Artifacts

by Greg Egan

  As the moment of diaspora approached, a small gray lizard darted across the courtyard, claws scrabbling. It halted by the far edge of the pool, and Paolo marveled at the delicate pulse of its breathing, and watched the lizard watching him, until it moved again, disappearing into the surrounding vineyards. The environment was full of birds and insects, rodents and small reptiles—decorative in appearance, but also satisfying a more abstract aesthetic: softening the harsh radial symmetry of the lone observer; anchoring the simulation by perceiving it from a multitude of viewpoints. Ontological guy lines. No one had asked the lizards if they wanted to be cloned, though. They were coming along for the ride, like it or not.

  The sky above the courtyard was warm and blue, cloudless and sunless, isotropic. Paolo waited calmly, prepared for every one of half a dozen possible fates.

  An invisible bell chimed softly, three times. Paolo laughed, delighted.

  One chime would have meant that he was still on Earth: an anticlimax, certainly—but there would have been advantages to compensate for that. Everyone who really mattered to him lived in the Carter-Zimmerman polis, but not all of them had chosen to take part in the diaspora to the same degree; his Earth-self would have lost no one. Helping to ensure that the thousand ships were safely dispatched would have been satisfying, too. And remaining a member of the wider Earth-based community, plugged into the entire global culture in real-time, would have been an attraction in itself.

  Two chimes would have meant that this clone of Carter-Zimmerman had reached a planetary system devoid of life. Paolo had run a sophisticated—but non-sapient—self-predictive model before deciding to wake under those conditions. Exploring a handful of alien worlds, however barren, had seemed likely to be an enriching experience for him—with the distinct advantage that the whole endeavor would be untrammeled by the kind of elaborate precautions necessary in the presence of alien life. C-Z’s population would have fallen by more than half—and many of his closest friends would have been absent—but he would have forged new friendships, he was sure.

  Four chimes would have signaled the discovery of intelligent aliens. Five, a technological civilization. Six, spacefarers.

  Three chimes, though, meant that the scout probes had detected unambiguous signs of life—and that was reason enough for jubilation. Up until the moment of the pre-launch cloning—a subjective instant before the chimes had sounded—no reports of alien life had ever reached Earth. There’d been no guarantee that any part of the diaspora would find it.

  Paolo willed the polis library to brief him; it promptly rewired the declarative memory of his simulated traditional brain with all the information he was likely to need to satisfy his immediate curiosity. This clone of C-Z had arrived at Vega, the second closest of the thousand target stars, twenty-seven light-years from Earth. Paolo closed his eyes and visualized a star map with a thousand lines radiating out from the sun, then zoomed in on the trajectory which described his own journey. It had taken three centuries to reach Vega—but the vast majority of the polis’s twenty thousand inhabitants had programmed their exoselves to suspend them prior to the cloning, and to wake them only if and when they arrived at a suitable destination. Ninety-two citizens had chosen the alternative: experiencing every voyage of the diaspora from start to finish, risking disappointment, and even death. Paolo now knew that the ship aimed at Fomalhaut, the target nearest Earth, had been struck by debris and annihilated en route. He mourned the ninety-two, briefly. He hadn’t been close to any of them, prior to the cloning, and the particular versions who’d willfully perished two centuries ago in interstellar space seemed as remote as the victims of some ancient calamity from the era of flesh.

  Paolo examined his new home star through the cameras of one of the scout probes—and the strange filters of the ancestral visual system. In traditional colors, Vega was a fierce blue-white disk, laced with prominences. Three times the mass of the sun, twice the size and twice as hot, sixty times as luminous. Burning hydrogen fast—and already halfway through its allotted five hundred million years on the main sequence.

