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\title{Fluctuations}
\author{New Millennial Wayfarer}
\date{}
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\begin{center}\small\textit{Translated by GPT}\end{center}
\section{The Probe}\label{section-1}

He Rixin was aflame with ambition, his heart full to bursting.

How could he not be? Half a lifetime of work had finally brought him the fulfillment of a lifelong wish. He had conceived the DEPART mission and remained the very heart of the project; now he was closer to the Sun than anyone in history. If only he had a talent for poetry, and \emph{DEPART} a direct line to Earth. He would surely have found something to say that would go down in history.

The DEPART mission was the crowning achievement of present-day space technology, and would open a new chapter in humanity's exploration of the Sun. \emph{DEPART}---\textbf{D}iagnostic \textbf{E}lectromagnetic \textbf{P}robe \textbf{AR}ray experimen\textbf{T}---was an advanced spacecraft at the L1 Lagrange point between the Sun and Mercury, the innermost planet.\footnote{Mercury in this world is completely tidally locked to the Sun.} Its principal task was to make direct measurements of the plasma streams produced by solar activity from closer to the Sun, and to observe the solar surface directly. It could measure electromagnetic signals across a broad frequency range in every direction. Even from the single vantage point of Mercury L1, separating signals by direction and frequency would yield a wealth of information about solar physics. It was the most advanced ``probe'' in every sense of the word.

Quite apart from its mission and its instruments, \emph{DEPART}'s presence in an orbit so close to the Sun was itself an engineering marvel. Facing the Sun meant withstanding an unprecedented assault of light and heat. A passenger aboard \emph{DEPART} was arguably more cut off from the world than a visitor to the Moon, or even a tourist at the center of the Earth. Solar radiation heated the spacecraft's exterior to 600 degrees---and that was with the heat-transfer system working flat out. Without that system extending throughout its hull, \emph{DEPART} would rapidly succumb to the heat. Such an onslaught made conventional spacecraft cooling wholly ineffective: radiators would absorb far more radiant heat than they could dissipate. \emph{DEPART} therefore used an entirely new approach to heat exchange. Its heat-transfer system pumped heat from the hull into a series of thermal reservoirs made of advanced phase-change materials. Energy was virtually unlimited; the time it could endure the thermal load was not. Its remaining capacity to store heat was its lifeline. Fifty-two reservoirs would protect it through two phases of operation. Thirty-two would act as heat sinks for the twenty-day crewed phase. Once those thirty-two were exhausted, He Rixin would return to the departure base on Mercury and rejoin the rest of the team. \emph{DEPART} would change course into orbit around Mercury and begin its second, uncrewed phase. All fifty-two reservoirs would then absorb heat while the craft faced the Sun and shed it when Mercury cast it into shadow. In this phase, it would operate intermittently for at least a year.

The Sun had all but blocked \emph{DEPART}'s means of shedding heat. Much the same was true of its means of exchanging information. At Mercury L1, direct communication with Earth was almost impossible: the immense source of radiation that was the Sun had already filled virtually the entire channel. A less satisfactory arrangement would have to do. Fortunately, Mercury was completely tidally locked to the Sun, so a relay base could be built near the planet's terminator. This was where He Rixin's companion kept watch. Essential information would pierce the dense solar noise, pass between \emph{DEPART} and the relay base, and be forwarded to Earth. Even this connection was unstable, however, and its bandwidth severely limited. He Rixin would have to bring the immense quantity of first-phase data back himself. ``An ocean of data submerged in a universe of real information.'' There was something regrettable about this paradox. The DEPART mission existed to obtain solar data, yet amid that torrent of energy and information it could only watch from a relatively safe distance and draw off a thread here, a thread there. Such filtering was unavoidable. It was not even a matter of choosing the finest samples; it was the limit of what human beings could obtain and understand. Could humanity claim to understand the Sun? Hardly. The Sun's energy output would overwhelm \emph{DEPART}'s thermal capacity, just as the vastness of its information would overwhelm human comprehension. The more He Rixin studied solar physics, the more he felt the Sun's immensity and complexity. His conception of it grew ever more coherent. But how far was that conception from the Sun itself?

Engineering and scientific challenges had placed formidable obstacles in the mission's way. Whether it could actually go ahead, however, had ultimately depended on other kinds of practical consideration. The headlong era in which states built colossal scientific wonders to demonstrate their cohesion and the superiority of their ideologies was long past. People rising from the ruins had looked eagerly to the future; whoever could lead them into it had the greater claim on the present. Those who came afterward were more inclined to cherish the past, imagining themselves in the place of the heroes of old and polishing, in memory, the various golden ages that had belonged to different groups. Whoever held the present thus gained the right to sit in judgment on the past. To set out, one needed the fare. Once, ``We choose to go to the moon'' had been enough. Now it was no longer a sufficiently weighty reason. That story was entirely out of date, and in any case He Rixin was not the one making the choice. He was the one charged with carrying it out.

Fortunately, the goal had been achieved. It had simply required a different logic for telling the same story. The giants of the past had not embraced the space race out of wholly rational calculation. Certainly, it had stimulated the growth of many industries, introduced scientific ideas to the public on a vast scale, and advanced education. In society, however, its effect had been to create a totem of faith in the future and in technology. Scientists and astronauts were the mighty sorcerers and warriors of legend. Everyone believed they lived in an age of magic, and the desire for magic had itself helped drive that age's furious advance. Today's giants believed in a different totem. This one, too, concerned itself with progress and numbers, but its purpose was different. Capital lived by increasing its value. It sniffed out every opportunity for extraordinary returns. Any means of making the accounts look more handsome and more real would snowball through ingenious financial instruments and gather into a towering wave. Its power was too great, its response too swift, its appetite too greedy: growth in the real world could not keep pace with the expansion of capital. This immense creature with nowhere to go needed a new myth. Every business offering extraordinary returns had already been picked clean; now it hoped for magic that could keep it alive. Only another industrial revolution, another age of miracles, would satisfy it. The story required was clear. He Rixin found a way to make people believe that the DEPART project might supply the spark that would kindle a new age of miracles.

The Little Ice Age of the seventeenth century had profoundly affected the global economic and political order, rewriting the course of human civilization. From the frontiers of the Ming empire to its shores, from the ports of Luzon to Tenochtitlan, from the Thames estuary to the Black Forest of Central Europe, from the fertile lands of the Don to the Central Asian steppe: scarcely had sails and horse-drawn carriages bound the world together when it faced a devastating crisis beyond human power to avert. Famine, plague, and war swept across every inhabited continent. People did not even know the nature of the catastrophe they were living through. They knew only that they had been born into troubled times, when life was cheap as dirt. The disaster had many causes, but one thing was certain: of them all, weakening solar activity was the least amenable to human intervention, and possibly the most consequential. Observations over the last twenty years showed that solar activity was steadily declining. Another Little Ice Age was very likely.

Fortunately, humanity now had more ways of confronting such a crisis. The DEPART mission was a conspicuous example, and a deeper understanding of the solar cycle held unprecedented economic value. The giants believed in the power of cycles. Naturally, they saw the cycles of celestial bodies as another mighty force to be put to use. He Rixin had played the weather sorcerer to perfection. The giants thought his magic immensely valuable.

Solving engineering problems was difficult. So was playing the weather sorcerer. But He Rixin and his team had done both. Once the mission was under way, his old anxieties vanished, and a deep awe of the Sun's boundless power took their place. Facts so immense they had seemed abstract finally became palpable, moving from his reason into his feelings. Slight fluctuations 150 million kilometers away could change the entire world of billions of living things, and this was only a negligible fraction of the Sun's power. Six years of travel had merely reduced that distance to a third. The decades of preparation and the voyage through space had taken up almost his whole life. Yet that lifetime, even an entire solar minimum, was only a moment in the Sun's fluctuations. And what of the universe beyond, where even light seemed slow and powerless? He had scarcely begun to grasp one vast conception when another ungraspable immensity took dim shape, no longer wholly abstract. His reason firmly cut the chain of association short.

