As they fell through the long, featureless aeons, five more times the dead hand of global glaciation fell on the planet, killing the oceans, squeezing out of existence all but the most primitive life-forms in the most marginal environments. It was a savage feedback cycle initiated every time life gained a significant foothold in the shal- low waters at the fringe of the continents.
David said, "It is the tragedy of Sisyphus. In the myth, Sisyphus had to roll the rock to the top of the mountain, only to watch it roll back again and again. Thus, life struggles to achieve complexity and significance, and is again and again crushed down to its most primitive level. It is a series of icy Wormwoods, over and over. Maybe those nihilist philosophers are right; maybe this is all we can expect of the universe, a relentless crushing of life and spirit, because the equilibrium state of the cosmos is death...."
Bobby said grimly, 'Tsiolkovski once called Earth the cradle of mankind. And so it is, in fact the cradle of life. But—"
"But," said David, "it's one hell of a cradle which crushes its occupants. At least this couldn't happen now. Not quite this way, anyhow. Life has developed complex feedback cycles, controlling the flow of mass and energy through Earth's systems. We always thought the living Earth was a thing of beauty. It isn't. Life has had to learn to defend itself against the planet's random geo- logical savagery."
At last they reached a time deeper than any of the hammer-blow glaciations.
This young Earth had little in common with the world it would become. The air was visibly thick—unbreath- able, crushing. There were no hills or shores, cliffs or forests. Much of the planet appeared to be covered by a shallow ocean, unbroken by continents. The seabed was a thin crust, cracked and broken by rivers of lava that scalded the seas. Frequently, thick gases clouded the planet for years at a time—until volcanoes thrust above die surface and sucked the gases back into the interior.
When it could be seen through the thick rolling smog, the sun was a fierce, blazing ball. The Moon was huge, the size of a dinner plate, though many of its familiar features were already etched into place.
But both Moon and sun seemed to race across the sky. This young Earth spun rapidly on its axis, frequently plunging its surface and its fragile cargo of life into night, and towering tides swept around the bruised planet.
The ancestors, in this hostile place, were unambitious: generation after generation of unremarkable cells living in huge communities close to me surface of shallow seas. Each community began as a spongelike mass of matter, which would shrivel back layer on layer until a single patch of green remained, floating on the surface, drifting across me ocean to merge with some older community.
The sky was busy, alive with me flashes of giant me- teors returning to deep space-'Trequently—terribly fre- quently—walls of water, kilometers high, would race around the globe and converge on a burning impact scar, from which a great shining body, an asteroid or comet, would leap into space, briefly illuminating the bruised sky before dwindling into the dark.
And the savagery and frequency of these backward impacts seemed to increase.
Now, abruptly, me green life of me algal mats began to migrate across the surface of the young, turbulent oceans, dragging the ancestor chain—and Bobby's view- point—with it. The algal colonies merged, shrank again, merged, as if shriveling back toward a common core.
At last they found themselves in an isolated pond, cupped in the basin of a wide, deep impact crater, as if on a flooded Moon: Bobby saw jagged run mountains, a stubby central peak. The pond was a livid, virulent green, and, somewhere within, the ancestor chains con- tinued their blind toil back toward inanimacy.
But now, suddenly, the green stain shriveled, reducing to isolated specks, and the surface of the crater lake was covered by a new kind of scum, a thick brownish mat.
"... Oh," David breathed, as if shocked. "We just lost chlorophyll. The ability to manufacture energy from sun- light. Do you see what's happened? This community of organisms was isolated from the rest by some impact or geological accident—the event that formed this crater, perhaps. It ran out of food here. The organisms were forced to mutate or die."
"And mutate they did," Bobby said. "If not—"
"If not, then not us."
Now there was a burst of violence, a blur of motion, overwhelming and unresolved—perhaps this was the vi- olent, isolating event David had hypothesized.
When it was over, Bobby found himself beneath the sea once more, gazing at a mat of thick brown scum that clung to a smoking vent, dimly lit by Earth's own in- ternal glow.
"Then it has come to this," said David. "Our deepest ancestors were rock-eaters: thennophiles, or perhaps even hyperthermophiles. That is, they relished high tem- perature. They consumed the minerals injected into the water by the vents: iron, sulphur, hydrogen ... Cmde, inefficient, but robust. They did not require light or oxy- gen, or even organic material."
Now Bobby sank into darkness. He passed through tunnels and cracks, diminished, squeezed, in utter dark- ness broken only by occasional dull red flashes.
"David? Are you still there?"
"I'm here."
"What's happening to us?"
"We're passing beneath the seabed. We're migrating through the porous basalt rock there. All the life on the planet is coalescing, Bobby, shrinking back along the ocean ridges and seafloor basalt beds, merging to a sin- gle point."
"Where? Where are we migrating to?"
