and emigrating to the cities. In the last few decades, a major fraction of the human population had abandoned a rustic way of life. As technology developed and the cities were polluted, the nights became starless. New generations grew to maturity wholly ignorant of the sky that had transfixed their ancestors and that had stimulated the modern age of science and technology. Without even noticing, just as astronomy entered a golden age most people cut themselves off from the sky, a cosmic isolationism that ended only with the dawn of space exploration.

     *  *  *

     Ellie would look up at Venus and imagine it was a world something like the Earth--populated by plants and animals and civilizations, but each of them different from the kinds we have here. On the outskirts of town, just after sunset, she would examine the night sky and scrutinize that unflickering bright point of light. By comparison with nearby clouds, just above her, still illuminated by the Sun, it seemed a little yellow. She tried to imagine what was going on there. She would stand on tiptoe and stare the planet down. Sometimes, she could almost convince herself that she could really see it; a swirl of yellow fog would suddenly clear, and a vast jeweled city would briefly be revealed. Air cars sped among the crystal spires. Sometimes she would imagine peering into one of those vehicles and glimpsing one of them.  Or she would imagine a young one, glancing up at a bright blue point of light in its sky, standing on tiptoe and wondering about the inhabitants of Earth. It was an irresistible notion: a sultry, tropical planet brimming over with intelligent life, and just next door.

     She consented to rote memorization, but knew that it was at best the hollow shell of education. She did the minimum work necessary to do well in her courses, and pursued other matters. She arranged to spend free periods and occasional hours after school in what was called "shop"--a dingy and cramped small factory established when the school devoted more effort to "vocational education" than was now fashionable. "Vocational education" meant, more than anything else, working with your hands. There were lathes, drill presses, and other machine tools which she was forbidden to approach, because no matter how capable she might be, she was still "a girl." Reluctantly, they granted her permission to pursue her own projects in the electronics area of the "shop." She built radios more or less from scratch, and then went on to something more interesting.

     She built an encrypting machine. It was rudimentary, but it worked. It could take any English- language message and transform it by a simple substitution cipher into something that looked like gibberish. Building a machine that would do the reverse--converting an encrypted message into clear when you didn't know the substitution convention--that was much harder. You could have the machine run through all the possible substitutions (A stands for B, A stands for C, A stands for D...), or you could remember that some letters in English were used more often than others. You could get some idea of the frequency of letters by looking at the sizes of the bins for each letter of type in the print shop next door. "ETAOIN SHRDLU," the boys in print shop would say, giving pretty closely the order of the twelve most frequently used letters in English. In decoding a long message, the letter that was most common probably stood for an E. Certain consonants tended to go together, she discovered; vowels distributed themselves more or less at random. The most common three-letter word in the language was "the." If within a word there was a letter standing between a T and an E, it was almost certainly H. If not, you could bet on R or a vowel. She deduced other rules and spent long hours counting up the frequency of letters in various schoolbooks before she discovered that such frequency tables had already been compiled and published. Her decrypting machine was only for her own enjoyment. She did not use it to convey secret messages to friends. She was unsure to whom she might safely confide these electronic and cryptographic interests; the boys became jittery or boisterous, and the girls looked at her strangely.

     *  *  *

     Soldiers of the United States were fighting in a distant place called Vietnam. Every month, it seemed, more young men were being scooped off the street or the farm and packed off the Vietnam. The more she learned about the origins of the war, and the more she listened to the public pronouncements of national leaders, the more outraged she became. The President and the Congress were lying and killing, she thought to herself, and almost everyone else was mutely assenting. The fact that her stepfather embraced official positions on treaty obligations, dominoes, and naked Communist aggression only strengthened her resolve. She began attending meetings and rallies at the college nearby. The people she met there seemed much brighter, friendlier, more alive than her awkward and lusterless high school companions. John Staughton first cautioned her and then forbade her to spend time with college students. They would not respect her, he said. They would take advantage of her. She was pretending to a sophistication she did not have and never would. Her style of dress was deteriorating. Military fatigues were inappropriate for a girl and a travesty, a hypocrisy, for someone who claimed to oppose the American intervention in Southeast Asia.

     Beyond pious exhortations to Ellie and Staughton not to "fight," her mother participated little in these discussions. Privately she would plead with Ellie to obey her stepfather, to be "nice." Ellie now suspected Staughton of marrying her mother for her father's life insurance--why else? He certainly showed no signs of loving her--and he was not predisposed to be "nice." One day, in some agitation, her mother asked her to do something for all their sakes: attend Bible class. While her father, a skeptic on revealed religions, had been alive, there was no talk of Bible class. How could her mother have married Staughton? The question welled up in her for the thousandth time. Bible class, her mother continued, would help instill the conventional virtues; but even more important, it would show Staughton that Ellie was willing to make some accommodation. Out of love and pity for her mother, she acquiesced.

     So every Sunday for most of one school year Ellie went to a regular discussion group at a nearby church. It was one of the respectable Protestant denominations, untainted by disorderly evangelism. There were a few high school students, a number of adults, mainly middle-aged women, and the instructor, the minister's wife. Ellie had never seriously read the Bible before and had been inclined to accept her father's perhaps ungenerous judgment that it was "half barbarian history, half fairy tales." So over the weekend preceding her first class, she read through what seemed to be the important parts of the Old Testament, trying to keep an open mind. She at once recognized that there were two different and mutually contradictory stories of Creation in the first two chapters of Genesis. She did not see how there could be light and days before the Sun was made, and had trouble figuring out exactly who it was that Cain had married. In the stories of Lot and his daughters, of Abraham and Sarah in Egypt, of the betrothal of Dinah, of Jacob and Esau, she found herself amazed. She understood that cowardice might occur in the real world--that sons might deceive and defraud an aged father, that a man might give craven consent to the seduction of his wife by the King, or even encourage the rape of his daughters. But in this holy book there was not a word of protest against such outrages. Instead, it seemed, the crimes were approved, even praised.

     When class began, she was eager for a discussion of these vexing inconsistencies, for an unburdening illumination of God's Purpose, or at least for an explanation of why these crimes were not condemned by the author or Author. But in this she was to be disappointed. The minister's wife blandly temporized. Somehow these stories never surfaced in subsequent discussion. When Ellie inquired how it was possible for the maidservants of the daughter of Pharaoh to tell just by looking that the baby in the bullrushes was Hebrew, the teacher blushed deeply and asked Ellie not to raise unseemly questions. (The answer dawned on Ellie at that moment.)

     When they came to the New Testament, Ellie's agitation increased. Matthew and Luke traced the ancestral line of Jesus back to King David. But for Matthew there were twenty-eight generations between David and Jesus; for Luke forty-three. There were almost no names common to the two lists. How could both Matthew and Luke be the Word of God? The contradictory genealogies seemed to Ellie a transparent attempt to fit the Isaianic prophecy after the event--cooking the data, it was called in chemistry lab. She was deeply moved by the Sermon on the Mount, deeply disappointed by the admonition to render unto Caesar what is Caesar's, and reduced to shouts and tears after the instructor twice sidestepped her questions on the meaning of "I bring not peace but the sword." She told her despairing mother that she had done her best, but wild horses wouldn't drag her to another Bible class.

     *  *  *

     She was lying on her bed. It was a hot summer's night. Elvis was singing, "One night with you, that's what I'm beggin' for." The boys at the high school seemed painfully immature, and it was difficult--especially with her stepfather's strictures and curfews--to establish much of a relationship with the young college men she met at lectures and rallies. John Staughton was right, she reluctantly admitted to herself, at least about this: The young men, almost without exception, had a penchant for sexual exploitation. At the same time, they seemed much more emotionally vulnerable than she had expected. Perhaps the one caused the other.

     She had half expected not to attend college, although she was determined to leave home. Staughton would not pay for her to go elsewhere, and her mother's meek intercessions were unavailing. But Ellie had done spectacularly well on the standardized college entrance examinations and found to her surprise her teachers telling her that she was likely to be offered scholarships by well-known universities. She had guessed on a number of multiple-choice questions and considered her performance a fluke. If you know very little, only enough to exclude all but the two most likely answers, and if you then guess at ten straight questions, the is about one chance in a thousand, she explained to herself, that you'll get all then correct. For twenty straight questions, the odds were one in a million. But something like a million kids probably took this test. Someone had to get lucky.

     Cambridge, Massachusetts, seemed far enough away to elude John Staughton's influence, but close enough to return from on vacation to visit her mother--who viewed the arrangement as a difficult compromise between abandoning her daughter and incrementally irritating her husband. Ellie surprised herself by choosing Harvard over the Massachusetts Institute of Technology.

     She arrived for orientation period, a pretty dark-haired young woman of middling height with a lopsided smile and an eagerness to learn everything. She set out to broaden her education, to take as many courses as possible apart from her central interests in mathematics, physics, and engineering. But there was a problem with her central interests. She found it difficult to discuss physics, much less debate it, with her predominantly male classmates. At first they paid a kind of selective inattention to her remarks. There would be a slight pause, and then they would go on as if she had not spoken. Occasionally they would acknowledge her remark, even praise it, and then again continue undeflected. She was reasonably sure her remarks were not entirely foolish, and did not wish to be ignored, much less ignored and patronized alternately. Part of it--but only a part--she knew was due to the softness of her voice. So she developed a physics voice, a professional voice: clear, competent, and many decibels above conversational. With such a voice it was important to be right. She had to pick her moments. It was hard to continue long in such a voice, because she was sometimes in danger of bursting out laughing. So she found herself leaning towards quick, sometimes cutting, interventions, usually enough to capture their attention; then she could go on for a while in a more usual tone of voice. Every time she found herself in a new group she would have to fight her way through again, just to dip her oar into the discussion. The boys were uniformly unaware even that there was a problem.

     Sometimes she would be engaged in a laboratory exercise or a seminar when the instructor would say, "Gentlemen, let's proceed," and sensing Ellie's frown would add, "Sorry, Miss Arroway, but I think of you as one of the boys." The highest compliment they were capable of paying was that in their minds she was not overtly female.

     She had to fight against developing too combative a personality or becoming altogether a misanthrope. She suddenly caught herself. "Misanthrope" is someone who dislikes everybody, not just men. And they certainly had a word for someone who hates women: "misogynist." But the male lexicographers had somehow neglected to coin a word for the dislike of men. They were almost entirely men themselves, she thought, and had been unable to imagine a market for such a word.

     More than many others, she had been encumbered with parental proscriptions. Her newfound freedoms--intellectual, social, sexual--were exhilarating. At a time when many of her contemporaries were moving toward shapeless clothing that minimized the distinctions between the sexes, she aspired to an elegance and simplicity in dress and makeup that strained her limited budget. There were more effective ways to make political statements, she thought. She cultivated a few close friends and made a number of casual enemies, who disliked her for her dress, for her political and religious views, or for the vigor with which she defended her opinions. Her competence and delight in science were taken as rebukes by many otherwise capable young women. But a few looked on her as what mathematicians call an existence theorem--a demonstration that a woman could, sure enough, excel in science--or even as a role model.

     At the height of the sexual revolution, she experimented with gradually increasing enthusiasm, but found she was intimidating her would-be lovers. Her relationships tended to last a few months or less. The alternative seemed to be to disguise her interests and stifle her opinions, something she had resolutely refused to do in high school. The image of her mother, condemned to a resigned and placatory imprisonment, haunted Ellie. She began wondering about men unconnected with the academic and scientific life.

     Some women, it seemed, were entirely without guile and bestowed their affections with hardly a moment's conscious thought. Others set out to implement a campaign of military thoroughness, with branched contingency trees and fallback positions, all to "catch" a desirable man. The word "desirable" was the giveaway, she thought. The poor jerk wasn't actually desired, only "desirable"--a plausible object of desire in the opinion of those others on whose account this whole sorry charade was performed. Most women, she thought, were somewhere in the middle, seeking to reconcile their passions with their perceived long-term advantage. Perhaps there were occasional communications between love and self-interest that escaped the notice of the conscious mind. But the whole idea of calculated entrapment made her shiver. In this matter, she decided, she was a devotee of the spontaneous. That was when she met Jesse.

     *  *  *

     Her date had taken her to a cellar bar off Kenmore Square. Jesse was singing rhythm and blues and playing lead guitar. The way he sang and the way he moved made clear what she had been missing. The next night she returned alone. She seated herself at the nearest table and locked eyes with him through both his sets. Two months later they were living together.

     It was only when his booking took him to Hartford or Bangor that she got any work done at all. She would spend her days with the other students: boys with the final generation of slide rules hanging like trophies from their belts; boys with plastic pencil holders in their breast pockets; precise, stilted boys with nervous laughs; serious boys spending all their waking moments becoming scientists. Absorbed in training themselves to plumb the depths of nature, they were almost helpless in ordinary human affairs, where, for all their knowledge, they seemed pathetic and shallow. Perhaps the dedicated pursuit of science was so consuming, so competitive, that no time was left to become a well-rounded human being. Or perhaps their social disabilities had led them to fields where the want would not be noticed. Except for science itself, she did not find them good company.

     At night there was Jesse, leaping and wailing, a kind of force of nature that had taken over her life. In the year they spent together, she could not recall a single night when he proposed they go to sleep. He knew nothing of physics or mathematics, buy he was wide awake inside the universe, and for a time so was she.

     She dreamed or reconciling her two worlds. She had fantasies of musicians and physicists in harmonious social concert. But the evenings she organized were awkward and ended early.

     One day he told her he wanted a baby. He would be serious, he'd settle down, he'd get a regular job. He might even consider marriage.

     "A baby?" she asked him. "But I'd have to leave school. I have years more before I'm done. If I had a baby, I might never go back to school."

     "Yeah," he said, "but we'd have a baby. You wouldn't have school, but you'd have something else."

     "Jesse, I need school," she told him.

     He shrugged, and she could feel their lives together slip off his shoulders and away. It lasted another few months, but it all had really been settled in that brief exchange. They kissed each other goodbye and he went off to California. She never heard his voice again.

     *  *  *

     In the late 1960s, the Soviet Union succeeded in landing space vehicles on the surface of Venus. They were the first spacecraft of the human species to set down in working order on another planet. Over a decade earlier, American radio astronomers, confined to Earth, had discovered that Venus was an intense source of radio emission. The most popular explanation had been that the massive atmosphere of Venus trapped the heat through a planetary greenhouse effect. In this view, the surface of the planet was stifling hot, much too hot for crystal cities and wondering Venusians. Ellie longed for some other explanation, and tried unsuccessfully to imagine ways in which the radio emission could come from high above a clement Venus surface. Some astronomers at Harvard and MIT claimed that none of the alternatives to a broiling Venus could explain the radio data. The idea of so massive a greenhouse effect seemed to her unlikely and somehow distasteful, a planet that had let itself go. But when the Venera spacecraft landed and in effect stuck out a thermometer, the temperature measured was high enough to melt tin or lead. She imagined the crystal cities liquifying (although Venus wasn't quite that hot), the surface awash in silicate tears. She was a romantic. She had known it for years.

     But at the same time she had to admire how powerful radio astronomy was. The astronomers had sat home, pointed their radio telescopes at Venus, and measured the surface temperature just about as accurately as the Venera probes did thirteen years later. She had been fascinated with electricity and electronics as long as she could remember. But this was the first time she had been deeply impressed by radio astronomy. You stay safely on your own planet and point your telescope with its associated electronics. Information about other worlds then comes fluttering down through the feeds. She marveled at the notion.

     Ellie began to visit the university's modest radio telescope in nearby Harvard, Massachusetts, eventually getting an invitation to help with the observations and the data analysis. She was accepted as a paid summer assistant at the National Radio Astronomy Observatory in Green Bank, West Virginia, and upon arrival, gazed in some rapture at Grote Reber's original radio telescope, constructed in his backyard in Wheaton, Illinois, in 1938, and now serving as a reminder of what a dedicated amateur can accomplish. Reber had been able to detect the radio emission from the center of the Galaxy when no one nearby happened to be starting up the car and the diathermy machine down the street was not in operation. The Galactic Center was much more powerful, but the diathermy machine was a lot closer.

     The atmosphere of patient inquiry and the occasional rewards of modest discovery were agreeable to her. They were trying to measure how the number of distant extragalactic radio sources increased as they looked deeper into space. She began to think about better ways of detecting faint radio signals. In due course, she graduated cum laude from Harvard and went on for graduate work in radio astronomy at the other end of the country, at the California Institute of Technology.

