Convergent Series Read online

  The Overcee touched down on a wide beach on the western shore of the smallest continent. Wall came out first, then Carv lowered a metal oblong as large as himself and followed it down. They wore lightly pressurized vac suits. Carv did nothing for twenty minutes while Wall opened the box out flat and set the carefully packed instruments into their grooves and notches. Finally Wall signaled, in an emphatic manner.

  By taking off his helmet.

  Carv waited a few seconds, then followed suit.

  Wall asked, "Were you waiting to see if I dropped dead?"

  "Better you than me." Carv sniffed the breeze. The air was cool and humid, but thin. "Smells good enough. No. No, it doesn't. It smells like something rotting."

  "Then I'm right. There's life here. Let's get down to the beach."

  The sky looked like a raging thunderstorm, with occasional vivid blue flashes that might have been lightning. They were flashes of sunlight penetrating tier upon tier of cloud. In that varying light Carv and Wall stripped off their suits and went down to look at the ocean, walking with shuffling steps in the light gravity.

  The ocean was thick with algae. Algae were a bubbly green blanket on the water, a blanket that rose and fell like breathing as the insignificant waves ran beneath. The smell of rotting vegetation was no stronger here than it had been a quarter of a mile back. Perhaps the smell pervaded the whole planet.

  The shore was a mixture of sand and green scum so rich that you could have planted crops in it.

  "Time I got to work," said Wall. "You want to fetch and carry for me?"

  "Later maybe. Right now I've got a better idea. Let's get the hell out of each other's sight for an hour."

  "That is brilliant. But take a weapon."

  "To fight off maddened algae?"

  "Take a weapon."

  Carv was back at the end of an hour. The scenery had been deadly monotonous. There was water below a green blanket of scum six inches deep; there was loamy sand, and beyond that dry sand; and behind the beach were white cliffs, smoothed as if by countless rainfalls. He had found no target for his laser cutter.

  Wall looked up from a binocular microscope, and grinned when he saw his pilot. He tossed a depleted pack of cigarettes. "And don't worry about the air plant!" he called cheerfully.

  Carv came up beside him. "What news?"

  "It's algae. I can't name the breed, but there's not much difference between this and any terrestrial algae, except that this sample is all one species."

  "That's unusual?" Carv was looking around him in wonder. He was seeing a new side to Wall. Aboard ship Wall was sloppy almost to the point of being dangerous, at least in the eyes of a Belter like Carv.

  But now he was at work. His small tools were set in neat rows on portable tables. Bulkier instruments with legs were on flat rock, the legs carefully adjusted to leave their platforms exactly horizontal. Wall handled the binocular microscope as if it might dissolve at a touch.

  "It is," said Wall. "No little animalcules moving among the strands. No variations in structure. I took samples from depths up to six feet. All I could find was the one algae. But otherwise— I even tested for proteins and sugars. You could eat it. We came all this way to find pond scum."

  They came down on an island five hundred miles south. This time Carv helped with the collecting. They got through faster that way, but they kept getting in each other's way. Six months spent in two small rooms had roused tempers too often. It would take more than a few hours on ground before they could bump elbows without a fight.

  Again Carv watched Wall go through his routines. He stood just within voice range, about fifty yards away, because it felt so good to have so much room. The care Wall exercised with his equipment still amazed him. How could he reconcile it with Wall's ragged fingernails and his thirty hours growth of beard?

  Well, Wall was a flatlander. All his life he'd had a whole planet to mess up, and not a crowded pressure dome or the cabin of a ship. No flat ever learned real neatness.

  "Same breed," Wall called.

  "Did you test for radiation?"

  "No. Why?"

  "This thick air must screen out a lot of gamma rays. That means your algae can't mutate without local radiation from the ground."

  "Carv, it had to mutate to get to its present form. How could all its cousins just have died out?"

  "That's your field."

  A little later Wall said, "I can't get a respectable background reading anywhere. You were right, but it doesn't explain anything."

