by Larry Niven
The Integral Trees
( Trees - 1 )
Larry Niven
Like much of Niven's work, the story is heavily influenced by the setting: a gas torus, a ring of air around a neutron star. The gas giant Goldblatt's World (abbreviated "Gold") orbits this star just outside its Roche sphere. Thus, Gold's gravity is insufficient to hold its atmosphere, which is pulled loose into an independent orbit around Voy. This orbiting air forms a ring known as the Gas Torus. The Gas Torus is huge — one million kilometers thick — but most of it is too thin to be habitable. The central part of the Gas Torus, where the air is thicker, is known as the Smoke Ring. The Smoke Ring supports a wide variety of life.
There is no “ground” in the Smoke Ring; it is a world consisting entirely of sky. Thus, most animals can fly, even the fish. Furthermore, since the Smoke Ring is in orbit, it is in free fall — there is no “up” or “down”…
First publiched in Analog in 1983.
Nominated for Nebula Award for Best Novel in 1984.
Nominated for Hugo Award for Best Novel in 1985.
The Integral Trees
by Larry Niven
This book is dedicated to Robert Forward, for the stories he's sparked in me, for his help in working out the parameters of the Smoke Ring and for his big roomy mind.
Prologue
Discipline
IT WAS TAKING TOO LONG, MUCH LONGER THAN HE HAD EXPECTED. Sharis Davis Kendy had not been an impatient man. After the change he had thought himself immune to impatience. But it was taking too long! What were they doing in there?
His senses were not limited. Sharis's telescopic array was powerful; he could sense the full electromagnetic spectrum, from microwave up to X-ray. But the Smoke Ring balked his view. It was a storm of wind, dust, clouds of water vapor, huge rippling drops of dirty water or thin mud, masses of free-floating rock; dots and motes and clumps of green, green surfaces on the drops and the rocks green tinges of algae in the clouds; trees shaped like integration signs, oriented radially to the neutron star and tufted with green at both ends; whale-sized creatures with vast mouths, to skim the green-tinged clouds.
Life was everywhere in the Smoke Ring. Claire Dalton had called it a Christmas wreath. Claire had been a very old woman before the State revived her as a corpsicle. The others had never seen a Christmas wreath; nor had Kendy. What they had seen, half a thousand years ago, was a perfect smoke ring several tens of thousands of kilometers across, with a tiny hot pinpoint in its center.
Their reports had been enthusiastic. Life was DNA-based, the air was not only breathable, but tasted fine.
Discipline presently occupied the point of gravitational neutrality behind Goldblatt's World, the L2 point. This close, the sky split equally into star-sprinkled, black- and green-tinged cloudscape. Directly below, a vast distorted whirlpool of storm hid the residue of a gas giant planet, a rocky nugget two and a half times the mass of Earth.
Sharis would not enter that inner region. The maelstrom of forces could damage his ship. He couldn't guess how long the seeder ramship must survive to accomplish his mission. He had waited more than half a thousand years already. The L2 point was still within the gas torus of which the Smoke Ring was only the densest part. Discipline was subject to slow erosive forces. He couldn't last forever in this place.
At least the crew were not extinct.
That would have hurt him terribly.
He had done his duty. Their ancestors had been mutineers, a potential threat to the State itself. To reeducate their descendants was his goal, but if the Smoke Ring had killed them…well, it would not have surprised him. It took more than breathable air to keep men alive. The Smoke Ring was green with the life that had evolved for that queer environment. Native life might well have killed of those Johnny-comelately rivals, the erstwhile crew of the seeder ramship Discipline.
Sharls would have grieved; but he would have been free to return home.
They'd call me an obsolete failure, he thought gloomily while his instruments sought a particular frequency in the radio range. A thousand years out of date by the time I'm home. They'd scrap the computer for certain. And the program? The Sharls Davis Kendy program might be copied and kept for the use of historians. Or not.