     *  *  *

     For a year, she apprenticed herself to David Drumlin. He had a worldwide reputation for brilliance and for not suffering fools gladly, but was at heart one of those men you can find at the top of every profession who are in a state of unrelieved anxiety that someone, somewhere, might prove smarter than they. Drumlin taught Ellie some of the real heart of the subject, especially its theoretical underpinnings. Although he was inexplicably rumored to be attractive to women, Ellie found him frequently combative and unremittingly self- involved. She was too romantic, he would say. The universe is strictly ordered according to its own rules. The idea is to think as the universe does, not to foist our romantic predispositions (and girlish longings, he once said) on the universe. Everything not forbidden by the laws of nature, he assured her--quoting a colleague down the hall--is mandatory. But, he went on, almost everything is forbidden. She gazed at him as he lectured, trying to divine this odd combination of personality traits. She saw a man in excellent physical condition: prematurely gray hair, sardonic smile, half-moon reading glasses perched toward the end of his nose, bow tie, square jaw, and remnants of a Montana twang.

     His idea of a good time was to invite the graduate students and junior faculty over for dinner (unlike her stepfather, who enjoyed a student entourage but considered having them to dinner an extravagance). Drumlin would exhibit an extreme intellectual territoriality, steering the conversation to topics in which he was the acknowledged expert and then swiftly dispatching contrary opinions. After dinner he would often subject them to a slide show of Dr. D. scuba diving in Cozumel or Tobago or the Great Barrier Reef. He was often smiling into the camera and waving, even in the underwater images. Sometimes there would be a submarine vista of his scientific colleague, Dr. Helga Bork. (Drumlin's wife would always object to these particular slides, on the reasonable grounds that most of the audience had already seen them at previous dinner parties. In truth, the audience had already seen all the slides. Drumlin would respond by extolling the virtues of the athletic Dr. Bork, and his wife's humiliation increased.) Many of the students gamely went along, seeking some novelty they had previously missed among the brain corals and the spiny sea urchins. A few would writhe in embarrassment or become absorbed in the avocado dip.

     A stimulating afternoon for his graduate students would be for them to be invited over, it twos or threes, to drive him to the edge of a favorite cliff near Pacific Palisades. Casually attached to his hang glider, he would leap off the precipice toward the tranquil ocean a few hundred feet below. Their job was to drive down the coast road and retrieve him. He would swoop down upon them, beaming exultantly. Others were invited to join him, but few accepted. He had, and delighted in, the competitive advantage. It was quite a performance. Others looked on graduate students as resources for the future, as their intellectual torchbearers to the next generation. But Drumlin, she felt, had quite a different view. For him, graduate students were gunslingers. There was no telling which of them might at any moment challenge him for the reigning title of "Fastest Gun in the West." They were to be kept in their places. He never made a pass at her, but sooner or later, she was certain, he was bound to try.

     In her second year at Cal Tech, Peter Valerian returned to campus from his sabbatical year abroad. He was a gentle and unprepossessing man. No one, least of all he himself, considered him especially brilliant. Yet he had a steady record of significant accomplishment in radio astronomy because, he explained when pressed, he "kept at it." There was one slightly disreputable aspect of his scientific career: He was fascinated by the possibility of extraterrestrial intelligence. Each faculty member, it seemed, was allowed one foible: Drumlin had hang gliding and Valerian had life on other worlds. Others had topless bars, or carnivorous plants, or something called transcendental meditation. Valerian had thought about extraterrestrial intelligence, abbreviated ETI, longer and harder--and in many cases more carefully--than anyone else. As she grew to know him better, it seemed that ETI provided a fascination, a romance, that was in dramatic contrast with the humdrum business of his personal life. This thinking about extraterrestrial intelligence was not work for him, but play. His imagination soared.

     Ellie loved to listen to him. It was like entering Wonderland or the Emerald City. Actually, it was better, because at the end of all his ruminations there was the thought that maybe this could really be true, could really happen. Someday, she mused, there might in fact and not just in fantasy be a message received by one of the great radio telescopes. But in a way it was worse, because Valerian, like Drumlin on other subjects, repeatedly stressed that speculation must be confronted with sober physical reality. It was a kind of sieve that separated the rare useful speculation from torrents of nonsense. The extraterrestrials and their technology had to conform strictly to the laws of nature, a fact that severely crimped many a charming prospect. But what emerged from this sieve, and survived the most skeptical physical and astronomical analysis, might even be true. You couldn't be sure, of course. There were bound to be possibilities that you had missed, that people cleverer than you would one day figure out.

     Valerian would emphasize how we are trapped by our time and our culture and our biology, how limited we are, by definition, in imagining fundamentally different creatures or civilizations. And separately evolved on very different creatures or civilizations. And separately evolved on very different worlds, they would have to be very different from us. It was possible that beings much more advanced than we might have unimaginable technologies--this was, in fact, almost guaranteed--and new laws of physics. It was hopelessly narrow-minded, he would say as they walked past a succession of stucco arches as in a De Chirico painting, to imagine that all significant laws of physics had been discovered at the moment our generation began contemplating the problem. There would be a twenty-first-century physics and twenty- second-century physics, and even a Fourth-Millennium physics. We might be laughably far off in guessing how a very different technical civilization would communicate.

     But then, he always reassured himself, the extraterrestrials would have to know how backward we were. If we were any more advanced, they would know about us already. Here we were, just beginning to stand up on our two feet, discovering fire last Wednesday, and only yesterday stumbling on Newtonian dynamics, Maxwell's equations, radio telescopes, and hints of Superunification of the laws of physics. Valerian was sure they wouldn't make it hard for us. They would try to make it easy, because if they wanted to communicate with dummies they would have to have a fighting chance if a message ever came. His lack of brilliance was in fact his strength. He knew, he was confident, what dummies knew.

     As a topic for her doctoral thesis, Ellie chose, with the concurrence of the faculty, the development of an improvement in the sensitive receivers employed on radio telescopes. It made use of her talents in electronics, freed her from the mainly theoretical Drumlin, and permitted her to continue her discussions with Valerian--but without taking the professionally dangerous step of working with him on extraterrestrial intelligence. It was too speculative a subject for a doctoral dissertation. Her stepfather had taken to denouncing her various interests as unrealistically ambitious or occasionally as deadeningly trivial. When he heard of her thesis topic through the grapevine (by now, she was not talking to him at all), he dismissed it as pedestrian.

     She was working on the ruby maser. A ruby is made mainly of alumina, which is almost perfectly transparent. The red color derives from a small chromium impurity distributed through the alumina crystal. When a strong magnetic field is impressed on the ruby, the chromium atoms increase their energy or, as physicists like to say, are raised to an excited state. She loved the image of all the little chromium atoms called to feverish activity in each amplifier, frenzied in a good practical cause--amplifying a weak radio signal. The stronger the magnetic field, the more excited the chromium atoms became. Thus the maser could be turned so that it was particularly sensitive to a selected radio frequency. She found a way to make rubies with lanthanide impurities in addition to the chromium atoms, so a maser could be tuned to a narrower frequency range and could detect a much weaker signal than previous masers. Her detector had to be immersed in liquid helium. She then installed her new instrument on one of Cal Tech's radio telescopes in Owens Valley and detected, at entirely new frequencies, what astronomers call the three-degree black-body background radiation--the remnant in the radio spectrum of the immense explosion that began this universe, the Big Bang.

     "Let's see if I've got this right," she would say to herself. "I've taken an inert gas that's in the air, made it into a liquid, put some impurities into a ruby, attached a magnet, and detected the fires of creation."

     She would then shake her head in amazement. To anyone ignorant of the underlying physics, it might seem the most arrogant and pretentious necromancy. How would you explain this to the best scientists of thousand years ago, who knew about air and rubies and lodestones, but not about liquid helium, stimulated emission, and superconducting flux pumps? In fact, she reminded herself, they did not have even the foggiest notion about the radio spectrum. Or even the idea of a spectrum--except vaguely, from contemplating the rainbow. They did not know that light was waves. How could we hope to understand the science of a civilization a thousand years ahead of us?

     It was necessary to make rubies in large batches, because only a few would have the requisite properties. None were quite of gemstone quality, and most were tiny. But she took to wearing a few of the larger remnants. They matched her dark coloring well. Even if it was carefully cut, you could recognize some anomaly in the stone set in a ring or a brooch: the odd way, for example, that it caught the light at certain angles from an abrupt internal reflection, or a peach-colored blemish inside the ruby red. She would explain to nonscientist friends that she liked rubies but couldn't afford them. It was a little like the scientist who first discovered the biochemical pathway of green plant photosynthesis, and who forever after wore pine needles or a sprig of parsley in his lapel. Colleagues, their respect for her growing, considered it a minor idiosyncrasy.

     *  *  *

     The great radio telescopes of the world are constructed in remote locations for the same reason Paul Gauguin sailed to Tahiti: For them to work well, they must be far from civilization. As civilian and military radio traffic has increased, radio telescopes had to hide--sequestered in an obscure valley in Puerto Rico, say, or exiled to a vast scrub desert in New Mexico or Kazakhstan. As radio interference continues to grow, it makes increasing sense to build the telescopes off the Earth altogether. The scientists who work at these isolated observatories tend to be dogged and determined. Spouses abandon them, children leave home at the first opportunity, but the astronomers stick it out. Rarely do they think of themselves as dreamers. The permanent scientific staff in remote observatories tend to be the practical ones, the experimentalists, the experts who know a great deal about antenna design and data analysis, and much less about quasars or pulsars. Generally speaking, they had not longed for the stars in childhood; they had been too busy repairing the carburetor in the family car.

     After receiving her doctorate, Ellie accepted an appointment as research associate at the Arecibo Observatory, a great bowl 305 meters across, fixed to the floor of a karst valley in the foothills of northwestern Puerto Rico. With the largest radio telescope on the planet, she was eager to employ her maser detector to look at as many different astronomical objects as she could--nearby planets and stars, the center of the Galaxy, pulsars and quasars. As a full-time member of the Observatory staff, she would be assigned a significant amount of observing time. Access to the great radio telescopes is keenly competitive, there being many more worthwhile research projects than can possibly be accommodated. So reserved telescope time for the resident staff is perquisite beyond price. For many of the astronomers, it was the only reason they would consent to live in such godforsaken places.

     She also hoped to examine a few nearby stars for possible signals of intelligent origin. With her detector system it would be possible to here the radio leakage from a planet like Earth even if it was a few light-years away. And an advanced society, intending to communicate with us, would doubtless be capable of much greater power transmissions than we were. If Arecibo, used as a radar telescope, was capable of transmitting one megawatt of power to a specific locale in space, then a civilization only a little bit in advance of ours might, she thought, be capable of transmitting a hundred megawatts or more. If they were intentionally transmitting to the Earth with a telescope as large as Arecibo but with a hundred-megawatt transmitter, Arecibo should be able to detect them virtually anywhere in the Milky Way Galaxy. When she thought carefully about it, she was surprised that, in the search for extraterrestrial intelligence, what could be done was so far ahead of what had been done. The resources that had been devoted to this question were trifling, she thought. She was hard pressed to name a more important scientific problem.

     The Arecibo facility was known to the locals as "El Radar." Its function was generally obscure, but it provided more than a hundred badly needed jobs. The indigenous young women were sequestered from the male astronomers, some of whom could be viewed at almost any time of day or night, full of nervous energy, jogging along the circumferential track that surrounded the dish. As a result, the attentions directed at Ellie upon her arrival, while not entirely unwelcome, soon became a distraction from her research.

     The physical beauty of the place was considerable. At twilight, she would look out the control windows and see storm clouds hovering over the other lip of the valley, just beyond one of the three immense pylons from which the feed horns and her newly installed maser system were suspended. At the top of each pylon, a red light would flash to warn off any airplanes that had improbably strayed upon this remote vista. At 4 A.M., she would step outside for a breath of air and puzzle to understand a massed chorus of thousands of local land frogs, called "coquis" in imitations of their plaintive cry.

     Some astronomers lived near the Observatory, but the isolation, compounded by ignorance of Spanish and inexperience with any other culture, tended to drive them and their wives toward loneliness and anomie. Some had decided to live at Ramey Air Force Base, which boasted the only English-language school in the vicinity. But the ninety-minute drive also heightened their sense of isolation. Repeated threats by Puerto Rican separatists, convinced erroneously that the Observatory played some significant military function, increased the sense of subdued hysteria, of circumstances barely under control.

     Many months later, Valerian came to visit. Nominally he was there to give a lecture, but she knew that part of his purpose was to check up on how she was doing and provide some semblance of psychological support. Her research had gone very well. She had discovered what seemed to be a new interstellar molecular cloud complex, and had obtained some very fine high time-resolution data on the pulsar at the center of the Crab Nebula. She had even completed the most sensitive search yet performed for signals from a few dozen nearby stars, but with no positive results. There had been one or two suspicious regularities. She observed the stars in question again and could find nothing out of the ordinary. Look at enough stars, and sooner or later terrestrial interference or the concatenation of random noise will produce a pattern that for a moment makes your heart palpitate. You calm down and check it out. If it doesn't repeat itself, you consider it spurious. This discipline was essential if she was to preserve some emotional equilibrium in the face of what she was seeking. She was determined to be as tough-minded as possible, without abandoning the sense of wonder that was driving her in the first place.

     From her scant supply in the community refrigerator, she had made a rudimentary picnic lunch, and Valerian sat with her along the very periphery of the bowl-shaped dish. Workmen repairing or replacing the panels could be seen in the distance, walking on special snowshoes so they did not tear the aluminum sheets and plunge through the ground below. Valerian was delighted with her progress. They exchanged bits of gossip and current scientific tidbits. The conversation turned to SETI, as the search for extraterrestrial intelligence was beginning to be called.

     "Have you ever though about doing it full time, Ellie?" he asked.

     "I haven't thought about it much. But it's not really possible, is it? There's no major facility devoted to SETI full-time anywhere in the world, as far as I know."

     "No, but there might be. There's a chance that dozens of additional dishes might be added to the Very Large Array, and make it into a dedicated SETI observatory. They'd do some of the usual kind of radio astronomy also, of course. It would be a superb interferometer. It's only a possibility, it's expensive, it needs real political will, and it's years away at best. Just something to think about."

     "Peter, I've just examined some forty-odd nearby stars of roughly solar spectral type. I've looked in the twenty-one centimeter hydrogen line, which everybody says is the obvious beacon frequency--because hydrogen is the most abundant atom in the universe, and so on. And I've done it with the highest sensitivity ever tried. There's not a hint of a signal. Maybe there's no one out there. Maybe the whole business is a waste of time."

     "Like life on Venus? That's just disillusionment talking. Venus is a hellhole of a world; it's just one planet. But there's hundreds of billions of stars in the Galaxy. You've looked at only a handful. Wouldn't you say it's a little premature to give up? You've done on-billionth of the problem. Probably much less than that, if you consider other frequencies."

     "I know, I know. But don't you have the sense that if they're anywhere, they're everywhere? If really advanced guys live a thousand light-years away, shouldn't they have an outpost in our backyard? You could do the SETI thing forever, you know, and never convince yourself that you'd completed the search."

     "Oh, you're beginning to sound like Dave Drumlin. If we can't find them in his lifetime, he's not interested. We're just beginning SETI. You know how many possibilities there are. This is the time to leave every option open. This is the time to be optimistic. If we lived in any previous time in human history, we could wonder about this all our lives, and we couldn't do a thing to find the answer. But this time is unique. This is the first time when anybody's been able to look for extraterrestrial intelligence. You've made the detector to look for civilizations on the planets of millions of other stars. Nobody's guaranteeing success. But can you think of a more important question? Imagine them out there sending us signals, and nobody on Earth is listening. That would be a joke, a travesty. Wouldn't you be ashamed of your civilization if we were able to listen and didn't have the gumption to do it?"

