Authors: Liu Cixin
Tags: #Science Fiction
In fact, that could never happen; never happen because the preceding helium flash would have already vaporized the Earth.
It was all to occur in 400 years; since then, 380 years had passed.
This stellar disaster would not only annihilate and consume every inhabitable telluric planet in the solar system, but it would also forever change the nature and orbits of the Jovian planets. After the primary helium flash, the heavy elements would re-accumulate in the core of the Sun and further helium flashes would repeatedly occur for a period of time. This was a “period” in the stellar sense, lasting many, many thousands of human lifetimes.
All of this made it impossible for humanity to continue living in the solar system, leaving only one last resort: The migration to another star. The technology of the time allowed for only one destination for this migration. That destination was Proxima Centauri, the star closest to ours, a mere 4.3 light-years away. But while it was easy to reach a consensus on the goal of the migration, the means were far more controversial.
To enrich the learning experience, our ship was turned back twice on the Pacific, giving us two sunrises. By then we had become accustomed to the sight and we started to believe that the children of the Southern Hemisphere, who were constantly exposed to the Sun, could actually exist and live. We continued our journey into the dawn, watching the Sun rise higher and higher in the sky. With it the temperatures too began to rise.
One day, as I was drowsily resting in my cabin, I was suddenly disturbed by the sound of a quarrel coming from outside. Moments later the door opened and Ling popped her head in.
“Hey, the Spaceship Faction and the Earth Faction are at it again!” she shouted excitedly.
I could not have cared less; after all, they had been fighting for almost 400 hundred years now. Nonetheless, I went outside with her for a quick look and saw a group of boys fighting. It was immediately obvious that Tung was up to his usual games again. His father was an incorrigible member of the Spaceship Faction, and was in fact still in prison for joining an insurgency against the Unity Government. Seeing Tung, I guessed that the apple hadn’t fallen far from the tree.
Ms. Xing and some of the burly sailors had managed to separate the fighting children, but it was no easy feat.
Even as he was being dragged away with a bloodied nose, Tung shouted, “Throw the Earth Faction overboard!” He pumped his fist in to emphasize his point.
“I am Earth Faction, too,” Ms. Xing said with exasperation. “Do you want to throw me overboard, too?”
“We'll throw every last one of the Earth Faction overboard!” Tung shouted, utterly unwilling to back down.
In those days, the Spaceship Faction was losing in public popularity and they had grown even more unruly as a result.
“Why do you hate us so much?” Ms. Xing asked.
“We don't want to wait for death together with you Earth Faction fool!” a couple of the Spaceship Faction kids immediately shouted in response.
“We will build the spaceships! All hail the spaceships!” they chanted.
Ms. Xing pressed the holographic emitter on her wrist. Immediately, a holographic image appeared in the air in front of us. We children stared at it in rapt attention and, at least for a moment, peace returned. Floating in front us was the image of a glittering and translucent glass sphere. The hermetically sealed sphere was about four inches in diameter. Two-thirds of it was filled with water. A small shrimp, a small sprig of coral and a bit of green algae swam in the water. The shrimp languidly moved about inside the sphere.
Ms. Xing said, “This is something Tung came up with for natural science class. There is more inside this small ball than meets the eye; it is also full of microscopic bacteria. All things inside it interact with and support one another. The shrimp eats the algae and draws oxygen from the water. It then discharges organic matter in its feces and it breathes out gaseous carbon dioxide. The bacteria further breakdown the discharge into inorganic matter and carbon dioxide. With the inorganic matter, the algae then use artificial sunlight to perform photosynthesis.”
We all gazed in awe as she explained to us the process.
“They thereby can manufacture nutrients, grow and reproduce, all while exuding oxygen for the shrimp to breathe,” she told us. “With nothing but sunlight, this ecological cycle should be infinitely self-perpetuating. It was the best class work I had ever seen and I was well aware that it encapsulated Tung's dreams, as well as the dreams of every other child of the Spaceship Faction,” she said fairly. “In essence, it is a miniature of the spaceship they so desire! Tung told me that he had designed it according to computations based on rigorous mathematical models and that he modified the genes of every life form in the sphere, ensuring that their metabolisms would achieve a perfect balance. He firmly believed that life within the sphere would endure, right down to the natural end of the shrimp's life. All of us teachers loved the project and we provided it with artificial sunlight at the required intensity. Convinced by Tung's calculations, we quietly wished that his little world would succeed. But today, just about a dozen days later ...”
