The Year's Best SF 25 # 2007

by Gardner Dozois (ed)

  Agent Gu shook his head in disbelief, when the old man fell silent. “The earth circle around the sun? You might as well say that the Dragon Throne exists to serve me, and not the other way around.”

  “You might indeed.” Ling smiled, his eyes twinkling.

  Cao swayed on his feet. He felt unsteady, as though he stood on the edge of a precipice, about to fall into the abyss.

  “Ling Xuan, you promised me one final fact about the Mexica,” Cao said uneasily.

  “So I did,” Ling said, nodding. “So I did. And I will tell you. It is this.”

  The old man leaned closer to Cao, and spoke softly, like thunder more distant than ever before, as though he were communicating some secret in confidence that he didn’t want the stars above to overhear.

  “The Mexica, as clever and bright and ferocious as they may be, are still blinded by their faith. The most learned among them honestly believes that the world is but a few hundred years old, and all evidence to the contrary is merely a test of their faith. We of the Middle Kingdom, I would argue, cling with as much tenacity to beliefs and superstitions no more grounded in reality than that, but with one notable difference. Ours is a culture that can produce a mind like Cui’s, a mind that challenges received wisdom, which questions the foundations of knowledge itself. If we manage to produce only one like him in every dozen generations, we will still manage, in the fullness of time, to conquer the universe. Like the fraction of worlds or the fraction of stars in the great immensity of the heavens, which ensure that we are not alone, just one small spark of genius in the vast sea of complacency will mean that history does not stand still.”

  Ling Xuan turned, and headed back the way they had come.

  “I am ready to return home to my cell now, thank you,” the old man said, calling back to Cao and Gu over his shoulder. “I have seen all I needed to see.”

  The next morning, as Cao Wen struggled to work out how to conclude his report, he received a visitor to his cubicle in the Ministry of War. It was Agent Gu, dressed in simple gray robes.

  “Gu? What are you doing here?”

  “At the request of Director Fei, I come to tell you that Ling Xuan, temporary resident of the Outside Depot, died in the night. From all signs, it was not a suicide, nor is there any indication of foul play.”

  Cao blinked, a confused expression spread across his face.

  “The old man died?”

  “Yes,” Gu replied. “Of extreme old age, or so I am given to understand.”

  “And yet he waited long enough to walk once more under the stars as a free man,” Cao observed.

  “Perhaps he felt that it was important enough to live for,” Gu said, unsure, “and having done so, his work was done.”

  Cao sighed, and shrugged his shoulders.

  “Strange timing, no doubt, but he was old, and the elderly have a habit of dying.” Cao regarded Gu’s plain gray robes. “But here you are, beyond the walls of the Eastern Depot yourself, and so adorned that you could pass for a simple merchant in the streets.”

  “Yes,” Agent Gu said with a smile that commingled embarrassment and pride. “It is the opinion of Director Fei that I have completed my training, and will be of better use to the Dragon Throne beyond the walls, rather than within.” Gu paused, and shifted uncomfortably. “Cao Wen, I must ask you. What are your thoughts about the things that Ling Xuan said to us in the night, about the sun and the earth and the stars, about the Middle Kingdom and the Mexica and all?”

  Cao Wen shrugged. “All I can say is that everything Ling reported to me these long weeks has been true, as far as I have been able to determine, the intelligence on the Mexica and the facts the old man learned from astronomer Cui alike. But who am I to judge?”

  Agent Gu nodded absently, and with a final bow departed, leaving Cao with his work.

  There remained only a few more characters to brush onto the final page, and then Cao’s detailed report on the astronomer Cui was complete. This appended to his report about the Mexica, Cao rolled up the papers, and slid them into a leather tube. Then he rose to his feet, arranged his robes around him, and headed toward the office of the Deputy Minister to hand in his survey.

  Glory

  GREG EGAN

  Looking back at the century that’s just ended, it’s obvious that Australian writer Greg Egan was one of the Big New Names to emerge in SF in the nineties, and is probably one of the most significant talents to enter the field in the last several decades. Already one of the most widely known of all Australian genre writers, Egan may well be the best new “hard science” writer to enter the field since Greg Bear, and is still growing in range, power, and sophistication. In the last few years, he has become a frequent contributor to Interzone and Asimov’s Science Fiction, and has made sales as well as to Pulphouse, Analog, Aurealis, Eidolon, and elsewhere; many of his stories have also appeared in various “Best of the Year” series, and he was on the Hugo Final Ballot in 1995 for his story “Cocoon,” which won the Ditmar Award and the Asimov’s Readers Award. He won the Hugo Award in 1999 for his novella “Oceanic.” His first novel, Quarantine, appeared in 1992; his second novel, Permutation City, won the John W. Campbell Memorial Award in 1994. His other books include the novels, Distress, Diaspora, and Teranesia, and three collections of his short fiction, Axiomatic, Luminous, and Our Lady of Chernobyl. His most recent book is the novel Schild’s Ladder.