     *  *  *

     Two hundred fifty-six images of the left world swam by on the left. Two hundred fifty-six images of the right world glided by on the right. He integrated all 512 images into a wraparound view of his surroundings. He was deep in a forest of great waving blades, some green, some etiolated, almost all larger than me. But he had no difficulty clambering up and over, occasionally balancing precariously on a bent blade, falling to the gentle cushion of horizontal blades below, and then continuing unerringly on his journey. He could tell he was centered on the trail. It was tantalizingly fresh. He would think of nothing, if that's where the trail led, of scaling an obstacle a hundred or a thousand times as tall as he was. He needed no pylons or ropes; he was already equipped. The ground immediately before him was redolent with a marker odor left recently, it must be, by another scout of his clan. It would lead to food; it almost always did. The food would spontaneously appear. Scouts would find it and mark the trail. He and his fellows would bring it back. Sometimes the food was a creature rather like himself; other times it was only an amorphous or crystalline lump. Occasionally it was so large that many of his clan would be required, working together, heaving and shoving it over the folded blades, to carry it home. He smacked his mandibles in anticipation.

     *  *  *

     "What worries me the most," she continued, "is the opposite, the possibility that they're not trying. They could communicate with us, all right, but they're not doing it because they don't see any point to it. It's like..."--she glanced down at the edge of the tablecloth they had spread over the grass--"like the ants. They occupy the same landscape that we do. They have plenty to do, things to occupy themselves. On some level they're very well aware of their environment. But we don't try to communicate with them. So I don't think they have the foggiest notion that we exist."

     A large ant, more enterprising than his fellows, had ventured onto the tablecloth and was briskly marching along the diagonal of one of the red and white squares. Suppressing a small twinge of revulsion, she gingerly flicked it back onto the grass--where it belonged.

    

     CHAPTER 3

White Noise

    

Heard melodies are sweet, but those unheard Are sweeter.

     -JOHN KEATS

"Ode on a Grecian Urn" (1820)

     The cruelest lies are often told in silence.

     -ROBERT LOUIS STEVENSON

Virginibus Puerisque (1881)

    

The pulses had been journeying for years through the great dark between the stars. Occasionally, they would intercept an irregular cloud of gas and dust, and a little of the energy would be absorbed or scattered. The remainder continued in the original direction. Ahead of them was a faint yellow glow, slowly increasing in brightness among the other unvarying lights. Now, although to human eyes it would still be a point, it was by far the brightest object in the black sky. The pulses were encountering a horde of giant snowballs.

    

Entering the Argus administration building was a willowy woman in her late thirties. Her eyes, large and set far apart, served to soften the angular bone structure of her face. Her long dark hair was loosely gathered by a tortoise barrette at the nape of her neck. Casually dressed in a knit T-shirt and khaki skirt, she strolled along a hallway on the first floor and entered a door marked "E. Arroway, Director." As she removed her thumb from the fingerprint deadlock, and observer might have noticed a ring on her right hand with an oddly milky red stone unprofessionally set in it. Turning on a desk lamp, she rummaged through a drawer, finally producing a pair of earphones. Briefly illuminated on the wall beside her desk was a quotation from the Parables of Franz Kafka:

    

Now the Sirens have a still more fatal weapon

    

than their song, namely their silence...

    

Someone might possibly have escaped from

    

their singing;

    

but from their silence, certainly never.

     Extinguishing the light with a wave of her hand, she made for the door in the semidarkness.

     In the control room she quickly reassured herself that all was in order. Through the window she could see a few of the 131 radio telescopes that stretched for tens of kilometers across the New Mexico scrub desert like some strange species of mechanical flower straining toward the sky. It was early afternoon and she had been up late the night before. Radio astronomy can be performed during daylight, because the air does not scatter radio waves from the Sun as it does ordinary visible light. To a radio telescope pointing anywhere but very close to the Sun, the sky is pitch black. Except for the radio sources.

     Beyond the Earth's atmosphere, on the other side of the sky, is a universe teeming with radio emission. By studying radio waves you can learn about planets and stars and galaxies, about the composition of great clouds of organic molecules that drift between the stars, about the origin and evolution and fate of the universe. But all these radio emissions are natural--caused by physical processes, electrons spiraling in the galactic magnetic field, or interstellar molecules colliding with one another, or the remote echoes of the Big Bang red-shifted from gamma rays at the origin of the universe to the tame and chill radio waves that fill all of space in our epoch.

     In the scant few decades in which humans have pursued radio astronomy, there has never been a real signal from the depths of space, something manufactured, something artificial, something contrived by an alien mind. There have been false alarms. The regular time variation of the radio emission from quasars and, especially, pulsars had at first been thought, tentatively, tremulously, to be a kind of announcement signal from someone else, or perhaps a radio navigation beacon for exotic ship that plied the spaces between the stars. But they had turned out to be something else--equally exotic, perhaps, as a signal from beings in the night sky. Quasars seemed to be stupendous sources of energy, perhaps connected with massive black holes at the centers of galaxies, many of them observed more than halfway back in time to the origin of the universe. Pulsars are rapidly spinning atomic nuclei the size of a city. And there had been other rich and mysterious messages that had turned out to be intelligent after a fashion but not very extraterrestrial. The skies were now peppered with secret military radar systems and radio communication satellites that were beyond the entreaty of a few civilian radio astronomers. Sometimes they were real outlaws, ignoring international telecommunications agreements. There were no recourses and no penalties. Occasionally, all nations denied responsibility. But there had never been a clear-cut alien signal.

     And yet the origin of life now seemed to be so easy--and there were so many planetary systems, so many worlds and so many billions of years available for biological evolution--that it was hard to believe the Galaxy was not teeming with life and intelligence. Project Argus was the largest facility in the world dedicated to the radio search for extraterrestrial intelligence. Radio waves traveled with the speed of light, faster than which nothing, it seemed, could go. They were easy to generate and easy to detect. Even very backward technological civilizations, like that on Earth, would stumble on radio early in their exploration of the physical world. Even with the rudimentary radio technology available--now, only a few decades after the invention of the radio telescope--it was nearly possible to communicate with an identical civilization at the center of the Galaxy. But there were so many places in the sky to examine, and so many frequencies on which an alien civilization might be broadcasting, that it required a systematic and patent observing program. Argus had been in full operation for more than four years. There had been glitches, bogeys, intimations, false alarms. But no message.

     *  *  *

     "Afternoon, Dr. Arroway."

     The lone engineer smiled pleasantly at her, and she nodded back. All 131 telescopes of Project Argus were controlled by computers. The system slowly scanned the sky on its own, checking that there were no mechanical or electronic breakdowns, comparing the data from different elements of the array of telescopes. She glanced at the billion-channel analyzer, a bank of electronics covering a whole wall, and at the visual display of the spectrometer.

     There was not really very much for the astronomers and technicians to do as the telescope array over the years slowly scanned the sky. If it detected something of interest, it would automatically sound an alarm, altering project scientists in their beds at night if need be. Then Arroway would go into high gear to determine if this one was an instrumental failure or some American or Soviet space bogey. Together with the engineering staff, she would devise ways of improving the sensitivity of the equipment. Was there any pattern, any regularity in the emission? She would delegate some of the radio telescopes to examine exotic astronomical objects that had been recently detected by other observatories. She would help staff members and visitors with projects unrelated to SETI. She would fly to Washington to keep interest high at the funding agency, the National Science Foundation. She would give a few public talks on Project Argus--at the Rotary Club in Socorro or the University of New Mexico in Albuquerque--and occasionally greet an enterprising reporter who would arrive, sometimes unannounced, in remotest New Mexico.

     Ellie had to take care that the tedium did not engulf her. Her co-workers were pleasant enough, but--even apart from the impropriety of a close personal relationship with a nominal subordinate--she did not find herself tempted into any real intimacies. There had been a few brief, torrid but fundamentally casual relationships with local men unconnected with the Argus project. In this area of her life, too, a kind of ennui, a lassitude, had settled over her.

     She sat down before one of the consoles and plugged in the earphones. It was futile, she knew, a conceit, to think that she, listening on one or two channels, would detect a pattern when the vast computer system monitoring a billion channels had not. But it gave her a modest illusion of utility. She leaned back, eyes half closed, an almost dreamy expression enveloping the contours of her face. She's really quite lovely, the technician permitted himself to think.

     She heard, as always, a kind of static, a continuous echoing random noise. Once, when listening to a part of the sky that included the star AC + 79 3888 in Cassiopeia, she felt she heard a kind of singing, fading tantalizingly in and out, lying just beyond her ability to convince herself that there was something really there. This was the star toward which the Voyager 1 spacecraft, now in the vicinity of the obit of Neptune, would ultimately travel. The spacecraft carried a golden phonograph record on which were impressed greetings, pictures, and songs from Earth. Could they be sending us their music at the speed of light, while we are sending ours to them only one ten-thousandth as fast? At other times, like now, when the static was clearly patternless, she would remind herself of Shannon's famous dictum in information theory, that the most efficiently coded message was indistinguishable from noise, unless you had the key to the encoding beforehand. Rapidly she pressed a few keys on the console before her and played two of the narrow-band frequencies against each other, on in each earphone. Nothing. She listened to the two planes of polarization of the radio waves, and then to the contrast between linear and circular polarization. There were a billion channels to choose from. You could spend your life trying to outguess the computer, listening with pathetically limited human ears and brains, seeking a pattern.

     Humans are good, she knew, at discerning subtle patterns that are really there, but equally so at imagining them when they are altogether absent. There would be some sequence of pulses, some configuration of the static, that would for an instant give a syncopated beat or a brief melody. She switched to a pair of radio telescopes that were listening to a known galactic radio source. She heard a glissando down the radio frequencies, a "whistler" due to the scattering of radio waves by electrons in the tenuous interstellar gas between the radio source and the Earth. The more pronounced the glissando, the more electrons were in the way, and the further the source was from the Earth. She had done this so often that she was able, just from hearing a radio whistler for the first time, to make an accurate judgment of its distance. This one, she estimated, was about a thousand light-years away--far beyond the local neighborhood of stars, but still well within the great Milky Way Galaxy.

     Ellie returned to the sky-survey mode of Project Argus. Again no pattern. It was like a musician listening to the rumble of a distant thunderstorm. The occasional small patches of pattern would pursue her and intrude themselves into her memory with such insistence that sometimes she was forced to go back to the tapes of a particular observing run to see if there was something her mind had caught and the computers had missed.

     All her life, dreams had been her friends. Her dreams were unusually detailed, well-structured, colorful. She was able to peer closely at her father's face, say, or the back of an old radio set, and the dream would oblige with full visual details. She had always been able to recall her dreams, down to the fine details--except for the times when she had been under extreme pressure, ad before her Ph.D. oral exam, or when she and Jesse were breaking up. But now she was having difficulty recalling the images in her dreams. And, disconcertingly, she began to dream sounds--as people do who are blind from birth. In the early morning hours her unconscious mind would generate some theme or ditty she had never heard before. She would wake up, give an audible command to the light on her night table, pick up the pen she had put there for the purpose, draw a staff, and commit the music to paper. Sometimes after a long day she would play it on her recorder and wonder if she had heard it in Ophiuchus or Capricorn. She was, she would admit to herself ruefully, being haunted by the electrons and the moving holes that inhabit receivers and amplifiers, and by the charged particles and magnetic fields of the cold thin gas between the flickering distant stars.

     It was a repeated single note, high-pitched and raucous around the edges. It took her a moment to recognize it. Then she was sure she hadn't heard it In thirty-five years. It was the metal pulley on the clothesline that would complain each time her mother gave a tug and put out another freshly washed smock to dry in the Sun. As a little girl, she had loved the army of marching clothespins; and when no one was about, would bury her face in the newly dried sheets. The smell, at once sweet and pungent, enchanted her. Could that be a whiff of it now? She could remember herself laughing, toddling away from the sheets, when her mother in one graceful motion swooped her up--to the sky it seemed--and carried her away in the crook of her arm, as if she herself were just a little bundle of clothes to be neatly arranged in the chest of drawers in her parents' bedroom.

     *  *  *

     "Dr. Arroway? Dr. Arroway?" The technician looked down on her fluttering eyelids and shallow breathing. She blinked twice, removed the headphones, and gave him a small apologetic smile. Sometimes her colleagues had to talk very loudly if they wished to be heard above the amplified cosmic radio noise. She would in turn compensate for the volume of the noise--she was loath to remove the earphones for brief conversations--by shouting back. When she was sufficiently preoccupied, a casual or even convivial exchange of pleasantries would seem to an inexperienced observer like a fragment of a fierce and unprovoked argument unexpectedly generated amidst the quiet of the vast radio facility. But now she only said, "Sorry. I must have drifted off."

     "It's Dr. Drumlin on the phone. He's in Jack's office and says he has an appointment with you."

     "Holy Toledo, I forgot."

     As the years had passed, Drumlin's brilliance had remained undiminished, but there were a number of additional personal idiosyncrasies that had not been in evidence when she had served briefly as his graduate student at Cal Tech. For example, he had the disconcerting habit now of checking, when he though himself unobserved, whether his fly was open. He had over the years become increasingly convinced that extraterrestrials did not exist, or at least that they were too rare, too distant to be detected. He had come to Argus to give the weekly scientific colloquium. But, she found, he had come for another purpose as well. He had written a letter to the National Science Foundation urging that Argus terminate its search for extraterrestrial intelligence and devote itself full-time to more conventional radio astronomy. He produced it from an inside pocket and insisted that she read it.

     "But we've only been at it four and a half years. We've looked at less than a third of the northern sky. This is the first survey that can do the entire radio noise minimum at optimum bandpasses. Why would you want to stop now?"

     "No, Ellie, this is endless. After a dozen years you'll find no sign of anything. You'll argue that another Argus facility has to be built at a cost of hundreds of millions of dollars in Australia or Argentina to observe the southern sky. And when that fails, you'll talk about building some paraboloid with a free-flying feed in Earth orbit so you can get millimeter waves. You'll always be able to think of some kind of observation that hasn't been done. You'll always invent some explanation about why the extraterrestrials like to broadcast where we haven't looked."

     "Oh, Dave, we've been through this a hundred times. If we fail, we learn something of the rarity of intelligent life--or at least intelligent life that thinks like we do and wants to communicate with backward civilizations like us. And if we succeed, we hit the cosmic jackpot. There's no greater discovery you can imagine."

     "There are first-rate projects that aren't finding telescope time. There's work on quasar evolution, binary pulsars, the chromospheres of nearby stars, even those crazy interstellar proteins. These projects are waiting in line because this facility--by fat the best phased array in the world--is being used almost entirely for SETI."

    

"Seventy-five percent for SETI, Dave, twenty-five percent for routine radio astronomy."

     "Don't call it routine. We've got the opportunity to look back to the time that the galaxies were being formed, or maybe even earlier than that. We can examine the cores of giant molecular clouds and the black holes at the centers of galaxies. There's a revolution in astronomy about to happen, and you're standing in the way."

     "Dave, try not to personalize this. Argus would never have been built if there wasn't public support for SETI. The idea for Argus isn't mine. You know they picked me as director when the last forty dishes were still under construction. The NSF is entirely behind--"

     "Not entirely, and not if I have anything to say about it. This is grandstanding. This is pandering to UFO kooks and comic strips and weak-minded adolescents."

     By now Drumlin was fairly shouting, and Ellie felt an irresistible temptation to tune him out. Because of the nature of her work an her comparative eminence, she was constantly thrown into situations where she was the only woman present, except for those serving coffee or making a stenotypic transcript. Despite what seemed like a lifetime of effort on her part, there was still a host of male scientists who only talked to each other, insisted on interrupting her, and ignored, when they could, what she had to say. Occasionally there were those like Drumlin who showed a positive antipathy. But at least he was treating her as he did many men. He was evenhanded in his outbursts, visiting them equally on scientists of both sexes. There were a rare few of her male colleagues who did not exhibit awkward personality changes in her presence. She ought to spend more time with them, she thought. People like Kenneth der Heer, the molecular biologist from the Salk Institute who had recently been appointed Presidential Science Adviser. And Peter Valerian, of course.

     Drumlin's impatience with Argus, she knew, was shared by many astronomers. After the first two years a kind of melancholy had pervaded the facility. There were passionate debates in the commissary or during the long and undemanding watches about the intentions of the putative extraterrestrials. We could not guess how different from us they might be. It was hard enough to guess the intentions of our elected representatives in Washington. What would the intentions be of fundamentally different kinds of beings on physically different worlds hundreds or thousands of light-years away? Some believed that the signal would not be transmitted in the radio spectrum at all but in the infrared or the visible or somewhere among the gamma rays. Or perhaps the extraterrestrials were signaling avidly but with a technology we would not invent for a thousand years.