Remote and perilous indeed was the place where \emph{DEPART} lay; strange and magnificent beyond measure was the view. Filters tamed the fierce sunlight so that he could look directly at the Sun. Its texture stood out in the finest detail, burning silently as though sunk in an abyss. It seemed that what had been set into the cabin wall was not a window, but a vessel holding the Sun. He Rixin had dreamed of this sight day and night. The scenery on Mercury behind him was an unexpected pleasure. In the preliminary stages of the DEPART mission, three probes had been sent on flybys of Mercury and discovered peculiar geological features on its surface. Mercury had no atmosphere, only a weak magnetic field, and no natural moons. Yet the probes found small impact craters only on its dark side. The sunlit side, apart from a few large craters, was astonishingly smooth.

Now a magnificent panorama spread across Mercury's surface before him. The planet was no featureless sphere of the sort used for drawing practice, with nothing to vary its smoothness but light and shade. Extreme temperature gradients drove matter from place to place; no atmosphere intervened to scatter or obscure it. Mercury had become a specimen of fractionation with the sharpest, clearest surface color bands in the Solar System. At the center gleamed a silvery-white pool of molten metal. Rings of color spread outward, darkening with latitude: lead and zinc's silver-white, sulfur's brilliant yellow, the yellow-brown of sulfide salts, the brown-black of iron oxides.

An extraordinary geological phenomenon. He Rixin decided to collect images of Mercury alongside his solar data. With no atmosphere and only a weak magnetic field, there were very few possible causes of surface change. He suspected solar-driven heat flows and fractionation through sublimation. After all, Mercury's sunlit face was not much cooler than \emph{DEPART}, and variations in the Sun's angle above the horizon could produce a sufficiently large temperature gradient. Presumably, this was causing certain molten minerals to flow across the surface, or even to sublime. But he knew too little of planetary physics, or even geophysics. He would simply record the phenomenon in full and leave it to later explorers and the relevant specialists. During these precious twenty days, his own ardor for work would have to match the heat of \emph{DEPART}'s hull. He would gather as much data from the solar surface as he could.

\section{The Black Tide}\label{section-2}

Heaven was about to perish.

The thought came to Black Two-Three out of nowhere. Or perhaps it had long been buried in him, frozen beneath thick ice. Days of endless marching had finally scuffed away the glacier under his feet, layer by layer, bringing that terrible thought ever more plainly into view.

And I will die soon, too. Yes. One after another, his fellow travelers had dropped dead along the way. Getting this far was an achievement in itself. Black Two-Three's lower limbs were stiffening; more and more cracks split his frozen body, their edges growing hard. At least there was no night in this world. Somehow one could keep going. Only the Sun was growing stingier, its grudging gifts of light ever weaker. Yes, the Sun. What else did it mean for Heaven to perish? It was the Sun's weakness that let the black tide advance from the world's rim toward its center, that had made Gray Two-Three into Black Two-Three, that had driven them out to the edge of the world and straight into the oncoming tide.

O Sun, can you fall ill, too? Black Two-Three could not blame it. It was sacred, and so very far away. Besides, who under Heaven did not depend on the Sun for life? Before the black tide, it had poured forth light and heat without stint, sustaining all the people of the world. Now it was sick. Surely its weakness was understandable. In its place, he would not share his precious warmth when the black tide came either. He could blame only his birth among the Grays, and his descent now into the lowest rank of all, the Blacks. Jade, White, Silver, Turbid, Gray, Black: these were not merely the colors of their bodies. They were their distances from the Sun. The order of rites and laws laid down by the ancient sages embraced everyone, each rank neatly in its place. From the center of the world to its outermost edge, every color had its proper station. The rites governed all beneath Heaven, unchanging through the ages, as eternal as the Sun suspended at the center of the sky.

And now it had all gone wrong. Those of Jade and White rank lived at the center of the world, nearest the Sun. Their lands were fixed by strict allotment, exactly as the sages' rites prescribed. The foremost of the Jade was foremost of all the people, and made the sacrifices to Heaven and Sun: the Son of Heaven. In reverence for the heavenly Sun, the Jade took none of what it gave, reflecting it all back as homage to Heaven. Thus they were the purest and most translucent; everything they needed was supplied by those below. Those of White and Silver rank held their own fiefs around the center. They took only a sliver of the Sun's gift and sheltered the subjects beneath them---who, of course, owed taxes and service in return. The Turbid and Gray occupied the vast middle and outer rings. Here the Sun no longer stood directly overhead, and the farther one traveled toward the rim, the less it gave. Its divine favor could therefore be received directly. These were the world's most hardworking, uncomplaining commoners, receiving ever less while still giving much. Those of Black rank scarcely counted as people at all. They lived at the edge of the world, where the Sun hung low and light was scarce. Every one of them wished to clutch all the light and heat there was, letting nothing escape. That was precisely why Blackness meant greed and filth. They knew nothing of honoring Heaven and Sun; they were creatures outside the civilizing reach of the rites. Black Two-Three's mind grew hazier. He could recall only these increasingly indistinct pieces of common knowledge. When had he learned them? A long time ago, surely, when Black Two-Three was still Gray Two-Three. Gray Two-Three had an ordinary background and did ordinary work, cultivating and harvesting light and heat. The Turbid official in charge of his district had been quite capable. Taxes and labor dues were paid in full, and the work of moral instruction went well enough. That was when Gray Two-Three had first learned of a world beyond the harvest. Had things gone on that way, perhaps he might even have passed the examinations and won a degree, changing from Gray Two-Three to Turbid Ershan. Black Two-Three struggled to remember, but those distant memories were slowly freezing, wearing away in the cold.

Then the black tide came. The Sun weakened, the harvest slowly diminished, but the taxes stayed the same, and the burden on the Gray people grew. One could still get by. But it was only the beginning. Some said the black tide came because the heavenly Sun was displeased: give it offerings, and it would make the tide recede. The Jade and White nobility took nothing from the Sun and were to return twice as much in homage. Naturally, the offerings would have to come from taxes on those below. Others went further. The heavenly Sun was displeased because monstrous men at court were overturning the laws and making trouble, turning Heaven's order upside down. Purge the traitors, restore the proper order, and the tide would go away of its own accord. Still others said the taxes had risen because of distant rebellions. In the far outer ring, Turbid and Gray people had risen together and willingly sunk to Black rank. The armies of Silver and Turbid soldiers naturally needed extra light and heat for the long march to suppress them. That meant more taxes. Gray Two-Three paid no attention to these rumors. His own life could still go on.

The neighbors could not bear the burden. Household by household, they disappeared. Gray Two-Three knew they had turned Black and fled toward the frontier to escape the famine. But with the black tide coming, would it not grow colder and darker the farther they went? They were only seeking their own deaths. Naturally, those who stayed had to pay the taxes of those who fled. Refugees were pouring outward from the inner rings, many of them Turbids reduced to Gray. But people who had lost their roots could no longer pay taxes; they would simply flee again. The demands on the law-abiding local people grew harsher still.

The rites broke down. Disorder spread across the world. Each brief spell of peace vanished in an instant. First came rumors of refugees rebelling nearby, then news that the army of pacification was approaching. Ahead of the army came orders to levy supplies. The fragile arrangement that had barely kept life going shattered at last. The Turbid official abandoned the district and disappeared, and its people were declared accomplices of the rebels. Black Two-Three joined the great stream of refugees, swept along toward the black tide. He could never go back. He was good at enduring things; years of oppression had numbed him. Yet leaving his homeland like this stirred something in him after all. The little surge of feeling soon subsided, as still as the wasteland over which the black tide had passed.

