"It must have been a rewarding time for you."
"Academically, yeah. I've never had any problem, academically. It's the rest of my life that's a piece of shit."
"Tell us what you discovered."
"I don't have my notes, my books—"
"Just tell us."
He sat up and stared into the face of the eerily unchanged boy—who, to his credit, did not flinch. “The first Caress destroyed almost everything of what went before, on the Shelf and presumably elsewhere. Almost, but not all. Some trace inscriptions, particularly carvings on stone, have survived. Images, fragmentary, and bits of text. Records of something in the sky."
"What something?"
"The galaxy is a disc of stars, a spiral. We, on a planet embedded in the disc, see this in cross-section, as a band of light in the sky. Much of it obscured by dust."
"And?"
"The ancients’ last records show two bands, at an angle to each other. There is evidence that the second band grew brighter, more prominent. The chronological sequence is difficult to establish—the best of these pieces were robbed and used as hearths or altar stones by the fallen generations that followed..."
"Nevertheless,” the boy prompted.
"Nevertheless, there is evidence that something came from out of the sky. Something huge. And then there are crude, fragmentary images—cartoons, really—of explosions. All over the sky. A million suns, suddenly appearing.” He imagined survivors, huddled in the ruins of their cities, scratching what they saw into fallen stones. “After that—nothing, for generations. People were too busy reinventing agriculture to do much astronomy. That was ten thousand years ago.
"The next bit of evidence comes from around three thousand years back, when a Natural Philosopher called HuroEldon established a new center of scholarship, at Foro and down on the Lowland ... Once again we started getting good astronomical records. And about that time, they observed in the sky—"
"Another band of stars."
"No. A spiral—a spiral of stars, ragged, the stars burning and dying, a wheel turning around a point of intense brightness. This object swam towards Old Earth, so it seemed, and at its closest approach there was a flare of dazzling new stars, speckled over the sky—but there was no Caress, not this time. The spiral receded into the dark."
"Tell us what you believe this means."
"I think it's clear. This other spiral is a galaxy like our own. The two orbit each other.” He mimed this with his fists, but his hands were shaking; shamed before the boy's steady gaze, he lowered his arms. “As twin stars may orbit one another. But galaxies are big, diffuse structures. They must tear at each other, ripping open those lacy spirals. Perhaps when they brush, they create bursts of starbirth. A Formidable Caress indeed.
"The last Caress was a first pass, when the second galaxy came close enough to our part of our spiral to cause a great flaring of stars—and that flaring, a rain of light falling from the blue, was what shattered our world. Then in HuroEldon's time, two billion years later, there was another approach—this one not so close; it was spectacular but did no damage, not to us. And then..."
"Yes?"
He shrugged, peering up at the construction-material roof of the cell. “The sky is ragged, full of ripped-apart spiral arms. The two galaxies continue to circle each other, perhaps heading for a full merger, a final smash. And that, perhaps, will cause a new starburst flare, a new Caress."
The boy stood silently, considering this, though one leg quivered, as if itchy. He asked: “When?"
"That I don't know. I tried to do some mathematics on the orbit. Long time since I stayed sober enough to see that through. But there's one more scrap of information in the archaeology. There was always a tradition that the second Caress would follow ten thousand years after the first, Shelf time. Maybe that's a memory of what the smart folk who lived before the first Caress were able to calculate. They knew, not only about the Caress that threatened them, but also what would follow. Remarkable, really."
"Ten thousand years,” the boy said. “Which is—"
"About now.” He grinned. “If the world ends, do you think they will let me out of here to see the show?"
"You have done remarkable work, Telni. This is a body of evidence extracted from human culture which we could not have assembled for ourselves.” Even as he spoke the boy trembled, and Telni saw piss swim down his bare leg.
Telni snorted. “You really aren't too good at running the people you herd, are you, machine?"
