N-Space

by Larry Niven

  Forward must have liked science fiction writers. He became one himself with Dragon’s Egg, which involves natives of a neutron star as described by the astronomer Frank Drake.

  So I had access to an expert on neutron stars and hypergravity.

  Please understand: I had a two-lobed novel in mind, two intimately related stories taking place twenty years apart. One story would speak of simple survival; one would speak of the founding of civilization. I wrote a fairly detailed outline [calling it THE SPOKE TREES] to nail down what I was after.

  Then I sent it to Robert Forward and asked for help.

  He gave it.

  The numbers weren’t too startling [to me]. I’d get about one-twentieth of a gravity in a big tree. Bob did have some surprises for me.

  First, I’d messed up some technical terms. Gas torus, plasma torus, flux tube are not interchangeable!

  Second…I had not realized that the winds at the endpoints of the trees would be even more powerful than the tide! And so my spoke trees—pointing through the neutron star, like spokes in a wagon wheel—were shaped by the wind into long S-shapes, integral signs, integral trees, and gained a good deal more detail.

  Details are where the fun is.

  I had already decided to maroon a handful of human beings in the Smoke Ring, leave them alone for five hundred years, then see what they were up to. I needed oxygen, and therefore green plants. I needed normal sunlight, so I made the neutron star [Levoy’s Star, or Voy] part of a binary. That implied oxygen; oxygen implied green plants. What else did I know about life-forms in free-fall and breathable atmosphere?

  Well—

  Water drops would come in all sizes, from fine mist through raindrops the size of your fist or your head up to blobs so big that the tide would pull them apart. [Call them ponds.] Whatever their size, they could not be considered stable. Whatever lives in a pond [call it a fish] might have to cross to another pond fairly frequently.

  So they’ll have lungs.

  And they’ll fly. In fact, any Smoke Ring life form will find some way of getting about. Wings are the most obvious way, and most life forms will have wings…but they won’t necessarily look like Earth’s birds.

  After all, there’s no gravity. In the Smoke Ring a bird with a broken wing can still fly! There’s no unique down; no need for bilateral symmetry. What’s required is thrust, not lift. I gave most of the Smoke Ring’s life forms trilateral symmetry, with plenty of room for evolution to fiddle around.

  The birds look like fish and the fish act like birds.

  The integral trees are more mobile than I at first realized. When a tree comes apart, both segments will eventually return to the median [the region where the air is thickest.] They do it by sailing: the tree is accelerated by the wind in its remaining tuft. [And when it reaches the median, where the fertilizer is adequate, it will not survive unless it can grow another tuft fast.]

  There are other sailing plants, and plants that spray seeds, and seeds that spray compressed air. There are plants like rubber-band helicopters. Everything moves.

  And how will humans adjust?

  I’m dealing with savages here. [My choice.] They’re environmentalists when they have to be: they keep their own region clean. Otherwise their philosophy may allow them to use their environment as they please.

  Thanks to Bob Forward and the winds, my trees gained a way of gathering fertilizer: branchlets migrate forward along the branch, into the treemouth, carrying whatever they’ve sieved from the wind. And the treemouth is the key to a lot of things.

  The treemouth is the tribe’s toilet, and its funeral parlor, and its garbage pit. “Feed the tree” is a truly comprehensive insult.

  I called the vegetation of the branch “the tuft.” I made the foliage edible. The tribe will dig tunnels through it in the normal course of events. I left the branchlets springy enough to be woven into wickerwork “huts.”

  I had to design laundry and cooking techniques…and techniques of hunting and making war…and social hierarchies, different for every environment, including table manners and eating tools…and language.

  The details are where the fun is. I talked with friends about the Smoke Ring. Several got in a contest to suggest weapons; I took the footbow from that. Later, someone suggested making wings; I used Isaac Asimov’s suggestion as to what they would look like.

  The cover for THE INTEGRAL TREES, by Michael Whelan, was the best I’d ever had. It should have been, for the effort he put into it! He read through the manuscript twice, then braced me at a world science fiction convention and held me prisoner for an hour while he asked questions.