With great care, Ms Xing produced the real glass sphere from a small box. The shrimp floated on the water's surface, dead. The water itself had gone a dismal shade of cloudy and the rotting algae inside had lost their green, and had now turned into a dead, woolly substance covering the coral.
“This small world is dead. Children, who can tell me why?” Ms. Xing asked, showing us the lifeless sphere.
Someone quickly called out an answer. “It is too small!”
Ms. Xing smiled and nodded. “You are right; it is too small. A small biosphere, no matter how precisely designed, can never withstand the test of time. It is no different with the vessel that the Spaceship Faction imagines.”
“We could build a spaceship the size of Shanghai or New York,” Tung retorted, his voice subdued, his eyes on the sphere.
“That is true, but that would be the limit of our current technology and compared to the Earth, such a biosphere would still be very small,” Ms. Xing replied gently. “Too small, in fact.”
“We can find a new planet,” Tung countered.
“Even your faction does not really believe that,” Ms. Xing said. “There are no available planets in Centaurus. The nearest fixed star with an available planet is eight-hundred-fifty light-years away. Even the fastest ship we can build can travel no more than zero-point-five percent of the speed of light. At that speed it would take us one-hundred seventy-thousand years just to get there. The spaceship's biosphere would not even be able to last a tenth of that. Children, only an ecological system the size of Earth, with its vigorous and all-encompassing biosphere, can exist in perpetuity. Should humanity leave Earth to travel across the universe,” she said, concluding her impassioned explanation, “it would be no different from an infant leaving its mother in the middle of a desert!”
“But,” Tung said, pausing before he continued in an almost pleading tone, “teacher, it's too late for us and too late for Earth. It is too late for it to reach sufficient speed and to make it far enough away. The Sun is about to explode!”
Ms. Xing would have none of that sort of talk. “It is not too late,” she told him, and us as we all listened in. “We must trust the Unity Government! How many times have I told you? Even if you don't believe, even if worst comes to worst, ‘At least humanity died with pride, fighting to the end!’ ”
Humanity's exodus would proceed in five steps: First, the Earth Engines' jets would be used to counteract the Earth's movement, stopping its rotation. Second, the engines' entire power would be used to set the Earth on a new path, accelerating the Earth into escape velocity, taking it away from the Sun. Third, in outer space, the Earth would continue to accelerate as it traveled to Proxima Centauri. Fourth, in transit, the Earth Engines would be re-aligned, the Earth's rotation would be restarted and the deceleration process initiated. And then fifth, the Earth would be moored in an orbit around Proxima Centauri, becoming its planet. People also called these five steps the “Reining Age”, the “Exodial Age”, the “First Wandering Age” (during acceleration), the “Second Wandering Age” (during deceleration), and the “New Sun Age”.
The entire exodus would last 2,500 years, about 100 generations.
Our ship continued its voyage, making its way into the Earth's night. Neither the light of the Sun nor the glow of the Earth Engines could be seen here. As we stood in the cool Atlantic breeze, we children saw our first starry sky.
God, the beauty of it was heartbreaking!
Ms. Xing arched her arm around the nearest few of us, as if to embrace us all with one hand. “Look, children,” she said as she pointed to the heavens with her other hand. “There is Centaurus and that is Proxima Centauri, our new home!” Tears began trickling down her face as she spoke those words, leading her to weep.
It was an emotionally infectious moment, seeing her tears. By the time she finished, we were all sobbing. All around us — even the sailors and the captain, hardened seafarers one and all — no one could stop the tears from welling up in their eyes. Through our tears we all looked in the direction that Ms. Xing was pointing, the stars in the sky twinkling as we cried. Only one point of light did not waver; a heavenly lighthouse on the distant shores of the wild sea of the night, a faint beacon for lonely travelers freezing in the cold desolation: The star of our hearts, Proxima Centauri. It was the only hope and support for a hundred future generations, set on a course through a sea of woes.