     Astronomers at other institutions were making extraordinary discoveries among the stars and galaxies, picking out hose objects which, by whatever mechanism, generated intense radio waves. Other radio astronomers published scientific papers, attended meetings, were uplifted by a sense of progress and purpose. The Argus astronomers tended not to publish and were usually ignored when the call went out for invited papers at the annual meeting of the American Astronomical Society or the triennial symposia and plenary sessions of the International Astronomical Union. So in consultation with the National Science Foundation, the leadership at Argus had reserved 25 percent of the observing time for projects unconnected with the search for extraterrestrial intelligence. Some important discoveries had been made--on the extragalactic objects that seemed, paradoxically, to be moving faster than light; on the surface temperature of Neptune's big moon, Triton; and on the dark matter in the outer reaches of nearby galaxies where no stars could be seen. Morale began to improve. The Argus staff felt they were making a contribution at the cutting edge of astronomical discovery. The time to complete a full search of the sky had been lengthened, it was true. But now their professional careers had some safety net. They might not succeed in finding signs of other intelligent beings, but they might pluck other secrets from the treasury of nature.

     The search for extraterrestrial intelligence--everywhere abbreviated SETI, except by those who talked somewhat more optimistically about communication with extraterrestrial intelligence (CETI)--was essentially an observing routine, the dull staple for which most of the facility had been built. But a quarter of the time you could be assured of using the most powerful array of radio telescopes on Earth for other projects. You had only to get through the boring part. A small amount of time had also been reserved for astronomers from other institutions. While the morale had improved noticeably, there were many who agreed with Drumlin; they glanced longingly at the technological miracle that Argus' 131 radio telescopes represented and imagined using them for their own, doubtless meritorious, programs. She was alternately conciliatory and argumentative with Dave, but none of it did any good. He was not in an amiable mood.

     Drumlin's colloquium was in part an attempt to demonstrate that there were no extraterrestrials anywhere. If we had accomplished so much in only a few thousand years of high technology, what must a truly advanced species, he asked, be capable of? They should be able to move stars about, to reconfigure galaxies. And yet, in all of astronomy there was no sign of a phenomenon that could not be understood by natural processes, for which an appeal to extraterrestrial intelligence had to be made. Why hadn't Argus detected a radio signal by now? Did they imagine just one radio transmitter in all of the sky? Did they realize how many billions of stars they had examined already? The experiment was a worthy one, but now it was over. They didn't have to examine the rest of the sky. The answer was in. Neither in deepest space not near the Earth was there any sign of extraterrestrials. They did not exist.

     In the question period, one of the Argus astronomers asked about the Zoo Hypothesis, the contention that the extraterrestrials were out there all right but chose not to make their presence known, in order to conceal from humans the fact that there were other intelligent beings in the cosmos--in the same sense that a specialist in primate behavior might wish to observe a troop of chimpanzees in the bush but not interfere with their activities. In reply, Drumlin asked a different question: Is it likely that with a million civilizations in the Galaxy--the sort of number he said was "bandied about" at Argus--there would not be a single poacher? How does it come about that every civilization in the Galaxy abides by an ethic of noninterference? Is it probable that not one of them would be poking around on the Earth?

     "But on Earth," Ellie replied, "poachers and game wardens have roughly equal levels of technology. If the game warden is a major step ahead--with radar and helicopters, say--then the poachers are out of business."

     The remark was greeted warmly by some of the Argus staff, but Drumlin only said, "You're reaching, Ellie. You're reaching."

     *  *  *

     To clear her head it was her practice to go for long solo drives in her one extravagance, a carefully maintained 1958 Thunderbird with removable hardtop and little glass portholes flanking the rear seat. Often she would leave the top at home and speed through the scrub desert at night, with the windows down and her dark hair streaming behind her. Over the years, it seemed, she had gotten to know every small impoverished town, every butte and mesa, and every state highway patrolman in southwestern New Mexico. After a night observing run, she would love to zoom past the Argus guard station (that was before the cyclone fencing went up), rapidly changing gears, and drive north. Around Santa Fe, the faintest glimmerings of dawn might be seen above the Sangre de Cristo Mountains. (Why should a religion, she asked herself, name its places after the blood and body, heart and pancreas of its most revered figure? And why not the brain, among other prominent but uncommemorated organs?)

     This time she drove southeast, toward the Sacramento Mountains. Could Dave be right? Could SETI and Argus be a kind of collective delusion of a few insufficiently hard-nosed astronomers? Was it true that no matter how many years went by without the receipt of a message, the project would continue, always inventing a new strategy for the transmitting civilization, continually devising novel and expensive instrumentation? What would be a convincing sign of failure? When would she be willing to give up and turn to something safer, something more guaranteed of results? The Nobeyama Observatory in Japan had just announced the discovery of adenosine, a complex organic molecule, a building block of DNA, sitting out there in a dense molecular cloud. She could certainly bust herself usefully in looking for life-related molecules in space, even if she gave up searching for extraterrestrial intelligence.

     On the high mountain road, she glanced at the southern horizon and caught a glimpse of the constellation Centaurus. In that pattern of stars the ancient Greeks had seen a chimerical creature, half man, half horse, who had taught Zeus wisdom. But Ellie could never make out any pattern remotely like centaur. It was Alpha Centauri, the brightest star in the constellation, that she delighted in. It was the nearest star, only four and a quarter light-years away. Actually, Alpha Centauri was a triple system, two suns tightly orbiting one another, and a third, more remote, circling them both. From Earth, the three stars blended together to form a solitary point of light. On particularly clear nights, like this one, she could sometimes see it hovering somewhere over Mexico. Sometimes, when the air had been laden with desert grit after several consecutive days of sand storms, she would drive up into the mountains to gain a little altitude and atmospheric transparency, get out of the car, and stare at the nearest star system. Planets were possible there, although very hard to detect. Some might be closely orbiting any one of the triple suns. A more interesting orbit, with some fair celestial mechanical stability, was a figure eight, which wrapped itself around the two inner suns. What would it be like, she wondered, to live on a world with three suns in the sky? Probably even hotter than New Mexico.

     *  *  *

     The two-lane blacktop highway, Ellie noticed with a pleasant little tremor, was lined with rabbits. She had seen them before, especially when her drives had taken her as far as West Texas. They were on all fours by the shoulders of the road; but as each would be momentarily illuminated by the Thunderbird's new quartz headlights, it would stand on its hind legs, its forelimbs hanging limply, transfixed. For miles there was an honor guard of desert coneys saluting her, so it seemed, as she roared through the night. They would look up, a thousand pink noses twitching, two thousand bright eyes shining in the dark, as this apparition hurled toward them.

     Maybe it's a kind of religious experience, she thought. They seemed to be mostly young rabbits. Maybe they had never seen automobile headlights. To think of it, it was pretty amazing, the two intense beams of light speeding along at 130 kilometers an hour. Despite the thousands of rabbits lining the road, there never seemed to be even one in the middle, near the lane marker, never a forlorn dead body, the ears stretched out along the pavement. Why were they aligned along the pavement at all? Maybe it had to do with the temperature of the asphalt, she thought. Or maybe they were only foraging in the scrub vegetation nearby and curious about the oncoming bright lights. But was it reasonable that none of them ever took a few short hops to visit his cousins across the road? What did they imagine the highway was? An alien presence in their midst, its function unfathomable, built by creatures that most of them had never seen? She doubted that any of them wondered about it all.

     The whine of her tires on the highway was a kind of white noise, and she found that involuntarily she was--here, too--listening for a pattern. She had taken to listening closely to many sources of white noise: the motor of the refrigerator starting up in the middle of the night; the water running for her bath; the washing machine when she would do her clothes in the little laundry room off her kitchen; the roar of the ocean during a brief scuba-diving trip to the island of Cozumel off Yucatan, which she had cut short because of her impatience to get back to work. She would listen to these everyday sources of random noise and try to determine whether there were fewer apparent patterns in them than in the interstellar static.

     She had been to New York City the previous August for a meeting of URSI (the French abbreviation for the International Scientific Radio Union). The subways were dangerous, she had been told, but the white noise was irresistible. In the clacka-clacka of this underground railway she had thought she heard a clue, and resolutely skipped half a day of meetings--traveling from 34th Street to Coney Island, back to midtown Manhattan, and then on a different line, out to remotest Queens. She changed trains at a station in Jamaica, and then returned a little flushed and breathless--it was, after all, a hot day in August, she told herself--to the convention hotel. Sometimes, when the subway train was banking around a steep curve, the interior bulbs would go out and she could see a regular succession of lights, glowing in electric blue, speeding by as if she were in some impossible hyper-relativistic interstellar spacecraft, hurtling through a cluster of young blue supergiant stars. Then, as the train entered a straight-away, the interior lights would come on again and she would become aware once again of the acrid smell, the jostling of nearby straphangers, the miniature television surveillance cameras (locked in protective cages and subsequently spray-painted blind), the stylized multicolored map showing the complete underground transportation system of the City of New York, and the high-frequency screech of the brakes as they pulled into the stations.

     This was a little eccentric, she knew. But she had always had an active fantasy life. All right, so she was a little compulsive about listening to noise. It did no harm that she could see. Nobody seemed to notice much. Anyway, it was job-related. If she had been so minded, she could probably have deducted the expense of her trip to Cozumel from her income tax because of the sound of the breakers. Well, maybe she was becoming obsessive.

     She realized with a start that she had arrived at the Rockefeller Center station. As she quickly stepped out through an accumulation of daily newspapers abandoned on the floor of the subway car, a headline of the News-Post had caught her eye: GUERRILLAS CAPTURE JOBURG RADIO. If we like them, they're freedom fighters, she thought. If we don't like them, they're terrorists. In the unlikely case we can't make up our minks, they're temporarily only guerrillas. On an adjacent scrap of newspaper was a large photo of a florid, confident man with the headline: HOW THE WORLD WILL END. EXCERPTS FROM THE REV. BILLY JO RANKIN'S NEW BOOK. EXCLUSIVELY THIS WEEK IN THE NEWS-POST. She had taken the headlines in at a glance and tried promptly to forget them. Moving through the bustling crowds to the meeting hotel, she hoped she was in time to hear Fujita's paper on homomorphic radio telescope design.

     *  *  *

     Superposed on the whine of the tires was a periodic thump at the joins of swathes of pavement, which had been resurfaced by different New Mexico road crews in different epochs. What if an interstellar message were being received by Project Argus, but very slowly--one bit of information every hour, say, or every week, or every decade? What if there were very old, very patient murmurs of some transmitting civilization, which had no way of knowing that we get tired of pattern recognition after seconds or minutes? Suppose they lived for tens of thousands of years. And taaaaalked verrrry slooooowwwwly. Argus would never know. Could such long-lived creatures exist? Would there have been enough time in the history of the universe for creatures who reproduced very slowly to evolve to high intelligence? Wouldn't the statistical breakdown of chemical bonds, the deterioration of their bodies according to the Second Law of Thermodynamics, force them to reproduce about as often as human beings do? And to have lifespans like ours? Or might they reside on some old and frigid world, where even molecular collisions occur in extreme slow motion, maybe only a frame a day. She idly imagined a radio transmitter of recognizable and familiar design sitting on a cliff of methane ice, feebly illuminated by a distant red dwarf sun, while far below waves of an ammonia ocean beat relentlessly against the shore--incidentally generating a white noise indistinguishable from that of the surf at Cozumel.

     The opposite was possible as well: the fast talkers, manic little creatures perhaps, moving with quick and jerky motions, who transmitted a complete radio message--the equivalent of hundreds of pages of English test--in a nanosecond. Of course, if you had a very narrow bandpass to your receiver, so you were listening only to a tiny range of frequencies, you were forced to accept the long time-constant. You would never be able to detect a rapid modulation. It was a simple consequence of the Fourier Integral Theorem, and closely related to the Heisenberg Uncertainty Principle. So, for example, if you had a bandpass of a kilohertz, you couldn't make out a signal that was modulated at fasted than a millisecond. It would be kind of a sonic blur. The Argus bandpasses were narrower than a hertz, so to be detected the transmitters must be modulating very slowly, slower than one bit of information a second. Still slower modulations--longer than hours, say--could be detected easily, provided you were willing to point a telescope at the source for that length of time, provided you were exceptionally patient. There were so many pieces of the sky to look at, so many hundreds of billions of stars to search out. You couldn't spend all your time on only a few of them. She was troubled that in their haste to do a full sky survey in less than a human lifetime, to listen to all of the sky at a billion frequencies, they had abandoned both the frantic talkers and the laconic plodders.

     But surely, she thought, they would know better than we what modulation frequencies were acceptable. They would have had previous experience with interstellar communication and newly emerging civilizations. If there was a broad range of likely pulse rates that the receiving civilization would adopt, the transmitting civilization would utilize such a range. Modulate at microseconds, modulate at hours. What would it cost them? They would, almost all of them, have superior engineering and enormous power resources by Earth standards. If they wanted to communicate with us, they would make it easy for us. They would send signals at many different frequencies. They would use many different modulation timescales. They would know how backward we are, and would have pity.

     So why had we received no signal? Could Dave possibly be right? No extraterrestrial civilizations anywhere? All those billions of worlds going to waste, lifeless, barren? Intelligent beings growing up only in this obscure corner of an incomprehensibly vast universe? No matter how valiantly she tried, Ellie couldn't make herself take such a possibility seriously. It dovetailed perfectly with human fears and pretentions, with unproved doctrines about life-after-death, with such pseudosciences as astrology. It was the modern incarnation of the geocentric solipsism, the conceit that had captured our ancestors, the notion that we were the center of the universe. Drumlin's argument was suspect on these grounds alone. We wanted to believe it too badly.

     Wait a minute, she thought. We haven't even examined the northern skies once with the Argus system. In another seven or eight years, if we've still heard nothing, that'll be the time to start worrying. This is the first moment in human history when it's possible to search for the inhabitants of other worlds. If we fail, we've calibrated something of the rarity and preciousness of life on our planet--a fact, if it is one, very much worth knowing. And if we succeed, we'll have changed the history of our species, broken the shackles of provincialism. With the stakes this high, you have to be willing to take some small professional risks, she told herself. She pulled off the side of the road and did a shallow racing turn, changed gears twice, and accelerated back toward the Argus facility. The rabbits, still lining the roadside, but now pinked by dawn, craned their necks to follow her departure.

    

     CHAPTER 4

Prime Numbers

    

Are there no Moravians in the Moon, that not a missionary has yet visited this poor pagan planet of ours to civilize civilization and Christianize Christendom?

     -HERMAN MELVILLE

White Jacket (1850)

     Silence alone is great; all else is weakness.

     -ALFRED DEVIGNY

La Mort du Loup (1864)

    

The cold black vacuum had been left behind. The pulses were now approaching an ordinary yellow dwarf star and had already begun spilling over the retinue of worlds in this obscure system. They had fluttered by planets of hydrogen gas, penetrated into moons of ice, breached the organic clouds of a frigid world on which the precursors of life were stirring, and swept across a planet a billion years past its prime. Now the pulses were washing against a warm world, blue and whit, spinning against the backdrop of the stars.

     There was life on this world, extravagant in its numbers and variety. There were jumping spiders at the chilly tops of the highest mountains and sulfur-eating worms in hot vents gushing up through ridges on the ocean floors. There were beings that could live only in concentrated sulfuric acid, and beings that were destroyed by concentrated sulfuric acid; organisms that were poisoned by oxygen, and organisms that could survive only in oxygen, that actually breathed the stuff.

     A particular lifeform, with a modicum of intelligence, had recently spread across the planet. They had outposts on the ocean floors and in low-altitude orbit. They had swarmed to every nook and cranny of their small world. The boundary that marked the transition of night into day was sweeping westward, and following its motion millions of these beings ritually performed their morning ablutions. They donned great-coats and dhotis; drank brews of coffee, tea, or dandelion; drove bicycles, automobiles, or oxen; and briefly contemplated school assignments, prospects for spring planting, and the fate of the world.

     The first pulses in the train of radio waves insinuated themselves through the atmosphere and clouds, struck the landscape and were partially reflected back to space. As the Earth turned beneath them, successive pulses arrived, engulfing not just this one planet but the entire system. Very little of the energy was intercepted by any of the worlds. Most of it passed effortlessly onward--as the yellow star and its attendant worlds plunged, in an altogether different direction, into the inky dark.