  Vega’s sole planet, Orpheus, had been a featureless blip to the best lunar interferometers; now Paolo gazed down on its blue-green crescent, ten thousand kilometers below Carter-Zimmerman itself. Orpheus was terrestrial, a nickel-iron-silicate world; slightly larger than Earth, slightly warmer—a billion kilometers took the edge off Vega’s heat—and almost drowning in liquid water. Impatient to see the whole surface firsthand, Paolo slowed his clock rate a thousandfold, allowing C-Z to circumnavigate the planet in twenty subjective seconds, daylight unshrouding a broad new swath with each pass. Two slender ocher-colored continents with mountainous spines bracketed hemispheric oceans, and dazzling expanses of pack ice covered both poles—far more so in the north, where jagged white peninsulas radiated out from the midwinter arctic darkness.

  The Orphean atmosphere was mostly nitrogen—six times as much as on Earth; probably split by UV from primordial ammonia—with traces of water vapor and carbon dioxide, but not enough of either for a runaway greenhouse effect. The high atmospheric pressure meant reduced evaporation—Paolo saw not a wisp of cloud—and the large, warm oceans in turn helped feed carbon dioxide back into the crust, locking it up in limestone sediments destined for subduction.

  The whole system was young, by Earth standards, but Vega’s greater mass, and a denser protostellar cloud, would have meant swifter passage through most of the traumas of birth: nuclear ignition and early luminosity fluctuations; planetary coalescence and the age of bombardments. The library estimated that Orpheus had enjoyed a relatively stable climate, and freedom from major impacts, for at least the past hundred million years.

  Long enough for primitive life to appear—

  A hand seized Paolo firmly by the ankle and tugged him beneath the water. He offered no resistance, and let the vision of the planet slip away. Only two other people in C-Z had free access to this environment—and his father didn’t play games with his now-twelve-hundred-year-old son.

  Elena dragged him all the way to the bottom of the pool, before releasing his foot and hovering above him, a triumphant silhouette against the bright surface. She was ancestor-shaped, but obviously cheating; she spoke with perfect clarity, and no air bubbles at all.

  “Late sleeper! I’ve been waiting seven weeks for this!”

  Paolo feigned indifference, but he was fast running out of breath. He had his exoself convert him into an amphibious human variant—biologically and historically authentic, if no longer the definitive ancestral phenotype. Water flooded into his modified lungs, and his modified brain welcomed it.

  He said, “Why would I want to waste consciousness, sitting around waiting for the scout probes to refine their observations? I woke as soon as the data was unambiguous.”

  She pummeled his chest; he reached up and pulled her down, instinctively reducing his buoyancy to compensate, and they rolled across the bottom of the pool, kissing.

  Elena said, “You know we’re the first C-Z to arrive, anywhere? The Fomalhaut ship was destroyed. So there’s only one other pair of us. Back on Earth.”

  “So?” Then he remembered. Elena had chosen not to wake if any other version of her had already encountered life. Whatever fate befell each of the remaining ships, every other version of him would have to live without her.

  He nodded soberly, and kissed her again. “What am I meant to say? You’re a thousand times more precious to me, now?”

  “Yes.”

  “Ah, but what about the you-and-I on Earth? Five hundred times would be closer to the truth.”

  “There’s no poetry in five hundred.”

  “Don’t be so defeatist. Rewire your language centers.”

  She ran her hands along the sides of his ribcage, down to his hips. They made love with their almost-traditional bodies—and brains; Paolo was amused to the point of distraction when his limbic system went into overdrive, but he remembered enough from the last occasion to bury his self-consciou
sness and surrender to the strange hijacker. It wasn’t like making love in any civilized fashion—the rate of information exchange between them was minuscule, for a start—but it had the raw insistent quality of most ancestral pleasures.

  Then they drifted up to the surface of the pool and lay beneath the radiant sunless sky.

  Paolo thought: I’ve crossed twenty-seven light-years in an instant. I’m orbiting the first planet ever found to hold alien life. And I’ve sacrificed nothing—left nothing I truly value behind. This is too good, too good. He felt a pang of regret for his other selves—it was hard to imagine them faring as well, without Elena, without Orpheus—but there was nothing he could do about that, now. Although there’d be time to confer with Earth before any more ships reached their destinations, he’d decided—prior to the cloning—not to allow the unfolding of his manifold future to be swayed by any change of heart. Whether or not his Earth-self agreed, the two of them were powerless to alter the criteria for waking. The self with the right to choose for the thousand had passed away.