On our return voyage, we saw the first sign that Earth had begun its journey. A gigantic comet had appeared in the night sky. It was the Moon, abandoned by humanity. The comet's tail was, in fact, the jet of Lunar Engines, pushing the Moon out of its orbit to ensure that there would be no catastrophic collision as the Earth began its acceleration. The Lunar Engines' trail covered the ocean in a blue glow and drowned out the stars. As it moved, the gravitational tide of the Moon riled up the ocean, raising towering waves. We quickly transferred to a plane to continue our journey to our destination in the Southern Hemisphere.
The day of departure had finally arrived!
When we deplaned, we were immediately blinded by the brilliant jets of the Earth Engines. Their plasma plumes were several magnitudes stronger than when we had last seen them. Even through closed eyes we could see that the beams had been righted and were now shooting straight toward the sky. The Earth Engines were running at full power.
The acceleration gave rise to 300-foot rolling, thunderous waves that assaulted every continent. Scorching hurricanes howled through the boiling froth, screaming through the countless towering beams of plasma with unbridled fury, uprooting almost every tree on Earth. Our planet had also become a gigantic comet, its blue tail piercing the dark of space.
Earth was on its way, and with it, all of humanity.
Just as we began our journey, my grandfather passed away, his burnt body ravaged by infection.
In his final moments, he repeated over and over, “Oh, Earth, my wandering Earth...”
The Exodial Age
fter we de-boarded, our school prepared to relocate us to a subterranean city; we would be among the first group of inhabitants. Our descent began when our school bus entered a massive tunnel which soon became a smaller corridor deep below, always sloping downward. After traveling for about half an hour, we were told that we had entered the city; but as I looked out of the bus' window as we drove on, I could only ask myself, 'What city?'
All I could see was an endless parade of labyrinthine, branching cave passages and countless sealed, metal doors. A row of floodlights hung from the cave’s high ceiling, bathing everything in a dull, metallic blue. I could not help but feel disheartened at the realization that, for most of the remainder of my life, this would be my world.
“Early humans lived in caves and so will we,” Ling said quietly, but not quietly enough for Ms. Xing not to hear.
Turning to us all, she intoned, “There is nothing we can do about it, children. The surface will soon become a very, very terrible place. It will be so bad, that your spit won't even make it to the ground. When the cold comes, it will freeze in mid-fall and when it is hot, it will evaporate even as it leaves your mouth!”
Our teacher had barely finished her admonishment when a younger child turned to me and asked, “The cold part I understand; it's 'cause the Earth will move further and further away from the Sun, but why will it get hot?”
“Idiot, didn't you learn about orbital acceleration?” I snapped back.
“No,” he responded, shirking.
It was Ling who took it upon herself to patiently explain the situation to the child, almost as if she wanted to dispel her erstwhile melancholy. “Things are different than you think. It’s like this: The Earth Engines are not that powerful. They can only accelerate the Earth a bit and certainly not enough to launch the Earth out of its solar orbit in one fell swoop. In fact, the Earth will circle the Sun fifteen orbits before it can escape! During these fifteen orbits, the Earth will slowly pick up speed. Right now, the Earth's orbital path is still pretty much circular, but as the Earth accelerates, its orbit will become increasingly elliptical. The faster it moves, the flatter the ellipse will become, and the more the Sun will be shifted toward one end of the orbit. When the Earth is at its farthest point away from the Sun, it will naturally be very cold.”
“Right, but it still doesn't make sense! When the Earth is furthest from the Sun, it will be very cold and when it is at the other end of the ellipse, its distance from the Sun will … hmm, let me think.” He thought for a moment. “No, the orbital dynamics states that we'll not get closer than we are now… So why should it get hotter?”
The child truly was a little genius. It was a real blessing that genetic memory engineering had brought such a child the memories of his father, making him the norm. Without them, even in 400 years we could not have realized the god-eclipsing miracle such as the Earth Engines.