    

Wearing a Dacron jacket displaying the word "Marauders" above a stylized felt volleyball, the duty officer, beginning the night shift, approached the control building. A klatch of radio astronomers was just leaving for dinner.

     "How long have you guys been looking for little green men? It's more than five years, isn't it now, Willie?"

     They chided him good-naturedly, but he could detect an edge to their banter.

     "Give us a break, Willie," another of them said. "The quasar luminosity program is going great guns. But it's gonna take forever if we only have two percent of the telescope time."

     "Sure, Jack, sure."

     "Willie, we're looking back toward the origin of the universe. There's a big stake in our program, too--and we know there's a universe out there; you don't know there's a single little green man."

     "Take it up with Dr. Arroway. I'm sure she'll be glad to hear your opinion, "he replied a little sourly.

     The duty officer entered the control area. He made a quick survey of dozens of television screens monitoring the progress of the radio search. They had just finished examining the constellation Hercules. They had peered into the heart of a great swarm of galaxies far beyond the Milky Way, the Hercules Cluster--a hundred million light-years away; they had tuned in on M-13, a swarm of 300,000 stars, give or take a few, gravitationally bound together, moving in orbit around the Milky Way Galaxy 26,000 light-years away; they had examined Ras Algethi, a double system, and Zeta and Lambda Herculis--some stars different from the Sun, some similar to it, all nearby. Most of the stars you can see with the naked eye are less that a few hundred light-years away. They had carefully monitored hundreds of little sectors of the sky within the constellation Hercules at a billion separate frequencies, and they had heard nothing. In previous years they had searched the constellations immediately west of Hercules--Serpens, Corona Borealis, Boötes, Canes Venatici... and there also they had heard nothing.

     A few of the telescopes, the duty officer could see, were devoted to picking up some missed data in Hercules. The remainder were aiming, boresighted, at an adjacent patch of sky, the next constellation east of Hercules. To people in the eastern Mediterranean a few thousand years ago, it had resembled a stringed musical instrument and was associated with the Greek culture hero Orpheus. It was a constellation named Lyra, the Lyre.

     The computers turned the telescopes to follow the stars in Lyra from starrise to starset, accumulated the radio photons, monitored the health of the telescopes, and processed the data in a format convenient for their human operators. Even one duty officer candies, a coffee machine, a sentence in elvish runes out of Tolkien by the Artificial Intelligence Laboratory at Stanford, and a bumper sticker reading BLACK HOLES ARE OUT OF SIGHT, Willie approached the command console. He nodded pleasantly to the afternoon duty officer, now collecting his notes and preparing to leave for dinner. Because the day's data were conveniently summarized in amber on the master display, there was no need for Willie to inquire about the progress of the preceding hours.

     "As you can see, nothing much. There was a pointing glitch--at least that's what it looked like--in forty-nine," he said, waving vaguely toward the window. "The quasar bunch freed up the one-tens and one- twenties about an hour ago. They seem to be getting very good data."

     "Yeah, I heard. They don't understand..."

     His voice trailed off as an alarm light flashed decorously on the console in front of them. On a display marked "Intensity vs. Frequency" a sharp vertical spike was rising.

     "Hey, look, it's a monochromatic signal."

     Another display, labeled "Intensity vs. Time," showed a set of pulses moving left to right and then off the screen.

     "Those are numbers," Willie said faintly. "Somebody's broadcasting numbers."

     "It's probably some Air Force interference. I saw an AWACS, probably from Kirtland, about sixteen hundred hours. Maybe they're spoofing us for fun."

     There had been solemn agreements to safeguard at least some radio frequencies for astronomy. But precisely because these frequencies represented a clear channel, the military found them occasionally irresistible. If global war ever came, perhaps the radio astronomers would be the first to know, their windows to the cosmos overflowing with orders to battle-management and damage-assessment satellites in geosynchronous orbit, and with the transmission of coded launch commands to distant strategic outposts. Even with no military traffic, in listening to a billion frequencies at once the astronomers had to expect some disruption. Lightning, automobile ignitions, direct broadcast satellites were all sources of radio interference. But the computers had their number, knew their characteristics and systematically ignored them. To signals that were more ambiguous the computer would listen with greater care and make sure they matched no inventory of data it was programmed to understand. Every now and then an electronic intelligence aircraft on a training mission--sometimes with a radar dish coyly disguised as a flying saucer camped on its haunches--would fly by, and Argus would suddenly detect unmistakable signatures of intelligent life. But it would always turn out to be life of a peculiar and melancholy sort, intelligent to a degree, extraterrestrial just barely. A few moths before, an F-29E with state-of-the-art electronic countermeasures passed overhead at 80,000 feet and sounded the alarms on all 131 telescopes. To the unmilitary eyes of the astronomers, the radio signature had been complex enough to be a plausible first message from an extraterrestrial civilization. But they found the westernmost radio telescope had received the signal a full minute before the easternmost, and it soon become clear that it was an object streaking through the thin envelop of air surrounding the Earth rather than a broadcast from some unimaginably different civilization in the depths of space. Almost certainly this one was the same thing.

     *  *  *

     The fingers of her right hand were inserted into five evenly spaced receptacles in a low box on her desk. Since the invention of this device, she was able to save half an hour a week. But there hadn't really been a great deal to do with that extra half hour.

     "And I was telling Mrs. Yarborough all about it. She's the one in the next bed, now that Mrs. Wertheimer passed on. I don't mean to toot my own horn, but I take a lot of credit for what you've done."

     "Yes, Mother."

     She examined the gloss on her fingernails and decided that they needed another minute, maybe a minute-thirty.

     "I was thinking about that time in fourth grade--remember? When it was pouring and you didn't want to go to school? You wanted me to write a note the next day saying you'd been out because you were sick. And I wouldn't do it. I said, `Ellie, apart from being beautiful, the most important thing in the world is an education. You can't do much about being beautiful, but you can do something about an education. Go to school. You never know what you might learn today.' Isn't that right?"

     "Yes, Mother."

     "But, I mean, isn't that what I told you then?"

     "Yes, I remember, Mom."

     The gloss on her four fingers was perfect, but her thumb still had a dull matte appearance.

     "So I got your galoshes and your raincoat--it was one of those yellow slickers, you looked cute as a button in it--and scooted you off to school. And that's the day you couldn't answer a question in Mr. Weisbrod's mathematics class? And you got so furious you marched down to the college library and read up on it till you knew more about it than Mr. Weisbrod. He was impressed. He told me."

     "He told you? I didn't know that. When did you talk to Mr. Weisbrod?"

     "It was a parent-teacher meeting. He said to me, `That girl of yours, she's a spunky one.' Or words to that effect. `She got so mad at me, she became a real expert on it.' `Expert.' That's what he said. I know I told you about it."

     Her feet were propped up on a desk drawer as she reclined in the swivel chair; she was stabilized only by her fingers in the varnish machine. She felt the buzzer almost before she heard it, and abruptly sat up.

     "Mom, I gotta go."

     "I'm sure I've told you this story before. You just never pay attention to what I'm saying. Mr. Weisbrod, he was a nice man. You never could see his good side."

     "Mom, really, I've gotta go. We've caught some kind of bogey."

     "Bogey?"

     "You know, Mom, something that might be a signal. We've talked about it."

     "There we are, both of us thinking the other one isn't listening. Like mother, like daughter."

     "Bye, Mom."

     "I'll let you go if you promise to call me right after."

     "Okay, Mom. I promise."

     Through the whole conversation, her mother's need and loneliness had elicited in Ellie a wish to end the conversation, to run away. She hated herself for that.

     *  *  *

     Briskly she entered the control area and approached the main console.

     "Evening, Willie, Steve. Let's see the data. Good. Now where did you tuck away the amplitude plot? Good. Do you have the interferometric position? Okay. Now let's see if there's any nearby star in that field of view. Oh my, we're looking at Vega. That's a pretty near neighbor."

     Her fingers were punching away at a keyboard as she talked.

     "Look, it's only twenty-six light-years away. It's been observed before, always with negative results. I looked at it myself in my first Arecibo survey. What's the absolute intensity? Holy Toledo. That's hundreds of janskys. You could practically pick that up on your FM radio.

     "Okay. So we have a bogey very near to Vega in the plane of the sky It's at a frequency around 9.2 gigahertz, not very monochromatic: The bandwidth is a few hundred hertz. It's linearly polarized and it's transmitting a set of moving pulses restricted to two different amplitudes."

     In response to her typed commands the screen now displayed the disposition of all the radio telescopes.

     "It's being received by 116 individual telescopes. Clearly it's not a malfunction in one or two of them. Okay, now we should have plenty of time baseline. Is it moving with the stars? Or could it be some ELINT satellite or aircraft?"

     "I can confirm sidereal motion, Dr. Arroway."

     "Okay, that's pretty convincing. It's not down here on Earth, and it probably isn't from an artificial satellite in a Molniya orbit, although we should check that. When you get a chance, Willie, call up NORAD and see what they say about the satellite possibility. If we can exclude satellites, that will leave two possibilities: It's a hoax, or somebody has finally gotten around to sending us a message. Steve, do a manual override. Check a few individual radio telescopes--the signal strength is certainly large enough--and see if there's any chance this is a hoax; you know, a practical joke by someone who wishes to teach us the error of our ways."

     "A handful of other scientists and technicians, alerted on their buzzers by the Argus computer, had gathered around the command console. There were half smiles on their faces. None of them was thinking seriously of a message from another world quite yet, but there was a sense of no-school-today, a break in the tedious routine to which they had become accustomed, and perhaps a faint air of expectation.

     "If any of you can think of any other explanation besides extraterrestrial intelligence, I want to hear about it," she said, acknowledging their presence.

     "There's no way it could be Vega, Dr. Arroway. The system's only a few hundred million years old. Its planets are still in the process of forming. There isn't time for intelligent life to have developed there. It has to be some background star. Or galaxy."

     "But then the transmitter power has to be ridiculously large," responded a member of the quasar group who had returned to see what was happening. "We need to get going right away on a sensitive proper motion study, so we can see if the radio source moves with Vega."

     "Of course, you're right about the proper motion, Jack," she said. "But there's another possibility. Maybe they didn't grow up in the Vega system. Maybe they're just visiting."

     "That's no good either. The system is full of debris. It's a failed solar system or solar system still in its early stages of development. If they stay very long, their spacecraft'll be clobbered."

     "So they only arrived recently. Or they vaporize incoming meteorites. Or they take evasive action if there's a piece of debris on a collision trajectory. Or they're not in the ring plane but in polar orbit, so they minimize their encounters with the debris. There's a million possibilities. But you're absolutely right; we don't have to guess whether the source is in the Vega system. We can actually find out. How long will that proper motion study take? By the way, Steve, this isn't your shift. At least tell Consuela you're going to be late for dinner."

     Willie, who had been talking on the phone at an adjacent console, was displaying a wan smile. "Well, I got through to a Major Braintree at NORAD. He swears up and down they have nothing that'll give this signal, especially not at nine gigahertz. 'Course, they tell us that every time we call. Anyway, he says they haven't detected any spacecraft at the right ascension and declination of Vega."

     "What about darks?"

     By this time there were many "dark" satellites with low radar cross sections, designed to orbit Earth unannounced and undetected until an hour of need. Then they would serve as backups for launch detection or communications in a nuclear war, in case the first-line military satellites dedicated to these purposes were suddenly missing in action. Occasionally a dark would be detected by one of the major astronomical radar systems. All nations would deny that the object belonged to them, and breathless speculation would erupt that an extraterrestrial spacecraft had been detected in Earth orbit. As the Millennium approached, the UFO cults were thriving again.

     "Interferometry now rules out a Molniya-type orbit, Dr. Arroway."

     "Better and better. Now let's take a closer look at those moving pulses. Assuming that this is binary arithmetic, has anybody converted it into base ten? Do we know what the sequence of numbers is? Okay, here, we can do it in our heads... fifty-nine, sixty-one, sixty-seven... seventy-one... Aren't these all prime numbers?"

     A little buzz of excitement circulated through the control room. Ellie's own face momentarily revealed a flutter of something deeply felt, but this was quickly replaced by a sobriety, a fear of being carried away, an apprehension about appearing foolish, unscientific.

     "Okay, let's see if I can do another quick summary. I'll do it in the simplest language. Please check if I've missed anything. We have an extremely strong, not very monochromatic signal. Immediately outside the bandpass of this signal there are no other frequencies reporting anything besides noise. The signal is linearly polarized, as if it's being broadcast by a radio telescope. The signal is around nine gigahertz, near the minimum in the galactic radio noise background. It's the right kind of frequency for anyone who wants to be heard over a big distance. We've confirmed sidereal motion of the source, so it's moving as if it's up there among the stars and not from some local transmitter. NORAD tells us that they don't detect any satellites-- ours or anybody else's--that match the position of this source. Interferometry excludes a source in Earth orbit anyway.

     "Steve has now looked at the data outside the automated mode, and it doesn't seem to be a program that somebody with a warped sense of humor put into the computer. The region of the sky we're looking at includes Vega, which is an A-zero main sequence dwarf star. It's not exactly like the Sun, but it's only twenty-six light-years away, and it has the prototype stellar debris ring. There are no known planets, but there certainly could be planets we don't know anything about around Vega. We're setting up a proper motion study to see if the source is well behind our line of sight to Vega, and we should have an answer in-- what?--a few weeks if we're restricted on our own, a few hours if we do some long-baseline interferometry.

     "Finally, what's being sent seems to be a long sequence of prime numbers, integers that can't be divided by any other number except themselves and one. No astrophysical process is likely to generate prime numbers. So I'd say--we want to be cautious, of course--but I'd say that by every criterion we can lay our hands on, this looks like the real thing.

     "But there's a problem with the idea that this is a message from guys who evolved on some planet around Vega, because they would have had to evolve very fast. The entire lifetime of the star is only about four hundred million years. It's an unlikely place for the nearest civilization. So the proper motion study is very important. But I sure would like to check out that hoax possibility some more."

     "Look," said one of the quasar survey astronomers who had been hovering in the back. He inclined his jaw to the western horizon where a faint pink aura showed unmistakably where the Sun had set. "Vega is going to set in another couple of hours. It's probably already risen in Australia. Can't we call Sydney and get them looking at the same time that we're still seeing it?"

     "Good idea. It's only middle afternoon there. And together we'll have enough baseline for the proper motion study. Give me that summary printout, and I'll telefax it to Australia from my office."

     With deliberate composure, Ellie left the assembled group crowded around the consoles and returned to her office. She closed the door very carefully behind her.

     "Holy shit!" she whispered.

     *  *  *

     "Ian Broderick, please. Yes. This is Eleanor Arroway at Project Argus. It's something of an emergency. Thanks, I'll hold on.... Hello, Ian? It's probably nothing, but we have a bogey here and wonder if you could just check it out for us. It's around nine gigahertz, with a few hundred hertz bandpass. I'm telefaxing the parameters now.... You have a feed good at nine gigahertz already on the dish? That's a bit of luck.... Yes, Vega is smack in the middle of the field of view. And we're getting what looks like prime number pulses.... Really. Okay, I'll hold on."

     She considered again how backward the world astronomical community still was. A joint computer data-basing system was still not on-line. Its value for asynchronous telenetting alone would...

     "Listen, Ian, while the telescope finishes slewing, could you set up to look at an amplitude-time plot? Let's call the low-amplitude pulses dots and the high-amplitude pulses dashes. We're getting... Yes that's just the pattern we've been seeing for the last half hour.... Maybe. Well, it's the best candidate in five years, but I keep remembering how badly the Soviets got fooled with that Big Bird satellite incident around '74. Well, the way I understand it, it was a U.S. radar altimetry survey of the Soviet Union for cruise missile guidance.... Yes, a terrain mapper. And the Soviets were picking it up on omnidirectional antennas. They couldn't tell where in the sky the signal was coming from. Al they knew was they were getting the same sequence of pulses from the sky at about the same time every morning. Their people assured them it wasn't a military transmission, so naturally they thought it was extraterrestrial.... No, we've excluded a satellite transmission already.

     "Ian, could we trouble you to follow it for as long as it's in your sky? I'll talk to you about VLBI later. I'm going to see if I can't get other radio observatories, distributed pretty evenly in longitude, to follow it until it reappears back here.... Yes, but I don't know if it's easy to make a direct phone call to China. I'm thinking of sending an IAU telegram.... Fine. Many thanks, Ian."