But they hadn't died. Eight Cargo and Repair Modules had gone with the original mutineers. Time and the corrosive environment must have ruined the CARMs; but at least one was still operational. Someone bad been using it as late as six years ago. And-there: the light he'd been searching for. For a moment it reached him clearly: the frequency of hydrogen burning with oxygen.
He fired a maser in ultrashort, high-powered pulses. "Kendy for the State. Kendy for the State. Kendy for the State."
The response came four seconds later, sluggish, weak, and blurred. Kendy pinpointed it and fine-focused his telescopes while he sent his next demand.
"Status. Tell me three times."
Kendy sorted the garbled respofise through a noise-eliminator program. The CARM was on manual, mostly functional, using attitude jets only, operating well inside its safety limits. Once it had been a simplified recording of Kendy's own personality. Now the program was deteriorating, growing stupid and erratic.
"Course record for the past hour."
It came. The CARM had been free-falling at low relative velocity up to forty minutes ago. Then, low-acceleration maneuvers, a course that looked like a dropped plate of spaghetti, a mad waste of stored fuel. Malfunction? Or…it could have been a dogfight-style battle.
War?
"Switch to my command."
Four seconds; then a signal like a scream of bewildered agony. Massive malfunction.
The crew must have disconnected the autopilot system on every one of the CARMs, half a thousand years ago. It had still been worth a try, as was his next message.
"Give me video link with crew."
"Denied."
Oh ho! The video link hadn't been disconnected! A block must have been programmed in, half a thousand years ago, by the mutineers. Certainly their descendants wouldn't know how to do that.
A block might be circumvented, eventually.
The CARM was too small to see, of course, but it must be somewhere near that green blob not far from Goldblatt's World. A cotton-candy forest. Plants within the Smoke Ring tended to be fluffy, fragile. They spread and divided to collect as much sunlight as possible, without worrying about gravity.
For half a thousand years Kendy had watched for signs of a developing civilization-for regular patterns in the floating masses, or infrared radiation from manufacturing centers, or industrial pollution: metal vapor, carbon monoxide, oxides of nitrogen. He hadn't found any of that. If the children of Discipline's crew were developing beyond savagery, it was not in any great numbers.
But they lived. Someone was using a CARM.
If only he could see them! Or talk to them. "Give me voiceover. Citizen, this is Kendy for the State. Speak, and your reward will be beyond the reach of your imagination."
"Amplify. Amplify. Amplify," sent the CARM.
Kendy was already sending at full amplification. "Cancel voiceover," he sent.
Not for the first time, he wondered if the Smoke Ring could have proved too kindly an environment. Creatures evolved in freefall would not have human strength. Humans could be the most powerful creatures in the Smoke Ring: happy as clams in there, and about as active. Civilization develops to protect against the environment.
Or against other men. War would be a hopeful sign…
If he could know what was going on! Kendy could perturb the environment in a dozen different ways. Cast them out of Eden and see what happened. But he dared not. He didn't know enough.
Kendy waited.
Chapter One
Quinn Tuft
GAVVING COULD HEAR THE RUSTLING AS HIS COMPANIONS tunneled upward. They stayed alongside the great flat wall of the trunk. Finger-thick spine branches sprouted from the trunk, divided endlessly into wire-thin branchlets, and ultimately flowered into foliage like green cotton, loosely spun to catch every stray beam of sunlight. Some light filtered through as green twilight.
Gavving tunneled through a universe of green cotton candy.
Hungry, he reached deep into the web of branchlets and pulled out a fistful of foliage. It tasted like fibrous spun sugar. It cured hunger, but what Gavving's belly wanted was meat. Even so, its taste was too fibrous…and the green of it was too brown, even at the edges of the tuft, where sunlight fell.
He ate it anyway and went on.
The rising howl of the wind told him he was nearly there. A minute later his head broke through into wind and sunlight.
The sunlight stabbed his eyes, still red and painful from this morning's allergy attack. It always got him in the eyes and sinuses. He squinted and turned his head, and sniffled, and waited while his eyes adjusted. Then, twitchy with anticipation, he looked up.