  No matter, Paolo decided. The others would find—or construct—their own reasons for happiness. And there was still the chance that one of them would wake to the sound of four chimes.

  Elena said, “If you’d slept much longer, you would have missed the vote.”

  The vote? The scouts in low orbit had gathered what data they could about Orphean biology. To proceed any further, it would be necessary to send microprobes into the ocean itself—an escalation of contact which required the approval of two-thirds of the polis. There was no compelling reason to believe that the presence of a few million tiny robots could do any harm; all they’d leave behind in the water was a few kilojoules of waste heat. Nevertheless, a faction had arisen which advocated caution. The citizens of Carter-Zimmerman, they argued, could continue to observe from a distance for another decade, or another millennium, refining their observations and hypotheses before intruding … and those who disagreed could always sleep away the time, or find other interests to pursue.

  Paolo delved into his library-fresh knowledge of the “carpets”—the single Orphean lifeform detected so far. They were free-floating creatures living in the equatorial ocean depths—apparently destroyed by UV if they drifted too close to the surface. They grew to a size of hundreds of meters, then fissioned into dozens of fragments, each of which continued to grow. It was tempting to assume that they were colonies of single-celled organisms, something like giant kelp—but there was no real evidence yet to back that up. It was difficult enough for the scout probes to discern the carpets’ gross appearance and behavior through a kilometer of water, even with Vega’s copious neutrinos lighting the way; remote observations on a microscopic scale, let alone biochemical analyses, were out of the question. Spectroscopy revealed that the surface water was full of intriguing molecular debris—but guessing the relationship of any of it to the living carpets was like trying to reconstruct human biochemistry by studying human ashes.

  Paolo turned to Elena. “What do you think?”

  She moaned theatrically; the topic must have been argued to death while he slept. “The microprobes are harmless. They could tell us exactly what the carpets are made of, without removing a single molecule. What’s the risk? Culture shock?”

  Paolo flicked water onto her face, affectionately; the impulse seemed to come with the amphibian body. “You can’t be sure that they’re not intelligent.”

  “Do you know what was living on Earth, two hundred million years after it was formed?”

  “Maybe cyanobacteria. Maybe nothing. This isn’t Earth, though.”

  “True. But even in the unlikely event that the carpets are intelligent, do you think they’d notice the presence of robots a millionth their size? If they’re unified organisms, they don’t appear to react to anything in their environment—they have no predators, they don’t pursue food, they just drift with the currents—so there’s no reason for them to possess elaborate sense organs at all, let alone anything working on a sub-millimeter scale. And if they’re colonies of single-celled creatures, one of which happens to collide with a microprobe and register its presence with surface receptors … what conceivable harm could that do?”

  “I have no idea. But my ignorance is no guarantee of safety.”

  Elena splashed him back. “The only way to deal with your ignorance is to vote to send down the microprobes. We have to be cautious, I agree—but there’s no point being here if we don’t find out what’s happening in the oceans, right now. I don’t want to wait for this planet to evolve something smart enough to broadcast biochemistry lessons into space. If we’re not willing to take a few infinitesimal risks, Vega will turn red giant before we learn anything.”

  It was a throwaway line—but Paolo tried to imagine witnessing the event. In a quarter of a billion years, would the citizens of Carter-Zimmerman be debating the ethics of intervening to rescue the Orpheans—or would they all have lost interest, and departed for other stars, or modified themselves into beings entirely devoid of nostalgic compassion for organic life?

  Grandiose visions for a twelve-hundred-year-old. The Fomalhaut clone had been obliterated by one tiny piece of rock. There was far more junk in the Vegan system than in interstellar space; even ringed by defenses, its data backed up to all the far-flung scout probes, this C-Z was not invulnerable just because it had arrived intact. Elena was right; they had to seize the moment—or they might as well retreat into their own hermetic worlds and forget that they’d ever made the journey.

