The Three-Body Problem

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.

Wang performed some computations in his head and realized that even if the entire population of Earth were arranged into such a phalanx, the whole formation would fit inside the Huangpu District of Shanghai. Though it was powerful, the phalanx also revealed the fragility of civilization.

Von Neumann said, “Your Imperial Majesty, your army is truly matchless. In an extremely short time, we have completed such complex training.”

Qin Shi Huang held on to the hilt of his long sword. “Even though the whole is complex, what each soldier must do is very simple. Compared to the training they went through to learn how to break the Macedonian Phalanx, this is nothing.”

Newton added, “And God blessed us with two consecutive Stable Eras to get them trained and ready.”

“Even in a Chaotic Era, my army continues to train. They will finish your calculations even if it’s a Chaotic Era.” Qin Shi Huang glanced over the phalanx with pride in his eyes.

“Then, Your Imperial Majesty, please give the great order!” Von Neumann’s voice trembled with excitement.

Qin Shi Huang nodded. A guard ran over, grabbed the hilt of the emperor’s sword, and stepped backwards. The bronze sword was so long that it was impossible for the emperor himself to pull it out of the scabbard. The guard knelt and handed the sword to the emperor. Qin Shi Huang lifted the sword to the sky, and shouted: “Computer Formation!”

Four giant bronze cauldrons at the corners of the platform came to life simultaneously with roaring flames. A group of soldiers standing on the sloping side of the pyramid facing the phalanx chanted in unison: “Computer Formation!”

On the ground below, colors in the phalanx began to shift and move. Complicated and detailed circuit patterns appeared and gradually filled the entire formation. Ten minutes later, the army had made a thirty-six kilometer square computer motherboard.