Hold Up The Sky

by Liu Cixin

  “Commence 3C Civilization Test!”

  The computer quickly identified the being’s thinking organ, an elliptical structure that hung at the center of an intricate plexus of nerves. The computer analyzed the structure of the brain in an instant and established a direct, high-speed information interface with it, bypassing all of the creature’s lower sensory organs.

  The civilization test consisted of a set of questions selected at random from an enormous database. Three correct answers were considered a pass. If a life-form failed to answer the first three questions correctly, the tester had two options: He could end the test and declare a failure, or he could provide more questions. Three correct answers were considered a pass, regardless of how many questions the tester asked.

  “3C Civilization Test, Question One: Please describe the smallest unit of matter you have discovered.”

  “Dee-dee, doo-doo-doo, dee-dee-dee-dee,” answered the balloon.

  “Incorrect. 3C Civilization Test, Question Two: According to your observations, in what direction does thermal energy flow through matter? Can its flow be reversed?”

  “Doo-doo-doo, dee-dee, dee-dee-doo-doo,” answered the balloon.

  “Incorrect. 3C Civilization Test, Question Three: What is the ratio of a circle’s circumference to its diameter?”

  “Dee-dee-dee-dee-doo-doo-doo-doo-doo,” answered the balloon.

  “Incorrect. 3C Civilization Test, Question Four …”

  “That’s enough,” said the High Archon, after the tenth question. “We don’t have much time.” He turned and signaled to the fleet commander.

  “Fire the singularity bomb!” ordered the commander.

  Strictly speaking, a singularity bomb was a sizeless object, a point in space, infinitely smaller than an atom. It had mass, though: the largest singularity bombs were billions of tons, and the smallest were more than ten million tons. When the bomb slid out of the arsenal of Vessel Red 69012, it appeared as a sphere, several thousand feet in diameter, that glowed with a faint fluorescence—radiation generated as the miniature black hole consumed the space dust in its path.

  Unlike black holes formed by the collapse of stars, these miniature black holes were formed at the beginning of the universe, tiny models of the universal singularity that preceded the big bang. Both the Carbon Federation and the Silicon Empire maintained fleets of ships that cruised the empty space beyond the galactic equator collecting these primordial black holes. Inhabitants of some marine planets called these fleets “deep-sea trawlers.” The “catches” that these fleets brought back were one of the most potent weapons in the galaxy, and the only weapon that could annihilate a star.

  The singularity bomb left its guide rail and accelerated along a force-field beam from the ship toward its target star. It arrived in short order, a dusty black hole that quickly plunged into the star’s fiery exterior. Stellar matter rushed from all directions in a turbulent arc toward the center of the black hole, where it disappeared. Copious radiation poured from the black hole, which appeared now as a blinding ball of light on the surface of the star, a diamond on the ring of the star’s circumference.

  As the black hole sank into the star’s interior, the radiant orb grew dimmer, revealing the enormous, hundred-million-mile-wide vortex that encircled the orb. The rotating vortex scattered the orb’s light in a kaleidoscopic display that looked, from the vantage of the ship, like a hideous, prismatic face. A moment later, the orb disappeared, as did the vortex, though more slowly; the star appeared to have returned to its original color and luminosity. This was the eye of the storm, the final moment of silence before annihilation.

  The voracious black hole sank toward the dense center of the star, devouring everything in its path. In less than a second, it swallowed a mass of stellar material greater than the mass of a hundred medium-sized planets. Super-strong radiation spread out from the black hole toward the surface of the star. Some of it escaped, but most of it was blocked by stellar material, adding enough energy to the star to disrupt its convection and knock it out of equilibrium. The star’s color began to shift, first from red to bright yellow, then to bright green, then to a deep, sapphire blue, and then to a forbidding violet. The radiation from the black hole by now was orders of magnitude more intense than the radiation from the star itself, and as more energy flowed out of the star in the form of nonvisible light, its violet color intensified—a spirit in agony, floating in the vastness of space. Within an hour, the star’s billion-year journey had come to a close.

  There was a flash of light that seemed to swallow the whole universe, then faded slowly away. Where the star had been, there was now a thin, spherical layer of material expanding rapidly, like a balloon being blown up. This was the surface of the star, swept outward in the explosion. As it expanded, it became transparent, and a second hollow sphere grew in its center, followed by a third. These waves of material were like exquisitely painted glass orbs, one inside another, and even the smallest of them had a surface area tens of thousands times larger than the original surface area of the star. The first wave vaporized the orange planet in an instant, though it was impossible to see its destruction against such a magnificent background. Compared to the size of the expanding stellar layer, the planet was a speck of dust, not even a dot on the surface of the orb.

  The smart fields of the High Archon and the senator darkened. “Do you find this work distressing?” asked the fleet commander.

  “Another species gone, like dew in the sun.”

  “Think of the Battle of the Second Arm, Your Excellency—more than two thousand supernovas detonated, one hundred and twenty thousand planets with life vaporized. We do not have the luxury to be sentimental.”

  The senator ignored the fleet commander. He addressed the High Archon directly. “Random planetary spot checks are unreliable. There may be signs of civilization elsewhere on a planet’s surface. We should implement area scans, as well.”