  The SMOKE RING cover was just as good.

  Authors can be nearly psychotic as regards the accuracy of a cover.

  A stranger in a bookstore once looked at that cover and said, “Oh, a fantasy!” Nope. It’s hard science fiction in a peculiar place.

  Bob Gleason and Tom Doherty were my guests for a few days in May. They came partly to give me some help with the book you’re reading now.

  I’d already chosen excerpts from various of my novels. I couldn’t decide what to take from THE INTEGRAL TREES and THE SMOKE RING. The books were relatively new; Tom and Bob had read them; let them give me some help.

  They spent most of a Friday rereading the books. Bob blames me for a blinding headache; Tom worked off the tension swimming back and forth in my pool, back and forth, like a damn machine. Their conclusion: there was nothing they could tear out of either book without it bleeding all over their hands.

  Heh heh heh. Jerry and I did that to Bob Gleason once before. We turned over to him a quarter-million words of LUCIFER’S HAMMER: too big a book to sell well, he thought. “I have this nightmare in which we sell millions of copies of LUCIFER’S HAMMER and lose a nickel on every book!” Bob sat down to cut it to size…and there wasn’t one damn word he could live without.

  Serve him right. He’s the man who taught us how to cut.

  But Niven doesn’t write excerpts; Niven writes novels!

  On the other hand…they couldn’t find an excerpt that would stand by itself. So they’re demanding that I write a short story instead!

  That’s work.

  Oh, well. I want to get back into the Smoke Ring universe anyway. There’s a novel I want to write…involving really peculiar creatures who may have been shaped in the supernova explosion that began the Smoke Ring. And I want to bring them home.

  • • • • • • • • • • • • • • • • • • • • • •

  CHAPTER ONE

  YEAR 419 DAY 110

  The light filtering through the foliage had an ominous tinge: white with no blue in it, white like dry bone.

  Alin crawled eastward through corridors that paralleled the branch. Slender branchlets grew airy, sweet stuff like green cotton candy, easy to brush aside. He ate the occasional handful of foliage without slowing. If nobody did that, the corridor would close completely.

  Already it was uncomfortably narrow. The in tuft had been deserted these past two years.

  Four boys crawled in Alin’s wake. Their rolled-up kites caught in the foliage, slowing them. Alin knew how to keep his bundle pointed straight ahead through the branchlets.

  The foliage thinned out, then ended in bare bark.

  There was no sky. Brighton Tree was embedded in fog: one eighty-three-klomter tree fading into an empty white universe.

  The boys caught up. Stevn trailed, looking down into the bone-white sky. Stevn was Alin’s oldest son, though the long, straight brown hair and the exaggerated frown were exactly his uncle David’s.

  Alin laughed at their disappointment. If Gilly or Stevn were relieved, Alin chose not to see that. He said, “Get out on the branch. This’ll be gone by the time we’re set up.”

  They crawled out along the bark, fingers and toes clinging. Mist streamed past them, blowing hard. In the point-oh-three tidal force of Brighton Tree, it was amazing how much water a tunic could hold.

&nbs
p; Halfway to nothing, Alin called a halt. “No wings, citizens. Today it’s kites. Frame them.”

  Each boy unwrapped what he had brought: two sheets of fabric, four brace poles almost as tall as himself, and fifty meters of lines. Bertam was the quickest. He had the bound kite strapped to his back at the waist, and the free kite assembled in his hands, while Gilly was still wrestling with fabric.

  Alin had not touched his own kites yet. Today his students would do without their teacher’s example.

  The fog shredded and streamed away, and suddenly there was sky.

  What had been fog could now be seen as a two-hundred-klomter river of cloud streaming east and away through a universe of blue sky. The forward fringe of it roiled as it dipped into the chaotic currents of the Clump.

  The Clump was an eternal sluggish storm a thousand klomters across. Matter tended to gather in the tidal anomaly sixty degrees ahead of Goldblatt’s World in its orbit around Levoy’s Star. From here the Clump covered almost half the sky, lit from behind by a rising Sun: flame-colored, darkening toward the axis.