  Egan fell silent for a couple of years at the beginning of the Oughts, but is back again with a vengeance, with stories in markets such as Asimov’s, Interzone, The New Space Opera, One Million A.D., MIT Technology Review, and Foundation 100. Coming up is a new novel, Incandescence, and a new collection, Dark Integers and Other Stories. He has a Web site at www.netspace.netau/^gregegan/.

  Egan has pictured galaxy-spanning civilizations in stories such as “Border Guards” and “Riding the Crocodile.” Here he sweeps us along with scientists who are willing to go to enormous lengths (including changing their species!) and travel across the galaxy in order to investigate a scientific mystery—one that inimical forces don’t want them to solve.

  1

  An ingot of metallic hydrogen gleamed in the starlight, a narrow cylinder half a meter long with a mass of about a kilogram. To the naked eye, it was a dense, solid object, but its lattice of tiny nuclei immersed in an insubstantial fog of electrons was one part matter to two hundred trillion parts empty space. A short distance away was a second ingot, apparently identical to the first, but composed of antihydrogen.

  A sequence of finely tuned gamma rays flooded into both cylinders. The protons that absorbed them in the first ingot spat out positrons and were transformed into neutrons, breaking their bonds to the electron cloud that glued them in place. In the second ingot, antiprotons became antineutrons.

  A further sequence of pulses herded the neutrons together and forged them into clusters; the antineutrons were similarly rearranged. Both kinds of cluster were unstable, but in order to fall apart, they first had to pass through a quantum state that would have strongly absorbed a component of the gamma rays constantly raining down on them. Left to themselves, the probability of them being in this state would have increased rapidly, but each time they measurably failed to absorb the gamma rays, the probability fell back to zero. The quantum Zeno effect endlessly reset the clock, holding the decay in check.

  The next series of pulses began shifting the clusters into the space that had separated the original ingots. First neutrons, then antineutrons, were sculpted together in alternating layers. Though the clusters were ultimately unstable, while they persisted they were inert, sequestering their constituents and preventing them from annihilating their counterparts. The end point of this process of nuclear sculpting was a sliver of compressed matter and antimatter, sandwiched together into a needle one micron wide.

  The gamma ray lasers shut down, the Zeno effect withdrew its prohibitions. For the time it took a beam of light to cross a neutron, the needle sat motionless in space.
Then it began to burn, and it began to move.

  The needle was structured like a meticulously crafted firework, and its outer layers ignited first. No external casing could have channeled this blast, but the pattern of tensions woven into the needle’s construction favored one direction for the debris to be expelled. Particles streamed backward; the needle moved forward. The shock of acceleration could not have been borne by anything built from atomic-scale matter, but the pressure bearing down on the core of the needle prolonged its life, delaying the inevitable.

  Layer after layer burned itself away, blasting the dwindling remnant forward ever faster. By the time the needle had shrunk to a tenth of its original size, it was moving at 98 percent of light speed; to a bystander, this could scarcely have been improved upon, but from the needle’s perspective, there was still room to slash its journey’s duration by orders of magnitude.

  When just one thousandth of the needle remained, its time, compared to the neighboring stars, was passing five hundred times more slowly. Still the layers kept burning, the protective clusters unraveling as the pressure on them was released. The needle could only reach close enough to light speed to slow down time as much as it required if it could sacrifice a large enough proportion of its remaining mass. The core of the needle could only survive for a few trillionths of a second, while its journey would take two hundred million seconds as judged by the stars. The proportions had been carefully matched, though: out of the two kilograms of matter and antimatter that had been woven together at the launch, only a few million neutrons were needed as the final payload.

  By one measure, seven years passed. For the needle, its last trillionths of a second unwound, its final layers of fuel blew away, and at the moment its core was ready to explode, it reached its destination, plunging from the near-vacuum of space straight into the heart of a star.

  Even here, the density of matter was insufficient to stabilize the core, yet far too high to allow it to pass unhindered. The core was torn apart. But it did not go quietly, and the shock waves it carved through the fusing plasma endured for a million kilometers: all the way through to the cooler outer layers on the opposite side of the star. These shock waves were shaped by the payload that had formed them, and though the initial pattern imprinted on them by the disintegrating cluster of neutrons was enlarged and blurred by its journey, on an atomic scale it remained sharply defined. Like a mold stamped into the seething plasma, it encouraged ionized molecular fragments to slip into the troughs and furrows that matched their shape, and then brought them together to react in ways that the plasma’s random collisions would never have allowed. In effect, the shock waves formed a web of catalysts, carefully laid out in both time and space, briefly transforming a small corner of the star into a chemical factory operating on a nanometer scale.

  The products of this factory sprayed out of the star, riding the last traces of the shock wave’s momentum: a few nanograms of elaborate, carbon-rich molecules, sheathed in a protective fullerene weave. Traveling at seven hundred kilometers per second, a fraction below the velocity needed to escape from the star completely, they climbed out of its gravity well, slowing as they ascended.