  The High Archon said, “I have discussed that possibility with the Senate. We must destroy hundreds of millions of stars in the isolation belt. We estimate the belt contains ten million planetary systems and fifty million planets. Our time is limited; we will not be able to conduct a full area scan on each planet. All we can feasibly do is widen the detection beam to scan larger random samples … and pray the civilizations that might exist here have spread uniformly across their planets’ surfaces.”

  *

  “Next, we’ll learn Newton’s second law.”

  He spoke as quickly as he could, to teach the children as much as possible in the short time he had left.

  “An object’s acceleration is directly proportional to the force acting on it, and inversely proportional to its mass. To understand that, you need to know what acceleration is. Acceleration is the rate at which an object’s speed changes over time. It’s different from speed—an object that’s moving fast isn’t necessarily accelerating rapidly, and a quickly accelerating object may not be moving fast. For example, say there’s an object moving at 110 meters per second. Two seconds later, it is moving at 120 meters per second. Its acceleration is 120 minus 110, divided by two … that’s five meters per second—no, five meters per second squared. Another object is moving at ten meters per second, but two seconds later, it’s moving at thirty meters per second. Its acceleration is thirty minus ten, divided by two—ten meters per second squared. The second object may not be as fast as the first, but its acceleration is greater! I mentioned squares—a square is just a number multiplied by itself …”

  He was surprised that his thinking was suddenly so clear. He knew what this meant: If life is a candle, his had burned to its base, and its wick had fallen and ignited the last bit of wax there, with a flame ten times brighter than before. His pain was gone and his body no longer felt heavy; in fact, he was barely aware of his body at all. The life he had left seemed to be in his brain, which worked furiously to convey all its knowledge to the children gathered around him. Language was a bottleneck—
he knew he didn’t have enough time. He fantasized that the knowledge he had spent his life accumulating—not much, but dear to him—was lodged in his brain like small pearls, and that as he spoke, a crystal ax chopped the pearls out of his brain onto the floor, where the children scrambled to gather them like sweets at New Year’s. It was a happy fantasy.

  “Do you understand?” he asked restlessly. He could no longer see the children around him, but he could still hear them.

  “We understand! Now please rest, teacher!”

  He felt his flame begin to sputter. “I know you don’t understand, but memorize it anyway. Someday, it will make sense to you. The acceleration of an object is directly proportional to the force acting on it, and inversely proportional to the object’s mass.”

  “We really do understand, teacher! Please, please rest!”

  With his last ounce of strength, he gave the children a command. “Recite it!”

  Through tears, the children began to chant. “The acceleration of an object is directly proportional to the force acting on it, and inversely proportional to the object’s mass. The acceleration of an object is directly proportional to the force acting on it, and inversely proportional to the object’s mass….”

  Hundreds of years ago, one of the world’s great minds emerged in Europe, wrote down these words. Now, in the twentieth century, they filled the air of China’s most remote mountain village, recited by a chorus of children in a thick, rural accent. In the sound of that sweet hymn, his candle burned out.

  The children gathered around his body and wept.

  Target Number: 500921473

  Absolute Magnitude: 4.71

  Evolutionary Stage: Middle Main Sequence

  Nine planets found

  This is Vessel Blue 84210 reporting

  “What an exquisite planetary system,” the fleet commander exclaimed.

  The High Archon agreed. “Indeed. Its small, rocky planets and gas giants are spaced with wonderful harmony, and its asteroid belt is in a beautiful location, like a necklace. And its farthest planet, a little dwarf covered in methane ice, suggesting the end of one thing and the beginning of another, like the final note of a musical cadence …”

  “This is Vessel Blue 84210. We are commencing a life scan on Planet One. This planet has no atmosphere, a slow rotation, and a huge temperature differential. Scan beam is firing. First random site: white. Second random site: white…. Tenth random site: white. Vessel Blue 84210 reports that this planet has no life.”

  “You could smelt iron on the surface of that planet. We shouldn’t waste time,” said the fleet commander.

  “We are commencing a life scan on Planet Two. This planet has a thick atmosphere; a high, uniform temperature; and substantial acidic cloud cover. Scan beam is firing. First random site: white. Second random site: white…. Tenth random site: white. Vessel Blue 84210 reporting—this planet has no life.”

  “I have a strong feeling that Planet Three harbors life. Scan thirty random sites,” said the High Archon, his message traveling instantly over the four-dimensional communicator to the duty officer of Vessel Blue 84210, over one thousand light-years away.

  “Excellency, our schedule is very tight,” said the fleet commander.

  “You have your orders,” said the High Archon resolutely.

  “Yes, Your Excellency.”

  “We are commencing a life scan on Planet Three. This planet has a medium-density atmosphere, and most of its surface is covered by ocean …”

  The first shot of the life-scan beam struck a circle of land in Asia around three miles across. In the light of day, the effect of the beam would have been visible to the naked eye—it turned every nonliving object in its field transparent. The scan hit the mountains of northwest China; in daylight, an observer would have seen a spectacular sight as sunlight refracted through the mountain range and the ground under her feet seemed to disappear, revealing an abyss into the depths of the planet. Living things—people, trees, grass—remained opaque, and their forms would have stood out clearly against the crystal background. However, this effect only lasted for the half a second it took the beam to initialize, and onlookers would likely assume they had imagined it. Besides, it was nighttime.

