The Three-Body Problem (24 page)

Although the method is simple, it shows how, mathematically, random brute force can overcome precise logic. It’s a numerical approach that uses quantity to derive quality. This is my strategy for solving the three-body problem. I study the system moment by moment. At each moment, the spheres’ motion vectors can combine in infinite ways. I treat each combination like a life form. The key is to set up some rules: which combinations of motion vectors are “healthy” and “beneficial,” and which combinations are “detrimental” and “harmful.” The former receive a survival advantage while the latter are disfavored. The computation proceeds by eliminating the disadvantaged and preserving the advantaged. The final combination that survives is the correct prediction for the system’s next configuration, the next moment in time.

“It’s an evolutionary algorithm,” Wang said.

“It’s a good thing I invited you along.” Shi Qiang nodded at Wang.

Yes. Only much later did I learn that term. The distinguishing feature of this algorithm is that it requires ultralarge amounts of computing power. For the three-body problem, the computers we have now aren’t enough.

Back then, in the temple, I didn’t even have a calculator. I had to go to the accounting office to get a blank ledger and a pencil. I began to build the math model on paper. This required a lot of work, and in no time at all I went through more than a dozen ledgers. The monks in charge of accounts were angry with me, but because the abbot wished it, they found me more paper and pen. I hid the completed calculations under my pillow, and threw the scratch paper into the incense burner in the yard.

One evening, a young woman suddenly dashed into my room. This was the first time a woman had shown up at my place. She clutched a few pieces of paper with burnt edges, the scratch paper I had thrown out.

“They tell me these are yours. Are you studying the three-body problem?” Behind her wide glasses, her eyes seemed to be on fire.

The woman surprised me. The math I used was unconventional, and my derivations took large leaps. But the fact that she could tell the subject of my study from a few pieces of scratch paper showed that she had unusual math talent and that she, like me, was very devoted to the three-body problem.

I didn’t have a good impression of the tourists and pilgrims. The tourists had no idea what they were looking at, only running around to snap pictures. As for the pilgrims, they looked much poorer than the tourists, and all seemed to be in a state of numbness, their intellect inhibited. But this woman was different. She looked like an academic. Later I found out that she had come with a group of Japanese tourists.

Without waiting for my answer, she added, “Your approach is brilliant. We’ve been searching for a method like this that could turn the difficulty of the three-body problem into a matter of massive computation. Of course, it would require a very powerful computer.”

I told her the truth. “Even if we were to use all the computers in the world, it wouldn’t be enough.”

“But you must have an adequate research environment, and there’s nothing like that here. I can give you the use of a supercomputer. I can also give you a minicomputer. Let’s leave together tomorrow morning.”

The woman, of course, was Shen Yufei. Like now, she was concise and authoritarian, but she was more attractive then. I’m naturally a cold person. I had less interest in women than the monks around me. This woman who didn’t adhere to conventional ideas about femininity was different, though. She attracted me. Since I had nothing to do anyway, I agreed right away.

That night, I couldn’t sleep. I draped a shirt over my shoulders and walked out into the yard. In the distance, I saw Shen in the dim temple hall. She knelt before the Buddha with lit joss sticks, and all her movements seemed full of piety. I approached noiselessly, and as I came by the door to the temple hall, I heard her whisper a prayer: “Buddha, please help my Lord break away from the sea of misery.”

I thought I must have heard wrong, but she chanted the prayer again.

“Buddha, please help my Lord break away from the sea of misery.”

I didn’t understand religion and had no interest in any of them, but I really couldn’t think of any prayer odder than this one. “What are you saying?” I blurted.

Shen ignored me. She kept her eyes barely closed, her hands clasped together in front of her, as though watching her prayer rise with the incense smoke toward the Buddha. After a long while, she finally opened her eyes and turned toward me. “Go to sleep. We have to get up early.” She didn’t even look at me.

“This ‘Lord’ you mentioned, is he part of Buddhism?” I asked.