Even so, I gave a snarky answer. “But there are still the Earth Engines, you dolt. Right now, more than ten-thousand of those giant blow-torches are being switched to full power. The Earth itself is basically just the ring that holds those rocket nozzles.” I shook my head in mock disgust. “Now just be quiet. You're annoying me!”
Thus we began our life underground. The subterranean cities spread across the continents. They were built one-third of a mile below the surface and each one had enough space for over a million inhabitants. Under the Earth’s surface, I finished primary school and entered middle school.
Most of my schooling concentrated on the physical sciences and engineering; the arts and philosophical subjects, on the other hand, were condensed to a bare minimum. The human race had no time for such distractions now. All in all, humanity was then probably the busiest it had ever been. The work never ceased and there was always more to do. Interestingly enough, the religions of the surface world vanished without a trace overnight. We still had history lessons, but our history books portrayed humanity's history under the Sun as life in a mythical paradise.
My father was an astronaut serving in the space fleet's Low Earth Orbit Wing. He was on the job almost constantly and I rarely saw him at home. I remember that in the fifth year of the Earth's acceleration, our entire family visited the seaside as the planet reached its aphelion. For us Aphelion Day was a holiday much like New Year or Christmas. At the furthest point from the Sun, we could indulge in a false sense of security.
We still needed to wear thermal suits to go to the surface. To keep us warm, these suits were fully sealed and powered by nuclear batteries. Once outside, the blinding light of Earth Engines' plasma jets was almost all that we could see. The brilliant glow of this forest of energy beams seemed to swallow the entire world. We had to travel for many hours in our flying car before we managed to escape their glow and we were actually able to see the sunlit seashore. The Sun itself had become tiny, no larger than a baseball. It hung in the sky, utterly unmoving, its distant rays only illuminating that one area with dawn-like light. Around us, the sky was the deepest blue we had ever seen and in it the stars were clearly visible. Looking into the distance, I for a moment wondered where the ocean had gone. Now before my eyes there was only a vast white, icy plain stretching to the horizon.
A large group of revelers had gathered on the frozen ocean, shooting fireworks into the dark blue sky. The mood of the celebration was truly extraordinary. All around I could see drunken party-goers rolling on the ice as my ears were assaulted by songs being belted out. It seemed that no one could agree on which song would be appropriate, leading to a cacophony of voices, all trying to outdo each other at the top of their lungs.
“Despite it all, they all want to live their own life and there's nothing wrong with that,” my father said. He paused, suddenly remembering something he had not yet shared. “Oh, I forgot to tell you all; I've fallen in love with Li Xing. I want to move out to live with her.”
“Who is she?” my mother asked tranquilly.
“My primary school teacher,” I answered in my father's stead. Having started middle school two years ago, I had no idea how my father had come to know Ms. Xing. Maybe he had met her at my graduation.
“Well, then go,” my mother said.
My father continued his thought. “I'm sure to tire of it after a while. I'll come back then. Does that sound all right?”
“If you want to, certainly,” my mother answered, calm as the frozen ocean all around. But then, a few moments later, her emotions were at last stirred. “Ah, look at how beautiful that one is!” she shouted, pointing at an exploding firework in the sky, genuinely moved by its spectacular display. “I bet it had a holo-projecter inside!”
Back then we were baffled when we watched films and read stories from the Pre-Solar Age. We just could not understand why people should invest so much emotion into matters that had nothing to do with survival. Watching a protagonist despair or cry over love was strange beyond words to us. In those days, the imminent threat of death and the desire to escape alive overwhelmed all else. The daily updates on the condition of the Sun and position of the Earth all but devoured our attention and ruled our emotions. This all-consuming focus gradually changed the essence of human psychology and spirituality. Love and all its foibles became mere distractions, just like a quick swig of a drink was for a gambler who cannot take his eyes off the spinning wheel.
Two months later, my father really did come back home, done living with Ms. Xing. My mother was neither happy, nor sad.
