Schild's Ladder

by Greg Egan

  In Tchicaya's view, the town's effective desertion didn't render it more interesting, and the freedom to wander the streets and fields at any hour was less appealing now, in winter, than in the ordinary summers when it was barely curtailed by parental authority anyway. Tchicaya thought of suggesting that they drop back into Slowdown and reemerge when the weather was warmer, but he was afraid of compromising their original deal. If he didn't stick to the letter of it, he could forget about holding Mariama to her word.

  Mariama wanted to catch a train to Hardy, further if possible, preferably circumnavigating the entire continent. In one weird concession to practicality, the trains moved at their ordinary speed, whisking commuters to their destinations in an eye blink. Understandably, though, departures were rare, and on examining the schedules it turned out that they could not have traveled anywhere and back in less than ten years.

  Tchicaya did his best to keep Mariama distracted, terrified that she might harbor a yearning for sabotage that went beyond playground equipment. She'd know it was futile to hope to succeed in damaging any of the town's infrastructure, but he could picture her delight at sirens wailing and people shuddering into motion around her. This image might have been unfair, but there was no point asking her for assurances; at best, that would only offend her, and at worst it might tempt her to act out his fears. So he tried to go along with any suggestions she made that weren't completely outlandish, but only after putting up enough resistance to keep her from becoming too bored, or too suspicious of his compliance.

  On their tenth night out of Slowdown, Tchicaya was woken by lukewarm fluid dripping onto his face. He opened his eyes in the pitch blackness, and rashly poked his tongue out to sample the fluid. It was water, but it had a complicated, slightly metallic taint. He pictured a crack in the ceiling, the heat from the radiator fins above them on the roof melting the surrounding frost.

  He slid out from the blankets without waking Mariama, and groped for the lamp. When he held it up, a faint liquid sheen was visible snaking down one thick coolant pipe, collecting in drops at a right-angled bend above the cushion where his head had lain.

  Mariama stirred, then shielded her eyes. “What is it?”

  “Just some water from the roof. We might have to shift.” He moved the lamp about, hunting for leaks along the other pipes. Then something different caught his eye, a flash of iridescent colors at the very top of the pipe that had proved to be the original culprit. “Is that oil?” Why would there be oil leaking from the roof? As far as Tchicaya knew, the plant's few moving parts were all inside the building, and they'd all be molecularly smooth if they made physical contact with each other at all. Maybe flakes of ice could catch the light like that. But what could make them thin and flat enough?

  There was sure to be a simple answer, but the puzzle gnawed at him. It was cold, and part of him wanted nothing more than to curl up beneath the blankets again—but what was the point of achieving a state in which no one could tell him to stop worrying and leave it till morning, if he didn't take advantage of his freedom to act on his curiosity immediately?

  He said, “I'm going up on the roof.”

  Mariama blinked at him in the lamplight, apparently at a loss for words.

  Tchicaya put on his shoes and walked outside, taking the lamp with him.

  He circled the building twice, before settling on a sturdylooking drainpipe. The lamp was attached to a chain; he hung it around his neck, like a pendant worn backward, and gripped the drainpipe between his forearms and knees. There were no handholds, and the frosted surface was slippery. The first time he found himself sliding back down, he panicked and almost let go, but the friction from the polymer surface was never enough to really hurt him. After ending up back on the ground twice, he found that if he tightened his grip the instant he began to slip, he could bring himself to a halt in a fraction of a second, and retain most of his hard-won altitude.

  He reached the roof with his limbs numb and his chest soaked in icy perspiration. He crouched on the sloped tiles, flapping his arms vigorously to try to restore the circulation, until he realized that this was driving him slowly backward toward the sevenmeter drop behind him. If he did real damage to his birth flesh, there'd be no prospect of concealing it from his parents. And to take on a new body at the age of twelve would make him a laughingstock for centuries.