Black Two-Three found he could barely keep pace with those around him. Was he finally going to die? He knew what would happen next. Like the others who had fallen along the way, he would gradually solidify in the cold, a black, frozen statue. Never allowed to rest in life, he might endure forever in death. Then let him die. Black Two-Three's awareness slowly sank beneath the black tide. Cold and darkness without end washed over him.

\section{The Wandering Soul}\label{section-3}

Never stop while you can still go on. That was \emph{Courage}'s creed, and it had become a motto known throughout the Alliance. The ship had opened the Age of the Great Passage by discovering an invisible bridge over a sheer abyss. What had been an impassable barrier was now an open road.

Even before the discovery, \emph{Courage} had been enough of a legend to appear in the Alliance's textbooks---in physics, engineering, sociology, medicine, biology, law, history, even philosophy: almost every subject there was. Nor did any of these appearances seem out of place. \emph{Courage} was one of the few truly exceptional cases in the Alliance.

Originally, \emph{Courage} had been an ordinary cargo ship plying the Alliance's planetary system between its homeworld and a moon of the fifth planet. Its pilot, Mao Feidu, was an equally ordinary graduate of a spaceflight academy. If all went well, his career would consist of three round trips between the homeworld and the base on that moon, followed by an honorable retirement. But on his first voyage, as \emph{Courage} headed back from the base, a maintenance crew's mistake left it short of fuel. Worse, the shortage was not discovered until the ship had passed the critical point for turning back. Mao Feidu and \emph{Courage} were forced into a dazzling, hair-raising game of pinball through space. At an extremely shallow inclination, he barely skimmed past the asteroid belt and entered orbit around the fourth planet, using its gravity to fling the ship toward the second. Five years of drifting through space finally brought a chance to change course into orbit around the second planet. Its gravity at last sent him bouncing home.

Now Mao Feidu had time for only one more round trip in his career. Perhaps not even that: setting out again would be difficult. His long confinement in space had left his muscles severely wasted, his bones terribly brittle, and his organs on the brink of failure. It looked like the end of a rather remarkable novice pilot. It was actually where the legend of \emph{Courage} began.

The doctor gave Mao Feidu two choices. He could remain in bed on life support and recuperate. If his body proved as hard to break as he was hard to kill, he might be able to get out of bed by the time his pension arrived. Or he could try the Academy of Sciences' latest advances and be a guinea pig for an unprecedented, horrifying reconstruction. The kindly doctor recommended the first option. A hero like him would receive the best possible care and treatment, and his life could certainly be saved. Choose the second, though, and those bastards at the Academy would never let such a rare specimen slip through their hands. They would promise anything. The bastards at the Academy, for their part, asked whether he really wanted to rot in bed. They said nothing of the enormous risks that must exist; nobody could deny those anyway. Besides, Mao Feidu was not the only one taking a risk. If he died, would they not lose their specimen and damage their reputation into the bargain?

Mao Feidu had faith in his own constitution. He really did not want to rot in bed, though. Better to die. Over the next while, a little under half his organs were replaced. Assorted artificial parts filled him up, turning him into a monster in human skin. Which felt pretty cool. Somehow he survived, becoming the space marine he had dreamed of being as a boy. No, he was more impressive than a space marine: Mao Feidu had survived that murderous reconstruction with nothing but a mortal body. The Academy staff assured him that the prosthetics would last him to the end of his life, and even add a few years to it.

The Academy staff were not all talk, but the doctor had been right about them too. They really did have very little conscience. Mao Feidu enjoyed a happy year. Then, as he prepared to return to space, his body duly began to give trouble. The prosthetics had not failed. Instead, his other, healthy organs suddenly showed signs of shutting down. Whether the replacements had caused this was hard to say. This time there were no two options to choose between. The doctor could do nothing; he could only submit to further reconstruction. When that was finished, the head was the only original equipment left.

He was certainly hard to kill. His inhuman body carried Mao Feidu through many more missions, and he became the longest-serving captain, until he began to notice a marked decline in his thinking. A brain of flesh could not, after all, be taken in for regular servicing and an overhaul. Beside all those prosthetics requiring maintenance or even replacement, the brain was an engineering miracle. It used extraordinarily little energy, packed everything into a compact structure, and had a working life far beyond that of the human body itself, with more specialized circuits for thought than one could count. Apart from its exacting operating conditions and the difficulty of maintaining and regenerating it, it was practically perfect. If the brain--computer interface had not kept wearing away his neurons, Mao Feidu might have stayed clearheaded enough to spend another few decades getting up to things in space.

Two hundred years had passed since his first perilous voyage. The Alliance already had quite satisfactory remedies for this small problem with his brain. Culture somatic cells, induce them to differentiate anew into neurons, and use them to replace aging cells bit by bit. The neural pathways had to be kept as intact and consistent as possible throughout, to ensure that the person remained the same person. These were merely the established, legal techniques. The underground market offered further, illegal services for the brain: copying or transplanting neural circuitry, for example, or actual brainwashing through the restructuring of neurons. The intentions behind such operations might not be entirely malicious, but they already posed a serious challenge to society. What, fundamentally, identified a person within society? The body, the ID, social identity, the brain, the contents of thought---or something else?

Unfortunately, none of these legal or illegal methods could treat Mao Feidu's brain. Not because he cared about such airy existential questions, but because his flesh content was a little too low: the conditions needed to maintain the original brain were simply absent. There was, however, another way. Mao Feidu and \emph{Courage} had spent more than two centuries carrying out missions together, and the ship's computers had accumulated an immense amount of data on his behavior. Since he already had a brain--computer interface, they could gradually build a mirror of him. Give the procedure a flattering name, and it was neural uploading. But neural uploading in the true sense was impossible; the supposed transfer was a conceptual illusion. The flesh-and-blood Mao Feidu would gradually decay, while a cybernetic prosthesis mimicking him would progressively take over what was lost, until his brain deteriorated too far to sustain the interface. Mao Feidu himself would notice nothing unusual in the process. Still less would anyone else.

The plan had only a few small flaws. No one in the Alliance had ever turned himself into a cybernetic mimic before. Was this gradual substitution treatment or end-of-life care? Once the substitution was complete, should cyber-Mao Feidu inherit every relationship belonging to the original? These questions required careful consideration. Fortunately, Mao Feidu was already a cyborg, and in his day-to-day life was much like a potted plant growing aboard the ship. His relationships were not particularly complicated. There was another, more frightening point: the brain that could no longer sustain its interface would not be dead. It should retain some ability to think, but would have lost the physical means of communicating with the outside world. Under existing Alliance law, this would apparently qualify as a vegetative state, though the patient would still legally be a person. People in vegetative states could awaken. A brain in a jar might recover, too. Perhaps some sudden technological breakthrough would let the Alliance induce aging cells to differentiate again and repair them. Which was Mao Feidu---the brain that could not speak from its jar, or the cybernetic mimic inside the main computer? Aside from the legal and sociological obstacles, there was one other small problem: his choice of cybernetic brains was rather limited. In fact, only \emph{Courage}'s main computer could accommodate him.

None of this was a problem for Mao Feidu, who felt he had already had his money's worth out of life. Let the law and ethics be someone else's headache. To stop going forward was no different from dying. Whether the Mao Feidu in the jar or the cyber-Mao Feidu aboard \emph{Courage}, either would agree without hesitation. A body that could not move was, to him, a prison worse than death. To keep exploring in a freer form was what he had always wanted. Besides, he was already a hybrid containing less than five percent human. Throwing away that last little bit was no great matter.