“Li Xing was very impressed with you. She told me you were a very creative student,” my father told me.
My mother, who had overheard our conversation, was genuinely puzzled. She asked, “Who is impressed with him?”
“Ms. Xing, my primary school teacher. Father just spent two months living with her,” I answered, just as perplexed as she.
“Oh, now I remember!” My mother laughed, shaking her head. “I am not even forty and my memory is already shot.” Looking up at the holographic starry sky that covered the ceiling of our house and then to the holographic forest on our walls, she continued. “You picked a good time to come back. You need to change these images. The kid and I are tired of seeing them and we don't know how to program the damn thing.”
When the Earth again began its long fall toward the Sun, all of us had entirely forgotten the episode.
One day, the news reported that the ocean was thawing. When we heard it, our family again made its way to the seashore. At that time Earth was just crossing Mars' orbit and with its approach, the strength of the Sun had again increased. It still should not have been enough to thaw the Earth on its own, but the Earth Engines ensured that the surface temperatures had reached rather pleasant heights. People everywhere were delighted that for once they did not need to wear their thermal suits.
Earth Engines still filled the sky of our hemisphere, but on the other half of the planet people could truly feel the Sun draw closer. Their sky was bright blue and the Sun was as brilliant as it had been before our exodus began.
We took our flying car and as we flew over the ocean, we could not spot any signs of thaw, instead seeing only a white expanse of ice. Disappointed, we got out of our car. Just as we closed the doors, we were shocked by an almighty rumble that seemed to rise from the very depths of the Earth. It sounded as if the entire planet was about to explode.
“That is the sound of the ocean!” my father shouted over the noise. “The rising temperatures are heating the thick sheets of ice unevenly, causing something very much like an earthquake.”
Suddenly, a sharp, discordant thunderclap pierced the low rumble and the people watching the ocean behind us began to cheer. I looked and saw a long crack appear, shooting across the frozen ocean like a vast, black lightning bolt; then, in the midst of the ongoing thunder, crack after crack appeared in the frozen ocean. Sea water erupted from these cracks, quickly forming torrents that spread across the icy plain.
On the way home, we looked out over the vast, long-barren land below. Weeds had begun to drill their way out of the soil, and all manner of flowers had sprung into full bloom, and tender leaves draped withered trees in green. Life had wasted no time, flourishing everywhere with vibrancy.
Every day that the Earth drew closer to the Sun tightened the hold of anxiety gripping humankind, making ever fewer choose to emerge to admire the now spring-like surface. Most of us remained hidden within the subterranean cities. We did so not to avoid the imminent heat, torrential rain, and hurricanes, but to elude the dread of the approaching Sun.
One day after I had already gone to bed, I overheard my mother quietly telling my father, “Maybe it really is too late.”
My father replied in equally hushed tones. “There were rumors like that at the first four perihelions.”
“But this time it's true. I heard it myself from Professor Qian Dele's wife,” came my mother’s quick and soft response. “He is an astronomer of the Navigation Commission. You all know him. Anyway, he himself told her that they have observed a further acceleration in the concentration of helium.”
“Listen, my dear, we must hold on to hope,” my father calmly but insistently replied. “Not because hope is real, but because we have to live up to nobility. In the Pre-Solar Age nobility meant money, power or talent, but now one must only hold to hope. Hope is the gold and the jewels of this age. No matter how long we live, we must hold fast to it!” He then added, “Tomorrow, please tell our child the same.”
Like everyone else, I felt ill at ease as the perihelion approached. One day, as I was going home from school I — without really knowing why — ended up in the city's central plaza. I stood by the round fountain in its middle, in turn looking down at its sparkling blue water and up to the ethereal ripples of light reflected by the gushing water below that played across the dome above me. After a while I noticed a familiar face. It was Ling, holding a little bottle in one hand and a small tube in the other. She was blowing soap bubbles, her eyes blankly following each string of bubbles as they floated away. She watched them until they vanished, only to blow another string.
“Aren't you a bit too old to find that amusing?” I asked her as I approached.
Ling looked at me in surprise and with a warm smile said, “Let's go on a journey!”