     Ellie paused in the doorway of the control room--they called it that with conscious irony, because it was the computers, in another room, that by and large did the controlling--to admire the small group of scientists who were talking with great animation, scrutinizing the data being displayed, and engaging in mild badinage on the nature of the signal. These were not stylish people, she thought. They were not conventionally good-looking. But there was something unmistakably attractive about them. They were excellent at what they did and, especially in the discovery process, were utterly absorbed in their work. As she approached, they fell silent and looked at her expectantly. The numerals were now being converted automatically from base 2 to base 10... 881, 883, 887, 907... each one confirmed as a prime number.

     "Willie, get me a world map. And please get me Mark Auerbach in Cambridge, Mass. He'll probably be at home. Give him this message for an IAU telegram to all observatories, but especially to all large radio observatories. And see if he'll check our telephone number for the Beijing Radio Observatory. Then get me the President's Science Adviser."

     "You're going to bypass the National Science Foundation?"

     "After Auerbach, get me the President's Science Adviser.'

     In her mind she thought she could hear one joyous shout amidst a clamor of other voices.

     *  *  *

     By bicycle, small truck, perambulatory mailman, or telephone, the single paragraph was delivered to astronomical centers all over the world. In a few major radio observatories--in China, India, the Soviet Union, and Holland, for example--the message was delivered by teletype. As it chattered in, it was scanned by a security officer or some passing astronomer, torn off, and with a look of some curiosity carried into an adjacent office. It read:

     ANOMALOUS INTERMITTENT RADIO SOURCE AT RIGHT ASCENSION 18h 34M, DECLINATION PLUS 38 DEGREES 41 MINUTES, DISCOVERED BY ARGUS SYSTEMATIC SKY SURVEY. FREQUENCY 9.24176684 GIGAHERTZ, BANDPASS APPROXIMATELY 430 HERTZ. BIMODAL AMPLITUDES APPROXIMATELY 174 AND 179 JANSKYS. EVIDENCE AMPLITUDES ENCODE SEQUENCE OF PRIME NUMBERS. FULL LONGITUDE COVERAGE URGENTLY NEEDED. PLEASE CALL COLLECT FOR FURTHER INFORMATION IN COORDINATING OBSERVATIONS. E. ARROWAY, DIRECTOR, PROJECT ARGUS, SOCORRO, NEW MEXICO, U.S.A.

     CHAPTER 5 Decryption Algorithm

    

Oh, speak again, bright angel...

     -WILLIAM SHAKESPEARE

     Romeo and Juliet

     The visiting scientists' quarters were now all occupied, indeed overcrowded, by selected luminaries of the SETI community. When the official delegations began arriving from Washington, they found no suitable accommodations at the Argus site and had to be billeted at motels in nearby Socorro. Kenneth der Heer, the President's Science Adviser, was the only exception. He had arrived the day after the discovery, in response to an urgent call from Eleanor Arroway. Officials from the National Science Foundation, the National Aeronautics and Space Administration, the Department of Defense, the President's Science Advisory Committee, the National Security Council, and the National Security Agency trickled in during the next few days. There were a few government employees whose precise institutional affiliations remained obscure.

     The previous evening, some of them stood at the base of Telescope 101 and had Vega pointed out to them for the first time. Obligingly, its blue-white light flickered prettily.

     "I mean, I've seen it before, but I never knew what it was called," one of them remarked. Vega appeared brighter than the other stars in the sky, but in no other way noteworthy. It was merely one of the few thousand naked-eye stars.

     The scientists were running a continuous research seminar on the nature, origin, and possible significance of the radio pulses. The project's public affairs office--larger than in most observatories because of widespread interest in the search for extraterrestrial intelligence--was assigned the task of filling in the lower-ranking officials. Every new arrival required an extensive personal briefing. Ellie, who was obliged to brief the senior officials, supervise the ongoing research, and respond to the entirely proper skeptical scrutiny being offered with some vigor by her colleagues, was exhausted. The luxury of a full night's sleep had eluded her since the discovery.

     At first they had tried to keep the finding quiet. After all, they were not absolutely sure it was an extraterrestrial message. A premature or mistaken announcement would be a public relations disaster. But worse than that, it would interfere with the data analysis. If the press descended, the science would surely suffer. Washington as well as Argus was keen to keep the story quiet. But the scientists had told their families, the International Astronomical Union telegram had been sent all over the world, and still rudimentary astronomical data-basing systems in Europe, North America, and Japan were all carrying news of the discovery.

     Although there had been a range of contingency plans for the public release of any findings, the actual circumstances had caught them largely unprepared. They drafted as innocuous a statement as they could and released it only when they had to. It caused, of course, a sensation.

     They had asked the media's forbearance, but knew there would be only a brief period before the press would descend in force. They had tried to discourage reporters from visiting the site, explaining that there was no real information in the signals they were receiving, just tedious and repetitive prime numbers. The press was impatient with the absence of hard news. "You can only do so many sidebars on `What is a prime number?'" one reporter explained to Ellie over the telephone.

     Television camera crews in fixed-wing air taxis and chartered helicopters began making low passes over the facility, sometimes generating strong radio interference easily detected by the telescopes. Some reporters stalked the officials from Washington when they returned to their motels at night. A few of the more enterprising had attempted to enter the facility unobserved--by beach buggy, motorcycle, and in one case on horseback. She had been forced to inquire about bulk rates on cyclone fencing.

     Immediately after der Heer arrived, he had received an early version of what was by now Ellie's standard briefing: the surprising intensity of the signal, its location in very much the same part of the sky as the star Vega, the nature of the pulses.

     "I may be the President's Science Adviser," he had said, "but I'm only a biologist. So please explain it to me slowly. I understand that if the radio source is twenty-six light-years away, then the message had to be sent twenty-six years ago. In the 1960s, some funny-looking people with pointy ears thought we'd want to know that they like prime numbers. But prime numbers aren't difficult. It's not like they're boasting. It's more like they're sending us remedial arithmetic. Maybe we should be insulted."

     "No, look at it this way," she said, smiling. "This is a beacon. It's an announcement signal. It's designed to attract our attention. We get strange patterns of pulses from quasars and pulsars and radio galaxies and God-knows-what. But prime numbers are very specific, very artificial. No even number is prime, for example. It's hard to imagine some radiating plasma or exploding galaxy sending out a regular set of mathematical signals like this. The prime numbers are to attract our attention."

     "But what for?" he had asked, genuinely baffled.

     "I don't know. But in this business you have to be very patient. Maybe in a while the prime numbers will turn off and be replaced by something else, something very rich, the real message. We just have to keep on listening."

     This was the hardest part to explain to the press, that the signals had essentially no content, no meaning--just the first few hundred prime numbers in order, a cycling back to the beginning, and again the simple binary arithmetic representations: 1, 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31... Nine wasn't a prime number, she'd explain, because it was divisible by 3 (as well as 9 and 1, of course). Ten wasn't a prime number because 5 and 2 went into it (as well as 10 and 1). Eleven was a prime number because it was divisible only by 1 and itself. But why transmit prime numbers? It reminded her of an idiot savant, one of those people who might be grossly deficient in ordinary social or verbal skills but who could perform mind- boggling feats of mental arithmetic--such as figuring out, after a moment's thought, on what day of the week June first in the year 11,977 will fall. It wasn't for anything; they did it because they liked doing it, because they were able to do it.

     She knew it was only a few days after receipt of the message, but she was at once exhilarated and deeply disappointed. After all these years, they had finally received a signal--sort of. But its content was shallow, hollow, empty. She had imagined receiving the Encyclopedia Galactica.

     We've only achieved the capacity for radio astronomy in the last few decades, she reminded herself, in a Galaxy where the average star is billions of years old. The chance of receiving a signal from a civilization exactly as advanced as we are should be minuscule. If they were even a little behind us, they would lack the technological capability to communicate with us at all. So the most likely signal would come from a civilization much more advanced. Maybe they would be able to write full and melodic mirror fugues: The counterpoint would be the theme written backwards. No, she decided. While this was a kind of genius without a doubt, and certainly beyond her ability, it was a tiny extrapolation from what human beings could do. Bach and Mozart had made at least respectable stabs at it.

     She tried to make a bigger leap, into the mind of someone who was enormously, orders of magnitude, more intelligent than she was, smarter than Drumlin, say, or Eda the young Nigerian physicist who had just won the Nobel Prize. But it was impossible. She could muse about demonstrating Fermat's Last Theorem or the Goldbach Conjecture in only a few lines of equations. She could imagine problems enormously beyond us that would be old hat to them. But she couldn't get into their minds; she couldn't imagine what thinking would be like if you were much more capable than a human being. Of course. Nor surprise. What did she expect? It was like trying to visualize a new primary color or a world in which you could recognize several hundred acquaintances individually only by their smells.... She could talk about this, but she couldn't experience it. By definition, it has to be mighty hard to understand the behavior of a being much smarter than you are. Buy even so, even so: Why only prime numbers?

     *  *  *

     The Argus radio astronomers had made progress in the last few days. Vega had a known motion--a known component of its velocity toward or away from the Earth, and a known component laterally, across the sky, against the background of more distant stars. The Argus telescopes, working together with radio observatories in West Virginia and Australia, had determined that the source was moving with Vega. Not only was the signal coming, as carefully as they could measure, from where Vega was in the sky; but the signal also shared the peculiar and characteristic motions of Vega. Unless this was a hoax of heroic proportions, the source of the prime number pulses was indeed in the Vega system. There was no additional Doppler effect due to the motion of the transmitter, perhaps tied to a planet, about Vega. The extraterrestrials had compensated for the orbital motion. Perhaps it was a kind of interstellar courtesy.

     "It's the goddamnedest most wonderful thing I ever heard of. And it's got nothing to do with our shop," said an official of the Defense Advanced Research Projects Agency, preparing to return to Washington.

     As soon as the discovery had been made, Ellie had assigned a handful of the telescopes to examine Vega in a range of other frequencies. Sure enough, they had found the same signal, the same monotonous succession of prime numbers, beeping away in the 1420 megahertz hydrogen line, the 1667 megahertz hydroxyl line, and at many other frequencies. All over the radio spectrum, with an electromagnetic orchestra, Vega was bleating out prime numbers.

     "It doesn't make sense," said drumlin, casually touching his belt buckle. "We couldn't have missed it before. Everybody's looked at Vega. For years. Arroway observed it from Arecibo a decade ago. Suddenly last Tuesday Vega starts broadcasting prime numbers? Why now? What's so special about now? How come they start transmitting just a few years after Argus starts listening?"

     "Maybe their transmitter was down for repairs for a couple of centuries," Valerian suggested, "and they just got it back on-line. maybe their duty cycle is to broadcast to us just one year out of every million. There are all those other candidate planets that might have life on them, you know. We're probably not the only kid on the block." But Drumlin, plainly dissatisfied, only shook his head.

     Although his nature was the opposite of conspiratorial, Valerian thought he had caught an undercurrent in Drumlin's last question: could all this be a reckless, desperate attempt by Argus scientists to prevent a premature closing down of the project? It wasn't possible. Valerian shook his head. As der Heer walked by, he found himself confronted by two senior experts on the SETI problem silently shaking their heads at one another.

     Between the scientists and the bureaucrats there was a kind of unease, a mutual discomfort, a clash of fundamental assumptions. One of the electrical engineers called it an impedance mismatch. The scientists were too speculative, too quantitative, and too casual about talking to anybody for the tastes of many of the bureaucrats. The bureaucrats were too unimaginative, too qualitative, too uncommunicative for many of the scientists. Ellie and especially der Heer tried hard to bridge the gap, but the pontoons kept being swept downstream.

     This night, cigarette butts and coffee cups were everywhere. The casually dressed scientists, Washington officials in light-weight suits, and an occasional flag-rank military officer filled the control room, the seminar room, the small auditorium, and spilled out of doors, where, illuminated by cigarettes and starlight, some of the discussions continued. But tempers were frayed. The strain was showing.

     *  *  *

     "Dr. Arroway, this is Michael Kitz, Assistant Secretary of Defense for C3I."

     Introducing Kitz and positioning himself just a step behind him, der Heer was communicating... what? Some unlikely mix of emotions. Bemusement in the arms of prudence? He seemed to be appealing for restraint. Did he think her such a hothead? "C3I"--pronounced cee-cubed-eye--stood for Command, Control, Communications, and Intelligence, important responsibilities at a time when the United States and the Soviet Union were gamely making major phased reductions in their strategic nuclear arsenals. It was a job for a cautious man.

     Kitz settled himself in one of the two chairs across the desk from Ellie, leaned forward, and read the Kafka quote. He was unimpressed.

     "Dr. Arroway, let me come right to the point. We're concerned about whether it's in the best interest of the United States for this information to be generally known. We were not overjoyed about your sending that telegram all over the world."

     "You mean to China? To Russia? To India?" Her voice, despite her best effort, had a discernible edge to it. "You wanted to keep the first 261 prime numbers secret? Do you suppose, Mr. Kitz, the extraterrestrials intended to communicate only with Americans? Don't you think that a message from another civilization belongs to the whole world?"

     "You might have asked our advice."

     "And risk losing the signal? Look, for all we know, something essential, something unique might have been broadcast after Vega had set her in New Mexico but when it was high in the sky over Beijing. These signals aren't exactly a person-to-person call to the U.S. of A. They're not even a person-to-person call to the Earth. It's station-to-station to any planet in the solar system. We just happened to be lucky enough to pick up the phone."

     Der Heer was radiating something again. What was he trying to tell her? That he liked that elementary analogy, but ease up on Kitz?

     "In any case," she continued, "it's too late. Everybody knows now that there's some kind of intelligent life in the Vega system."

     "I'm not sure it's too late, Dr. Arroway. You seem to think there'll be some information-rich transmission, a message, still to come. Dr. der Heer here"--he paused to listen to the unexpected assonance--"Dr. der Heer says you think these prime numbers are an announcement, something to make us pay attention. If there is a message and it's subtle--something those other countries wouldn't pick up right away--I want it kept quiet until we can talk about it."

     "Many of us have wants, Mr. Kitz, she found herself saying sweetly, ignoring der Heer's raised eyebrows. There was something irritating, almost provocative, about Kitz's manner. And probably hers as well. "I, for example, have a want to understand what the meaning of this signal is, and what's happening on Vega, and what it means for the Earth. It's possible that scientists in other nations are the key to that understanding. Maybe we'll need their data. Maybe we'll need their brains. I could imagine this might be a problem too big for one country to handle all by itself."

     Der Heer now appeared faintly alarmed. "Uh, Dr. Arroway. Secretary Kitz's suggestion isn't all that unreasonable. It's very possible we'd bring other nations in. All he's asking is to talk about it with us first. And that's only if there's a new message."

     His tone was calming but not unctuous. She looked at him closely again. Der Heer was not a patently handsome man, but he had a kind and intelligent face. He was wearing a blue suit and a crisp oxford shirt. His seriousness and air of self-possession were moderated by the warmth of his smile. Why, then, was he shilling for this jerk? Part of his job? Could it be that Kitz was talking sense?

     "It's a remote contingency anyway." Kitz sighed as he got to his feet. "The Secretary of Defense would appreciate your cooperation." He was trying to be winning. "Agreed?"

     "Let me think about it," she replied, taking his proffered hand as if it were a dead fish.

     "I'll be along in a few minutes, Mike," der Heer said cheerfully.

     His hand on the lintel of the door, Kitz had an apparent afterthought, removed a document from his inside breast pocket, returned, and placed it gingerly on the corner of her desk. "Oh yes, I forgot. Here's a copy of the Hadden Decision. You probably know it. It's about the government's right to classify material vital to the security of the United States. Even if it didn't originate in a classified facility."

     "You want to classify the prime numbers?" she asked, her eyes wide in mock incredulity.

     "See you outside, Ken."

     She began talking the moment Kitz left her office. "What's he after? Vegan death rays? World blower-uppers? What's this really about?"

     "He's just being prudent, Ellie. I can see you don't think that's the whole story. Okay. Suppose there's some message--you know, with real content--and in it there's something offensive to Muslims, say, or to Methodists. Shouldn't we release it carefully, so the United States doesn't get a black eye?"

