"What?" After leaving the scrap parts collection bin at the east end of town, Youji became furious. "That old man!"
The scrap parts collection bin was actually something more like a public facility. If anyone had unwanted scrap parts, they could stockpile them here. Then, if someone was short on money for the moment, they could come here and take a few parts free of charge.
The town also hired people who had lost the ability to work to maintain the parts here. They had either lost the prosthetics they needed for work and lacked the credit to borrow money for new ones, or their Biological Brains had suffered such severe damage that it affected their mobility.
Their job was to preserve the "barely usable" scrap metal with rustproof oil and silicone gel.
It was just that, much as Youji's mother would store a pair of prosthetic hands for years, parts were not sent here until their metal fatigue was nearly at its limit.
But Xiang Shan did not need particularly good parts.
These parts were not for his own use, either. He had another purpose for them.
Yet they ran into an unexpected complication.
One of the old men responsible for maintenance kept telling Xiang Shan, "You've made it big," and clung to him without letting go. This made it impossible for Xiang Shan to pick out parts properly. In the end, Xiang Shan had no choice but to select several brand-new pieces from the parts he had just bought and hand them over to the maintenance workers.
The maintenance workers happily carried off screws, diodes, and the like in their arms.
"You normally don't need to pay anything when you come here in an emergency!"
"Enough, Youji. That was just some unplanned surplus, meant as backup supplies." Xiang Shan stopped Youji. He was not particularly angry. To him, it was like handing out wedding candy after getting married. Something good had happened to him—at least, everyone thought it was good—so it was not too much to let everyone share a little of the joy.
Only, the recipients had changed from children to several old men who had nearly regressed into children.
That line, "You've made it big," had even amused him for a while.
"Looks like even in this era, people are still people..."
"What?" Youji did not understand.
"People are really complicated. They can be kind and evil, good and bad—sometimes I truly worry that I slept for too long, and the people of today have become people I don't recognize... Forget it. Why am I telling you this?" Xiang Shan shook his head.
Even now, humanity could still show kindness and malice. That was good.
Of course, a little "malice" also existed. Thinking carefully about it, Dr. Schultz's attitude when inviting him online... could that have been a test? Did refusing to go online mean something in this era?
But that was not a major problem.
—Of course, that did not mean he would forgive "true malice."
"Remembering my own past just now was too much of a shock." Xiang Shan brought up something else. "Youji, you remember, right? At first, I had not intended to step forward. Someone pushed me out. Did you see that person? Who was standing behind me at the time?"
Although he had originally intended to step forward, and although the matter had ultimately ended well, that did not mean he would forgive the person who pushed him. The nature of it was different.
The person who had shoved him had intended to kill him, and had acted on that intention.
Youji smacked his forehead. Xiang Shan defeating the martial artist had been so shocking that everyone had forgotten about this.
"I didn't see." Youji sounded somewhat guilty, but there was also a trace of nervousness in his voice. "Xiang Shan, what are you going to do... What would a Vagrant usually do at a time like this?"
"I'll explain it to you when I get the chance." Xiang Shan patted Youji's back. "All right, good children should go home now."
"Go home?" Youji stared at him. "What about you, Xiang Shan?"
"Naturally, I'm going to do what I need to do." Xiang Shan said, "What comes next is not suitable for good children. Go home and sleep. I'll tell you the result tomorrow."
"No!" Youji knew Xiang Shan was definitely going to do what a "Vagrant" did. How could he possibly leave now?
Xiang Shan tried to send him away several times, but Youji refused to go home. In the end, Xiang Shan sighed. "Fine. I was planning to teach you some things anyway... I'll take you along. But later, speak less and watch more. Understand?"
Youji nodded excitedly, then asked curiously, "Aren't you going to keep working on your prosthetic body, Xiang Shan?"
"No." Xiang Shan shook his head. "I do want to build myself a prosthetic body as soon as possible, but there is something more important to do first. And it can only be done outside town—if you want to come, carry the parts for me."
The two quickly arrived at a secluded place. It was the road they usually took to the garbage mountain, and no one came here at night.
The moonlight was especially bright tonight. Xiang Shan adjusted the lenses in his eyes and suddenly discovered something incredible.
He saw a line on the moon, visible to the naked eye, like a scratch across a flatbread. At the same time, within the moon's halo, there was an additional thin line that was difficult to make out with the naked eye.
It was a very small ring.
Something had once happened on the moon that had completely altered its surface, even tearing off a tiny amount of matter from it and forming a ring so faint it barely seemed to exist.
"Today, I finally had the leisure to look at the moon, and I ended up seeing something unbelievable..." Xiang Shan's vocalizer once again failed to comprehend his complicated emotions. "I'm starting to wonder whether I woke after sleeping for many years, or simply crossed into a parallel world..."