  "Shall we go somewhere else?"

  "Yah."

  They set down in deep ocean, and when the ship stopped bobbing Carv went out the airlock with a glass bucket. "Its a foot thick out there," he reported. "No place for a Disneyland. I don't think I'd want to settle here."

  Wall sighed his agreement. The green scum lapped thickly at the Overcee's gleaming metal hull, two yards below the sill of the airlock.

  "A lot of planets must be like this," said Carv. "Habitable, but who needs it?"

  "And I wanted to be the first man to found an interstellar colony."

  "And get your name in the newstapes, the history books—"

  "—And my unforgettable face on every trivis in the solar system. Tell me, shipmate, if you hate publicity so much, why have you been trimming that Vandyke so prettily?"

  "Guilty. I like being famous. Just not as much as you do."

  "Cheer up then. We may yet get all the hero worship we can stand. This may be something bigger than a new colony."

  "What could be bigger than that?"

  "Set us down on land and I'll tell you."

  On a chunk of rock just big enough to be called an island, Wall set up his equipment for the last time. He was testing for food content— again, using samples from Carv's bucket of deep ocean algae.

  Carv stood by, a comfortable distance away, watching the weird variations in the clouds. The very highest were moving across the sky at enormous speeds, swirling and changing shape by the minutes and seconds. The noonday light was subdued and early. No doubt about it, Sirius B-IV had a magnificent sky.

  "Okay, I'm ready." Wall stood up and stretched. "This stuff isn't just edible. I'd guess it would taste as good as the food supplements they were using on Earth before the fertility laws cut the population down to something reasonable. I'm going to taste it now."

  The last sentence hit Carv like an electric shock. He was running before it was quite finished, but long before he could get there his crazy partner had put a dollup of green scum in his mouth, chewed and swallowed. "Good," he said.

  "You-utter-damned-fool."

  "Not so. I knew it was safe. The stuff had an almost cheesy flavor. You could get tired of it fast, I think, but that's true of anything."

  "Just what are you trying to prove?"

  "That this alga was tailored as a food plant by biological engineers. Carv, I think we've landed on somebody's private farm."

  Carv sat heavily down on a rainwashed white rock. "Better spell that out," he said, and heard that his voice was hoarse.

  "I was going to. Suppose there was a civilization that had cheap, fast interstellar travel. Most of the habitable planets they found would be sterile, wouldn't they? I mean, life is an unlikely sort of accident."

  "We don't have the vaguest idea how likely it is."

  "All right, pass that. Say somebody finds this planet, Sirius B-IV, and decides it would make a nice farm planet. It isn't good for much else, mainly because of the variance in lighting, but if you dropped a specially bred food alga in the ocean, you'd have a dandy little farm. In ten years there'd be oceans of algae, free for the carting. Later, if they did decide to colonize, they could haul the stuff inland and use it for fertilizer. Best of all, it wouldn't mutate. Not here."

  Carv shook his head to clear it. "You've been in space too long."

  "Carv, the plant looks bred— like a pink grapefruit. And where did all its cousins go? Now I can tell you. They got poured out of the breeding va
t because they weren't good enough."

  Low waves rolled in from the sea, low and broad beneath their blanket of cheesy green scum. "All right," said Carv. "How can we disprove it?"

  Wall looked startled. "Disprove it? Why would we want to do that?"

  "Forget the glory for a minute. If you're right, we're trespassing on somebody's property without knowing anything about the owner— except that he's got dirtcheap interstellar travel, which would make him a tough enemy. We're also introducing our body bacteria onto his pure edible algae culture. And how would we explain, if he suddenly showed up?"

  "I hadn't thought of it that way."

  "We ought to cut and run right now. It's not as if the planet was worth anything."

  "No. No, we can't do that."

  "Why not?"

  The answer gleamed in Wall's eyes.

  Turnbull, listening behind his desk with his chin resting in one hand, interrupted for the first time in minutes. "A good question. I'd have gotten out right then."