     "Ken, don't bullshit me. That man is an Assistant Secretary of Defense. If they're worried about Muslims and Methodists, they would have sent me an Assistant Secretary of State, or--I don't know--one of those religious fanatics who preside at presidential prayer breakfasts. You're the President's Science Adviser. What did you advise her?"

     "I haven't advised her anything. Since I've been here, I've only talked to her once, briefly, on the phone. And I'll be frank with you, she didn't give me any instructions about classification. I thought what Kitz said was way off base. I think he's acting on his own."

     "Who is he?"

     "As far as I know, he's a lawyer. He was a top executive in the electronics industry before joining the Administration. He really knows C3I, but that doesn't make him knowledgeable about anything else."

     "Ken, I trust you. I believe you didn't set me up for this Hadden Decision threat." She waved the document in front of her and paused, seeking his eyes. "Do you know that Drumlin thinks there's another message in the polarization?"

     "I don't understand."

     "Just a few hours ago, Dave finished a rough statistical study of the polarization. He's represented the Stokes parameters by Poin-caré spheres; there's a nice movie of them varying in time."

     Der Heer looked at her blankly. Don't biologists use polarized light in their microscopes? she asked herself.

     "When a wave of light comes at you--visible light, radio light, any kind of light--it's vibrating at right angles to your line of sight. If that vibration rotates, the wave is said to be elliptically polarized. If it rotates clockwise, the polarization is called right-handed; counterclockwise, it's left-handed. I know it's a dumb designation. Anyway, by varying between the two kinds of polarization, you could transmit information. A little right polarization and that's a zero; a little left and it's a one. Follow? It's perfectly possible. We have amplitude modulation and frequency modulation, but our civilization, by convention, ordinarily just doesn't do polarization modulation.

     "Well, the Vega signal looks as if it has polarization modulating. We're busy checking it out right now. But Dave found that there wasn't an equal amount of the two sorts of polarization. It wasn't left polarized as much as it was right polarized. It's just possible that there's another message in the polarization that we've missed so far. That's why I'm suspicious about your friend. Kitz isn't just giving me general gratuitous advice. He knows we may be onto something else."

     "Ellie, take it easy. You've hardly slept for four days. You've been juggling the science, the administration, and the press. You've already made one of the major discoveries of the century, and if I understand you right, you might be on the verge of something even more important. You've got every right to be a little on edge. And threatening to militarize the project was clumsy of Kitz. I don't have any trouble understanding why you're suspicious of him. But there's some sense to what he says."

     "Do you know the man?"

     "I've been in a few meetings with him. I can hardly say I know him. Ellie, if there's a possibility of a real message coming in, wouldn't it be a good idea to thin out the crowd a little?"

     "Sure. Give me a hand with some of the Washington deadwood."

     "Okay. And if you leave that document on your desk, someone'll be in here and draw the wrong conclusion. Why don't you put it away somewhere?"

     "You're going to help?"

     "If the situation stays anything like what it is now, I'll help. We're not going to make our best effort if this thing gets classified."

     Smiling, Ellie knelt before her small office safe, and punched in the six-digit combination, 314159. She took one last glance at the document that was titled in large black letters THE UNITED STATES VS. HADDEN CYBERNETICS, and locked it away.

     *  *  *

     It was a group of about thirty people--technicians and scientists associated with Project Argus, a few senior government officials, including the Deputy Director of the Defense Intelligence Agency in civilian clothes. Among them were Valerian, Drumlin, Kitz, and der Heer. Ellie was the only woman. They had set up a large television projection system, focused on a two-meter-by-two-meter screen set flush against the far wall. Ellie was simultaneously addressing the group and the decryption program, her fingers on the keyboard before her.

     "Over the years we've prepared for the computer decryption of many kinds of possible messages. We've just learned from Dr. Drumlin's analysis that there's information in the polarization modulation. All that frenetic switching between left and right means something. It's not random noise. It's as if you're flipping a coin. Of course, you expect as many heads as tails, but instead you get twice as many heads as tails. so you conclude that the coin is loaded or, in our case, that the polarization modulation isn't random; it has content.... Oh, look at this. What the computer has just now told us is even more interesting. The precise sequence of heads and tails repeats. It's a long sequence, so it's a pretty complex message, and the transmitting civilization must want us to be sure to get it right.

     "Here, you see? This is the repeating message. We're now into the first repetition. Every bit of information, every dot and dash--if you want to think of them that way--is identical to what it was in the last block of data. Now we analyze the total number of buts. It's a number in the tens of billions. Okay, bingo! It's the product of three prime numbers."

     Although Drumlin and Valerian were both beaming, it seemed to Ellie they were experiencing quite different emotions.

     "So what? What do some more prime numbers mean?" a visitor from Washington asked.

     "It means--maybe--that we're being sent a picture. You see, this message is made of a large number of bits of information. Suppose that large number is the product of three smaller numbers; it's a number times a number times a number. So there's three dimensions to the message. I'd guess either it's a single static three-dimensional picture like a stationary hologram, or it's a two-dimensional picture that changes with time--a movie. Let's assume it's a movie. If it's a hologram, it'll take us longer to display anyway. We've got an ideal decryption algorithm for this one."

     On the screen, they made out an indistinct moving pattern composed of perfect whites and perfect blacks.

     "Willie, put in some gray interpolation program, would you? Anything reasonable. And try rotating it about ninety degrees counterclockwise."

     "Dr. Arroway, there seems to be an auxiliary sideband channel. Maybe it's the audio to go with the movie."

     "Punch it up."

     The only other practical application of prime numbers she could think of was public-key cryptography, now widely used in commercial and national security contexts. One application was to make a message clear to dummies; the other was to keep a message hidden from the tolerably intelligent.

     Ellie scanned the faces before her. Kitz looked uncomfortable. Perhaps he was anticipation some alien invader or, worse, the design drawings of a weapon too secret for her staff to be trusted with. Willie looked very earnest and was swallowing over and over again. A picture is different from mere numbers. The possibility of a visual message was clearly rousing unexamined fears and fantasies in the hearts of many of the onlookers. Der Heer had a wonderful expression on his face; for the moment he seemed much less the official, the bureaucrat, the presidential adviser, and much more the scientist.

     The picture, still unintelligible, was joined by a deep rumbling glissando of sounds, sliding first up and then down the audio spectrum until it gravitated to rest somewhere around the octave below middle C. Slowly the group became aware of faint but swelling music. The picture rotated, rectified, and focused.

     Ellie found herself staring at a black-and-white grainy image of... a massive reviewing stand adorned with an immense art deco eagle. Clutched in the eagle's concrete talons...

     "Hoax! It's a hoax!" There were cries of astonishment, incredulity, laughter, mild hysteria.

     "Don't you see? You've been hoodwinked," Drumlin was saying to her almost conversationally. He was smiling. "It's an elaborate practical joke. You've been wasting the time of everybody here."

     Clutched in the eagle's concrete talons, she could now see clearly, was a swastika. The camera zoomed in above the eagle to find the smiling face of Adolf Hitler, waving to a rhythmically chanting crowd. His uniform, devoid of military decorations, conveyed a modest simplicity. The deep baritone voice of an announcer, scratchy but unmistakably speaking German, filled the room. Der Heer moved toward her.

     "Do you know German?" she whispered. "What's it saying?"

     "The Fuehrer," he translated slowly, "welcomes the world to the German Fatherland for the opening of the 1936 Olympic Games."

    

     CHAPTER 6

Palimpsest

    

And if the Guardians are not happy, who else can be?

     -ARISTOTLE

The Politics

Book 2, Chapter 5

    

As the plane reached cruising altitude, with Albuquerque already more than a hundred miles behind them, Ellie idly glanced at the small white cardboard rectangle imprinted with blue letters that had been stapled to her airline ticket envelope. It read, in language unchanged since her first commercial flight, "This is not the luggage ticket (baggage check) described by Article 4 of the Warsaw Convention." Why were the airlines so worried, she wondered, that passengers might mistake this piece of cardboard for the Warsaw Convention ticket? Why had she never seen one? Where were they storing them? In some forgotten key event in the history of aviation, an inattentive airline must have forgotten to print this caveat on cardboard rectangles and was sued into bankruptcy by irate passengers laboring under the misapprehension that this was the Warsaw luggage ticket. Doubtless there were sound financial reasons for this worldwide concern, never otherwise articulated, about which pieces of cardboard are not described by the Warsaw Convention. Imagine, she thought, all those cumulative lines of type devoted instead to something useful--the history of world exploration, say, or incidental facts of science, or even the average number of passenger miles until your airplane crashed.

     If she had accepted der Heer's offer of a military airplane, she would be having other casual associations. But that would have been far too cozy, perhaps some aperture leading to an eventual militarization of the project. They had preferred to travel by commercial carrier. Valerian's eyes were already closed as he finished settling into the seat beside her. There had been no particular hurry, even after taking care of those last-minute details on the data analysis, with the hint that the second layer of the onion was about to unpeel. They had been able to make a commercial flight that would arrive in Washington well before tomorrow's meeting; in fact, in plenty of time for a good night's sleep.

     She glanced at the telefax system neatly zipped into a leather carrying case under the seat in front of her. It was several hundred kilobits per second faster than Peter's old model and displayed much better graphics. Well, maybe tomorrow she would have to use it to explain to the President of the United States what Adolf Hitler was doing on Vega. She was, she admitted to herself, a little nervous about the meeting. She had never met a President before, and by late-twentieth-century standards, this one wasn't half bad. She hadn't had time to get her hair done, much less a facial. Oh well, she wasn't going to the White House to be looked at.

     What would her stepfather think? Did he still believe she was unsuited for science? Or her mother, now confined to a wheelchair in a nursing home? She had managed only one brief phone call to her mother since the discovery over a week ago, and promised herself to call again tomorrow.

     As she had done a hundred times before, she peered out the airplane window and imagined what impression the Earth would make on an extraterrestrial observer, at this cruising altitude of twelve or fourteen kilometers, and assuming the alien had eyes something like ours. There were vast areas of the Midwest intricately geometrized with squared, rectangles, and circles by those with agricultural or urban predilections; and, as here, vast areas of the Southwest in which the only sign of intelligent life was an occasional straight line heading between mountains and across deserts. Are the worlds of more advanced civilizations totally geometrized, entirely rebuilt by their inhabitants? Or would the signature of a really advanced civilization be that they left no sign at all? Would they be able to tell in one swift glance precisely which stage we were in some great cosmic evolutionary sequence in the development of intelligent beings?

     What else could they tell? From the blueness of the sky, they could make a rough estimate of Loschmidt's Number, how many molecules there were in a cubic centimeter at sea level. About three times ten to the nineteenth. They could easily tell the altitudes of the clouds from the length of their shadows on the ground. If they knew that the clouds were condensed water, they could roughly calculate the temperature lapse rate of the atmosphere, because the temperature had to fall to about minus forty degrees Centigrade at the altitude of the highest clouds she could see. The erosion of landforms, the dendritic patterns and oxbows of rivers, the presence of lakes and battered volcanic plugs all spoke of an ancient battle between land-forming and erosional processes. Really, you could see at a glance that this was an antique planet with a brand new civilization.

     Most of the planets in the Galaxy would be venerable and pretechnical, maybe even lifeless. A few would harbor civilizations much older than ours. Worlds with technical civilizations just beginning to emerge must be spectacularly rare. It was probably the only quality fundamentally unique about the Earth.

     Through lunch, the landscape slowly turned verdant as they approached the Mississippi Valley. There was hardly any sense of motion in modern air travel, Ellie thought. She looked at Peter's still sleeping form; he had rejected with some indignation the prospect of an airline lunch. Beyond him, across the aisle, was a very young human being, perhaps three months old, comfortably nestled in its father's arms. What was an infant's view of air travel? You go to a special place, walk into a large room with seats in it, and sit down. The room rumbles and shakes for four hours. Then you get up and walk off. Magically, you're somewhere else. The means of transportation seems obscure to you, but the basic idea is easy to grasp, and precocious mastery of the Navier-Stokes equations is not required.

 

It was late afternoon when they circled Washington, awaiting permission to land. She could make out, between the Washington Monument and the Lincoln Memorial, a vast crowd of people. It was, she had read only an hour earlier in the Times telefax, a massive rally of black Americans protesting economic disparities and educational inequities. Considering the justice of their grievances, she thought, they had been very patient. She wondered how the President would respond to the rally and to the Vega transmission, on both of which some official public comment would have to be made tomorrow.

     *  *  *

     "What do you mean, Ken, `They get out'?"

     "I mean, Ms. President, that our television signals leave this planet and go out into space."

     "Just exactly how far do they go?"

     "With all due respect, Ms. President, it doesn't work that way."

     "Well, how does it work?"

     "The signals spread out from the Earth in spherical waves, a little like ripples in a pond. They travel at the speed of light--186,000 miles a second--and essentially go on forever. The better some other civilization's receivers are, the farther away they could be and still pick up our TV signals. Even we could detect a strong TV transmission from a planet going around the nearest star."

     For a moment, the President stood ramrod straight, staring out the French doors into the Rose Garden. She turned toward der Heer. "You mean... everything?"

     "Yes. Everything."

     "You mean to say, all that crap on television? The car crashes? Wrestling? The porno channels? The evening news?"

     "Everything, Ms. President." Der Heer shook his head in sympathetic consternation.

     "Der Heer, do I understand you correctly? Does this mean that all my press conferences, my debates, my inaugural address, are out there?"

     "That's the good news, Ms. President. The bad news is, so are all the television appearances of your predecessor. And Dick Nixon. And the Soviet leadership. And so are a lot of nasty things your opponent said about you. It's a mixed blessing."

     "My God. Okay, go on." The President had turned away from the French doors and was now apparently preoccupied in examining a marble bust of Tom Paine, newly restored from the basement of the Smithsonian Institution, where it had been consigned by the previous incumbent.

     "Look at it this way: Those few minutes of television from Vega were originally broadcast in 1936, at the opening of the Olympic Games in Berlin. Even though it was only shown in Germany, it was the first television transmission on Earth with even moderate power. Unlike the ordinary radio transmission in the thirties, those TV signals got through our ionosphere and trickled out into space. We're trying to find out exactly what was transmitted back then, but it'll probably take some time. Maybe that welcome from Hitler is the only fragment of the transmission they were able to pick up on Vega.

     "So from their point of view, Hitler is the first sign of intelligent life on Earth. I'm not trying to be ironic. They don't know what the transmission means, so they record it and transmit it back to us. It's a way of saying `Hello, we heard you.' It seems to me a pretty friendly gesture."

     "Then you say there wasn't any television broadcasting until after the Second World War?"

     "Nothing to speak of. There was a local broadcast in England on the coronation of George the Sixth, a few things like that. Big time television transmission began in the late forties. All those programs are leaving the Earth at the speed of light. Imagine the Earth is here"--der Heer gestured in the air--"and there's a little spherical wave running away from it at the speed of light, starting out in 1936. It keeps expanding and receding from the Earth. Sooner or later, it reaches the nearest civilization. They seem to be surprisingly close, only twenty-six years for the Berlin Olympics to return to Earth. So the Vegans didn't take decades to figure it out. They must have been pretty much tuned, all set up, ready to go, waiting for our first television signals. They detect them, record them, and after a while play them back to us. But unless they've already been here--you know, some survey mission a hundred years ago--they couldn't have known we were about to invent television. So Dr. Arroway thinks this civilization is monitoring all the nearby planetary systems, to see if any of its neighbors develop high technology."

     "Ken, there's a lot of things her to think about. Are you sure those--what do you call them, Vegans?--you sure they don't understand what that television program was about?"

     "Ms. President, there's no doubt they're smart. That was a very weak signal in 1936. Their detectors have to be fantastically sensitive to pick it up. But I don't see how they could possibly understand what it means. They probably look very different from us. They must have different history, different customs. There's no way for them to know what a swastika is or who Adolf Hitler was."

     "Adolf Hitler! Ken, it makes me furious. Forty million people die to defeat that megalomaniac, and he's the star of the first broadcast to another civilization? He's representing us. And them. It's that madman's wildest dream come true."

     She paused and continued in a calmer voice. "You know, I never thought Hitler could manage that Hitler salute. He never gave it straight on, it was always skewed at some wacko angle. And then there was that fruity bent elbow salute. If anyone else had done his Heil Hitlers so incompetently he would've been sent to the Russian front."