Youji plopped down onto the ground. The huge pile of parts on his back clanked loudly. "Xiang Shan, no matter what you're doing, there was no need to come this far... I'm exhausted..."
Xiang Shan stopped and looked around.
This place was far from anything that looked like a signal base station, far from anywhere cameras might be hidden.
Good.
Xiang Shan silently took the scrap parts from Youji's hands. "Youji, remember what you are about to see. Remember it with your Biological Brain. Never forget it, even if you die!"
Xiang Shan fitted gears onto transmission shafts, then laid several shafts across the discarded frame of some mechanical tool, forming the foundation of a mechanical structure. Then the gears meshed with one another, and the transmission shafts crossed and interlocked.
Youji's eyes widened. "Xiang Shan, Xiang Shan, what is this? It looks amazing..."
"Of course it's amazing." Xiang Shan stared intently at the device he was building as memories kept surfacing in his mind.
He knew this structure.
"What kind of amazing thing is it? Can it defeat bad people?"
"Didn't I tell you? Watch carefully." Xiang Shan snapped at him. "If you want to learn my skills, you have to memorize this completely."
Youji pursed his lips. "I don't even know what it is..."
Xiang Shan's hands paused for several seconds.
The man said solemnly, "Then remember this well. This structure is called a Turing Machine."
Youji watched Xiang Shan work.
Xiang Shan assembled the scrap parts into an extremely ugly, simple machine. It had no power source; it used a gear structure, with friction allowing kinetic energy to pass from one gear to another... It even had a crank handle as its power source.
Youji scratched his head. "This is... the thing you wanted me to remember?"
It was ugly and crude, and to make sure the gears could complete this final operation, Xiang Shan had used all the lubricant given to him by the old maintenance workers. That made it look black and greasy, especially disgusting.
Xiang Shan nodded, then turned the crank by hand.
The kinetic energy from his hand changed direction through the gears, split apart, and traveled throughout the machine.
The sound of metal meshing and colliding...
Xiang Shan murmured, "This is it."
"Xiang Shan..." Youji awkwardly pointed something out. "It looks like scrap metal."
Xiang Shan raised his head, stared at Youji, and said loudly, "The material it is made of is scrap metal, but its structure is not. You must remember its name—the Turing Machine!"
The man's gaze fell upon the machine again, and his tone softened. "It is the computer from the Dawn of Hongmeng, the greatest product humanity gained in its study of mathematics, and the origin of all Inner Power."
"Inner Power?"
"Every martial art you have heard of, including those you saw at the Paralympics, as well as those used by me and that dog, is merely Outer-School Martial Arts." Xiang Shan closed his eyes. "Of course, there are also Inner-School Techniques."
"Outer-School Martial Arts are specialized tactics elevated from the art of war. Inner-School Techniques are the product of intelligence and artificial intelligence improving one another."
"Inner Power was also called Hacker Technology in ancient times. But those primitive hackers could not directly manipulate code and computing resources through their Biological Brains as Vagrants could now. They had to face an output device called a 'screen,' then use an input device called a 'keyboard' to interfere with that world—those were merely the limits of mortals. A Vagrant's Inner Power is a hundred times more miraculous than that. But at its root, Inner Power truly evolved from Hacker Technology."
The relationship between Hacker Technology and a Vagrant's Inner Power was like that between the first single-celled organism in the primordial ocean and the higher life forms that came later. The latter might be mysterious and dazzling, but it had always developed from the foundation laid by the former.
"All Inner Power is based on the power of computing machines, and all computers originate from this great engineering structure..."
A trace of fervor entered Xiang Shan's voice.
The Turing Machine.
In 1920, David Hilbert, the greatest mathematician in the world at the time, leader of the Göttingen School, and proposer of the famous "Twenty-Three Problems," launched an assault on the very source of mathematics. He put forward the concept of "Metamathematics"—mathematics that studied mathematics.
If one mastered Metamathematics, one would have mastered all mathematics.
And at the core of Metamathematics were three propositions—completeness, consistency, and computability.
Completeness: every mathematical problem could be proven or disproven.
Consistency: every mathematical assertion was either true or false; there could be no proof of a contradiction that was both true and false.
Computability: every mathematical proof could be obtained through a feasible process and a finite number of operations.
As long as these three problems were solved, humanity could use machines to crack every mathematical problem—the "ultimate answer" to mathematics would effectively fall into human hands.
Mathematicians all over the world became obsessed with these three problems.
And the Turing Machine was the divine tool that shattered these three great challenges.
It was a structure filled with "wisdom."
Youji applauded. Three parts of that applause were perfunctory, but three parts were sincere as well. "But Xiang Shan, what does this have to do with the Inner Power we were talking about..."