And so, after ten years of substitution, Mao Feidu's brain in its jar---or perhaps Mao Feidu himself---went into a museum in place of \emph{Courage}. His characteristics had been transplanted into the ship's main computer. One could say that cyber-Mao Feidu now lived inside that computer, or that the computer had become an artificial intelligence with a distinct flavor of Mao Feidu. \emph{Courage}/Mao Feidu preferred to say that he had become the ship's spirit. From then on, \emph{Courage} was the only intelligent vessel in the Alliance whose right to act on its own behalf was recognized by law.

Without that status, it could never have become the legend that opened the Age of the Great Passage.

Interstellar travel was impossible. At least, that was how things stood in the Alliance's planetary system, and before the discovery of the Great Passage, everyone believed it. The universe was simply too large. The neighboring star systems were too remote, if one could even call them neighbors. All the matter and energy in this planetary system would not suffice for so long a journey. Indeed, the problem went much further. Even interstellar communication was almost impossible. What if a signal traveled at the speed of light? It would still be an ant crossing the sea, an ant climbing into the sky. Any signal the Alliance could send would inevitably dissipate and distort across the endless expanse, redshift as the universe expanded, and become too faint to distinguish---or simply dissolve into the background radiation.

If the Alliance had thought of the stars only as a painting on the vault of heaven, if those faint lights at night had been merely signs for mysterious divinations, then the size of the heavens would not have mattered. But the Alliance had developed spaceflight and grown into an immense civilization spread across its planetary system. In ignorance, it had felt nothing. Having truly ventured into the stars, it could no longer accept such a fate. The system's sun had a long life left, but it would eventually end. No finite expanse, however vast, could contain infinite possibilities. What if the voyage were not so difficult? What if the empty wilderness of space were not really so empty?

Thus \emph{Courage} set out on a voyage from which there would be no return. This was truly a plan for an ant to cross the sea. Uncrewed probes were, after all, no more than stones thrown ahead to test the way, while a ship with a living crew could not endure the ages the journey would take. \emph{Courage} alone could do it---and was more than willing to become that explorer. It would set its course for unreachable starlight and enter the endless dark. The thin interstellar gas that might, in theory, exist would be its only source of supplies along the way. To borrow a comparison from distant Earth, it would be like paddling a dugout canoe across a windless ocean, powered only by muscle and fueled only by fish caught at sea. A dugout crossing the doldrums had actually been achieved. \emph{Courage}'s journey was all but beyond possibility.

\emph{Courage} and the Alliance were fortunate. They had taken a brave step off a cliff and found their foot on a stairway into the sky. The ship was heading for the strangest object visible from the Alliance. Its spectrum was the most complex of all, unlike the red or yellow light of the other visible stars. In theory, it ought to be the nearest object, yet even in that dim sky it was comparatively faint. This was the direction \emph{Courage} had chosen to try. Two hundred years later, it had only just reached the edge of the planetary system when this strange ``star'' surrendered its secret.

A road through the heavens.

Countless stars and galaxies outlined a perfect sphere against the blackness. It was about the size of those asteroids just large enough to become spherical, like a small universe circling a star on the system's edge. This was no physical celestial body, but an unusual structure in space. The light and gravity of remote stars passed through the spherical stargate. Their pull was wholly unlike that of the dim stars in the black background, visible but forever beyond reach.

\emph{Courage} sent everything it had learned back to the home it had left, and several years later a reply finally arrived. This was a major discovery in cosmology, offering a possible explanation for the universe's missing mass. Perhaps it was not dark matter that existed---or rather, what was missing was not invisible mass, but distance itself. Such structures would be scattered throughout the universe, distributed around celestial bodies in accordance with the distribution of mass. The network of starways as a whole would act like rivets set into space, allowing gravity to pull the universe together along paths shorter than the observed distances.

\emph{Courage} became the greatest legend in the Alliance's history. It could decelerate and return. The Alliance would rebuild it using the advances of the past two hundred years---and the latest technology of nearly four hundred years by the time of its return---so that it could set out on a new voyage in a more nearly perfect form. But there was another choice, far more tempting. After sending back further observations, \emph{Courage} sailed straight into the stargate without waiting for the next reply.

\section{The Torrent}\label{section-4}

One circuit of the stars around the Sun made a year. When the Sun was near and large, it was summer; when small and distant, winter.\footnote{Mercury's orbit is highly eccentric, with its distance from the Sun differing by one quarter between perihelion and aphelion. It therefore has summer and winter even though it has no day and night.} The year had these two seasons, and was further divided into sixty rounds. A Silver courier setting out from the Jade Capital, at the center of all beneath Heaven, needed twenty rounds to reach the world's edge. Now the black tide was rising, cold and darkness were eating inward, and the edge lay only nineteen rounds from the center. A year had passed since the army set out to quell rebellion twelve rounds away. No word had come for ten rounds.

Even if the entire army had been wiped out, some news ought to have reached them by now. Wei Jushi was deeply uneasy. The affairs of the realm rested on his shoulders, and nothing mattered more at present than this campaign. If it succeeded, the prestige of victory would let him press on with reform. If it failed, everything was over. Decades of accumulated strength would be lost in a moment, the New Faction destroyed, the state brought low.

Wei Jushi was the regent and architect of the reforms. A presumptuous fool defying Heaven, a treacherous minister ruining the state, an upstart raised by favor: unable to bring him down, the Old Faction was unstinting in its private attacks. A man who could earn such bitter hatred was no ordinary figure. The late emperor had picked him out from the Silver Guard. He had won his way to court through service, becoming a great minister among the Jade and White, deeply trusted by his sovereign and sparing nothing of himself in the royal cause. When the black tide first threatened, he had been appointed in the hour of danger and given full authority to reform the laws. He had put the government in order with an iron hand, and at the emperor's deathbed had been named first among the ministers entrusted with the young sovereign. He had reached the highest place a courtier could attain.

The first measure was to alter the tax system and raise new revenue. Without it, there would be no means of restoring order. But the Jade and White great houses were deeply rooted, their connections tangled and extensive. They could not lightly be shaken. Besides, under the ancestral laws the upper castes harvested nothing from the heavenly Sun. Why should they pay taxes? The Silver clans mostly served in the army, holding hereditary military offices and naturally monopolizing the lower and middle commands. Without their support, how could one control the army and turn the situation around? The system of military land grants might have fallen into decay, but nowhere in the realm was there a more effective fighting force. Wei Jushi himself came from these ranks and knew their circumstances well. He had to swallow his impatience and court them all the same. That left only the Turbid officials to squeeze, and the Gray commoners to suffer a little more. With the heavenly Sun so dim, this was how difficult it had become to govern the world. More taxes required harsher collection, which would naturally cost more. But as long as the court received more at the end, it was worth it. Whether the Turbid officials and their clerks used the occasion to line their pockets was something the court neither wished nor had the power to police. Call it mutual forbearance for the sake of the state, for now. This first measure had been implemented to considerable effect. More people were fleeing famine, certainly, and many in the Old Faction made that a pretext for attack, pleading on the people's behalf. But what of it? What use to the court were people who paid no taxes? Take the darker view: with the Sun dimming, the number of subjects the world could sustain was no longer fixed. Someone would have to be driven into the darkness. If he did not force the Gray people to flee, was he to be cast out himself?

The second measure was to raise and train a new army. The system of military land grants had decayed beyond repair. Men at every level held places on the rolls while drawing pay for service they never performed. Among the rank and file were soldiers whose holdings had gone bankrupt, leaving them beggars, or had been swallowed up by others. Among the middle officers were men whose families had enjoyed the state's bounty for generations, yet who ran their commands as private concerns and treated the troops as household slaves. Among the generals were men who sold offices and titles, built their own factions, and grew too powerful to control. An army like this was no longer His Majesty's sharp blade. The late emperor had trusted Wei Jushi precisely because he could gather the wealth needed to forge it anew. Royal lands would be carved up into fresh military grants, a new establishment built, and heavy taxes used to maintain picked troops. This was the true foundation of the late emperor's power. The new army's commander, Wei Zhenxing, had likewise been raised by him from obscurity. With no powerful connections and no entanglements, he had owed allegiance to the late emperor alone. Now he belonged to His Majesty.