Gavving was fourteen years old, as measured by passings of the sun behind Voy. He had never been above Quinn Tuft until now.
The trunk went straight up, straight out from Voy. It seemed to go out forever, a vast brown wall that narrowed to a cylinder, to a dark line with a gentle westward curve to it, to a point at infinity-and the point was tipped with green. The far tuft.
A cloud of brown-tinged green dropped away below him, spreading out into the main body of the tuft. Looking east, with the wind whipping his long hair forward; Gavving could see the branch emerging from its green sheath as a half-klomter of bare wood: a slender fin.
Harp's head popped out, and his face immediately dipped again, out of the wind. Laython next, and he did the same. Gavving waited. Presently their faces lifted. Harp's face was broad, with thick bones, its brutal strength half-concealed by golden beard. Laython's long, dark face was beginning to sprout strands of black hair.
Harp called, "We can crawl around to lee of the trunk. East. Get out of this wind."
The wind blew always from the west, always at gale velocities. Laython peered windward between his fingers. He bellowed, "Negative! How would we catch anything? Any prey would come right out of the wind!"
Harp squirmed through the foliage to join Laython. Gavving shrugged and did the same. He would have liked a windbreak…and Harp, ten years older than Gavving and Laython, was normally in charge. It seldom worked out that way.
"There's nothing to catch," Harp told them. "We're here to guard the trunk. Just because there's a drought doesn't mean we can't have a flash flood. Suppose the tree brushed a pond?"
"What pond? Look around you! There's nothing near us. Voy is too close. Harp, you've said so yourself!"
"The trunk blocks half our view," Harp said mildly.
The bright spot in the sky, the sun, was drifting below the western edge of the tuft. And in that direction were no ponds, no clouds, no drifting forests…nothing but blue-tinged white sky split by the white line of the Smoke Ring, and on that line, a roiled knot that must be Gold.
Looking up, out, he saw more of nothing…faraway streamers of cloud shaping a whorl of storm…a glinting fleck that might indeed have been a pond, but it seemed even more distant than the green tip of the integral tree. There would be no flood.
Gavving had been six years old when the last flood came. He remembered terror, panic, frantic haste. The tribe had bufrowed east along the branch, to huddle in the thin foliage where the tuft tapered into bare wood. He remembered a roar that drowned the wind, and the mass of the branch itself shuddering endlessly. Gavving's father and two apprentice hunters hadn't been warned in time. They had been washed into the sky.
Laython started off around the trunk, but in the windward direction. He was half out of the foliage, his long arms pulling him against the wind. Harp followed. Harp had given in, as usual. Gavving snorted and moved to join them.
It was tiring. Harp must have hated it. He was using claw sandals, but he must have suffered, even so. Harp had a good brain and a facile tongue, but he was a dwarf. His torso was short and burly; his muscular arms and legs had no reach, and his toes were mere decoration. He stood less than two meters tall. The Grad had once told Gavving, "Harp looks like the pictures of the Founders in the log. We all looked like that once."
Harp grinned back at him, though he was puffing. "We'll get you some claw sandals when you're older."
Laython grinned too, superciliously, and sprinted ahead of them both. He didn't have to say anything. Claw sandals would only have hampered his long, prehensile toes.
Night had cut the illumination in half. Seeing was easier, with the sunglare around on the other side of Voy. The trunk was a great brown wall three klomters in circumference. Gavving looked up once and was disheartened at their lack of progress. Thereafter he kept his head bent to the wind, clawing his way across the green cotton, until he heard Laython yell.
"Dinner!"
A quivering black speck, a point to port of windward. Laython said, "Can't tell what it is."
Harp said, "It's trying to miss. Looks big."
"It'll go around the other side! Come on!"
They crawled, fast. The quivering dot came closer. It was long and narrow and moving tail-first. The great translucent fin blurred with speed as it tried to win clear of the trunk. The slender torso was slowly rotating.
The head came in view. Two eyes glittered behind the beak, one hundred and twenty degrees apart.
