Convergent Series

by Charles Sheffield

  And plenty to think about.

  Rebka closed his eyes and sorted through his worries.

  Begin with Max Perry. After only a couple of days of exposure to the man it was clear that there were two Max Perrys. One was a quiet, dull bureaucrat, someone whom Rebka would expect to find in a dead-end job on any rat-hole world in the Phemus Circle. But somewhere under that there was a second personality, an energetic and subtle person with strong ideas of his own. The second Max Perry seemed to wake only on random occasions.

  No, that was wrong. The other Max awoke when Quake was the issue, and only then. And Max II must be the clever and determined man that Perry had been, all of the time, seven years before—when he was assigned to Dobelle.

  Rebka leaned back in his seat, physically relaxed and mentally active. So. Accept that there was a mystery in Max Perry. But ask if that mystery justified pulling a senior, action-oriented man like Hans Rebka away from a key project involving exploration of Paradox to become an amateur psychologist on the minor world of Opal.

  It did not add up. If the men and women who ran the Phemus Circle were good at anything, it was at conserving resources; and human resources were the most precious of all.

  Look for another motive, another reason for his being assigned there.

  Rebka was not naive enough to believe that his superiors would tell him the whole story behind his assignments. They might not even know the whole story. He had found that out the hard way, on Pelican's Wake. A troubleshooter was expected to be able to operate without a full deck, and Rebka functioned best when he was forced to work things out for himself.

  Terraforming of Quake and Opal?

  His superiors must know that as soon as he saw the planetary doublet of Dobelle he would evaluate both worlds as possible subjects for terraforming. Was that the real reason he had been assigned there? To set in motion that project?

  Still it did not feel right.

  So add in some of the other variables. Four groups were requesting a visit to Quake at Summertide. He might believe that one was a genuine coincidence—the Alliance Council had no reputation for deceit—but four at once was not plausible.

  And the upcoming Summertide would be the biggest ever. Maybe that was the key. They were there for that special Summertide.

  Again, it did not feel complete. Darya Lang had told him that she did not know it was to be a specially big Summertide until Perry had told her.

  Rebka believed her. But that belief itself was suspect. He had left a woman companion behind him on the station orbiting Paradox. No matter what his brain told him, his glands were probably seeking a replacement. In the first two minutes with Lang he had been aware of an attraction between them. And that must make him more cautious in dealing with her, since he wanted to believe her.

  Lang did not know that Opal and Quake were scheduled for monster Summertides. Fine. Believe that, and still it did not mean that she was what she pretended to be. She could have another and more complex role to play.

  Was she what she claimed to be? That could be checked. Before he left Starside, Rebka had already sent an encrypted message through the Bose communications net, asking for confirmation by Circle intelligence that Darya Lang was an expert on Builder artifacts. The reply would be waiting when they returned from Quake. Until then, questions regarding Lang had to be put to one side.

  But there were plenty of other questions left. Hans Rebka was interrupted by a light touch on his arm. He opened his eyes.

  Max Perry was gesturing upward, along the line of the Umbilical. Quake loomed above them, half again as big as when they had started. But at the moment it reflected only the murky dried-blood light of Amaranth. Mandel was hidden behind the planet, and as Summertide approached, its dwarf companion was swinging in closer. Soon night would disappear completely on Quake and Opal.

  "What's happening?" Rebka said. "I thought the Umbilical ran all the way between Opal and Quake." He should have been a little nervous, because it was sheer vacuum outside the car; but Perry had a smile on his face, and he certainly did not act like a man facing disaster.

  "It does," he said. "We're approaching the Winch. We have to be shunted here, and reconnected on the other side of Midway Station. Travelers can go into the station if they want to—it's well equipped, power and food and shelter—but I see no point in that. If you like we can take a closer look at Midway on the way back."

  As Perry spoke, the car they were riding in was swinging away from the main cable and running through a series of gates and connecting rails. Quake had vanished. Midway Station was off to the right. Rebka could see a whole line of ports, any one of them big enough to accept the capsule. He looked back to the place where the main cable of the Umbilical disappeared into bright blue nothingness and then, a few kilometers farther on, reappeared.