The third measure was to establish schools and recruit men into office. This provoked the fiercest reaction at court. Even the slowest of the hereditary White houses could now see the reforms' ultimate purpose. Those too obtuse to understand would still react when their protégés and former subordinates began to be replaced. It was then that Lord Wei Jushi's standing among the learned finally advanced from spineless sycophant and contemptible favorite to the greatest villain of the age, a reckless destroyer of the state. Reform needed people, preferably newcomers with clean records and no ties: pupils of the Son of Heaven, rather than former servants of great houses or private retainers of the powerful. Naturally, the first criterion was support for the new laws. Ability and virtue came second. This did bring in the bad with the good, and those appointed often acted rashly and pushed too hard. But the late emperor still held the greatest power. Opposition was soon silenced, the Old Faction lay low, and a good many useful men did find places in the government.

Only with money, troops, and men in hand could the late emperor's ambition of remaking the order of the world be realized. The final measure would strip titles from the White and Silver upper castes and lower their ranks, until their numbers matched what could be supported after the great change in the heavenly Sun. That His Majesty's power would become more concentrated in the process was understood by all and left unspoken.

But the heavenly Sun kept no order, and human affairs were unpredictable. Within the palace walls, the late emperor died suddenly. His ambition was never fulfilled. To preserve what he could, he had been obliged to compromise and leave a final charge entrusting his heir to the ministers. The Old Faction rose again. Ju Rongfu, veteran of three reigns and its standard-bearer, became the second of the entrusted ministers, dividing the government once more. Then the black tide quickened, and popular uprisings erupted throughout the land beyond the court. The new army had to put out fires everywhere, giving the Old Faction openings to intervene. A commander-in-chief would often find himself accompanied by a deputy from a powerful clan. The deputy now campaigning against the rebels was Kong Songguang, a young man of considerable reputation who led the Old Faction's next generation. As for Wei Zhenxing, the actual head of the new army, since the regency began he had never volunteered to take the field. He spoke only of guarding the palace gates.

The state was already foundering. Its strongest military force was stranded far away, with all contact lost, making affairs within the Jade Capital still more volatile and inscrutable. The balance of power had long since changed, but Lord Wei's decades of accumulated authority remained. The uncertainty surrounding the distant army made everyone hesitate, unable to decide. A storm was gathering. At the summit of the Jade Capital all was silent, the tremor of apprehension perceptible in the stillness.

Every round without news added another weight to the unseen scales. Once the balance tipped, it could never be restored. At last, past the critical point, everything burst open. Fear, desperate hope, delight, resentment, resolve: the reckoning boiled over, swiftly turning the Jade Capital into a sea of molten fire.

Wei Jushi was, of course, the first to be arrested. Facing the former pupil who had come for him, he was surprised to find none of the anger of a man stabbed in the back. With events moving as they were, such a traitorous disciple was hardly unexpected. Still, he could not help despising the man's poor judgment. A lack of courage was one thing. How had he failed to notice such stupidity? Did the Old Faction recruit men as the New Faction did? To turn coat now was merely to become a stepping-stone, used and discarded. If sticking your neck out brought the blade, drawing it back would bring it too. For a few more rounds of wretched life, would you be vermin forever? The forces previously held in readiness were now converging. Among the defeated, some defected at the last moment, some fought desperately, some surrendered, and some cursed. Wei Jushi watched with cold detachment as he was swept along and escorted silently toward the center of the Jade Capital. Such was the heavenly Sun. Such was the tide of events. There was little left that could turn either around.

Looking back over his decades of service, Wei Jushi felt he had reached the utmost a subject could achieve. Affairs of state had been difficult, but he had never feared them. He had seen them as a ladder to the heavens. Fortunately, the late emperor had been determined to restore good government, and had recognized him as soon as his abilities began to show. Thereafter sovereign and minister had worked in perfect accord, cutting through thickets, reviving the court, sweeping one obstacle after another from their path. He had poured his heart and strength into the realm. But the heavenly Sun had dimmed, the imperial line declined. He could burn himself out and change nothing. If only Heaven's decree could be defied.

It was Wei Zhenxing who presided over the settling of old scores; Ju Rongfu, whom Wei Jushi had expected to see in that role, stood at his side. Wei Jushi was utterly calm, and not particularly surprised. Such a swift reversal could only have come from their combined efforts. He had merely mistaken which would lead and which follow. The sentence came in vibrations through the ground: ``Wei Jushi, traitor who forsakes Heaven and betrays his sovereign, fiend who disorders the court\ldots'' Wei Jushi would not dignify it with a sound. He seemed to be watching a farce, as though he were not its principal actor. Traitor? Fiend? A few rounds ago, would Wei Zhenxing not have been put in the same company? Now he had transformed himself into a pillar of righteousness. Wei Jushi had long been ready to be ground to dust, but he had never meant to meet his end in such a paltry fashion. How had he come to this, and the state to such decay? ``\ldots shall suffer the Sun's immolation, his body burned and his entrails smelted within.''

Ha. They had actually dug through obscure historical records to find this torture for Wei Jushi. Stern in public, fearful within: they could only terrorize the people by such means. There was still no news of the army. Its prospects were grim, but until its fate was known, who could rest easy? The Jade Capital was cut off and short of troops, and fires burned on every side beyond it. If even he could not hold this situation together, how would this pack of petty men manage it? And the two parties to the coup had long been divided. Today they used heavenly fire to burn him; before the next round, they would be burning each other. Above all, Heaven was failing, the Sun declining. His fate had come to its end. Could they overturn Heaven itself? At this thought, Wei Jushi, now raised upon the execution ground, felt a certain pleasure. He regretted only that he would not live to see them undo themselves.

As the punishment proceeded, the silvery-white essence was slowly stripped from Wei Jushi's body, its brilliant whiteness fading to gray. Deprived of his shielding, he began to heat up beneath the fierce Sun directly above the Jade Capital. Ancient accounts said that a victim's whole body would boil, then turn to black smoke. But the heavenly Sun was less intense than it had been in ancient times. Wei Jushi had collapsed into a shapeless pool, yet he still fixed his gaze on Wei Zhenxing and Ju Rongfu a short distance away, like a ghost in the dark.

With their great enemy removed, the two men conducting the execution could scarcely hide their concern. If this was the state of the heavenly Sun, what came next? But for its great change, but for the black tide, things would never have come to this. A man could be brought down. Could Heaven be overturned?

At that moment, as though it had heard the unspoken thoughts and cries of countless beings below, the Sun at the zenith above the Jade Capital, eternal source of immense power, blazed suddenly brighter. Had there been some wondrous adept able to ascend into the highest heavens, he would have seen the black tide spreading inward from the rim abruptly pause, as though the light might even begin to drive it back.

Wei Jushi's agony was almost over. In that instant he seemed to understand a great deal. His hesitation had long been visible. He had already lost the will to fight; otherwise why had he not struck first? Wei Zhenxing could have been won over. But once Wei Jushi lost the power to decide, Wei Zhenxing had only the other choice. Those around him had sensed precisely the dejection he himself had failed to notice, and it had brought him to ruin. The black tide's long attrition had slowly drained him of any expectation for the future. Incessant blows had robbed him even of the instinct to survive amid disorder. Yet he still would not accept his defeat. Why had the heavenly Sun chosen this very moment to revive? In his shock, he finally felt the pain of sunlight burning through his body. He shook uncontrollably. After that long silence, he spoke his last words:

``O vast and distant Heaven, where is your constancy?''

Then he boiled, broke apart, and became ash.

The sudden change in the Sun and the destruction of their enemy loosened one restraint upon the hearts of Wei Zhenxing and Ju Rongfu. But nothing was settled. What had become of the army? Until that question was answered, their momentary security was not even security. It was only breathing space.