  He rose up on his haunches and waddled across the roof, as wary of gravity now as if he'd been back in Slowdown. He had no idea whether he was heading in the right direction; the dark shapes looming ahead of him might have been anything. He stopped to work the lamp around from his back to a more useful position, and noticed a long gash along the inside of his right leg, wet with blood. Something had cut him as he'd slipped along the drainpipe, but the wound wasn't painful, so it couldn't be too deep.

  Up close, the radiator fins were massive, each as wide as his outstretched arms. He ambled around the structure, shining the lamp into the angled gaps between the fins, hunting for the source of the leak.

  Mariama called out to him, “What have you found?” She was outside, on the ground somewhere.

  “Nothing, yet.”

  “Do you want me to come up?”

  “Suit yourself.” He felt a twinge of guilt at the way that would sound, but it was hardly an expression of lofty disdain by the standards she'd set. This was the first thing he'd done since he'd joined her that wasn't part of some complicated strategy to please her, or confound her. He had to be indifferent to her, just this once, or he'd go mad.

  When the lamplight finally returned the rainbow sheen he'd glimpsed from inside the building, it was unmistakable. An irregular, glistening patch of some filmy substance covered half the fin. Tchicaya approached, and touched it with a fingertip. The substance was slightly sticky, and the film clung to his finger for a fraction of a millimeter as he pulled away. When it parted from his skin he could feel it snap back elastically, rather than tearing like something viscous and treacly. He held his finger up for inspection; the skin was unstained, and when he rubbed it against his thumb there was no moisture or slickness at all. This wasn't any kind of oil he'd seen before, and it definitely wasn't ice.

  He held the lamp closer to the surface, hunting for some sign of a damaged coolant channel. This had to be the residue left behind by a leak, though why the coolant would contain some sticky impurity was beyond him. Antifreeze? He was shivering with cold, but he was in a stubborn frame of mind.

  A small hole appeared in the film at the center of the circle of lamplight, and grew before his eyes. He held the lamp as still as he could; once the boundary of the film had retreated into the penumbra cast by the lamp's housing, the hole stopped growing.

  Tchicaya moved the lamp to another spot. The same thing happened: the lamplight seemed to melt the film away. But the beam carried no heat whatsoever. Was it driving some kind of photochemical reaction?

  He turned back to the original rent in the film. It had shrunk to half the size it had grown to when he moved the lamp away. He made a hole in the film in a third location, then took the lamp back to inspect the second hole. It was closing up, too.

  Tchicaya stepped out from the gap between the fins and sat huddled on the roof tiles, his teeth chattering. Maybe the light broke up whatever molecules the film was made from, while the chemical process that had formed it in the first place rebuilt it when he took the light away. Some mixtures of simple chemicals could behave in a complicated fashion. He had no right to start summoning up phrases from his biology lessons, like negative phototropism.

  His arms were shaking. Mariama had been silent since their last exchange; she had probably gone back to bed.

  He rose to his feet, and scrupulously searched the other parts of the radiator, but it was only one side of one fin that bore any visible trace of the film.

  He took a knife from his pocket, opened it, and scraped it over the film. The surface appeared unchanged, but when he lifted the knife there was a waxy residue visible alon
g the edge of the blade.

  He walked around the structure, counting the fins as he went, orienting himself with the stars. He closed his eyes and pictured the arc the sun would make as it crossed the sky; it was an easier task now than it would have been before he'd sat for a year in the front room of his house and watched the ribbon of fire shift with the seasons. He stepped between two of the fins and dislodged whatever had adhered to the knife onto the clean surface of the radiator.

  He looked up at the sky again. A million stars, a million dead worlds. Only four planets had ever held anything different. His hunch was sure to be disproved, but the prospect only made him smile. There were some things so large and outlandish that you could only wish for them with your tongue in your cheek, and to be disappointed when they failed to appear would be like throwing a tantrum and cursing the world because the sun failed to rise at your beck and call.