  "Not if you'd just spent six months in a two-room cell with the end of everything creeping around the blankets."

  "I see." Turnbulls hand moved almost imperceptibly, writing, NO WINDOWS IN OVERCEE #2!

  Oversized viewscreen?

  "It hadn't hit me that hard. I think I'd have taken off if I'd been sure Wall was right, and if I could have talked him into it. But I couldn't, of course. Just the thought of going home then was enough to set Wall shaking. I thought I might have to knock him on the head when it came time to leave. We had some hibernation drugs aboard, just in case."

  He stopped. As usual, Turnbull waited him out.

  "But then I'd have been all alone." Rappaport finished his drink, his second, and got up to pour a third.

  The bourbon didn't seem to affect him. "So we stood there on that rocky beach, both of us afraid to leave and both afraid to stay..."

  ***

  Abruptly Wall got up and started putting his tools away. "We can't disprove it, but we can prove it easily enough. The owners must have left artifacts around. If we find one, we run. I promise."

  "There's a big area to search. If we had any sense we'd run now."

  "Will you drop that? All we've got to do is find the ramrobot probe. If there's anyone watching this place they must have seen it come down. We'll find footprints all over it."

  "And if there aren't any footprints? Does that make the whole planet clean?"

  Wall closed his case with a snap. Then he stood, motionless, looking very surprised. "I just thought of something," he said.

  "Oh, not again."

  "No, this is for real, Carv. The owners must have left a long time ago."

  "Why?"

  "It must be thousands of years since there were enough algae here to use as a food supply. We should have seen ships taking off and landing as we came in. They'd have started their colony too, if they were going to. Now it's gone beyond that. The planet isn't fit for anything to live on, with the soupy oceans and the smell of things rotting."

  "No."

  "Dammit, it makes sense!"

  "It's thin. It sounds thin even to me, and I want to believe it. Also, it's too pat. It's just too close to the best possible solution we could dream up. You want to bet our lives on it?"

  Wall hoisted his case and moved toward the ship. He looked like a human tank, moving in a stormy darkness lit by shifting, glaring beams of blue light. Abruptly he said, "There's one more point. That black border. It has to be contaminated algae. Maybe a land-living mutant, that's why it hasn't spread across the oceans. It would have been cleaned away if the owners were still interested."

  "All right. Hoist that thing up and let's get inside."

  "Hmph?"

  "You've finally said something we can check. The eastern shore must be in daylight by now. Let's get aboard."

  At the border of space they hovered, and the Sun burned small and blinding white at the horizon. To the side Sirius A was a tiny dot of intense brilliance.

  Below, where gaps in the cloud cover penetrated all the way to the surface, a hair-thin black line ran along the twisting beach of Sirius B-IV's largest continent. The silver thread of a major river exploded into a forking delta, and the delta was a black triangle shot with lines of silvery green.

  "Going to use the scope?"

  Carv shook his head. "We'll see it close in a few minutes."

  "You're in quite a hurry, Carv."

  "You bet. According to you, if that black stuff is some form of life, then this farm's been deserted for thousands of years at least. If it isn't, then what is it? It's too regular to be a natural formation. Maybe it's a conveyor belt."

  "That's right. Calm me down. Reassure me."

  "If it is, we go up fast and run all the way home." Carv pulled a lever and the ship dropped from under them. They fell fast. Speaking with only half his attention, Carv went on. "We've met just one other sentient race, and they had nothing like hands and no mechanical culture. I'm not complaining, mind you.

  A world wouldn't be fit to live in without dolphins for company. But why should we get lucky twice? We don't want to meet the farmer, Wall."

  The clouds closed over the ship. She dropped more slowly with every kilometer. Ten kilometers up she was almost hovering. Now the coast was spread below them. The black border was graded: black as night on Pluto along the sea, shading off to the color of the white sand and rocks along the landward side.