Ignoring the dribble on his leg, Powpy spoke on. “Regarding the work, however. We are adept at calculation. Perhaps we can take these hints and reconstruct the ancients’ computations, or even improve on them."
"So you'll know the precise date of the end of the world. That will help. Come back and tell me what you figure out."
"We will.” The boy turned and walked away, leaving piss footprints on the smooth floor.
Telni laughed at him, lay back on his bunk, and tried to sleep.
It was to be a very long time before Telni saw the Weapon and its human attendant again.
* * * *
"He refuses to die. It's as simple as that. There's nothing but his own stubbornness keeping him alive."
His hearing was so bad now that it was as if his ears were stuffed full of wool. But, lying there on his pallet, he could hear every word they said.
And, though he needed a lot of sleep now, he was aware when they moved him into the Morgue, ready for him to die, ready to capture his Effigy-spirit when it was released from his seventy-two-year-old body. “You can wheel me in here if you like, you bastards.” He tried to laugh, but it just made him cough. “I'm just going to lie here as long as it takes."
"As long as it takes for what?"
"For it to come back again."
But, more than thirty years since his last visitation, only a handful of the medical staff knew what he was talking about.
In the end, of course, it came.
He woke from another drugged sleep to find a little boy standing beside his bed. He struggled to sit up. “Hey, Powpy. How's it going with you? For you it must be, what, a year since last time? You've grown. You're not afraid of me, are you? Look, I'm old and disgusting, but at least I can't slap you around the head any more, can I?"
He thought he saw a flicker of something in the boy's eyes. Forgiveness? Pity? Contempt? Well, he deserved the latter. But then the kid spoke in that odd monotone, so familiar even after all these years. “We were here at the beginning of your life. Now here we are at the end."
"Yes.” He tried to snap his fingers, failed. “Just another spark in the flames for you, right? And now you've come to see me give up my Effigy so you can trap it in this box of yours."
"We would not describe it as—"
He grabbed the boy's arm, trying to grip hard. “Listen, Weapon. You can have my Effigy. What do I care? But I'm not going to die like this. Not here, not now."
"Then where, and when?"
"Fifty years,” he whispered. He glanced at the medical staff, who hovered at the edges of the Building. “I did my own calculations. Took me ten years. Well, I had nothing better to do ... Fifty years, right? That's all we've got left, until the fireworks."
The boy said gravely, “We imagine our model of the galaxies’ interaction is somewhat more sophisticated than yours. But your answer is substantially correct. You understand that this Caress will be different. Those on the Platform will survive. The construction material of the Buildings will shelter them. That was one purpose of the Platform in the first place. And from this seed the recovery after the Caress should be much more rapid."
"But the cities of the Shelf—Foro, Puul—"
"People will survive in caves, underground. But the vast loss of life, the destruction of the ecology, their agricultural support—"
"Well, it serves those bastards right. They lost interest in talking to me decades ago.” Which was true. But since the War of the Cities, there had be
en a thousand years of peace on the Shelf, all of which he'd lived through—incredible to be a witness to so much history—and they had built something beautiful and splendid up there, a chain of cities like jewels in the night. In his head he imagined a race of Minas, beautiful, clear-eyed, laughing. “Well. There's nothing I can do for them.” He struggled to sit straighter. “But there's something I want you to do for me. You owe me, you artefact. I did everything you asked of me, and more. Now you're going to take away my soul. Well, you can have it. But you can give me something back in return. I want to see the Caress."
"You have only weeks to live. Days, perhaps."
"Take me down into the red. No matter how little time I have left, you can find a pit deep enough on this time-shifted world to squeeze in fifty Platform years.” Exhausted, he fell back coughing; a nurse hurried over to catch him and lower him gently to his blankets. “And one more thing."
"More demands?"
"Let this boy go."
* * * *
When Telni woke again, he found himself staring up at a sky of swirling blue stars. “Made it, by my own blueshifted arse."
A face hovered over him, a woman's. “Don't try to move."
