Tau Zero

by Poul Anderson

  Nonetheless, Reymont haled Nilsson to the interview room.

  Ingrid Lindgren took her place behind its desk, in uniform. She had lost weight, and her eyes were shadowed. The cabin thrummed abnormally loud, and frequent shocks went through bulkheads and deck. The ship felt irregularities in the clouds as gusts, currents, vortices of an ongoing creation of worlds.

  “Can this not wait till we have made our passage, Constable?” she asked, alike in anger and weariness.

  “I don’t think so, madame,” Reymont replied. “Should an emergency arise, we need people convinced it’s worth coping with.”

  “You accuse Professor Nilsson of spreading disaffection. The articles provide for free speech.”

  His chair creaked beneath the astromoner’s shifting weight. “I am a scientist,” he declared waspishly. “I have not only the right but the obligation to state what is true.”

  Lindgren regarded him with disfavor. He was letting a scraggly beard grow on his chins, had not bathed of late, and was in grimy coveralls.

  “You don’t have the right to spread horror stories,” Reymont said. “Didn’t you notice what you were doing to some of the women, especially, when you talked the way you did at mess? That’s what decided me to intervene; but you’d been building up the trouble for quite a while before, Nilsson.”

  “I merely brought out into the open what has been common knowledge from the start,” the fat man retorted. “They hadn’t the courage to discuss it in detail. I do.”

  “They hadn’t the meanness. You do.”

  “No personalities,” Lindgren said. “Tell me what happened.” She had recently been taking her meals alone in her cabin, pleading busyness, and was not seen much off watch.

  “You know,” Nilsson said. “We’ve raised the subject on occasion.”

  “What subject?” she asked. “We’ve talked about many.”

  “Talked, yes, like reasonable people,” Reymont snapped. “Not lectured a tableful of shipmates, most of them feeling low already.”

  “Please, Constable. Proceed, Professor Nilsson.”

  The astronomer puffed himself up. “An elementary thing. I cannot comprehend why the rest of you have been such idiots as not to give it serious consideration. You blandly assume we will come to rest in a Virgo galaxy and find a habitable planet. But tell me how. Think of the requirements. Mass, temperature, irradiation, atmosphere, hydrosphere, biosphere … the best estimate is that 1 per cent of the stars may have planets which are any approximation to Earth.”

  “That,” Lindgren said. “Why, certainly—”

  Nilsson was not to be deprived of his platform. Perhaps he didn’t bother to hear her. He ticked points off on his fingers. “If 1 per cent of the stars are suitable, do you realize how many we will have to examine in order to have an even chance of finding what we seek? Fifty! I should have thought anyone aboard would be capable of that calculation. It is conceivable that we will be lucky and come upon our Nova Terra at the first star we try. But the odds against this are ninety-nine to one. Doubtless we must try many. Now the examination of each involves almost a year of deceleration. To depart from it, in search elsewhere, requires another year of acceleration. Those are years of ship’s time, remember, because nearly the whole period is spent at velocities which are small compared to light’s and thus involve a tau factor near unity: which, in addition, prevents our going above one gravity.

  “Hence we must allow a minimum of two years per star. The even chance of which I spoke — and mind you, it is only even — the odds are as good that we will not find Nova Terra in the first fifty stars as they are that we will — this chance requires a hundred years of search. Actually it requires more, because we shall have to stop from time to time and laboriously replenish the reaction mass for the ion drive. Antisenescence or no, we will not live that long.

  “Therefore our whole endeavor, the risks we take in this fantastic dive straight through the galaxy and out into intergalactic space, it is all an exercise in futility. Quod erat demonstrandum.”

  “Among your many loathsome characteristics, Nilsson,” Reymont said, “is your habit of droning the obvious through your nose.”

  “Madame!” the astronomer gasped. “I protest! I shall file charges of personal abuse!”

  “Cut back,” Lindgren ordered. “Both of you. I must admit your conduct offers provocation, Professor Nilsson. On the other hand, Constable, may I remind you that Professor Nilsson is one of the most distinguished men in his vocation that Earth has … Earth had. He deserves respect.”