“No.”

“Then…?”

Shen said nothing, just hurried away. I didn’t get a chance to ask anything else. I repeated the prayer to myself over and over, and it seemed to grow even stranger. Eventually, I became frightened. I rushed over to the abbot’s room and knocked on his door.

“What does it mean if someone prays to the Buddha to help another Lord?” I then told him the details of what I saw.

The abbot silently looked at the book in his hand, but he was thinking about what I said, not reading. Then he said, “Please leave me for a bit. Let me think.”

I turned and left, knowing that it was unusual. The abbot was very learned. Usually, he could answer any question about religion, history, and culture without having to think. I waited outside the door for about the time it took to smoke a cigarette, and the abbot called for me.

“I think there’s only one possibility.” His expression was grim.

“What? What could it be? Could there be some religion whose god needs worshippers to pray to the gods of other religions to save it?”

“Her Lord really exists.”

This response confused me. “Then … the Buddha doesn’t exist?” As soon as I said it I realized how rude it sounded. I apologized.

The abbot slowly waved his hand at me. “I told you, the two of us can’t talk about Buddhism. The existence of the Buddha is a kind of existence that you cannot comprehend. But the Lord she’s talking about exists in a way that you can understand.… I can say no more concerning this matter. All I can do is counsel you against leaving with her.”

“Why?”

“It’s just a feeling. I feel that behind her are things that you and I cannot imagine.”

I left the abbot’s room and walked through the temple toward my room. The night had a full moon. I looked up at it and thought it a silvery, strange eye that gazed down at me, the light suffused with an eerie chill.

The next day, I did leave with Shen—I couldn’t stay in the temple the rest of my life, after all. But I didn’t think that over the next few years, I would live the life of my dreams. Shen fulfilled her promise. I had a minicomputer and a comfortable environment. I even left the country several times to use supercomputers—not time-sharing, but having the whole CPU to myself. She had a lot of money, though I didn’t know where it came from.

Later, we got married. There wasn’t much love or passion, just mutual convenience. We both had things we wanted to get done. As for me, the few years after that could be described as a single day. My time passed peacefully. In her house, I was taken care of and did not have to worry about food or clothing, so that I could devote myself to the study of the three-body problem. Shen never interfered with my life. The garage had a car that I could drive anywhere. I’m sure she wouldn’t even have minded if I brought another woman home. She only paid attention to my research, and the only thing we talked about day to day was the three-body problem.

“Do you know what else Shen has been up to?” Shi Qiang asked.

“Just the Frontiers of Science. She’s busy with it all the time. Lots of people show up every day.”

“She didn’t ask you to join?”

“Never. She never even talks to me about it. I don’t care, either. That’s just the way I am. I don’t want to care about anything. She knows it, and says I’m an indolent man without any sense of purpose. The organization doesn’t suit me and would interfere with my research.”

“Have you made any progress with the three-body problem?” Wang asked.

Compared with the general state of the field, my progress could be said to be a breakthrough. Some years ago, Richard Montgomery of UCSC and Alain Chenciner of Université Paris Diderot discovered another stable, periodic solution to the three-body problem.
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Under appropriate initial conditions, the three bodies will chase each other around a fixed figure-eight curve. After that, everyone was keen to find such special stable configurations, and every discovery was greeted with joy. Only three or four such configurations have been found so far.

But my evolutionary algorithm has already discovered more than a hundred stable configurations. Drawings of their orbits would fill a gallery with postmodern art, but that’s not my goal. The real solution to the three-body problem is to build a mathematical model so that, given any initial configuration with known vectors, the model can predict all subsequent motion of the three-body system. This is also what Shen Yufei craves.

But my peaceful life ended yesterday.

*   *   *

“This is the crime you’re reporting?” Shi Qiang asked.

“Yes. A man called yesterday and told me that if I didn’t cease my research, I would be killed.”

“Who was he?”

“I don’t know.”

“Phone number?”