  "I don't see any winch."

  "You won't." The second Max Perry was back, alert and energetic. "That's just a name we give it. You see, Opal and Quake are in a near-circular mutual orbit, but their separation distance varies all the time—anything up to four hundred kilometers. A permanent Umbilical can't work unless you have something to reel in or pay out cable. That's what the Winch does."

  "That hole in space?"

  "Right. It works fine, and at Summertide it reels in extra so that the coupling is lost at the surface of Quake. And it's smart enough to leave the tether on Opal intact. But it's all Builder technology. We have no idea where the cable goes to or comes from, or how it knows what to do. People on Quake and Opal don't care, so long as they can raise or lower the Umbilical through the special control sequences."

  Perry's reluctance to visit Quake had vanished at liftoff from Opal. He was peering forward as they rounded the bulk of Midway Station, seeking Quake again in the sky ahead.

  The capsule moved back to attach to the new length of the Umbilical, and they began to pick up speed. Soon they passed the mass center of the Dobelle system, and there was a clear sense of falling toward Quake, their own centrifugal force adding to Quake's gravity. The dark planet grew visibly, minute by minute, in the sky ahead of them. They began to see more surface detail.

  And Rebka could see another change in Perry. The younger man's breathing was faster. He was staring at Quake's approaching surface with rapt attention, his eyes bright and staring. Rebka was willing to bet that his pulse rate had increased.

  But what was down there? Rebka would have given a lot to see Quake through Max Perry's eyes.

  * * *

  Quake had no sea-sized water bodies, but it did have plenty of rivers and small lakes. All around them grew the characteristic dark-green and rust-colored vegetation. Most of it was tough and prickly, but in certain places there flourished a cover of lush ferns, soft and resilient. One of those areas was on the biggest lake's shore, not far from the foot of the Umbilical. It was a natural place for a person to sink down and rest. Or for two people to find other pleasures

  Amy was talking, her voice breathless in his ear. "You're the expert, aren't you?"

  "I don't know about that." He sounded lazy, relaxed. "But I probably know as much about this place as anyone."

  "Same thing. So why won't you bring me here again? You could, Max, if you wanted to. You control the access."

  "I shouldn't have brought you here at all."

  The feeling of power. He had done it originally to show off his new authority, but once on the planet there were other and better reasons. Quake was still safe, still far from Summertide, yet already there was volcanic dust high in the atmosphere. The evenings, flaming in every eight hours, were an unspeakable beauty of red, purple, and gold. He knew of nothing like it in the rest of the universe—nothing he had read, nothing he had heard rumored. Even with his eyes closed, he would still see those glorious colors.

  He had wanted to show it off to Amy—and he did not want to stop looking himself, not just yet. He lay on his back, gazing up past the shattering sunset to the brightening disk of Opal. By his side, Amy had
broken off one of the soft fronds of fern and was tickling his bare chest. After a few moments she moved over him, blocking his view of Opal and gazing down at him with wide, serious eyes.

  "You will, won't you? You will, you definitely will. Say you will."

  "Will what?" He was feigning incomprehension.

  "Will bring me here again. Closer to Summertide."

  "I definitely won't." He rolled his head from side to side on the soft ferns, too lazy to lift it fully. He felt like the king of the world. "It wouldn't be safe, Amy. Not then."

  "Not at Summertide. I get out well before that, while it's still safe. Nobody stays here then."

  "So I could leave with you, when it's still safe. Couldn't I?"

  "No. Not near Summertide."

  Amy was moving her body down toward him, as the last light bled from the air of Quake. He could no longer see her face. It had faded with the dying light.

  "I could." Her lips were an inch away from his. "Say I could. Say yes."

  "No," he repeated. "Not close to Summertide."

  But Amy did not reply. She was busy with other arguments.

  CHAPTER 5

  Summertide

  minus thirty.