  “Not the way he behaves,” Reymont said. “Or smells.”

  “Be polite, Constable, or I’ll charge you myself.” Lindgren drew breath. “You don’t seem to make allowance for humanness. We are adrift in space and time; the world we knew is a hundred thousand years in its grave; we are rushing nearly blind into the most crowded part of the galaxy; we may at any minute strike something that will destroy us; at best, we must look forward to years in a cramped and barren environment. Don’t you expect people to react to that?”

  “Yes, madame, I do,” Reymont said. “I do not expect them to behave so as to make matters worse.”

  “There is some truth in that,” Lindgren conceded.

  Nilsson squirmed and looked sulky. “I was trying to spare them disappointment at the end of this flight,” he muttered.

  “Are you absolutely certain you weren’t indulging your ego?” Lindgren sighed. “Never mind. Your standpoint is legitimate.”

  “No, it isn’t,” Reymont contradicted. “He gets his 1 per cent by counting every star. But obviously we aren’t going to bother with red dwarfs — the vast majority — or blue giants or anything outside a fairly narrow spectral range. Which reduces the field of search by a whopping factor.”

  “Make the factor ten,” Nilsson said. “I don’t really believe that, but let’s postulate we have a 10 per cent probability of finding Nova Terra at any one of the Sol-type stars we try. That nevertheless requires us to hunt among five to get our even chance. Ten years? More like twenty, all things considered. The youngest among us will be getting past his youth. The loss of so many reproductive opportunities means a corresponding loss of heredity; and our gene pool is minimal to start with. If we wait several decades to beget children, we can’t beget enough. Few will be grown to self-sufficiency by the time their parents start becoming helpless with advancing age. And in any case, the human stock will die out in three or four generations. I know something about genetic drift, you see.”

  His expression grew smug. “I didn’t wish to hurt feelings,” he said. “My desire was to help, by showing your concept of a bold pioneer community, planting humankind afresh in a new galaxy … showing that for the infantile fantasy which it is.”

  “Have you an alternative?” Lindgren inquired.

  A tic began in Nilsson’s face. “Nothing but realism,” he said. “Acceptance of the fact that we will never leave this ship. Adjustment of our behavior to that fact.”

  “Is it the reason you’ve been soldiering on the job?” Reymont demanded.

  “I dislike your term, sir, but it is true there is no point in building equipment for long-range navigation. We are not going anywhere that makes any difference. I cannot even get enthusiatic about Fedoroff’s and Pereira’s proposals concerning the life support systems.”

  “You understand, I suppose,” Reymont said, “that for maybe half the people aboard, the logical thing to do once they’ve decided you’re right, is to commit suicide.”

  “Possibly.” Nilsson shrugged.

  “Do you hate life so much yourself?” Lindgren asked.

  Nilsson half got up and fell down again. He gobbled. Reymont surprised both his listeners by turning soft-mannered:

  “I didn’t fetch you here only to get your gloom-peddling stopped. I’d rather know why you haven’t been thinking how to improve our chances.”

  “How can they be?”

  “That’s what I want to learn fr
om you. You’re the observational expert. As I recall, you were in charge of programs back home which located something like fifty planetary systems. You actually identified individual planets, and typed them, across light-years. Why can’t you do the same for us?”

  Nilsson pounced. “Ridiculous! I see that I must explain the topic in kindergarten terms. Will you bear with me, First Officer? Pay attention, Constable.

  “Granted, an extremely large space-borne instrument can pick out an object the size of Jupiter at a distance of several parsecs. This is provided the object gets good illumination without becoming lost in the glare of its sun. Granted, by mathematical analysis of perturbation data gathered over a period of years, some idea can be obtained about companion planets which are too small to photograph. Ambiguities in the equations can, to a degree, be resolved by close interferometric study of flare-type phenomena on the star; planets do exert a minor influence upon those cycles.

  “But” — his finger prodded Reymont’s chest — “you do not realize how uncertain those results are.

  Journalists delighted in trumpeting that another Earthlike world had been discovered. The fact always was, however, that this was one possible interpretation of our data. Only one among numerous possible size and orbit distributions. And subject to a gross probable error. And this, mind you, with the largest, finest instruments which could be constructed. Instruments such as we do not have with us here, nor have room for if we could somehow build them.

