Tau Zero

“M-m-m … yes, in a way… Ai-Ling, you know Iwasaki pretty well. Do you think he can manage without tranquilizers? The doctor and I weren’t sure.”

“Hush.” Her palm covered his mouth. “None of that.”

“But—”

“No, I will not have it. The ship isn’t going to fall apart if you get one decent night’s sleep.”

“Well … well … maybe not.”

“Close your eyes. Let me stroke your forehead — there. Isn’t that better already? Now think of nice things.”

“Like what?”

“Have you forgotten? Think of home. No. Best not that, I suppose. Think of the home we are going to find. Blue sky. Warm bright sun, light falling through leaves, dappling the shade, blinking on a river; and the river flows, flows, flows, singing you to sleep.”

“Um-m-m.”

She kissed him very lightly. “Our own house. A garden. Strange colorful flowers. Oh, but we will plant seeds from Earth too, roses, honeysuckle, apple, rosemary for remembrance. Our children…”

He stirred. The fret returned to him. “Wait a minute, we can’t make personal commitments. Not yet. You might not want, uh, any given man. I’mfondofyou, of course, but—”

She brushed his lids shut again before he saw the pain on her. “We are daydreaming, Charles,” she laughed low. “Stop being all solemn and literal-minded. Just think about children, everyone’s children, playing in a garden. Think about the river. Forests. Mountains. Bird song. Peace.”

He tightened an arm around her slenderness. “You’re a good person.”

“You are yourself. A good person who ought to be cuddled. Would you like me to sing you to sleep?”

“Yes.” His words were becoming indistinct. “Please. I like Chinese music.”

She continued smoothing his brow while she drew breath.

The intercom circuit clicked shut. “Constable,” said Telander’s voice, “are you there?”

Reymont snapped awake. “Don’t,” Chi-Yuen begged.

“Yes,” Reymont said, “here I am.”

“Would you come to the bridge? Confidential.”

“Aye, aye.” Reymont undid his lifeline and pulled the pajama top over his head.

“They could not give you five minutes, could they?” Chi-Yuen said.

“Must be serious,” he answered. “Don’t mention it around until you hear from me.” In a few motions he had resumed coverall and shoes and was on his way.

Telander and, surprisingly, Nilsson awaited him. The captain looked as if he had been struck in the belly. The astronomer was excited but had not wholly lost his self-command of recent months. He clutched a bescribbled sheet of paper.

“Navigation difficulties, eh?” Reymont deduced. “Where’s Boudreau?”

“This doesn’t concern him immediately,” Nilsson said. ‘‘I have been computing the significance of observations I’ve made with the newest instruments. I have reached a, ah, frustrating conclusion.”

Reymont wrapped fingers around a grip and hung in the stillness, regarding them. The fluorolight cast the hollows of his face into shadow. The gray streaks which had lately appeared in his hair stood forth sharp by contrast. “We can’t make that galactic clan ahead of us after all,” he foretold.

“That’s right.” Telander drooped.

“No, not right in a strict sense,” Nilsson declared fussily. ‘‘We will pass through. In fact, we will pass through not only the general region, but — if we choose — through a quite a fair number of galaxies within certain of the families which comprise the clan.”

“You can distinguish thatmuch detail already?” Reymont wondered; “Boudreau couldn’t.”

“I told you I have new equipment, with its balkiness now tinkered out,” Nilsson said. “You recollect that after Ingrid gave me some special lessons, I became able to work in free fall with a degree of efficiency. The precision of my data seems even more than hoped for when, ah, we instigated the project. Yes, I have a reasonably accurate map of that part of the clan which we might traverse. On such basis, I have calculated what options are open to us.”

“Get to the point. God damn you!” Reymont yelled. At once he curbed himself, inhaled, and said: “Apologies. I’m a little overwrought. Please go on. Once we get in where the jets have a decent amount of matter to work on, why can’t we brake?”

“We can,” Nilsson replied quickly. “Certainly we can. But our inverse tau is immense. Remember, we acquired it by passing through the densest attainable portions of several galaxies, en route to interclan space. It was necessary. I don’t dispute the wisdom of the decision. Nevertheless, the result is that we are limited in what paths we can take that intersect the space occupied by this clan. The paths form a rather narrow conoidal volume, as you might guess.”

Reymont gnawed his lip. “And it turns out there doesn’t happen to be enough matter in that cone.”

“Correct.” Nilsson’s head bobbed. “Among other things, the difference in velocity between us and these galaxies, due to the expansion of space, reduces the effectiveness of our Bussard engine more than it reduces the amount of deceleration required.”

His professorial ma

The pompous voice cut off, the beady eyes looked expectant. Reymont met them rather than Telander’s sick, gutted stare. “Why am I being told this, and not Lindgren?” he asked.

A tenderness made Nilsson, briefly, another man. “She works cruelly hard. What can she do here? I thought I had best let her sleep.”

“Well, what can I do?”

“Give me … us … your advice,” Telander said.

“But sir, you’re the captain!”

“We have been over this ground before, Carl. I can, well, yes, I suppose I can make the decisions, issue the commands, order the routines, which will take us crashing on through space.” Telander extended his hands. They trembled like autumn leaves. “More than that I can no longer do, Carl. I have not the strength left. You must tell our shipmates.”

“Tell them we’ve failed?” Reymont grated. “Tell them, in spite of everything we did, we’re damned to fly on till we go crazy and die? You don’t want much of me, do you, Captain?”

“The news may not be that bad,” Nilsson said.

Reymont snatched at him, missed and hung with a raw noise in his throat. “We have some hope?” he managed finally.

The fat man spoke with a briskness that turned his pedantry into a sort of bugle call: “Perhaps. I have no worthwhile data. The distances are too vast. We ca

“Someplace, eventually, we could meet the right configuration. Either an especially large clan through whose galaxy-densest portions we can lay a course; or else two or three clans, rather close to each other, more or less along a straight line, so that we can pass through them in succession; or else one whose velocity with respect to us happens to be favorable. Do you see? If we could come upon something like that, we would be in reasonable shape. We would be able to brake in a few years of ship’s time.”

“What are the odds?” Reymont’s words clanked.

Now Nilsson shook his head. “I ca

“How long is sufficiently long?” Reymont made a gesture to halt. ‘‘don’t bother answering. I can tell. It’s on the order of billions of years. Tens of billions, maybe. That means we’ve got to have a lower tau yet. A tau so low that we can actually circumnavigate the universe … in years or in months. And that, in turn, means we can’t start slowing as we enter this clan up ahead. No. We accelerate again. After we’ve passed through — well, we should have a shorter period of ship’s time in free fall than the current one has been, until we strike another clan. Probably there, too, we’ll find it advisable to accelerate, ru