  Other trees floated around Brighton Tree, all on a level, dark against the bright Clump. Their trunks were vertical lines bent into near-horizontal branches at the in and out ends.

  A Navy spinner ship puffed toward the grove, too distant for detail, leaving a white thread of smoke.

  The boys were ready. Alin looked them over and said, “Good. Bertam, jump.”

  Bertam rolled forward and dropped into the violet-white glare of Voy. Alin wondered if he had closed his eyes. The wind gripped the kite on his back, the bound kite, and pulled him east.

  “Stevn, go. Marlo. Gilly, go. Go!”

  Gilly clutched the branch in terror.

  They were calling Alin Newbry “Kitemaster” because he could fly with kites. “Kitemaster” instead of “Liftmaster’s Apprentice”; but this was his first group of students. It had yet to be demonstrated that the Kitemaster could teach.

  Every child took flying lessons with wings or jet pods, when he or she was old enough. Some were frightened. Some were reckless. Some were clumsy. Alin had watched, then chosen six, drilled them with their equipment for seven sleeps, taken them out onto the bare branch and drilled them there—and lost two more to their fear—

  And he was about to lose another, on their first real flight.

  “Jump or don’t jump, Gilly, but you know the choices.” Alin assembled his kites rapidly. “Don’t let me beat you into the sky.”

  Gilly jumped with no grace, like a rag doll flung into the wind. A moment later the boy was using everything Alin had taught him. Left arm and leg reached out to turn him, then in again. Now he faced east, free kite clutched against his chest; the kite on his back blocked it from the wind. Now his hands and feet reached cautiously out, holding the running lines with fingers and toes. The free kite wafted east, and caught the wind.

  Alin rolled into the sky.

  Almost he felt Gilly’s fear. Why would anyone jump out of a perfectly good tree? Wings had been new to Brighton Tree when Alin was a baby, but kites, now…Alin Newbry was Brighton Tree’s expert with kites. He’d seen his first pair of kites less than a year ago, and possessed them immediately thereafter.

  The wind pulled him east. Voy blazed violet-white below him. The bound kite framed him, two spokes at right angles. Kites were more awkward than a good pair of wings bound to one’s ankles; but kites didn’t have to be flapped or pedaled. They pulled themselves.

  Bertam was nicely under sail. His free kite (banded red and white) deployed east-and-inward, pulling him away from Brighton Tree. His arms bowed to the pull. Bertam hadn’t grown to his full strength yet.

  Marlo was under sail too (yellow with a broad scarlet stripe). He seemed to be trying to join Bertam. Not a good idea. Collisions! But Bertram was laughing at Marlo, sailing away, racing.

  Stevn (orange swordbird on black) was all tangled up.

  Gilly was slow. Alin thought he could see the boy’s tongue between his teeth. Slow, but he wasn’t making any mistakes. His free kite (black stars on scarlet) flapped and eased east, then east-and-in. Gilly moved after the others, sailing, flying without effort, wearing a wide white smile.

  The laws of motion throughout the Smoke Ring were: East takes you out, out takes you west, west takes you in, in takes you east; north and south bring you back. Today’s goal was to sail outward, then return to Brighton Tree’s midpoint. Still, Alin wouldn’t be too disappointed if a boy wound up somewhere else.

  The East Grove was nineteen trees positioned far enough from the Clump to get decent tide. Any tree would send wingmen to rescue a lost boy. A mistake need not be dangerous. Capability Tree was an obvious target, east and a little in…

  And Natlee was hardly speaking to him, because he was trying to teach their oldest son to fly.

  Alin was now moving almost with the wind’s velocity. He deployed his free kite (a moby seen face-on, yellow on a scarlet background), but kept it on a short line. Was he going to have to rescue Stevn? Stevn was working more carefully now, getting himself untangled, glancing at Alin every few seconds while he tried to separate his running lines.

  Stevn would overreact if his teacher-father began shouting instructions. Alin did too much of that anyway. Give him another few breaths.

  One of the trees was getting longer.

  Alin blinked. Capability Tree was separating into two halves.