  “No, even at home, me sole way to get detailed information about extrasolar planets was to send a probe and later a manned expedition. In our case, the sole way is to decelerate for a close survey. And thereafter, I am convinced, to go on. Because you must be aware that a planet which otherwise seems ideal can be sterile or can have a native biochemistry that is useless or outright deadly to us.

  “I implore you, Constable, to learn a little science, a little logic, and a bare touch of realism. Eh?” Nilsson ended with a crow of triumph.

  “Professor—” Lindgren tried.

  Reymont smiled crookedly. “Don’t worry, madame,” he said. “No fight will come of it. His words don’t diminish me.”

  He inspected the other man. “Believe it or not,” he went on, “I knew what you’ve told us. I also knew you are, or were, an able fellow. You made innovations, designed gadgets, that were responsible for a lot of discoveries. You were doing a fine job for us till you quit. Why not put your brain to work on the problems we have?”

  “Will you be so good as to condescend to suggest a procedure?” Nilsson sneered.

  “I’m no scientist, nor much of a technician,” Reymont said. “Still, a few things look obvious to me. Let’s suppose we have entered our target galaxy. We’ve shed the ultra-low tau we needed to get there, but we have one yet of … oh, whatever is convenient. Ten to the minus third, maybe? Well, that gives you a terrifically long baseline and cosmic-time period to make your observations. In the course of weeks or months, ship’s time, you can collect more data on a given star than you had on any of Sol’s neighbors. I should think you could find ways to use relativity effects to give you information that wasn’t available at home. And naturally, you can observe a large number of Sol-type stars simultaneously. So you’re bound to find some you can prove — prove with exact figures that leave no reasonable doubt — have planets with masses and orbits about like Earth’s.”

  “Assuming that, the question of atmosphere, biosphere, will remain. We need a short-range look.”

  “Yes, yes. Must we stop to take it, though? Suppose, instead, we lay out a course which brings us hard by the most promising suns, in sequence, while we continue to travel near light-speed. In cosmic time, we’ll have hours or days to check whatever planet interests us. Spectroscopic, thermoscopic, photographic, magnetic, write your own list of clues. We can get a fair idea of conditions on the surface. Biological conditions too. We could look for items like thermodynamic disequilibrium, chlorophyl-reflection spectra, polarization by microbe populations based on L-amino acids … yes, I imagine we can get an excellent notion of whether that planet is suitable. At low tau, we can examine any number in a small stretch of our own time. We’ll have to use automation and electronics, in fact; we ourselves couldn’t work fast enough. Then, when we’ve identified the right world, we can return to it. That will take a couple of years, agreed. But they’ll be endurable years. We’ll know, with high probability, that we have a home waiting for us.”

  Color mounted in Lindgren’s features. Her eyes grew less dull. “Good’Lord,” she said, “why didn’t you speak of this before?” “I’d other problems on my mind,” Reymont answered. “Why didn’t you, Professor Nilsson?”

  “Because the whole thing is absurd,” the astronomer snorted. “You presuppose instrumentation we do not have.”

  “Can’t we build it? We have tools, precision equipment, construction supplies, skilled workmen. Your team has already made progress.”

  “You demand speed and sensitivity increased by whole orders of magnitude over anything that ever existed.”

  “Well?” Reymont said.

  Nilsson and Lindgren stared at him. The ship trembled.

  “Well, why can’t we develop what we need?” Reymont asked in a puzzled voice. “We have some of the most talented, highly trained, imaginative people our civilization produced. They include every branch of science; what they don’t know, they can find in the microtapes; they’re used to interdisciplinary work.

  “Suppose, for instance, Emma Glassgold and Norbert Williams got together to draw up the specifications for a device to detect and analyze life at a distance. They’d consult others as needed. Eventually they’d employ physicists, electronicians, and the rest for the actual building and debugging. Meanwhile, Professon Nilsson, you may have been in charge of a group making tools for remote planetography. In fact, you’re the logical man to head up the entire program.”

