Cixin Liu - The Dark Forest

If the Trisolaran Fleet had maintained a constant acceleration over the past five years, it would pass the second snow patch today.

Fitzroy arrived at the Hubble II Space Telescope Control Center early. Ringier laughed when he saw him. “General, why do you remind me of a child who wants another present so soon after Christmas?”

“Didn’t you say that they would cross the snow patch today?”

“That’s right, but the Trisolaran Fleet has only traveled 0.22 light-years, so it’s still four light-years away. Light reflected from its passage through the snow won’t reach Earth for another four years.”

“Oh, I’m sorry. I forgot about that,” Fitzroy said with an embarrassed shake of his head. “I really wanted to see them again. This time, we’ll be able to measure their speed and acceleration at the time of passage, and that’s very important.”

“I’m sorry. We’re outside the light cone.”

“What’s that?”

“It’s what physicists call the cone shape that light describes as it emanates along the time axis. It’s impossible for people outside the cone to comprehend events taking place inside the cone. Think about it: Information about who-knows-how-many major events in the universe is flying toward us right now at the speed of light. Some of it has been traveling for hundreds of millions of years, but we’re still outside the light cones of those events.”

“Fate lies within the light cone.”

Ringier considered this, then gave him an appreciative nod. “General, that’s an excellent analogy! But sophons outside the light cone can see events on the inside.”

“So the sophons have changed fate,” Fitzroy said with feeling, and turned back to an image-processing terminal. Five years before, the young engineer Harris had started to cry at the sight of the brush, and afterward had suffered from depression so severe that he became practically useless at his job and was let go. No one knew where he had ended up.

Fortunately, there weren’t many people like him.

Temperatures were cooling rapidly these days, and it had started to snow, causing the green to gradually disappear from the surrounding area and a thin layer of ice to freeze on the surface of the lake. Nature lost its bright coloring, like a color photograph turned black-and-white. Warm weather here had always been short-lived, but to Luo Ji, the Garden of Eden felt like it had lost its aura since the departure of his wife and child.

Winter was a season for thinking.

When Luo Ji began to think, he was surprised to find that his thoughts were already in progress. He remembered back to middle school and a lesson a teacher had taught him for language arts exams: First, take a look at the final essay question, then start the exam from the top, so that as you work on the exam, your subconscious will be thinking over the essay question, like a background process in a computer. Now he knew that from the moment he became a Wallfacer, his thinking had started up and had never stopped. The entire process was subconscious and he had never been aware of it.

He quickly retraced the steps his thoughts had already completed.

He was now certain that everything about his current situation stemmed from his chance encounter with Ye Wenjie nine years ago. Afterward, he had never spoken of the meeting with anyone for fear of causing unnecessary trouble for himself, but with Ye Wenjie gone, the meeting was a secret known only to him and Trisolaris. In those days, only two sophons had reached Earth, but he could be certain that on that evening, they had been there by Yang Dong’s grave, listening to their every word. And the fluctuation in their quantum formation that instantly crossed the space of four light-years meant that Trisolaris had also been listening.

But what had Ye Wenjie said?

Secretary General Say had been wrong about one thing. Luo Ji’s never-begun research into cosmic sociology was quite likely the immediate reason why Trisolaris wanted to kill him. Of course, Say didn’t know that the project had been Ye Wenjie’s suggestion, and although it had just seemed to Luo Ji like an excellent opportunity to make scholarship entertaining, he had been looking for just such an opportunity. Prior to the Trisolar Crisis, the study of alien civilization was indeed a sensational project that would have garnered easy media attention.

The aborted research project wasn’t important in and of itself. What mattered was the instruction that Ye Wenjie had given him, so that’s where Luo Ji’s mind was stuck.

Over and over again he recalled her words: Suppose a vast number of civilizations are distributed throughout the universe, on the order of the number of detectable stars. Lots and lots of them. The mathematical structure of cosmic sociology is far clearer than that of human sociology.

The factors of chaos and randomness in the complex makeups of every civilized society in the universe get filtered out by the immense distance, so those civilizations can act as reference points that are relatively easy to manipulate mathematically.

First: Survival is the primary need of civilization. Second: Civilization continuously grows and expands, but the total matter in the universe remains constant.

One more thing: To derive a basic picture of cosmic sociology from these two axioms, you need two other important concepts: chains of suspicion and the technological explosion. I’m afraid there won’t be that opportunity…. Well, you might as well just forget I said anything. Either way, I’ve fulfilled my duty.

He had returned countless times to these words, analyzing each sentence from every angle and chewing over every word. The component words had been strung into a set of prayer beads, and like a pious monk he stroked them time and again; and unstrung them, scattered them, and restrung them in different orders until a layer of each had been worn away.

Try as he might, he couldn’t extract the clue from those words, the clue that made him the only person that Trisolaris wanted to destroy.

During his lengthy contemplation he strolled aimlessly. He walked along the desolate lakeside, walked through the wind as it grew ever colder, oftentimes completing a circuit of the lake unawares. Twice he even walked to the foot of the snow peak, where the patch of exposed rock that looked like a moonscape was blanketed with snow, becoming one with the snowcap ahead of him. Only then did his mood leave the track of his thoughts, Zhang Yan’s eyes appearing before his own in the boundless blank white of the natural painting. But he was now able to keep his mood in check and continue turning himself into a thinking machine.

A month went by without him knowing it, and then winter came in full force. But he still conducted his lengthy thought process outside, sharpening his mind on the cold.

By this time, most of the prayer beads had been worn faint, except for twenty-one of them. These ones seemed only to get newer the more he polished them, and now emitted a faint light:

Survival is the primary need of civilization.

Civilization continuously grows and expands, but the total matter in the universe remains constant.

He fixated on these two sentences, the axioms Ye Wenjie had proposed for cosmic civilization. Although he did not know their ultimate secret, his long meditation told him that the answer lay within them.

But it was too simple a clue. What could he and the human race gain from two self-evident rules?

Don’t dismiss simplicity. Simple means solid. The entire mansion of mathematics was erected on a foundation of this kind of irreducibly simple, yet logically rock-solid, axiom.

With this in mind, he looked around him. All that surrounded him was huddled up against the icy cold of winter, but most of the world still teemed with life. It was a living world brimming with a complex profusion of oceans, land, and sky as vast as the foggy sea, but all of it ran according to a rule even simpler than the axioms of cosmic civilization: survival of the fittest.