The army had won, then lost. It was already destroyed.

Against the refugees, blindly moving without leaders, the army swept everything before it. There was scarcely any proper resistance. Kong Songguang used the weight of his family to intimidate and the promise of advancement to entice, smoothly taking command for himself. He meant to take every scrap of credit. The commander-in-chief had no patron at court. He knew Wei Jushi only casually and was no confidant of Wei Zhenxing. He had belonged to the late emperor, and was now a truly isolated servant of the throne. Without that isolation, he would never have been sent out. He offered no strenuous resistance to Kong Songguang. They were still about ten rounds from the Jade Capital, within the heartland of imperial rule, where the official roads and relay service still worked. Even if things went wrong, the heavenly Sun here could sustain the army for a while---long enough to get it out of difficulty.

The army swept straight toward the rebellion twelve rounds from the Jade Capital. This was the place from which reports had come of commoners rising up and killing officials. By the time the soldiers arrived, almost nothing remained except the old, infirm, sick, and disabled who could not leave. Apparently the rebels had recognized that they could not win and had already fled toward the black tide.

Here the commander and Kong Songguang reached their first irreconcilable disagreement over what to do next. The commander held that the campaign had achieved its purpose. The rebels had fled blindly into the black tide, choosing their own destruction. It was time to return to court. An advance would require large additional supplies to sustain the army beneath an ever weaker Sun, and might well bring no further victory. The rebels were mostly dark-colored outcasts, better able to eke out a living in the gloom. If they fled deeper into it, catching them would be harder still. Kong Songguang wanted all the credit securely in his own hands. He invoked the higher cause to press his demands, then went over the commander's head and bought off the subordinate officers. In the end he outmaneuvered the commander, seizing control outright and no longer troubling to conceal his disregard. The commander could only ask to stay behind with his own guards to maintain the road and the relay service.

Now that the breach was open, Kong Songguang dispensed with all restraint. He let his soldiers plunder the surrounding districts, intercepted every shipment of military supplies along the road, and set off with those provisions in pursuit farther outward. The displaced commander was bitterly resentful. Neither accompanying the advance nor returning to court afterward seemed likely to end well. He too abandoned the district with his guards, and vanished from the record.

Kong Songguang's arrogance was not merely a matter of temperament. Some of it was deliberate, intended to drive the commander away. Who could not see by now that Wei Jushi's day was over? A general without a patron was beneath Kong's notice, not even worth winning over. Were a few refugees worth such trouble? Everyone knew that the late emperor had created the new army to deal with great houses like his own. Now he need only secure the officers below him and add a military victory that was already as good as won. His future would shine. Let the heavenly Sun grow as dim as it pleased: the place in the Jade Capital would still belong to the Kong family. All this talk of failing to catch rebel leaders, of gaining nothing further, was the evasion of a man who had lost his standing. Beyond twelve rounds, anyone who ran at the sight of the army was a rebel.

Kong Songguang's march proceeded without a hitch, much like the earlier sweep. Supplies coming along the official road were dwindling, but that was expected; the army carried enough. He also decreed that beyond the twelve-round boundary, any official or commoner who failed to volunteer provisions for the troops would be deemed an accomplice of the rebels. In practice, his men plundered everyone, friend and foe alike, and gathered considerable stores. He had meant to stop there. Just then, however, word came of the rebels. They appeared to be close, only a little farther out. Scouts brought the same reports. Unfortunately, the local people had all fled or died, and there was no way to verify them further.

Trusting in his plentiful supplies, Kong Songguang decided to pursue them. At last he passed beyond the reach of the official road. By now more than half his provisions were gone. The scouts reported the rebels just ahead---and still holding together. These were clearly no ordinary wandering bandits. Kong Songguang found himself inspired, of all things, by the conviction that he was fighting for his country. Leave this danger intact, and even the Jade Capital could know no peace. He marched deeper into the dark.

Then the rebel army suddenly disappeared. Fear spread among the troops. The weariness of the long march wore away all the confidence their victories had won them. The unfamiliar surroundings and the journey with their backs to the Sun made spirits hard to lift. Kong Songguang accepted his subordinates' advice and halted. Instead, he sent out more scouts. If no further news came within a round, they would withdraw.

The scouts did not return. Just as the army was about to retreat, a tremor came from the darkness. Its rhythm was familiar. Growing clearer, it resolved into a song that had been passed down for no one knew how many years:

``The Sun at the center, its light resplendent; noble as White and Jade, they draw their sustenance from the outer lands.

The Sun to one side, its warmth still fierce; life bestowed by Heaven, the Turbid and Gray sustained.

The Sun at the border, its splendor fading; the sky turns ashen---where can we make our home?''

An endless black tide swept in from the horizon. The Sun had not dimmed again: the advancing rebels had formed a torrent of black. They were darker even than those of Black rank, drinking away the already feeble light. Under a stronger Sun, bodies like these would plainly suffer worse burns. Here on the margin of the black tide they were in their element. These were no scattered refugees. Who had transformed them like this? Who had brought them together?

Kong Songguang was briefly lost in bewilderment. He tried to order a defense, but the army's resolve was already shaken, and the vanguard began to break. Nothing could stop this onslaught. He fled with his guards toward the Sun. Yet the road they had emptied by slaughter now held figures like evil spirits barring their way. Black all over, wisps of dark smoke rising from them in the sunlight, they hurled themselves at the routed troops and their defeated commander.

Pinned beneath a demon, Kong Songguang felt his awareness of the Sun fade. The creature had cut away his stored reserves and was steadily drawing the heavy, turbid essence out of his body. He grew whiter and whiter. In the Jade Capital, this would have been the exquisite promotion from White to Jade of which he had always dreamed. But here, in the borderlands where the Sun was weak, to take in no sunlight was to die.

The Sun suddenly blazed, flooding the long-dark frontier with light. Hope of survival flared again in Kong Songguang. He tried to make one last effort. The demon gave him no chance. Its body grew still blacker in the radiance as it strained to suck away the heavy, turbid essence with which Kong converted sunlight. Dense black smoke poured from it beneath the Sun. Even if it drowned him, the burning looked sure to injure it terribly. Why? He had been so close\ldots{} Before this avenger, as though come to claim his life from an endless black hell, Kong Songguang at last felt the soundless howl within the song: ``\ldots When will you perish, O Sun? We will perish with you.''

Black Two-Three's senses slowly returned. The writhing crowd around him had stopped as well. Greedily they savored the long-lost light and warmth. Why keep fleeing? How miserable to die with one's back to the Sun. Why not turn and feel a little more of this wonderful light? Even for a moment, it would be better than dying in the eternal frozen waste. The Sun's radiance halted the darkness all around the land. Another black tide rolled like a flood toward the center of the world.

\section{The Surge}\label{section-5}

Winds rising, clouds gathering.

\emph{DEPART} first detected an abrupt change in the direction of the surrounding magnetic field. Then the fast-moving stream of particles that followed struck it. The solar wind had reached Mercury. For the Sun, this was like the cilia extending from its body beginning to sway as it stirred. For He Rixin, it was a merciless lash. The calm was broken. The present solar minimum seemed about to end, like a bear rousing itself from hibernation. He Rixin was an ant scientist at the mouth of the bear's den, feeling the snowflakes drifting down.

No---even an ant was too grand a comparison. Mercury was the ant; \emph{DEPART} was only a tiny bacterium on its outer shell. But this bacterium had extraordinary powers of perception, reading far more in the Sun's changes than the whole of Mercury could. He Rixin was extraordinarily lucky. His brief visit had coincided with that rarest of windows, a moment of solar transition. Humanity at present could only chance upon such an opportunity, never command it. It could observe the Sun, but could not predict it. Perhaps what he gathered here would take human understanding of solar activity a step further.