  Four years passed, but the molecules were stable against the ravages of space. By the time they’d traveled a billion kilometers, they had almost come to a halt, and they would have fallen back to die in the fires of the star that had forged them if their journey had not been timed so that the star’s third planet, a gas giant, was waiting to urge them forward. As they fell toward it, the giant’s third moon moved across their path. Eleven years after the needle’s launch, its molecular offspring rained down on to the methane snow.

  The tiny heat of their impact was not enough to damage them, but it melted a microscopic puddle in the snow. Surrounded by food, the molecular seeds began to grow. Within hours, the area was teeming with nanomachines, some mining the snow and the minerals beneath it, others assembling the bounty into an intricate structure, a rectangular panel a couple of meters wide.

  From across the light-years, an elaborate sequence of gamma ray pulses fell upon the panel. These pulses were the needle’s true payload, the passengers for whom it had merely prepared the way, transmitted in its wake four years after its launch. The panel decoded and stored the data, and the army of nanomachines set to work again, this time following a far more elaborate blueprint. The miners were forced to look farther afield to find all the elements that were needed, while the assemblers labored to reach their goal through a sequence of intermediate stages, carefully designed to protect the final product from the vagaries of the local chemistry and climate.

  After three months’ work, two small fusion-powered spacecraft sat in the snow. Each one held a single occupant, waking for the first time in their freshly minted bodies, yet endowed with memories of an earlier life.

  Joan switched on her communications console. Anne appeared on the screen, three short pairs of arms folded across her thorax in a posture of calm repose. They had both worn virtual bodies with the same anatomy before, but this was the first time they had become Noudah in the flesh.

  “We’re here. Everything worked,” Joan marveled. The language she spoke was not her own, but the structure of her new brain and body made it second nature.

  Anne said, “Now comes the hard part.”

  “Yes.” Joan looked out from the spacecraft’s cockpit. In the distance, a fissured blue-gray plateau of water ice rose above the snow. Nearby, the nanomachines were busy disassembling the gamma ray receiver. When they had erased all traces of their handiwork, they would wander off into the snow and catalyze their own destruction.

  Joan had visited dozens of planet-bound cultures in the past, taking on different bodies and languages as necessary, but those cultures had all been plugged in to the Amalgam, the metacivilization that spanned the galactic disk. However far from home she’d been, the means to return to familiar places had always been close at hand. The Noudah had only just mastered interplanetary flight, and they had no idea that the Amalgam existed. The closest node in the Amalgam’s network was seven light-years away, and even that was out of bounds to her and Anne now: they had agreed not to risk disclosing its location to the Noudah, so any transmission they sent could only be directed to a decoy node that they’d set up more than twenty light-years away.

  “It will be worth it,” Joan said.

  Anne’s Noudah face was immobile, but chromatophores sent a wave of violet and gold sweeping across her skin in an expression of cautious optimism. “We’ll see.” She tipped her head to the left, a gesture preceding a friendly departure.

  Joan tipped her own head in response, as if she’d been doing so all her life. “Be careful, my friend,” she said.

  “You too.”

  Anne’s ship ascended so high on its chemical thrusters that it shrank to a speck before igniting its fusion engine and streaking away in a blaze of light. Joan felt a pang of loneliness; there was no predicting when they would be reunited.

  Her ship’s software was primitive; the whole machine had been scrupulously matched to the Noudah’s level of technology. Joan knew how to fly it herself if necessary, and on a whim she switched off the autopilot and manually activated the ascent thrusters. The control panel was crowded, but having six hands helped.

  2

  The world the Noudah called home was the closest of the system’s five planets to their sun. The average temperature was one hundred and twenty degrees Celsius, but the high atmospheric pressure allowed liquid water to exist across the entire surface. The chemistry and dynamics of the planet’s crust had led to a relatively flat terrain, with a patchwork of dozens of disconnected seas but no globe-spanning ocean. From space, these seas appeared as silvery mirrors, bordered by a violet and brown tarnish of vegetation.

  The Noudah were already leaving their most electromagnetically promiscuous phase of communications behind, but the short-lived oasis of Amalgam-level technology on Baneth, the gas giant’s moon, had had no t
rouble eavesdropping on their chatter and preparing an updated cultural briefing that had been spliced into Joan’s brain.

  The planet was still divided into the same eleven political units as it had been fourteen years before, the time of the last broadcasts that had reached the node before Joan’s departure. Tira and Ghahar, the two dominant nations in terms of territory, economic activity, and military power, also occupied the vast majority of significant Niah archaeological sites.

  Joan had expected that they’d be noticed as soon as they left Baneth—the exhaust from their fusion engines glowed like the sun—but their departure had triggered no obvious response, and now that they were coasting they’d be far harder to spot. As Anne drew closer to the home world, she sent a message to Tira’s traffic control center. Joan tuned in to the exchange.