  Darya Lang had a terrible sense of anticlimax. To come so far, to steel herself for confrontation and danger and exciting new experiences . . . and then to be left to cool her heels for days on end, while others decided when—and if—she would be allowed to undertake the final and most crucial part of her journey!

  No one in the Alliance had suggested that her task on Quake would be easy. But also no one had suggested that she might have trouble reaching Opal's sister world once she got to the Dobelle system. So far she had not even even seen Quake, except from a distance. She was stuck on Opal's Starside for an indefinite period, with nothing to do, only short-range transportation available to her, and no say in what happened next.

  Perry had given her a whole building to herself, just outside the spaceport. He had assured her that she had complete freedom to wander as she chose, talk to anyone she liked, and do anything that she wanted to.

  Very kind of him. Except that there was no one else in the building, and nothing there but living quarters—and he had told her to be available to meet as soon as he returned. He and Rebka were sure to be away for days. Where was she supposed to go? What was she supposed to do?

  She called maps of Opal onto the display screens. To anyone accustomed to the fixed continents and well-defined land-water boundaries of Sentinel Gate, the maps were curiously unsatisfying. The ocean floor contours of Opal were shown as permanent planetery features, but they seemed to be the only geographic constants. For the Slings themselves she could find no more than the present positions and drift rates of a couple of hundred of the largest of them; plus—an unsettling set of data—the approximate thickness and estimated lifetime of each Sling. At the moment she was standing on a layer of material less than forty meters deep, with a thickness that changed unpredictably every year.

  She turned off the display and sat rubbing her forehead. She did not feel good. Part of it might be the reduced gravity, only four-fifths of standard here on Opal's Starside. But maybe part of it was disorientation produced by rapid interstellar travel. Every test insisted that the Bose Drive produced no physical effects on humans. But she recalled the inhabitants of the old Arks, who permitted themselves only subluminal travel and claimed that the human soul could travel no faster than light-speed.

  If the Ark dwellers were correct, her soul would be a long time catching up with her.

  Darya went to the window and stared up at Opal's cloudy sky. She felt lonely and very far from home. She wished that she could catch a glimpse of Rigel, the nearest supergiant to Sentinel Gate, but the cloud layer was continuous. She was lonely, and she was also annoyed. Hans Rebka might be an interesting character, and interested in her—she had seen the spark in his eyes—but she had not come so far to have all her plans thwarted by the whim of some back-world bureaucrat.

  The way she was feeling, it would be better to walk around the Sling than to remain cooped up inside the low, claustrophobic building. She went outside, to find that a steady drizzle was beginning to fall. Exploration of the Sling on foot in those conditions might be difficult—the surface was uneven clumps of sedges and ferns, on a light and friable soil bound by a tight-rooted and slippery tangle of ground vines.

  But she went barefoot all the time at home, and her naked toes could catch a good purchase on the tough vines. She bent down and slipped off her shoes.

  The ground became more uneven outside the controlled area of the spaceport, and it was tough going. But she needed the exercise. She had traveled a good kilometer and was all set to walk for a long time when a dense clump of ferns a few meters in front of her produced an angry hiss. The tops of the plants bowed down and flattened under the weight of some large, low-slung, and invisible body.

  Darya gasped and jumped backward, sitting down hard on the wet soil. Barefoot walking—or walking of any kind—suddenly seemed like a very bad idea. She scurried back to the spaceport and requisitioned a car. It had a limited flying range, but it could take her past the edge of the Sling and permit her a look at Opal's ocean.

  "You didn't have to worry," said the engineer who gave her the car. He was insisting on showing her how to use the simple controls, though she was quite sure she could have worked them out for herself. "Nothing bad ever makes it shoreside here, an' people didn't bring in nothing dangerous when she was first settled. Nothin' poisonous here, neither. You was all right."

  "What was it?"

  "Big ole tortoise." He was a tall, pale-skinned man with a filthy coverall, a gap-toothed smile, and a very casual manner. "Weighs mebbe half a ton, eats all the time. But only ferns an' grasses an' stuff. You could ride on his back and he'd never notice you."

  "A native form?"