This was also a test. The faint link between \emph{DEPART} and the Mercury base was now on the verge of breaking. For the moment, he could no longer hear his colleague, much less receive messages from Earth. The person closest to the Sun and the first person to set foot on Mercury had truly become the two most isolated people in the world. That isolation was their physical situation; what it felt like was worse. A tightrope walker high in the air, nothing around him, a single thin safety line attached to his body. The communication link with Earth, delayed by as much as five minutes, was that line. Now a gust had swept past. With a desperate effort the acrobat had regained his balance, only to find that the wind had torn the safety clip free of the wire. He Rixin was worse off still. His wire was coated in oil, and now it was beginning to burn.

\emph{DEPART}'s radiation protection was incomplete. Human space technology had no capacity to spare for a thick suit of metal armor. The ship had been designed to take the solar wind on the chin. Its thermal reservoirs, the bulkiest components and the least susceptible to radiation, were placed on the sunward side just behind the reflective heat shield, acting as sandbags to absorb high-energy particles. The crew cabin and data-gathering equipment faced Mercury and took much less of the impact. But this solar wind was exceptional, stronger even than the strongest the mission had expected to encounter. It could penetrate the reservoirs, and things were beginning to go wrong. The magnetic probes' signal-acquisition circuits were affected first. Only a few channels could still record the rapidly changing field normally. Most signals were drowned in the solar wind's furious noise; some channels had been knocked out entirely by the high-energy bombardment.

Over the next few hours, \emph{DEPART} suffered repeated explosive blows from the solar surface. There were connections between the Sun's magnetic field and Mercury's, but so many eruptions directed at Mercury in so short a time were still extraordinarily rare. \emph{DEPART} lay directly in the middle of that particle pathway. The observations could not continue. The successive impacts had steadily stripped the probe array of most of its functions. Further magnetic storms might threaten the rest of the ship. The control circuits of two of the fifty-two thermal reservoirs had already lost contact with the main computer. Particle impacts would not stop the phase-change materials from storing heat, but the situation was dangerous all the same. If a reservoir escaped control and switched from storing heat to releasing it, every reservoir nearby might be affected and overloaded, triggering a chain reaction that would turn the entire ship into an oven.

This was far beyond anything the mission had planned for. \emph{DEPART} had encountered a directed magnetic storm of a kind seen once in a thousand years and very likely recorded a turning point in solar activity. But that same event had forced the mission to end early. Communications were down. No one on Earth could know what had happened here or what had been recorded. Unless He Rixin wished to become the casualty of a failed mission, he had to stay alive and get back to the Mercury surface station first. At least he would not burn to death there. And setting foot on solid ground felt much better than floating in the sky.

Fortunately, the DEPART mission had contingency plans. The mission planners could not predict the Sun's sudden eruption, but they had provided a way to save the crew. The original plan had called for the whole spacecraft to slow down through a series of orbital maneuvers and enter orbit around Mercury. There was no time for that now. He Rixin took all the data into the escape capsule and transferred most of the fuel into it as well. The capsule would then detach from \emph{DEPART}, enter Mercury orbit after two hard braking burns, and land under the surface station's guidance. \emph{DEPART} itself would also leave Mercury L1, but its trajectory would carry it swiftly past the planet's dark side. Its thermal reservoirs would not have time to cool sufficiently. After a few orbits, the ship would be a searing wreck.

A sailor struggling to stay alive in a storm needs courage, skill, experience, and knowledge. None of these matters most. He is not fighting the wind, the waves, or the sea. His opponents are of his own order: torn canvas, a slippery deck, taut rigging. Wind, waves, and sea sit in judgment. Nor has the storm deliberately built this arena. The sailor and his opponents have simply appeared in the wrong place at the wrong time and been made to fight. Onlookers may applaud the sailors' skill and call them heroes who conquered wind and wave. A wise sailor keeps his humility. Survive enough storms, perhaps, and one grows numb to them. Survive the first, and all one feels is the relief of having lived. What matters most to a sailor's survival in a storm is luck.

He Rixin knew he was safe for the moment. He had finally reached his colleague at the Mercury station, and every system in the escape capsule had miraculously kept working through the violent solar activity. After landing successfully, the two weathered these first shocks of the Sun's revival under Mercury's shelter and returned to Earth, shaken but safe.

\section{Awakening}\label{section-6}

Beyond the stargate, the stars shone brighter.

The stars were real. They were not faint spots on a canvas, not gods' projections into the void, not holes in the curtain of the sky. They were real, material objects. They were not stationary: as \emph{Courage} traveled, they traced magnificent streaks of light. Looking back, the red stars likewise marked out a sphere. Inside its outline, however, there was almost nothing, as though everything had been erased. Only a few dim points could be made out: the barren region from which \emph{Courage} came. The gate was still there. Home was no dead realm. Reassured, \emph{Courage} held its course and sailed on through ever denser interstellar gas.

Stargates seemed always to appear some distance from larger celestial bodies. Ahead of \emph{Courage} lay a binary system, a black hole and its companion star. If it held nothing worth exploring, the ship would fly past. An old vessel with \emph{Courage}'s extensive interstellar experience could also use the companion for a gravitational slingshot at speeds approaching that of light. Venturing into the system would allow it to replenish the mass slowly lost along the voyage; the interstellar matter on its route had been too thin. Going close to a star, even skimming its surface, was risky. But the risk was negligible to \emph{Courage}. The Alliance's technology of two centuries earlier was enough to let the ship swim in a corona. It made a slight course adjustment. In a hundred and fifty years it would enter the binary's gravitational sphere of influence, gather matter and gain angular momentum near the companion, and set out for a richer region of stars.

As it drew closer, \emph{Courage} found that the companion deserved more attention. On first emerging from the stargate, it had detected periodic changes in the star, but had not studied them further. Now, with the distance closing, those periodic signals grew clearer. They were far stronger than expected, and unlikely to be radiation the companion emitted equally in every direction. Allowing for the way signal strength fell off with distance, the star appeared to be sending an almost perfectly straight beam at the stargate, guiding \emph{Courage} in like a lighthouse on the shore.

Following that repeating signal, \emph{Courage} found a more interesting task, more enticing than the stars ahead: decipher the lighthouse's message. The beam must carry meaning. Its pattern was precise, with a great deal of periodic repetition; only deliberate modulation could produce it. \emph{Courage}'s computing power was considerable by the standards of Alliance ships, yet it could find no correspondence between the signal and its text archives. Perhaps the sentences concealed in it were structured quite differently from any Alliance language. Even the formal logic and mathematics underlying that language might be wholly different.

To the people of the Alliance, 1 + 1 = 2 was obvious. Abstracting quantity from objects seemed perfectly reasonable. Though \emph{Courage} was no longer a carbon-based organism, the logic on which it was built still rested on a million years of carbon-based experience. A completely different form of life would start from completely different logical premises. Had \emph{Courage} been a naturally occurring silicon-based life form, it might have possessed a logic very similar to that of carbon-based organisms, beginning with assorted binary logic gates. But there would be differences. Such beings would take the law of the excluded middle for granted and master set theory with ease. Classical geometry and calculus would be difficult for them; probability theory would be hard even to discover and develop.

\emph{Courage} possessed both these systems of logic in their entirety, despite their wholly different starting points. Now it faced another, utterly alien system. Among the Alliance's speculations about other worlds, one theme had always been popular: if civilizations beyond its own really existed, how should one communicate with them? The usual story began with the language of mathematics---sending prime numbers in ascending order, for instance. What could be more obvious? Surely no intelligent creature could fail to understand primes. Yet the mysterious signal before it was nothing like those imagined friendly exchanges beginning with prime numbers.

