Poul Anderson - Tau Zero

“How can they be?”

“That’s what I want to learn from 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.