  He made his way to the edge of the roof, his breath frosting in front of him.

  As he was climbing down the drainpipe, his leg began to throb. His body had managed to close the wound, and now it was warning him not to break the temporary seal of collagen it had woven across the gap in his skin. As he adjusted his legs to shift the pressure away from the cut, Tchicaya made a decision: he wanted to remember this night, he wanted it to leave a mark. He instructed his Exoself never to permit the cells of his skin to grow back in their normal pattern across the wound. For the first time, he would let the world scar him.

  “Why do we need to borrow your parents' ladder?”

  Tchicaya waved Mariama back from the toolshed. “I'm hoping it won't trigger any alarms. If I tried to borrow someone else's, that might look like I was stealing.” He didn't want her taking part in the act, though. That the house had permitted her to enter uninvited, and even borrow his clothes without his permission, proved that it was prepared to show some tolerance toward his friends. His parents had never been obsessed with safeguarding their possessions, so it was not surprising that they hadn't programmed any paranoid, hair-trigger responses. He didn't want to push his luck, though.

  When he emerged from the shed, Mariama said, “Yes, but what do we need it for? What's so interesting, up on the roof?”

  Tchicaya swung the ladder toward her, making her jump back. “Probably nothing.” He had planned to show her the film on the coolant pipes inside the building when she woke that morning, but by daylight the sight had been so drab and uninspiring that he'd changed his mind; she'd probably looked herself, and seen nothing but a mild discoloration. She'd laugh at his naiveté when he finally described his experiment, but he didn't care. “We'll find out tonight.”

  Mariama was puzzled. “What's to stop me going up there before nightfall?”

  Tchicaya tightened his grip on the ladder, but even if he could keep it from her, she wouldn't need it.

  He said, “Nothing. I'm asking you to wait, that's all.”

  This answer seemed to please her. She smiled back at him sunnily.

  “Then I'll wait.”

  The ladder couldn't stretch to the full height of the roof, and Tchicaya had to argue with it before it would extend itself at all.

  “It's not safe,” the ladder wailed.

  “I've already been up there once, without any help from you,” he protested. He showed it his new pink scar. “I'll climb up the drainpipe again if I have to. You can either make this as safe as possible, or you can stay on the ground and be completely useless.”

  The ladder gave in. Tchicaya gripped the bottom end firmly while a wave of deformation swept along the length of the device. As the side rails stretched, material was redistributed into new rungs. In its final shape, paper-thin, the ladder was still a meter too short to touch the edge of the roof, but it would bring it within reach.

  Mariama said, “After you.”

  Tchicaya had planned to follow her up, so he'd have a chance to catch her if she slipped, but he'd been assuming that she'd demand to go first anyway, so he had no argument prepared. He mounted the ladder and began to ascend. He didn't need to look down to know when she'd joined him; he could feel the structure vibrating with a second load.

  If she did fall and injure herself, she could retreat at will into the painless world of her Qusp. An accident would mean discovery and shame, but no great suffering. Yet Tchicaya's hands shook at the thought of it, and he could not imagine feeling differently. The structure of his mind had been passed down with only a few small modifications from the original human form, shaped by evolution in the Age of Death, leaving him with the choice between embracing its impulses in all their absurdity—like ancient figures of speech whose literal meaning bore no resemblance to anything people still did—or struggling to invent a whole new vocabulary to replace them. If you cared about someone, what could replace the sick feeling of the misery you'd feel if they came to harm? The bodiless, he knew, had found their own, varied answers, but the idea that he might one day do the same made him giddy.

  He peered down.

  Mariama said, “What?”

  “Nothing.”

  The long climb was far easier than it had been the night before, but Tchicaya found the act of reaching back to grab hold of the gutter a lot more disconcerting while perched on the top rung of the ladder than when he'd gripped the drainpipe firmly with his legs. He hoisted himself up and clambered onto the roof, then moved away from the edge quickly so he wouldn't be in Mariama's way. Seconds later, she was beside him.