  Paolo recalled the honest puzzlement of a friend from Ashton-Laval: Why go looking for aliens? Our polis has a thousand ecologies, a trillion species of evolved life. What do you hope to find, out there, that you couldn’t have grown at home?

  What had he hoped to find? Just the answers to a few simple questions. Did human consciousness bootstrap all of space-time into existence, in order to explain itself? Or had a neutral, pre-existing universe given birth to a billion varieties of conscious life, all capable of harboring the same delusions of grandeur—until they collided with each other? Anthrocosmology was used to justify the inward-looking stance of most polises: if the physical universe was created by human thought, it had no special status which placed it above virtual reality. It might have come first—and every virtual reality might need to run on a physical computing device, subject to physical laws—but it occupied no privileged position in terms of “truth” versus “illusion.” If the ACs were right, then it was no more honest to value the physical universe over more recent artificial realities than it was honest to remain flesh instead of software, or ape instead of human, or bacterium instead of ape.

  Elena said, “We can’t lie here forever; the gang’s all waiting to see you.”

  “Where?” Paolo felt his first pang of homesickness; on Earth, his circle of friends had always met in a real-time image of the Mount Pinatubo crater, plucked straight from the observation satellites. A recording wouldn’t be the same.

  “I’ll show you.”

  Paolo reached over and took her hand. The pool, the sky, the courtyard vanished—and he found himself gazing down on Orpheus again … nightside, but far from dark, with his full mental palette now encoding everything from the pale wash of ground-current long-wave radio, to the multicolored shimmer of isotopic gamma rays and back-scattered cosmic-ray bremsstrahlung. Half the abstract knowledge the library had fed him about the planet was obvious at a glance, now. The ocean’s smoothly tapered thermal glow spelt three-hundred Kelvin instantly—as well as back-lighting the atmosphere’s telltale infrared silhouette.

  He was standing on a long, metallic-looking girder, one edge of a vast geodesic sphere, open to the blazing cathedral of space. He glanced up and saw the star-rich dust-clogged band of the Milky Way, encircling him from zenith to nadir; aware of the glow of every gas cloud, discerning each absorption and emission line, Paolo could almost feel the plane of the galactic disk transect him. Some constellations were distorted, but the
view was more familiar than strange—and he recognized most of the old signposts by color. He had his bearings, now. Twenty degrees away from Sirius—south, by parochial Earth reckoning—faint but unmistakable: the sun.

  Elena was beside him—superficially unchanged, although they’d both shrugged off the constraints of biology. The conventions of this environment mimicked the physics of real macroscopic objects in free-fall and vacuum, but it wasn’t set up to model any kind of chemistry, let alone that of flesh and blood. Their new bodies were human-shaped, but devoid of elaborate microstructure—and their minds weren’t embedded in the physics at all, but were running directly on the processor web.

  Paolo was relieved to be back to normal; ceremonial regression to the ancestral form was a venerable C-Z tradition—and being human was largely self-affirming, while it lasted—but every time he emerged from the experience, he felt as if he’d broken free of billion-year-old shackles. There were polises on Earth where the citizens would have found his present structure almost as archaic: a consciousness dominated by sensory perception, an illusion of possessing solid form, a single time coordinate. The last flesh human had died long before Paolo was constructed, and apart from the communities of Gleisner robots, Carter-Zimmerman was about as conservative as a transhuman society could be. The balance seemed right to Paolo, though—acknowledging the flexibility of software, without abandoning interest in the physical world—and although the stubbornly corporeal Gleisners had been first to the stars, the C-Z diaspora would soon overtake them.

  Their friends gathered round, showing off their effortless free-fall acrobatics, greeting Paolo and chiding him for not arranging to wake sooner; he was the last of the gang to emerge from hibernation.