     "But isn't there a difference? He was only returning the salutes of others. He wasn't Heiling Hitler."

     "Oh yes he was," returned the President and, with a gesture, ushered der Heer out of the Rose Room and down a corridor. Suddenly she stopped and regarded her Science Adviser.

     "What if the Nazis didn't have television in 1936? Then what would have happened?"

     "Well, then I suppose it would be the coronation of George the Sixth, or one of the transmissions about the New York World's Fair in 1939, if any of them were strong enough to be received on Vega. Or some programs from the late forties, early fifties. You know, Howdy Doody, Milton Berle, the Army- McCarthy hearings--all those marvelous signs of intelligent life on Earth."

     "Those goddamn programs are our ambassadors into space... the Emissary from Earth." She paused a moment to savor the phrase. "With an ambassador, you're supposed to put your best foot forward, and we've been sending mainly crap to space for forty years. I'd like to see the network executives come to grips with this one. And that madman Hitler, that's the first news they have about Earth? What are they going to think of us?"

     *  *  *

     As der Heer and the President entered the Cabinet Room, those who had been standing in small groups fell silent, and some who had been seated made efforts to stand. With a perfunctory gesture, the President conveyed a preference for informality and casually greeted the Secretary of State and an Assistant Secretary of Defense. With a slow and deliberate turn of the head, she scanned the group. Some returned her gaze expectantly. Others, detecting an expression of minor annoyance on the President's face, averted their eyes.

     "Ken, isn't that astronomer of yours here? Arrowsmith? Arrowroot?"

     "Arroway, Ms. President. She and Dr. Valerian arrived last night. Maybe they've been held up in traffic."

     "Dr. Arroway called from her hotel, Ms. President," volunteered a meticulously groomed young man. "She said there were some new data coming through on her telefax, and she wanted to bring it to this meeting. We're supposed to start without her."

     Michael Kitz leaned forward, his tone and expression incredulous. "They're transmitting new data on this subject over an open telephone, insecure, in a Washington hotel room?"

     Der Heer responded so softly that Kitz had to lean still further forward to hear. "Mike, I think there's at least commercial encryption on her telefax. But remember there are no security guidelines established in this matter. I'm sure that Dr. Arroway will be cooperative if guidelines are established."

     "All right, let's begin," said the President. "This is a joint informal meeting of the National Security Council and what for the time being we're calling the Special Contingency Task Group. I want to impress on all of you that nothing said in this room--I mean nothing--is to be discussed with anyone who isn't here, except for the Secretary of Defense and the Vice President, who are overseas. Yesterday, Dr. der Heer gave most of you a briefing on this unbelievable TV program from the star Vega. It's the view of Dr. der Heer and others"--she looked around the table--"that it's just a fluke that the first television program to get to Vega starred Adolf Hitler. But it's... an embarrassment. I've asked the Director of Central Intelligence to prepare an assessment of any national security implications in all of this. Is there any direct threat from whoever the hell is sending this? Are we going to be in trouble if there's some new message, and some other country decodes it first? But first let me ask, Marvin, does this have anything to do with flying saucers?"

     The Director of Central Intelligence, an authoritative man in late middle age, wearing steel-rimmed glasses, summarized. Unidentified Flying Objects, called UFO's, have been of intermittent concern to the CIA and the Air Force, especially in the '50s and '60s, in part because rumors about them might be a means for hostile power to spread confusion or to overload communications channels. A few of the more reliably reported incidents turned out to be penetrations of U.S. air space or overflights of U.S. overseas bases by high-performance aircraft from the Soviet Union or Cuba. Such overflights are a common means of testing a potential adversary's readiness, and the United States had more than its fair share of penetrations, and feints at penetration, of Soviet air space. A Cuban MiG penetrating 200 miles up the Mississippi Basin before being detected was considered undesirable publicity by NORAD. The routine procedure had been for the Air Force to deny that any of its aircraft were in the vicinity of the UFO sighting, and to volunteer nothing about unauthorized penetrations, thus solidifying public mystification. At these explanations, the Air Force Chief of Staff looked marginally uncomfortable but said nothing.

     The great majority of UFO reports, the DCI continued, were natural objects misapprehended by the observer. Unconventional or experimental aircraft, automobile headlights reflected off overcast, balloons, birds, luminescent insects, even planets and stars seen under unusual atmospheric conditions, had all been reported as UFO's. A significant number of reports turned out to be hoaxes or real psychiatric delusions. There had been more than a million UFO sightings reported worldwide since the term "flying saucer" had been invented in the late '40s, and not one of them seemed on good evidence to be connected with an extraterrestrial visitation. But the idea generated powerful emotions, and there were fringe groups and publications, and even some academic scientists, that kept alive the supposed connection between UFO's and life on other worlds. Recent millenarian doctrine included its share of saucer-borne extraterrestrial redeemers. The official Air Force investigation, called in one of its final incarnations Project Blue Book, had been closed down in the '60s for lack of progress, although a low-level continuing interest had been maintained jointly by the Air Force and the CIA. The scientific community had been so convinced there was nothing to it that when Jimmy Carter requested the National Aeronautics and Space Administration to make a comprehensive study of UFO's, NASA uncharacteristically refused a presidential request.

     "In fact," interjected one of the scientists at the table, unfamiliar with the protocol in meetings such as this, "the UFO business has made it more difficult to do serious SETI work."

     "All right." The President sighed. "Is there anybody around this table who thinks UFO's and this signal from Vega have anything to do with each other?" Der Heer inspected his fingernails. No one spoke.

     "Just the same, there's going to be an awful lot of I-told-you-so's from the UFO yo-yos. Marvin, why don't you continue?"

     "In 1936, Ms. President, a very faint television signal transmits the opening ceremonies of the Olympic Games to a handful of television receivers in the Berlin area. It's an attempt at a public relations coup. It shows the progress and superiority of German technology. There were a few earlier TV transmissions, but all at very low power levels. Actually, we did it before the Germans. Secretary of Commerce Herbert Hoover made a brief television appearance on... April twenty-seventh, 1927. Anyway, the German signal leaves the Earth at the speed of light, and twenty-six years later it arrives on Vega. They sit on the signal for a few years--whoever `they' are--and then send it back to us hugely amplified. Their ability to receive that very weak signal is impressive, and their ability to return it at such high power levels is impressive. There certainly are security implications here. The electronic intelligence community, for example, would like to know how such weak signals can be detected. Those people, or whatever they are, on Vega are certainly more advanced than we are--maybe only a few decades further along, but maybe much further along than that.

     "They've given us no other information about themselves--except at some frequencies the transmitted signal doesn't show the Doppler effect from the motion of their planet around their star. They've simplified that data reduction step for us. They're... helpful. So far, nothing of military or any other interest has been received. All they've been saying is that they're good at radio astronomy, they like prime numbers, and they can return our first TV transmission back to us. It couldn't hurt for any other nation to know that. And remember: All those other countries are receiving this same three-minute Hitler clip, over and over again. They just haven't figured out how to read it yet. The Russians or the Germans or someone is likely to tumble to this polarization modulation sooner or later. My personal impression, Ms. President--I don't know if State agrees--is that it would be better if we released it to the world before we're accused of covering something up. If the situation remains static--with no big change from where we are right now-- we could think about making a public announcement, or even releasing that three-minute film clip.

     "Incidentally, we haven't been able to find any record from German archives of what was in that original broadcast. We can't be absolutely sure that the people on Vega haven't made some change in the content before sending it back to us. We can recognize Hitler, all right, and the part of the Olympic stadium we see corresponds accurately to Berlin in 1936. But if at that moment Hitler had really been scratching his mustache instead of smiling as in that transmission, we'd have no way to know."

     Ellie arrived slightly breathless, followed by Valerian. They attempted to take obscure chairs against the wall, but der Heer noticed and directed the President's attention to them.

     "Dr. arrow-uh-way? I'm glad to see you've arrived safely. First, let me congratulate you on a splendid discovery. Splendid. Um, Marvin..."

     "I've reached a stopping point, Ms. President."

     "Good. Dr. Arroway, we understand you have something new. Would you care to tell us about it?"

     "Ms. President, sorry to be late, but I think we've just hit the cosmic jackpot. We've.. It's... Let me try and explain it this way: In classical times, thousands of years ago, when parchment was in short supply, people would write over an old parchment, making what's called a palimpsest. There was writing under writing under writing. This signal from Vega is, of course, very strong. As you know, there's the prime numbers, and `underneath' them, in what's called polarization modulation, this eerie Hitler business. But underneath the sequence of prime numbers and underneath the retransmitted Olympic broadcast, we've just uncovered an incredibly rich message--at least we're pretty sure it's a message. As far as we can tell, it's been there all along. We've just detected it. It's weaker than the announcement signal, but I'm embarrassed we didn't find it sooner."

     "What does it say?" the President asked. "What's it about?"

     "We haven't the foggiest idea, Ms. President. Some of the people at Project Argus tumbled to it early this morning Washington time. We've been working on it all night."

     "Over an open phone?" asked Kitz.

     "With standard commercial encryption." Ellie looked a little flushed. Opening her telefax case, she quickly generated a transparency printout and, when an overhead projector, cast its image against a screen.

     "Here's all we know up to now: We'll get a block of information comprising about a thousand bits. There'll be a pause, and then the same block will be repeated, bit for bit. Then there'll be another pause, and we'll go on to the next block. It's repeated as well. The repetition of every block is probably to minimize transmission errors. They must think it's very important that we get whatever it is they're saying down accurately. Now, let's call each of these blocks of information a page. Argus is picking up a few dozen of these pages a day. But we don't know what they're about. They're not a simple picture code like the Olympic message. This is something much deeper and much richer. It appears to be, for the first time, information they've generated. The only clue we have so far is that the pages seem to be numbered. At the beginning of every page there's a number in binary arithmetic. See this one here? And every time another pair of identical pages shows up, it's labeled with the next higher number. Right now we're on page... 10,413. It's a big book. Calculating back, it seems that the message began about three months ago. We're lucky to have picked it up as early as we did."

     "I was right, wasn't I?" Kitz leaned across the table to der Heer. "This isn't the kind of message you want to give to the Japanese or the Chinese or the Russians, is it?"

     "Is it going to be easy to figure out?" the President asked over the whispering Kitz.

     "We will, of course, make out best efforts. And it probably would be useful to have the National Security Agency work on it also. But without an explanation from Vega, without a primer, my guess is that we're not going to make much progress. It certainly doesn't seem to be written in English or German or any other Earthly language. Our hope is that the Message will come to an end, maybe on page 20,000 or page 30,000, and then start right over from the beginning, so we'll be able to fill in the missing parts. Maybe before the whole Message repeats, there'll be a primer, a kind of McGuffey's Reader, that will enable us to understand the Message."

     "If I may, Ms. President--"

     "Ms. President, this is Dr. Peter Valerian of the California Institute of Technology, one of the pioneers in this field."

     "Please go ahead, Dr. Valerian."

     "This is an intentional transmission to us. They know we're here. They have some idea, from having intercepted out 1936 broadcast, of where our technology is, of how smart we are. They wouldn't be going to all this trouble if they didn't want us to understand the Message. Somewhere in there is the key to help us understand it. It's only a question of accumulating all the data and analyzing it very carefully."

     "Well, what do you suppose the Message is about?"

     "I don't see any way to tell, Ms. President. I can only repeat what Dr. Arroway said. It's an intricate and complex Message. The transmitting civilization is eager for us to receive it. Maybe all this is one small volume of the Encyclopedia Galactica. The star Vega is about three times more massive than the Sun and about fifty times brighter. Because it burns its nuclear fuel so fast, it has a much shorter lifetime than the Sun--"

     "Yes. Maybe something's about to go wrong on Vega," the Director of Central Intelligence interrupted. "Maybe their planet will be destroyed. Maybe they want someone else to know about their civilization before they're wiped out."

     "Or," offered Kitz, "maybe they're looking for a new place to move to, and the Earth would suit them just fine. Maybe it's no accident they chose to send us a picture of Adolf Hitler."

     "Hold on," Ellie said, "there are a lot of possibilities, but not everything is possible. There's no way for the transmitting civilization to know whether we've received the Message, much less whether we're making any progress in decoding it. If we find the Message offensive we're not obliged to reply. And even if we did reply, it would be twenty-six years before they received the reply, and another twenty-six years before they can answer it. The speed of light is fast, but it's not infinitely fast. We're very nicely quarantined from Vega. And if there's anything that worries us about this new Message, we have decades to decide what to do about it. Let's not panic quite yet." She enunciated these last words while offering a pleasant smile to Kitz.

     "I appreciate those remarks, Dr. Arroway," returned the President. "But things are happening fast. Too damn fast. And there are too many maybes. I haven't even made a public announcement about all of this. Not even the prime numbers, never mind the Hitler bullcrap. Now we have to think about this `book' you say they're sending. And because you scientists think nothing of talking to each other, the rumors are flying. Phyllis, where's that file? Here, look at these headlines."

     Brandished successively at arm's length, they all carried the same message, with minor variations in journalistic artistry: "Space Doc Says Radio Show from Bug-Eyed Monsters," "Astronomical Telegram Hints at Extraterrestrial Intelligence," "Voice from Heaven?" and "The Aliens Are Coming! The Aliens Are Coming! "She let the clippings flutter tot he table.

     "At least the Hitler story hasn't broken yet. I'm waiting for those headlines: `Hitler Alive and Well in Space, U.S. Says.' And worse. Much worse. I think we'd better curtail this meeting and reconvene later."

     "If I may, Ms. President," der Heer interrupted haltingly, with evident reluctance. "I beg your pardon, but there are some international implications that I think have to be raised now."

     The President merely exhaled, acquiescing.

     Der Heer continued. "Tell me if I have this right, Dr. Arroway. Every day the star Vega rises over the New Mexico desert, and then you get whatever page of this complex transmission--whatever it is--they happen to be sending to the Earth at the moment. Then, eight hours later or something, the star sets. Right so far? Okay. Then the next day the star rises again in the east, but you've lost some pages during the time you weren't able to look at it, after it had set the previous night. Right? So it's as if you were getting pages thirty through fifty and then pages eighty through a hundred, and so on. No matter how patiently we observe, we're going to have enormous amounts of information missing. Gaps. Even if the message eventually repeats itself, we're going to have gaps."

     "That's entirely right." Ellie rose and approached an enormous globe of the world. Evidently the White House was opposed to the obliquity of the Earth; the axis of this globe was defiantly vertical. Tentatively, she gave it a spin. "The Earth turns. You need radio telescopes distributed evenly over many longitudes if you don't want gaps. Any one nation observing only from its own territory is going to dip into the message and dip out--maybe even at the most interesting parts. Now this is the same kind of problem that an American interplanetary spacecraft faces. It broadcasts its findings back to Earth when it passes by some planet, but the United States might be facing the other way at the time. So NASA has arranged for three radio tracking stations to be distributed evenly in longitude around the Earth. Over the decades they've performed superbly. But..." Her voice trailed off diffidently, and she looked directly at P.L. Garrison, the NASA Administrator. A thin, sallow, friendly man, he blinked.

     "Uh, thank you. Yes. It's called the Deep S[ace Network, and we're very proud of it. We have stations in the Mojave Desert, in Spain, and in Australia. Of course, we're underfunded, but with a little help, I'm sure we could get up to speed."

     "Spain and Australia?" the President asked.

     "For purely scientific work," the Secretary of State was saying, "I'm sure there's no problem. However, if this research program had political overtones, it might be a little tricky."

     American relations with both countries had become cool of late.

     "There's no question this has political overtones," the President replied a little testily.

     "But we don't have to be tied to the surface of the earth," interjected an Air Force general. "We can beat the rotation period. All we need is a large radio telescope in Earth orbit."

     "All right." The President again glanced around the table. "Do we have a space radio telescope? How long would it take to get one up? Who knows about this? Dr. Garrison?"

     "Uh, no, Ms. President. We at NASA have submitted a proposal for the Maxwell Observatory in each of the last three fiscal years, but OMB has removed it from the budget each time. We have a detailed design study, of course, but it would take years--well, three years anyway--before we could get it up. And I feel I should remind everybody that until last fall the Russians had a working millimeter and submillimeter wave telescope in Earth orbit. We don't know why it failed, but they'd be in a better position to send some cosmonauts up to fix it than we'd be to build and launch one from scratch."