  "Naw." The short lesson on aircar use was over, but he was in no hurry to leave. "No vertebrates native to Opal. Biggest thing ashore is a kind o' four-legged crab."

  "Is there anything dangerous out in the ocean?"

  "Not to you 'n' me. Least, not dangerous by design. When you get a ways offshore, watch for a big, green hump coming up to the surface, 'bout a kilometer across. That'll be a Dowser. It'll damage boats now an' agin, but only 'cause it don't know they're there."

  "Suppose one came up underneath a Sling?"

  "Now why'd she be dumb enough to do that?" His voice was teasing. "She come up for air and sunlight, an' there's none of them under a Sling. Go find yourself a Dowser—seein' one's a real experience. They come up a lot at this time of year. An' you were lucky to meet that ole tortoise, you know. 'Nother few days and he'll be off. They're leaving extra early."

  "Where are they going to?"

  "Ocean. Where else? They know Summertide is on the way, and they want to be nice an' cozy when it comes. Must know it's going to be extra big this year."

  "Will they be safe there?"

  "Sure. Worst thing that can happen to one of 'em is he gets to sit high and dry for a while at real low tide. Couple of hours later, he's back swimmin'."

  He stepped down from the running board on the left side of the car. "If you want to find the quickest way to the edge of the Sling, fly low an' see where the turtles' heads are pointing. That'll get you straight there." He wiped his hands on a dirty rag, leaving them as black as when he started, and gave Darya the warmest, most admiring smile. "Anyone ever tell you you walk an' move real nice? You do. If you want company when you get back, I'll be here. I live right near. Name's Cap."

  Darya Lang took off wondering about the worlds of the Phemus Circle. Or was it was just in the air of Opal, the thing that led men to look at her differently? In twelve adult years on Sentinel Gate she had had one love affair, received maybe four compliments, and noticed half a dozen admiring looks. Here it was two in two days.

  Well, Legate Pereira had told her not to be surprised by anything that happened outside A
lliance territory. And House-uncle Matra had been a lot more explicit when he learned where she was going: "Everyone on the Circle worlds is sex-mad. They have to be, or they'd die out."

  The big turtles were not visible at the flying height she chose, but a path to the edge of the Sling was easy to find. She flew out over the ocean for a while and was gratified to see the monstrous green back of a Dowser rising from the deep. From a distance it could have been a smaller, perfectly round Sling, until the moment when the whole back opened to ten thousand mouths, and each released a hissing spout of white vapor. After ten minutes the vents slowly closed, but the Dowser remained basking in the warm surface water.

  Darya realized for the first time what perfect ecological sense the Slings made on a tidal waterworld like Opal. The tides were a destructive force on worlds like Sentinel Gate, where the rising and falling ocean waters were impeded in their movement by fixed land boundaries. But here everything could move freely, with the Slings riding buoyantly on the changing water surface. In fact, although the Sling that bore Starside's spaceport must even at that very moment be moving up or down in response to the gravitational pull of Mandel and Amaranth, it was completely at rest relative to the ocean's surface. Any disruptive force came from third-order effects produced by its large area.

  The life-forms should be equally safe. Unless a Dowser were unlucky enough to be caught in an area where extra-low tides left the ocean bed exposed, the animal should be totally unaware of Summertide.

  Darya flew to a point near the edge of the Sling, far enough inland to feel comfortable, and set the car down. It was not raining there, and there was even a suggestion that the disk of Mandel might show its face through the clouds. She climbed out and looked around. It was strange to be on a world so empty of people that there was no one to be seen from horizon to horizon. But it was not an unpleasant experience. She walked closer to the edge of the Sling. The soft-stemmed, long-leaved plants that fringed the ocean were bowed down with yellow fruit, each one as big as her fist. If Cap could be believed, they were safe to eat, but that seemed like an unnecessary risk. Although her intestinal flora and fauna had been boosted on arrival by forms suited to Opal, the microorganisms inside her were probably still deciding who did what. She walked closer to the ragged boundary of the Sling, took off her shoes, and leaned forward to scoop up a handful of seawater. That much she was willing to chance.