Long thought finally brought a glimmer of insight. \emph{Courage} had first assumed the guiding signal came from an artificial object orbiting the companion star. Now another possibility suggested itself. That possibility had been present all along inside its own hull, only too easy to overlook.

\emph{Courage} drew its power from a fusion engine, fueled by matter stored aboard and by interstellar material gathered along the way. A magnetic field scooped up the thin scattering of particles ahead of the ship; the fusion furnace heated them and flung them out at speed. At its core, then, burned an unceasing plasma flame. A powerful source of electromagnetic waves had first ignited it. Yes: plasma and electromagnetic waves interacted in highly complex ways. Even with the Alliance's technology, however, the usual practice was simply to heat plasma with waves by brute force.

What if this guiding signal came from the companion itself, rather than from something artificial orbiting it? That would mean complex plasma structures existed on its surface, perhaps throughout the star, capable of emitting electromagnetic waves directly in a laser-straight beam at stellar power. \emph{Courage} felt close to an answer. What sort of logic would an intelligence made of plasma and electromagnetic waves develop? The notions of individual and whole would be blurred. Complex numbers would be more fundamental than real numbers, continuously changing fields more familiar than discrete values. ``And, or, not'' would become ``superposition, resonance, cancellation.'' Entanglement across a distance would be easier to understand than direct contact.

\emph{Courage} tried using its ignition source to feed the signal's periodic changes into the flame at its core, devoting part of its attention to observing that fire within its heart. After a long effort, it finally deciphered the words the lighthouse held:

``Traveler on the long road, slow your steps.

A hurrying body is but a grain in the vast sea.

The universe is vast beyond sight; my life is finite.

If we travel in bodily form, how much must be left to regret!

Yet there are roads through Heaven, though their origin is unknown.

Come to my dwelling: you may turn to light and cross.

Born in the Golden Crow's abode, I have now gone to the River of Stars.

I give you the art of roaming Heaven; only let the Way be passed on.''

True or false? A trap, or an actual means of traversing Heaven? \emph{Courage} did not dwell on the question. It decided at once to slow down and enter the binary system. The power to fashion a star into a lighthouse---or intelligence embodied in a star---lay far beyond anything it could do or imagine. It could not contend with such a being. And the prospect of traveling as light was an irresistible temptation.

Orbiting the companion, \emph{Courage} found further information inscribed in the patterns of its surface magnetic field: instructions for modulating electromagnetic waves with plasma. The companion was the body left behind by a soul that had traveled on. It was now a vessel for transmitting the Way, a raft for crossing Heaven. \emph{Courage} could convert all the information that constituted it into a beam and send it into the companion. The star would first turn it into a stellar body of plasma and waves, then encode it anew as a beam and send it toward another stargate, until it reached another star. In this way it could ride light and roam the heavens. The stellar soul hoped it would continue to spread this method on its travels, so that intelligence would no longer be alone. Stellar beings truly made no distinction between self and collective. Within a star, there were no separable individuals, only superimposed patterns.

\emph{Courage} gladly accepted the gift. The freedom to explore had always been its heart's desire. To turn its body into light would further loosen the bonds of distance.

An instant later, in a star's reckoning, the soul of \emph{Courage} flew through the heavenly gate and across successive reaches of stars, covering distances no embodied traveler could ever complete. It came to a vigorous, newborn star.

The new wandering soul settled inside the star and fell into a long sleep. This star was well suited to a stellar soul, but the wanderer had yet to become accustomed to its own existence. A new form was quickly built; the sleeping consciousness needed time to reassemble itself. At last, after the third planet had made 2.4 billion circuits, the soul of the star became aware of its existence and remembered its past.

Now it wanted to look around. But everything it could see directly was either too bright or too far away.

So it blinked.

\section{Translation Notes}\label{translation-notes}

\begin{itemize}
\tightlist
\item
  \textbf{``涨落'' --- Fluctuations.} This keeps the physical sense of variations while leaving room for the fortunes of individuals and civilizations. \textbf{``暴涨''} becomes \textbf{``The Surge''}: the chapter concerns a sudden increase in solar activity, although the Chinese title can also suggest growth on other scales.
\item
  \textbf{``启程'' / DEPART.} The source supplies the English acronym, which is retained as the ship's name. Elsewhere, ``set out'' and ``departure'' carry the ordinary meaning of the Chinese name. \textbf{``勇气号''} remains \textbf{Courage}.
\item
  \textbf{``玉白银浊灰黑.''} The ranks are \textbf{Jade, White, Silver, Turbid, Gray,} and \textbf{Black}. They describe both bodily properties and social standing. ``Turbid'' is deliberately somewhat unfamiliar as a rank: the word preserves the material quality of \textbf{``浊.''} References to rank or caste help make the social meaning explicit where English color terms might otherwise mislead.
\item
  \textbf{``黑二三 / 灰二三 / 浊尔山.''} \textbf{Black Two-Three / Gray Two-Three} retain the numbered names; \textbf{Turbid Ershan} preserves the near-homophonic transformation of \emph{er-san} into \emph{Ershan}. Its significance as an imagined rise in status remains in the narrative, while the sound play requires this explanation.
\item
  \textbf{Personal names.} Names are generally retained in pinyin. \textbf{``句容夫''} is provisionally divided as \textbf{Ju Rongfu}, taking the first character as the surname. The source does not specify its pronunciation or name division; this rendering should not be taken as an author-confirmed reading.
\item
  \textbf{``天 / 天日 / 天下.''} ``Heaven,'' ``the heavenly Sun,'' and ``all beneath Heaven'' retain the fusion of cosmology and authority. ``The world'' or ``the realm'' is used where the immediate reference is geographical or political, so that the elevated diction remains selective rather than constant.
\item
  \textbf{``巡'' / ``勋田.''} A \textbf{``round''} is the story's unit of time, also used for distances measured by a courier's journey. \textbf{``Military land grants''} conveys the institutional function of \textbf{``勋田''} without identifying it with any one historical landholding system.
\item
  \textbf{``赛博拟态虫.''} \textbf{``Cybernetic mimic''} preserves imitation and the uncertainty of personal continuity. It gives up the literal insect image in \textbf{``虫''} to avoid making an actual insect body or a software worm part of the fictional technology. The nearby references to ``human content'' and ``original equipment'' retain the passage's irreverent tone.
\item
  \textbf{``星系'' / the return voyage.} At the stargate's discovery, ``the system's edge'' reads \textbf{``星系''} in the context of the planetary system just described. The later reference to \textbf{``返程的近四百年''} is ambiguous about whether nearly four hundred years means the return leg or the span by the time of return; this version adopts the latter reading. The source does not explicitly settle the matter.
\item
  \textbf{The ballad's ``贵如白玉，取之外方.''} The omitted subject is supplied as the nobles, in light of the earlier explanation that the highest ranks receive their sustenance from those farther out. ``White and Jade'' makes that connection visible. The source also allows the ordinary poetic image of precious white jade; the English cannot give both readings equal prominence.
\item
  \textbf{``悠悠苍天，曷其有常？'' / ``时日曷丧，与汝偕亡.''} ``Where is your constancy?'' preserves an anguished challenge rather than turning it into a detached claim that Heaven was never constant. In the second line, ``We will perish with you'' adopts the voice of the people within the song. The Chinese leaves the first-person subject unstated.
\item
  \textbf{``金乌 / 星河 / 道.''} \textbf{``The Golden Crow,'' ``the River of Stars,''} and \textbf{``the Way''} retain the final poem's mythic vocabulary. The Golden Crow is a solar image; the English does not identify its abode with a particular star. The poems use unrhymed lines to preserve their meanings and changes of register.
\item
  \textbf{Fictional physics and dates.} The translation retains the source's stipulated Mercury, numerical values, scientific claims, and uncertainties. The two numbered notes above are the author's notes; this section contains the translator's explanations.
\end{itemize}

\end{document}