  In the direct center of the beam’s field was the village school.

  “First random site … we’ve got green! Vessel Blue 84210 reporting—we have discovered life on target number 500921473, Planet Three!”

  The beam began automatically to sort the many life-forms it had hit, entering them into its database in order of complexity and according to an initial intelligence estimate. At the top of the list was a group of life-forms inside a square shelter. The beam narrowed and focused on the shelter.

  The High Archon’s smart field received an image transmission from Vessel Blue 84210. He projected it onto the black background, and in an instant, he was standing within a projection of the village school. The image-processing system had removed the shelter from view, but the life-forms inside were still hard to make out, as their bodies were so similar to the silicon-based planetary surface around them. The computer eliminated all nonliving objects in the image, including the larger, lifeless body the other beings encircled, and the beings now appeared suspended in a void. Even so, they were still dull and colorless, like a bunch of plants. This was clearly not a species with any remarkable phenotypic features.

  Vessel Blue 84210 was an interstellar warship as large as Earth’s moon, and in its position outside Jupiter’s orbit, it was like an extra planet in the solar system. It fired a four-dimensional beam that moved through three-dimensional space nearly instantaneously. In a moment, the beam had arrived at Earth and pierced the roof of the village school’s dorm. It scanned the eighteen children inside down to their elementary particles and transmitted the enormous amount of data back into space at an unimaginable rate. The main computer of Vessel Blue 84210 had a storage capacity larger than the universe itself; in an instant, digital copies of the children were constructed and stored there.

  The eighteen children floated in an endless void whose color was indescribable. In fact, it didn’t strictly have a color. It was a limitless field of perfect transparency. The children instinctively tried to grab hold of nearby classmates, but their hands passed through their bodies without resistance. They were terrified. The computer detected their fear and judged that they required some familiar objects for comfort, so it altered the color of the simulation’s background to match their home planet’s sky. Immediately, the children saw a cloudless, sunless, deep blue sky. There was no ground beneath them, just endless blue, the same as above, and they were the only things in it.

  The computer reassessed the digital children and found they were still panicking. In a hundred-millionth of a second, it understood why: Whereas most life in the galaxy had no fear of floating, these creatures were different in that they lived on land. The computer added Earth-like gravity and a ground to the simulation. The children were astonished to find under their feet a pure white plain, extending into infinity in all directions and crossed by a neat, regular black grid, like a huge piece of writing paper. A few children crouched down to touch the ground, and it was the smoothest surface they had ever touched; they tried taking a few steps, but the ground was completely frictionless and didn’t move beneath them. They wondered why they didn’t fall down. One child took off a shoe and threw it level with the ground. It slid along at a regular speed, and the children watched it glide off into the distance, never decelerating.

  They had seen Newton’s first law.

  A melodious, ethereal voice permeated the digital universe.

  “Commencing 3C Civilization Test. Question One: Please describe the basic principles of biological evolution on your planet. Is it driven by natural selection or spontaneous mutations?”

  The children had no idea. They stayed silent.

  “3C Civilization Test, Question Two: Please briefly describe the source of a star’s power.”

&nbs
p; Silence.

  …

  “3C Civilization Test, Question Ten: Please describe the chemical composition of the liquid in your planet’s oceans.”

  The children still did not speak.

  The shoe had slid off into the horizon, where it became a black point and disappeared.

  “That’s enough!” said the fleet commander to the High Archon, one thousand light-years distant. “We won’t be able to complete the first phase of the project on time if we keep on like this.”

  The High Archon’s smart field vibrated slightly, signaling his consent.

  “Fire the singularity bomb!”

  The beam containing the command shot through four-dimensional space and arrived immediately at Vessel Blue 84210, which was holding its position in the solar system. A faintly glowing ball left the long track at the front of the ship and accelerated along an invisible force field toward the sun.

  The High Archon, the senator, and the fleet commander turned their attention to another region of the isolation belt, where several planetary systems with life had been discovered, the most advanced of which was a brainless, mud-dwelling worm. Exploding stars filled the region, like galactic fireworks. They all thought of the Battle of the Second Arm.

  A while later, a small portion of the High Archon’s smart field split off from the rest and turned its attention back to the solar system. He heard the captain of Vessel Blue 84210.

  “Prepare to exit the blast radius. T minus thirty to warp. Commence countdown!”

  “A moment, please. How long until the singularity bomb reaches its target?” asked the High Archon, attracting the attention of the fleet commander and the senator.

  “It’s passing the orbit of the system’s first planet. Approximately ten minutes to impact.”

  “We will take five minutes to continue the test.”

  “Yes, Your Excellency.”

  The duty officer of Vessel Blue 84210 continued administering the test. “3C Civilization Test, Question Eleven: What is the relationship between the three sides of a right triangle on a flat plane in three-dimensional space?”