Cixin Liu - The Three-Body Problem

“The whole world is going to be under his rule because he has an army of more than thirty million preparing to conquer Europe. All right, let’s go see him.” Von Neumann turned to Newton. “Drop the sword.” Newton obeyed.

The three of them entered the pyramid, and just as they were about to emerge from the tunnel into the Great Hall, a guard insisted that they strip off all their clothes. Newton objected. “We’re famous scholars. No one of our stature would carry hidden weapons!”

As the two sides explored this stalemate, a deep, male voice came from the Great Hall. “Is it the foreigner who discovered the three laws of motion? Let him and his companions in.”

They entered the Great Hall. The First Emperor was pacing back and forth, his robe and his famous long sword both dragging along the ground. As he turned to gaze at the three scholars, Wang realized that his eyes were the same as the eyes of King Zhou of Shang and Pope Gregory.

“I already know the purpose of your visit. You’re Europeans. Why not go find Caesar? His empire is vast. Surely he can find you thirty million men.”

“But my most honored Emperor, do you know what kind of army he has? Do you know what shape his empire is in? In the magnificent eternal city of Rome, even the river that flows through the city has been heavily polluted. Do you know the cause?”

“Military industrial production?”

“No, Great Emperor, it’s the vomit from Romans after their binge and purge feasts. When the nobles attend the feasts, stretchers have already been prepared for them under the tables. When they’ve eaten so much that they can no longer move, the servants carry them home. The entire empire has sunk into a quagmire of extravagance from which they cannot extricate themselves. Even if Caesar could organize an army of thirty million, it would not have the quality and strength necessary to perform this great calculation.”

“I am aware of that,” Qin Shi Huang said. “But Caesar is waking up and reinvigorating his army. The wisdom of Westerners is terrifying. You are not more intelligent than the men of the East, but you can see the right path. For example, Copernicus could figure out that there are three suns, and you could come up with your three laws. These are very impressive accomplishments. We here in the East cannot, for now, match them. I don’t possess the ability to conquer Europe. My ships are not good enough, and the supply lines cannot be maintained for long enough to go over land.”

“That’s why your empire must continue to develop, Great Emperor!” Von Neumann seized the opportunity. “If you can master the pattern of the suns’ movements, you will be able to make the most of each Stable Era, and also avoid the damage brought by each Chaotic Era. This way, your progress will be much faster than Europe’s. Believe us, we’re scholars. As long as we can use the three laws of motion and calculus to accurately forecast the movements of the suns, we do not care who conquers the world.”

“Of course I need to predict the suns’ movements. But if you want me to gather thirty million men, you must at least demonstrate for me how such calculations would be conducted.”

“Your Imperial Majesty, please give me three soldiers. I will demonstrate.” Von Neumann grew excited.

“Three? Only three? I can easily give you three thousand.” Qin Shi Huang glanced at Von Neumann, distrustful.

“Your Imperial Majesty, you mentioned just now the defect in the Eastern mind when it comes to scientific thinking. This is because you have not realized that even the complicated objects of the universe are made from the simplest elements. I only need three.”

Qin Shi Huang waved his hand and three soldiers came forward. They were all very young. Like other Qin soldiers, they moved like order-obeying machines.

“I don’t know your names,” Von Neumann said, tapping the shoulders of two of the soldiers. “The two of you will be responsible for signal input, so I’ll call you ‘Input 1’ and ‘Input 2.’” He pointed to the last soldier. “You will be responsible for signal output, so I’ll call you ‘Output.’” He shoved the soldiers to where he wanted them to stand. “Form a triangle. Like this. Output is the apex. Input 1 and Input 2 form the base.”

“You could have just told them to stand in the Wedge Attack Formation,” Qin Shi Huang said, glancing at Von Neumann contemptuously.

Newton took out six small flags: three white, three black. Von Neumann handed them out to the three soldiers so that each held a black flag and a white flag. “White represents 0; black represents 1. Good. Now, listen to me. Output, you turn around and look at Input 1 and Input 2. If they both raise black flags, you raise a black flag as well. Under all other circumstances, you raise the white flag.”

“I think you should use some other color,” Qin Shi Huang said. “White means surrender.”

The excited Von Neumann ignored him. He shouted orders at the three soldiers. “Begin operation! Input 1 and Input 2, you can raise whichever flag you want. Good. Raise! Good. Raise again! Raise!”

Input 1 and Input 2 raised their flags three times. The first time they were black-black, the second time white-black, and the third time black-white. Output reacted correctly each time, raising the black flag once and the white one twice.

“Very good. Your Imperial Majesty, your soldiers are very smart.”

“Even an idiot would be capable of that. Tell me, what are they really doing?” Qin Shi Huang looked baffled.

“The three soldiers form a computing component. It’s a type of gate, an AND gate.” Von Neumann paused to let the emperor digest this information.

Qin Shi Huang said impassively, “I’m not impressed. Continue.”

Von Neumann turned to the three soldiers again. “Let’s form another component. You, Output: if you see either Input 1 or Input 2 raise a black flag, you raise the black flag. There are three situations where that will be true: black-black, white-black, black-white. When it’s white-white, you raise the white flag. Understand? Good lad, you’re really clever. You’re the key to the correct functioning of the gate. Work hard, and the emperor will reward you! Let’s begin operation. Raise! Good, raise again! Raise again! Perfect. Your Imperial Majesty, this component is called an OR gate.”

Then, Von Neumann used the three soldiers to form a NAND gate, a NOR gate, an XOR-gate, an XNOR-gate, and a tristate gate. Finally, using only two soldiers, he made the simplest gate, a NOT gate, or an inverter: Output always raised the flag that was opposite in color from the one raised by Input.

Von Neumann bowed to the emperor. “Now, Your Imperial Majesty, all the gate components have been demonstrated. Aren’t they simple? Any three soldiers can master the skills after one hour of training.”

“Don’t they need to learn more?” Qin Shi Huang asked.

“No. We can form ten million of these gates, and then put the components together into a system. This system will then be able to carry out the calculations we need and work out those differential equations for predicting the suns’ movements. We could call the system… um…”

“A computer,” Wang said.

“Ah, good!” Von Neumann gave Wang a thumbs-up. “Computer—that’s a great name. The entire system is a large machine, the most complex machine in the history of the world.”

The passage of in-game time sped up. Three months went by.

Qin Shi Huang, Newton, Von Neumann, and Wang all stood on the platform at the apex of the pyramid. This platform was similar to the one where Wang had met Mozi. It was filled with astronomical instruments, some of which were of recent European design. Below them, a magnificent phalanx of thirty million Qin soldiers was arrayed on the ground. The entire formation fit inside a square six kilometers on each side. As the sun rose, the phalanx remained still like a giant carpet made of thirty million terra-cotta warriors. But when a flock of birds wandered above the phalanx, the birds immediately felt the potential for death from below and scattered anxiously in chaos.