  “We should have used ropes, and grappling hooks,” she said. “Like they do on mountains.”

  “I never thought of that,” Tchicaya admitted.

  “I was joking.”

  “It might have been fun, though.” It might have been safer.

  “Are you going to let me in on the big secret now?”

  Tchicaya feigned indifference. “I did warn you: there's probably nothing to see.” He aimed the lamp's beam across the roof, but deliberately kept it low. “This way.”

  They crossed the tiles together in silence. When they reached the radiator, Tchicaya showed her the patch of iridescent film he'd discovered the night before.

  Mariama examined it. Tchicaya had half-expected her to identify the substance immediately, puncturing his fantasy with a far simpler explanation, but she was as baffled as he was. When he showed her how the film responded to the lamplight, she said, “Is that why you thought there'd be nothing here? You expected the sunlight to destroy it?”

  “No. This surface ought to be in the shade all day.”

  “It would still get some light from the sky, though.”

  “That's true,” he conceded. “But if it was there last night, it either had to be able to survive that much indirect sunlight, or it had to have formed after sunset, at least once. So why wouldn't it be here again?”

  Mariama nodded patiently. “All right. So what were you warning me not to expect?”

  Tchicaya's throat tightened. “I scraped some off, and put it on another fin. One that should have been about equally shaded. To see if it would...” He couldn't say the word.

  “To see if it would grow?”

  He nodded stupidly.

  Mariama whooped with delight. “Where!” She clutched at the lamp, but when he held on to it she didn't fight him for it. Instead, she took hold of his arm and said, “Will you show me? Please?”

  They stumbled around the radiator, helping each other stay balanced. Tchicaya told himself he didn't care what they found; when there turned out to be nothing, they could laugh at his grandiose delusions together.

  “This is the one.” He aimed the lamp into the wedge-shaped space between the fins, but he couldn't hold it still. “Do you see anything?”

  Mariama put an arm around him, steadying his whole body to steady the lamp.

  There was a patch of the film in front of them, an oval about the size of his hand, at exactly the height where he would have scraped the knife clean.

  Mariama took the lamp, and knelt to inspect the patch
more closely. It began to shrink immediately; she pulled the light away.

  “This wasn't here last night?”

  “No.”

  “So it must be a new...” She struggled for the right word.

  “Colony? Do you think that's what it is?”

  “I don't know.”

  She turned to him. “But it is alive? It has to be!”

  Tchicaya was silent for a moment. He'd thought the result would settle the issue, but now he was having second thoughts. The evidence was still too flimsy to support the extraordinary conclusion. “There are chemicals that do some strange things,” he said. “I'm not sure what this proves.”

  Mariama rose to her feet. “We have to wake someone, and show them. Right now.”

  Tchicaya was horrified. “But then they'll know what we did.

  They'll know we broke Slowdown.”

  “No one will care. Don't you know how rare this is?”

  He nodded. “But you promised me—”

  Mariama laughed. “We're not going to be in trouble! This is a thousand times more important!”

  Apart from Earth itself, native life had only been found on three worlds. Simple and microbial, but in each case unique. Every biosystem used different chemistry, different methods of gathering energy, different structural units, different ways of storing and transmitting information. On the crassest, most pragmatic level, this knowledge might be of little value: technology had long ago surpassed nature's ability to do all of these things efficiently. But each rare glimpse at a separate accident of biogenesis cast light on the nature and prospects of life. The roof of this building would become the most talked-about location for a hundred light-years.

  Tchicaya said, “What if it's something we brought ourselves? That wouldn't be much of a discovery.”

  “Such as what? Nothing we brought can mutate freely: every cell in every crop, every cell in our bodies, has fifty different suicide enzymes that kill off the lineage at the first genetic error. This could no more be ours than if they found some strange machine out in the ice that nobody owned up to making.”