"You're in the way.” He tried to sit up, failed, but kept struggling until she helped him up and he could see.
He was on a plain—on the ground, his pallet set on red, rusty dirt, down on the ground for the first time in his life. Something like a rail track curled across his view. Buildings of construction material were scattered around like a giant's toys. He got the immediate sense this was a kind of camp, not permanent.
And figures moved in the distance. At first sight they looked human. But then something startled them, and they bucked and fled, on six legs.
"What are those?"
"They are called Centaurs.” Powpy was standing beside him, his neck umbilical connecting him to the Weapon, which hovered as impassive as ever, though a little rusty dirt clung to its sleek hide. “Human hybrids."
"You were going to let this kid go."
"He will be released,” said the woman sternly. “My name's Ama, by the way."
Which had been his mother's name. He felt a stab of obscure guilt. “Glad to meet you."
"You should be. I'm a nurse. I volunteered to stay with you, to keep you alive when they brought you down here."
"No family, I take it."
"Not any more. And when this business is done, I'll be taking Powpy here back up top, to the Platform."
"His mother and father—"
"Long dead,” she whispered.
"We're all orphans here, then."
Powpy said solemnly, “We will have to shelter in a construction-material Building to ride out the Caress. We are deep enough that it should be brief—"
"How deep?"
"We are on the Abyss. Once the bed of a deep ocean. Below the offshore plains you call the Lowland ... Deep enough."
"Nice sky."
"Most of the stars’ radiation is blueshifted far beyond your capacity to see it."
"And how long—ow!” There was a sharp pain in his chest.
Ama grabbed him and lowered him back against a heap of pillows. “Just take it easy. That was another heart attack."
"Another..."
"They've been coming thick and fast."
"That Weapon won't want me dying out in the open. Not after all this."
"We have a Morgue designated just over there,” Ama said. “Your bed's on wheels."
"Good planning."
"Not long now,” murmured Powpy.
But he, the boy, wasn't looking at the sky. Telni touched Powpy's chin, and lifted his face. “He should see this for himself."
"Very well,” the Weapon said through the boy's mouth.
"Why, Weapon? Why the grand experiment? Why the Platform? Why are you so fascinated by the Effigies?"
"We believe the Effigies are not native to the Earth, any more than the spindlings or the lightmoss or—"
"But they're pretty closely bound up to humans. They live and die with us."
"They do not die. So we believe. We have mapped disturbances, deep in the Earth ... We believe there is a kind of nest of them, a colony of the Effigies that dwells deep in the core of Old Earth. They emerge to combine with humans, with infants at birth. Some infants—we don't know how they choose. And we don't know how they bond either. But after the human carrier's death, the Effigy symbiote is released, and returns to the core colony. Something of the human is taken with it. We believe."
"Memories."
"Perhaps."
"And are these memories brought back up from this core pit the next time an Effigy surfaces?"
"Perhaps. Everything about this world is designed, or modified. Perhaps the purpose is to preserve something of the memory of humanity across epochal intervals."
"Maybe this is why I always felt like something in me really doesn't belong in this time or place."
"Perhaps. We must study this at second hand. It is something about humanity that no machine shares."
"I think you're jealous. Aren't you, machine? You can farm us, keep us as lab animals. But you can't have this."
"No reliable mapping between human emotions and the qualia of our own sensorium..."
But he didn't hear the rest. Another stabbing in his chest, a pain that knifed down his left arm. The nurse leaned over him.
And the sky exploded. They weren't just new stars. They were stars that detonated, each flaring brighter than the rest of the sky put together, then vanishing as quickly, blown-out matches.
"Supernovas,” said the boy, Powpy. “That is the ancient word. A wave of supernovas, triggered by the galaxy collision, giant exploding stars flooding nearby space with lethal radiation, a particle sleet..."
But Telni couldn't talk, couldn't breathe.
"He's going,” the nurse said. “Get him to the Morgue."