  Hardness fell from him. He exclaimed, eager as a boy: “Why, this is precisely what we’ve needed! A fascinating, vital sort of job that demands everything everybody can give. Those whose specialties aren’t called for, they’ll be in it too — assistants, draftsmen, manual workers… I suppose we’ll have to remodel a cargo deck to accommodate the gear… Ingrid, it’s a way to save not just our lives but our minds!”

  He sprang to his feet. She did too. Their hands clasped.

  Suddenly they became aware of Nilsson. He sat less than dwarfish, hunched, shivering, collapsed.

  Lindgren went to him in alarm. “What’s wrong?”

  His head did not lift. “Impossible,” he mumbled. “Impossible.”

  “Surely not,” she urged. “I mean, you wouldn’t have to discover new laws of nature, would you? The basic principles are known.”

  “They must be applied in unheard-of ways.” Nilsson covered his face. “God better me, I haven’t the brains any longer.”

  Lindgren and Reymont exchanged a look above his bent back. She shaped unspoken words. Once he had taught her the Rescue Corps trick of lip reading when spacesuit radios were unusable. They had practiced it as something that made them more private and more one. “Can we succeed without him?”

  “I doubt it. He is the best chief for that kind of project. At least, lacking him, our chance is poor.”

  Lindgren squatted down beside Nilsson. She laid an arm across his shoulders. “What’s the trouble?” she asked most softly.

  “I have no hope,” he snuffled. “Nothing to live for.”

  “You do!”

  “You know Jane … deserted me … months ago. No other woman will — Why should I care? What’s left for me?”

  Reymont’s lips formed, “So behind everything was self-pity.” Lindgren frowned and shook her head.

  “No, you’re mistaken, Elof,” she murmured. “We do care for you. Would we ask for your help if we didn’t honor you?.”

  “My mind.” He sat straight and glared at her out of swimming eyes. “You want my intelligence, ri
ght. My advice. My knowledge and talent. To save yourselves. But do you want me? Do you think of me as, as a human being? No! Dirty old Nilsson. One is barely polite to him. When he starts to talk, one finds the earliest possible excuse to leave. One does not invite him to one’s cabin parties. At most, if desperate, one asks him to be a fourth for bridge or to start an instrument development effort. What do you expect him to do? Thank you?”

  “That isn’t true!”

  “Oh, I’m not as childish as some,” he said. “I’d help if I were able. But my mind is blank, I tell you. I haven’t had an original thought in weeks. Call it fear of death paralyzing me. Call it a sort of impotence. I don’t care what you call it. Because you don’t care either. No one has offered me friendship, company, anything. I have been left alone in the dark and the cold. Do you wonder that my mind is frozen?”

  Lindgren looked away, hiding what expressions chased across her. When she confronted Nilsson again, she had put on calm.

  “I can’t say how sorry I am, Elof,” she told him. “You are partly to blame yourself. You acted so, well, self-sufficient, we assumed you didn’t want to be bothered. The way Olga Sobieski, for instance, doesn’t want to. That’s why she moved in with me. When you joined Hussein Sadek—”

  “He keeps the panel closed between our halves,” Nilsson shrilled. “He never raises if. But the soundproofing is imperfect. I hear him and his girls in there.”

  “Now we understand.” Lindgren smiled. “To be quite honest, Elof, I’ve grown bored with my current existence.”

  Nilsson made a strangled noise.

  “I believe we have some personal business to discuss,” Lindgren said. “Do … do you mind. Constable?”

  “No,” said Reymont. “Of course not.” He left the cabin.

  Chapter 15

  Leonora Christine stormed through the galactic nucleus in twenty thousand years. To those aboard, the time was measured in hours. They were hours of dread, while the hull shook and groaned from stress, and the outside view changed from total darkness to a fog made blinding and blazing by crowded star clusters. The chance of striking a sun was not negligible; hidden in a dust cloud, it could be in front of the ship in one perceived instant. (No one knew what would happen to the star. It might go nova. But certainly the vessel would be destroyed, too swiftly for her crew to know they were dead.) On the other hand, this was the region where inverse tau mounted to values that could merely be estimated, not established with precision, absolutely not comprehended.