"To the deep rock. Bobby. A point a kilometer down. It will be the last retreat of life. All life on Earth has come from this cache, deep in the rock, this shelter."
"And what," Bobby asked with foreboding, "did life have to shelter fromT
"We are about to find out, I fear."
David lifted them up, and they hovered in the foul air of this lifeless Earth.
There was light here, but it was dim and orange, like twilight in a smoggy city. The sun must be above the horizon, but Bobby could not locate it precisely, or the giant Moon. The atmosphere was palpably thick and crushing. The ocean churned below, black, in some places boiling, and me fractured seabed was laced with fire.
The graveyard is truly empty now, Bobby thought. Save for that one small deep-buried cache—containing my most remote ancestors—these young rocks have given up all their layered dead.
And now a blanket of black cloud gathered, as if hurled across the sky by some impetuous god. An in- verted rain began, rods of water that leapt from the dap- pled ocean surface to the swelling clouds.
A century wore by, and still the rain roared upward out of the ocean, its ferocity undiminished—indeed, so voluminous was the rain that soon ocean levels were dropping perceptibly. The clouds thickened further and the oceans dwindled, forming isolated brine pools in the lowest hollows of Earth's battered, cracked surface.
It took two thousand years. The rain did not stop until the oceans had returned to the clouds, and the land was dry.
And the land began to fragment further.
Soon bright glowing cracks in the exposed land were widening, brightening, lava pulsing and flowing. At last there were only isolated islands left, shards of rock which shriveled and melted, and a new ocean blanketed the Earth: an ocean of molten rock, hundreds of meters deep.
Now a new reversed rain began: a hideous storm of bright molten rock, leaping up from me land. The rock droplets joined the water clouds, so mat the atmosphere became a hellish layer of glowing rock droplets and steam.
"Incredible," David shouted. The Earth is collecting an atmosphere of rock vapor, forty or fifty kilometers thick, exerting hundreds of times the pressure of our air. The heat energy contained in it is stupendous.... The planet's cloud tops must be glowing. Eartfa is shining, a star of rock vapor."
But me rock rain was drawing heat away from the battered land and—rapidly, within a few months—the land had cooled to solidity. Beneath a glowing sky, liq- uid water was beginning to form again, new oceans co- alescing out of the cooling clouds.
But the oceans were formed boiling, their surfaces in contact with rock vapor. And between the oceans, mountains formed, unmelting from puddles of slag.
And now a wall of light swept past Bobby, dragging after it a front of boiling clouds and steam in a burst of unimaginable violence. Bobby screamed—
David slowed their descent into time.
Earth was restored once again.
The blue-black oceans were calm. The sky, empty of cloud, was a greenish dome. The battered Moon was disturbingly huge, the Man's face familiar to Bobby— save for a missing right eye ... And mere was a second sun, a glowing ball that outshone the Moon, with a tail that stretched across the sky.
"A green sky," murmured David. ''Strange. Methane, perhaps? But how ..."
"What," Bobby said, '"the hell is thatT
'*0h, the comet? A real monster. The size of modem- day asteroids like Vesta or Pallas, perhaps five hundred kilometers across. A hundred thousand times the mass of the dinosaur killer."
"The size of the Wormwood."
"Yes. Remember that the Earth itself was formed from impacts, coalescing from a hail of planetesimals that or- bited the young sun. The greatest impact of all was prob- ably the collision with another young world that nearly cracked us open."
"The impact that formed the Moon."
"After that the surface became relatively stable—but still, the Earth was subject to immense impacts, tens or hundreds of them within a few hundred million years, a bombardment whose violence we can't begin to imagine. The impact rate tailed off as the remnant planetesimals were soaked up by the planets, and there was a halcyon period of relative quiescence, lasting a few hundred mil- lion years ... and then, this. Earth was unlucky to meet such a giant so late in the bombardment. An impact hot enough to boil the oceans, even melt the mountains."
"But we survived," Bobby said grimly.
"Yes. In our deep, hot niche."
They fell down into the Earth once more, and Bobby was immersed in rock with his most distant ancestors, a scraping of thermophilic microbes.
He waited in darkness, as countless generations peeled back.
Then, in a blur, he saw light once more.
He was rising up some kind of shaft—like a well— toward a circle of green light, the sky of this alien, pre- bombardment Earth. The circle expanded until he was lifted into the light.
He had some trouble interpreting what he saw next.
He seemed to be inside a box of some glassy material. The ancestor must be here with him, one crude cell among millions subsisting in this container. The box was set on some form of stand, and from here, he could look out over—
"Oh, dear God," said David.
It was a city.
Bobby glimpsed an archipelago of small volcanic is- lands, rising from the blue sea. But me islands had been linked by wide, flat bridges. On the land, low walls marked out geometrical forms—they looked like fields— but this was not a human landscape; the shapes of these fields seemed to be variants of hexagons. There were even buildings, low and rectangular, like airplane han- gars. He glimpsed movement between the buildings, some kind of traffic, too distant to resolve.