He glimpsed two creatures running up—they were six-legged people, Centaurs—and his bed was shoved forward, across the rusty dirt towards the enclosure of a Building. He tried to protest, to cling to his view of that astounding sky as long as he could. But he couldn't even breathe, and it felt as if a sword were being twisted in his chest.
They got him indoors. He lay back, rigid with pain, staring at a construction material roof that seemed to recede from him.
And a glow, like the glow of the sky outside, suffused the inside of his head, his very eyes.
"It's happening,” he heard the nurse say, wonder in her voice. “Look, it's rising from his limbs ... His heart has stopped.” She straddled him and pounded at his chest, even as a glow lit up her face, the bare flesh of her arms—a glow coming from him.
He remembered a glimmering tetrahedron, looming, swallowing him up.
He heard Powpy call, “Who are you? Who are you?"
And suddenly he knew, as if his eyes had suddenly focused, after years of myopia. With the last of the air in his lungs he struggled to speak. “Not again. Not again!"
The nurse peered into his eyes. “Stay with me, Telni!"
"Who are you?"
"My name is Michael Poole."
The light detonated, deep inside him.
Suddenly he filled this box of Xeelee stuff, and he rattled, anguished. But there was the door, a way out. Somehow he fled that way, seeking the redshift.
And then—
Copyright © 2009 Stephen Baxter
(EDITOR'S NOTE: This story is set a few centuries after the events of “The Lowland Expedition” [April 2006].)
[Back to Table of Contents]
Science Fact: PLATE TECTONICS, GOLDILOCKS, AND THE LATE HEAVY BOMBARDMENT: WHY EARTH ISN'T MARS OR VENUS by Richard A. Lovett
In my part of the world, weather forecasts are the subject of much joking—hard to get right, sometimes even as little as twenty-four hours in advance. But in the billion-year time frame, the Earth's weather is easier to predict. Warm but not too hot, cool but not too cold. Not much chance of f
reezing the oceans solid or evaporating them away completely.
This didn't have to be the case. Mars and Venus appear to have started out quite Earthlike, but then veered into climate dead-ends: one frozen, the other baking in a runaway greenhouse. Why then is Earth's climate so stable? Even when something tips it out of whack—like the giant ice age of Snowball Earth (in which the ice caps spread nearly to the Equator[1]), our planet recovers.
Partly, of course, this is a side effect of a lucky position in the Solar System. Not only are we in the Sun's habitable zone, where planets won't automatically wind up like Mercury or Pluto, but of the three worlds in this zone, we're the Goldilocks planet. “In very simple terms,” says Victor Baker, a planetary geologist at the University of Arizona's Lunar and Planetary Laboratory, “Venus is too hot, Mars is too cold, and Earth is just right."
But that's just the starting point. In the 4.5 billion years since the Solar System formed, the Sun has brightened by about 25%, but our climate has barely changed. Obviously, something is keeping it stable.
In the old days, scientists and science fiction writers credited the Earth's oversized moon with our planet's habitability. The theory was a bit vague, but was based in part on the observation that the Earth and Moon are a unique pairing.[2] Venus is moonless, and the two moons of Mars, Phobos and Deimos, are tiny. Maybe, the theory went, life-supporting planets, here or in other solar systems, might also need big moons.
In fact, the latest theories indeed suggest that the Moon plays a role—something we'll discuss later in this article. But two other factors are much more important: plate tectonics and water. In combination, these interact with carbon dioxide to form a very effective global thermostat.
This process begins with volcanoes.
Volcanoes spew out more than molten rock. They also produce gas, a major component of which is carbon dioxide. As anyone familiar with the global warming debate knows, carbon dioxide is a “greenhouse gas” that traps infrared radiation that would otherwise escape to space. Glass does the same thing, which is why greenhouses can stay warm without heaters and why the inside of your car gets so hot in the summer.
Analog SFF, December 2009 Page 4