"Swordbird," Harp decided. He stopped moving.
Laython called, "Harp, what are you doing?"
"Nobody in his right mind goes after a swordbird."
"It's still meati And it's probably starving too, this far in!"
Harp snorted. "Who says so? The Grad? The Grad's full of theory, but he doesn't have to hunt."
The swordbird's slow rotation exposed what should have been its third eye. What showed instead was a large, irregular, fuzzy green patch. Laython cried, "Fluff! It's a bead injury that got infected with fluff. The thing's injured, Harp!"
"That isn't an injured turkey, boy. It's an injured swordbird."
Laython was half again Harp's size, and the Chairman's son to boot. He was not easy to discipline. He wrapped long, strong fingers around Harp's shoulder and said, "We'll miss it if we wait here e.rguing! I say we go for Gold." And he stood up.
The wind smashed at him. He wrapped toes and one fist in branchlets, steadied himself, and semaphored his free arm. "Hiyo! Swordbird! Meat, you copsik, meat!"
Harp made a sound of disgust.
It would surely see him, waving in that vivid scarlet blouse. Gavving thought, hopefully, We'll miss it, and then it'll be past. But he would not show cowardice on his first hunt.
He pulled his line loose from his back. He burrowed into the foliage to pound a spike into solid wood, and moored the line to it. The middle was attached to his waist. Nobody ever risked losing his line. A hunter who fell into the sky might still find rest somewhere, if he had his line.
The creature hadn't seen them. Laython swore. He hurried to anchor his own line. The business end was a grapnel: hardwood from the finned end of the branch. Laython swung the grapnel round his head, yelled, and flung it out.
The swordbird must have seen, or heard. It whipped around, mouth gaping, triangular tail fluttering as it tried to gain way to starboard, to reach their side of the trunk. Starving, yes! Gavving hadn't grasped that a creature could see him as meat until that moment.
Harp frowned. "It could work. If we're lucky it could smash itself against the trunk."
The swordbird seemed bigger every second: bigger than a man, bigger than a hut-all mouth and wings and tail. The tail was a translucent membrane enclosed in a V of bone spines with serrated edges. What was it doing this far in? Swordbirds fed on creatures that fed in
the drifting forests, and there were few of these, so far in toward Voy. Little enough of anything. The creature did look gaunt, Gavving thought; and there was that soft green carpet over one eye.
Fluff was a green plant parasite that grew on an animal until the animal died. It attacked humans too. Everybody got it sooner or later, some more than once. But hnmRns had the sense to stay in shadow until the fluff withered and died. Laython could be right. A head injury, sense of direction fouled up and it was meat, a mass of meat as big as the bachelors' longhut. It must be ravenous…and now it turned to face them.
An isolated mouth came toward them: an elliptical field of teeth, expanding.
Laython coiled line in frantic haste. Gavving saw Harp's line fly past him, and tearing himself out of his paralysis, he threw his own weapon.
The swordbird whipped around, impossibly fast, and snapped up Gavving's harpoon like a tidbit. Harp whooped. Gavving froze for an instant; then his toes dug into the foliage while he hauled in line. He'd hooked it.
The creature didn't try to escape: it was still fluttering toward them.
Harp's grapnel grazed its side and passed on. Harp yanked, trying to hook the beast, and missed again. He reeled in line for another try.
Gavving was armpit-deep in branchlets and cotton, toes digging deeper, hands maintaining his deathgrip on the line. With eyes on him, he continued to behave as if he wanted contact with the killer beast. He bellowed, "Harp, where can I hurt it?"
"Eye sockets, I guess."
The beast had misjudged. Its flank smashed bark from the trunk above their heads, dreadfully close. The trunk shuddered. Gavving howled in terror. Laython howled in rage and threw his grapnel ahead of it.
It grazed the swordbird's flank. Laython pulled hard on the line and sank the hardwood tines deep in flesh.
The swordbird's tail froze. Perhaps it was thinking things over, watching them with two good eyes while the wind pulled it west.