  Wall said, "Maybe the tides carry the dead algae inland. They'd decay there. No, that won't work. No moon. Nothing but solar tides."

  They were a kilometer up. And lower. And lower.

  The black was moving, flowing like tar, away from the drive's fusion flame.

  ***

  Rappaport had been talking down into his cup, his words coming harsh and forced, his eyes refusing to meet Turnbull's. Now he raised them. There was something challenging in that gaze.

  Turnbull understood. "You want me to guess? I won't. What was the black stuff?"

  "I don't know if I want to prepare you or not. Wall and I, we weren't ready. Why should you be?"

  "All right, Carver, go ahead and shock me."

  "It was people.

  Turnbull merely stared.

  "We were almost down when they started to scatter from the downblast. Until then it was just a dark field, but when they started to scatter we could see moving specks, like ants. We sheered off and landed on the water offshore. We could see them from there."

  "Carver, when you say people, do you mean— people? Human?"

  "Yes. Human. Of course they didn't act much like it..."

  ***

  A hundred yards offshore, the Overcee floated nose up. Even seen from the airlock, the natives were obviously human. The telescope screen brought more detail.

  They were no terrestrial race. Nine feet tall, men and women both, with wavy black hair growing from the eyebrows back to halfway down the spine, hanging almost to the knees. Their skins were dark, as dark as the darkest Negro, but they had chisel noses and long heads and small, thin-lipped mouths.

  They paid no attention to the ship. They stood or sat or lay where they were, men and women and children jammed literally shoulder to shoulder. Most of the seaside population was grouped in large rings with men on the outside and women and children protected inside.

  "All around the continent," said Wall.

  Carv could no more have answered than he could have taken his eyes off the scope screen.

  Every few minutes there was a seething in the mass as some group that was too far back pulled forward to reach the shore, the food supply. The mass pushed back. On the fringes of the circles there were bloody fights, slow fights in which there were apparently no rules at all.

  "How?" said Carv, "How?"

  Wall said, "Maybe a ship crashed. Maybe there was a caretaker's family here, and nobody ever came to pick them up. They must be the farmer's children, Carv."

  "How long have they been here?"

&nb
sp; "Thousands of years at least. Maybe tens or hundreds of thousands." Wall turned his empty eyes away from the screen. He swiveled his couch so he was looking at the back wall of the cabin. His dreary words flowed out into the cabin.

  "Picture it, Carv. Nothing in the world but an ocean of algae and a few people. Then a few hundred people, then hundreds of thousands. They'd never have been allowed near here unless they'd had the bacteria cleaned out of them— to keep the algae from being contaminated. Nothing to make tools out of, nothing but rock and bone. No way of smelting ores, because they wouldn't even have fire. There's nothing to burn. They had no diseases, no contraceptives, and no recreation but breeding. The population would have exploded like a bomb. Because nobody would starve to death, Carv. For thousands of years nobody would starve on Sirius B-IV."

  "They're starving now."

  "Some of them. The ones that can't reach the shore." Wall turned back to the scope screen. "One continual war," he said after awhile. "I'll bet their height comes from natural selection."

  Carv hadn't moved for a long time. He had noticed that there were always a few men inside each protective circle, and that there were always men outside going inside and men inside going outside.

  Breeding more people to guard each circle. More people for Sirius B-IV.

  The shore was a seething blackness. In infrared light it would have shown brightly, at a temperature of 98.6 degrees Fahrenheit.

  "Let's go home," said Wall.

  "Okay."

  ***

  "And did you?"

  "No."

  "In God's name, why not?"

  "We couldn't. We had to see it all, Turnbull. I don't understand it, but we did, both of us. So I took the ship up and dropped it a kilometer inshore, and we got out and started walking toward the sea.

  "Right away, we started finding skeletons. Some were clean. A lot of them looked like Egyptian mummies, skeletons with black dried skin stretched tight over the bones. Always there was a continuous low rustle of— well, I guess it was conversation. From the beach. I don't know what they could have had to talk about.