And now something was moving toward him.
It looked like a trilobite, perhaps. A low segmented body that glittered under the green sky. Sets of legs— six or eight?—that flickered with movement. Something like a head at the front.
A head with a mouth that held a tool of gleaming metal.
The head was raised toward him. He tried to make out the eyes of this impossible creature. He felt as if he could reach out and touch that chitinous face, and—
—and me world imploded into darkness.
They were two old men who had spent too long in vir- tual reality, and the Search Engine had thrown them out Bobby, lying there stunned, thought il was probably a blessing.
He stood, stretched, rubbed his eyes.
He blundered through the Wonnworks. its solidity and grime seeming unreal after me four-billion-year specta- cle he had endured. He found a coffee drone, ordered two cups, gulped down a hot mouthful. Then, feeling somewhat restored to humanity, he returned to his brother. He held out the coffee until David—mouth open, eyes glazed—sat up to take it.
"The Sisyphans," David murmured, his voice dry.
"What?"
"That's what we must call them. They evolved on early Earth, in the interval of stability between the early and late bombardments. They were different from us.... That methane sky. What could thai have meant? Perhaps even their biochemistry was novel, based on sulphur compounds, or with ammonia as a solvent, or..." He grabbed Bobby's arm. "And of course you understand that they need have had little in common with the crea- tures they selected for the cache. The cache of our an- cestors- No more than we have with the exotic flora and fauna which still cling to the deep-sea vents in our world. But they—the thermophiles, our ancestors—were the best hope for survival...."
"David, slow down. What are you talking about?"
David looked at him, baffled. "Don't you understand yet? They were intelligent. The Sisyphans. But they were doomed. They saw it coming, you see."
"The great comet."
"Yes. Just as we can see our own Wormwood. And they knew what it would do to -their world: boil the oceans, even melt the rock for hundreds of meters down. You saw them. Their technology was primitive. They were a young species. They had no way to escape the planet, or outlive the impact themselves, or deflect the impactor. They were doomed, without recourse. And yet they did not succumb to despair."
"They buried the cache—deep enough so the heat pulse couldn't reach it."
"Yes. You see? They labored to preserve life—us, Bobby—even in the midst of the greatest catastrophe the planet has suffered.
"And that is our destiny, Bobby. Just as the Sisyphans preserved their handful of thermophilic microbes to out- live the impact—just as those algal mats and seaweed struggled to outlast the savage glaciation episodes, just as complex life, evolving and adapting, survived the later catastrophes of volcanism and impact and geolog- ical accident—so must we. Even the Joined, the new evolution of mind, are part of a single thread which reaches back to the dawn of life itself."
Bobby smiled. "Remember what Hiram used to say? 'There's no limit to what we can achieve, if we work together.' "
"Yes. That's it exactly. Hiram was no fool."
Fondly, Bobby touched his brother's shoulder. "I think—"
—and, once again, without warning, the world im- ploded into darkness.
Epilogue
- - fcrfobby. Please wake up. Bobby. Can you hear ... Dme?..."
The voice came to him, as if from afar. A woman's voice. He heard the voice, understood the words, even before a sense of his body returned.
His eyes were closed.
He was lying flat on his back on what felt like a deep, soft bed. He could feel his limbs, the slow pulse of his heart, the swell of his breath- Everything seemed normal-
And yet he knew it was no^ something was wrong, as subtly askew as the violet sky of the Cretaceous.
He felt unaccountably afraid.
He opened his eyes.
A woman's face hovered before him- fine-boned, blue-eyed, blond hair, some lines at the eyes. She might have been forty, even fifty. Yet he recognized her.
". . - Mary?"
Was it his voice?
He raised his hand. A bony wrist protruded from a sleeve of some silvery fabric. The hand was fine-boned, the fingers narrow and long, like a pianist's.
Was it his hand?
Mary—if it was Mary—leaned forward and cupped his face. "You're awake. Thank Hiram for that. Can you understand me?"
"Yes. Yes, I—"
"What do you remember?"
"David. The Wormworks. We were—"
"Traveling. Yes. Good; you remember. On his Anas- tasis David told us what you had seen."
Anastasis. he thought. Resurrection. His fear deep- ened.
&nbs
p; He tried to sit up. She helped him. He felt weak, light.
He was in a smooth-walled chamber. It was dark. A doorway led to a corridor, flooded with light. There was a single small window, circular. It revealed a slab of blue and black.
Blue Earth. Black sky.
The air of Earth was clear as glass. There was a silver tracery over the blue oceans, some kind of structure, hundreds of kilometers above the surface. Was he in orbit? No; the Earth was not turning. He was in some kind of orbital tower, then.
Arthur C Clarke - Light Of Other Days Page 35