“Don’t know. Caller ID showed nothing.”

“Anything related to report?”

“Don’t know.”

Da Shi laughed and tossed his cigarette butt into an ashtray. “You went on and on forever, and in the end all you have to report is one line and a few ‘I don’t know’s?”

“If I hadn’t gone on like that, would you have understood the import of that call? Also, if that were all, I wouldn’t have come here. I’m lazy, remember? But there was another thing: It was the middle of the night—I don’t know if it was today or yesterday—and I was in bed. As I was drifting halfway between sleep and wakefulness, I felt something cold moving on my face. I opened my eyes and saw Shen Yufei, and I almost died of fright.”

“What’s so frightening about seeing your wife in the middle of the night?”

“She stared at me in a way that I had never seen. The light from outside fell on her face, and she looked like a ghost. She held something in her hand: a gun! Moving the barrel over my face, she told me that I had to continue working on the three-body problem. Otherwise she’d kill me.”

“Oh, now this is getting interesting.” Da Shi gave a satisfied nod. He lit another cigarette.

“Interesting? Look, I’ve nowhere to go. That’s why I came to you.”

“Tell us exactly what she said.”

“She said: ‘If you succeed in solving the three-body problem, you will be the savior of the world. If you stop now, you’ll be a sinner. If someone were to save or destroy the human race, then your possible contribution or sin would be exactly twice as much as his.’”

Da Shi blew out a thick cloud of smoke and stared at Wei Cheng until he squirmed. He pulled a notepad out of the mess on his desk and picked up a pen. “You wanted us to take notes, right? Repeat what you just said.”

Wei did.

Wang said, “What she said is indeed strange. What does she mean by exactly twice as much?”

Wei blinked. “This seems pretty serious. When I came, the officer on duty immediately sent me to see you. It looks like you’ve already been paying attention to Shen and me.”

Da Shi nodded. “Let me ask you something else: Do you think the gun your wife held was real?” He saw that Wei didn’t know how to answer. “Could you smell gun oil?”

“Yes, there was definitely an oily smell.”

“Good.” Da Shi, who had been sitting on his desk, jumped off. “Finally we have an opening. Suspected illegal possession of firearms is enough to justify a search. I’ll leave the paperwork until tomorrow, because we have to move right away.”

He turned to Wang. “No rest for the weary. I have to ask you to come and advise me some more.” Then he turned to Xu Bingbing, who’d been silent the whole time. “Bingbing, right now I have only two men on duty, and that’s not enough. I know the Information Security Division isn’t used to fieldwork, but I need you to come along.”

Xu nodded, glad to leave the smoke-filled office.

*   *   *

In addition to Da Shi and Xu, the team for conducting the search consisted of Wang Miao, Wei Cheng, and two other officers from the Criminal Division. The six of them rode through the predawn darkness in two police cars, heading toward Wei’s neighborhood at the edge of the city.

Xu and Wang were in the backseat. As soon as the car started, she whispered to Wang, “Professor Wang, your reputation in
Three Body
is very high.”

Somebody mentioned
Three Body
in the real world!
Wang was excited, right away feeling close to this young woman in a police uniform. “Do you play?”

“I’m responsible for monitoring and tracking it. An unpleasant task.”

Wang anxiously asked, “Can you tell me its background? I really want to know.”

In the faint light coming through the car window, Wang saw Xu give a mysterious smile. “We want to know as well. But all its servers are outside the country. The system and firewall are very secure and hard to penetrate. We don’t know much, but we can be sure it’s not operated for profit. The software quality is uncommonly high, and the amount of information contained in it even more unusual. It doesn’t even seem like a game.”

“Have there been any…” Wang carefully picked the right words. “…
supernatural
signs?” Wang’s night had been filled with coincidences: He had been called in to discuss the three-body problem with Wei Cheng immediately after he solved the
Three Body
game. And now Xu was telling him she was monitoring the game. Something didn’t seem right.