  There was no warning. There was only the numbing sight of a tree ripped in half at the midpoint, pulling ponderously apart, leaving a smoky trail of debris. One end fell into white Voylight, one toward the never-seen stars.

  There were fifty to sixty people in Capability Tree, not counting children.

  The Admiralty ship was still no more than a dot at the end of a vapor trail running through hazy blue-white. Alin watched the white curve as he worked his line.

  Stevn had his line out now, east-and-in, as he’d been taught. He’d begun to accelerate.

  Alin let his lines out gradually. The free kite pulled east-and-in, but he wrestled it horizontal. It went almost slack. Alin didn’t stand a chance of catching any of the boys already in flight, not even Gilly. He’d have to catch Stevn.

  The white curve of the Navy ship’s path remained almost straight. They hadn’t seen.

  Alin passed out from Stevn; he let his free kite swing drastically inward, to pull him in earshot.

  “Stevn!”

  “It’s all right, Kitemaster. I’ve got it.”

  “Look at Capability Tree!”

  Stevn needed a moment to orient himself, and another to wonder if he had the right direction, and then—“What on Earth?”

  “They need help. Now—”

  “Dad, Dad, the whole tree’s torn apart!”

  “Don’t lose it, boy. They need help. Do you think you can reach that Navy ship? Look straight east!”

  The boy looked. “I’m not sure, Dad.”

  Frightened. “It has to be done. The haze may be blocking their view. Get their attention. We need Navy for rescue work. You don’t have to get aboard. We’ll come for you…” Stevn was drifting out of earshot. “Get their attention and tell them about Capability Tree!”

  His kite was pulling him strongly now. He’d pass in from the debris cloud if he weren’t careful.

  The halves of the tree were already widely separated, in toward Voy and out into the sky. Alin manipulated the free kite out…out…waited until he felt no strain on the lines, then tilted the kite and let it continue moving. It was east of him now, blown toward him on a slack line. He tilted his body to adjust the bound kite, gathered as much of the line as he could, and was ready when it pulled taut.

  By then he was deep inside a cloud of shredded bark, and a hundred million bark-dwelling insects were getting lost in his nose and mouth and ears. He spit and snorted and blinked and looked around for citizens needing rescue.

  None yet. The free kite pulled westward, slowing him…and now he was among big cylindrica
l blocks of mud. He tilted both kites edge-on to the wind, and was at rest.

  The stench struck him like a blow.

  Over a dozen human lifetimes an integral tree swallows immense quantities of…stuff.

  Foliage at both tufts spreads wide to sieve birds and lesser plants out of the wind. A pond impacts somewhere on the trunk; tide slides the water and the mud core down into the nearer tuft. Branchlets gradually migrate forward along the branch, through the tuft and into the treemouth, carrying foliage and everything embedded in it: mud and water, plants, dead animals, even old huts that men have woven from the living branchlets. Humans use the great conical pit as a toilet and garbage service and mortuary. Everything disappears into the treemouth, to feed the tree.

  A tree has a mouth at both ends, and no anus. Tide pulls hard on an integral tree. The accumulating mud weakens its structure. The time comes when it must be rid of its mud core.

  It pulls apart at the midpoint, and starts over as twins.

  The core of Capability Tree had broken into cylindrical segments. The stench was horrid. Alin resisted breathing, for fear of inhaling foul dust. But the dust seemed to be all bark dust.

  There was music in the wind, nonsense-words sung in a high, sweet contralto.

  “We located the Titanic two miles deep in the Atlantic,

  And we didn’t know quite where that ship went down!”

  Alin knew that voice. Where was she? “Harp!”

  “Well, we photographed the wreck even down below her decks,

  But those monsters in the lakes just can’t be found.”

  North-and-out: human shapes clung to a black cylinder of mud. Alin shouted, “Hello!”

  The singer stopped. A man’s voice shouted from the mud-log. “Hello?”

  “Do you have line?”

  “Yes!”

  The unseen bard sang again:

  “Twenty-six miles by one short mile

  and a hundred fathoms deep.

  Jagged rock at the bottom of the Loch