CAT Chapter 22: Lost In Space (4)

A pair of clear, almond-shaped eyes, with pupils slightly larger than usual, glared at him in anger, like a little cat.

Lin Si was amused by this scene and chuckled. “Why do you say that?”

Ling Yi replied, “You’re not talking to me properly!”

Lin Si let out a laugh.

He rarely laughed, and when he did, it was only a hint of a smile in his eyes, hardly any sound.

It was a soft breathy sound, as though coming from his chest, and it was very pleasant. Ling Yi was particularly sensitive to this sound. He shuddered, his ears turning hot, and then, in a mix of embarrassment and anger, he flung himself at Lin Si a few times.

Lin Si pinned him down, casually petting him, back and forth.

Ling Yi stubbornly ignored him.

The colonel’s snake had bitten its own tail in frustration. He quit the game, looked ahead, and saw the two people rolling around again, clearly no longer concerned with his own business. He pouted and started a new game.

Ling Yi had been enjoying his time aboard the ship, but after returning to Zone 6, he realized things weren’t quite as he expected.

Lin Si sent the new data to his communicator.

“You should start learning calculus,” Lin Si said.

Ling Yi quickly flipped through the material, his guard up.

—There was a lot, and it was complicated.

“When we left Earth, higher education had become universal, but it seems most people’s calculus skills don’t have a solid foundation.” Lin Si frowned slightly, as if he couldn’t understand this situation, but soon returned to his usual neutral expression. “So I’ve decided not to let you learn on your own. I’ll teach you every night. The beginning of calculus is limits, so that’s what we’ll cover tonight.”

An hour passed.

Ling Yi stared blankly, his eyes vacant.

Lin Si wrote elegant, smooth lines of text on the white paper with a ballpen.

The handwriting was beautiful, but the content was the opposite—at least in Ling Yi’s eyes.

Lin Si finished a line and said, “This is infinity.”

Ling Yi looked at the Greek letter, which resembled an upside-down number 3, his expression slightly troubled.

Lin Si said, “Recite the definition of infinitesimals.”¹

“For any arbitrary, extremely small positive number, there always exists another positive number such that… when the distance between the independent variable and a constant is smaller than this number, the function value will be smaller than the first number, and then… this function value is called an infinitesimal as the independent variable approaches the constant.”

After reciting it, he blinked in confusion.

Lin Si asked, “Did you get it?”

Ling Yi nodded at first, then shook his head. “Why not just say it’s smaller than any number?”

“Because saying that it’s ‘smaller than any number’ is human language, not the mathematical language,” Lin Si replied. “For science to develop freely, it must break away from the disturbances of philosophy and theology. These metaphysical subjects always try to find loopholes in human language and use them as weapons against natural sciences. For example, they believed that one-third plus two-thirds equals one, which is different from the 0.999 repeating result when adding fractions in decimal form, so they claimed mathematics was unreliable.”

He glanced at Ling Yi, whose expression suggested partial understanding, and continued, “This is an old paradox. A more intricate analog can be found in Zeno’s paradoxes, which you may explore further within the database for detailed analysis. Zeno’s paradoxes actually caused a huge problem in math during the 17th century, called the ‘second mathematical crisis.’ The issue wasn’t fully resolved until mathematicians finally defined infinitesimals—the concept you just recited—with precision. The resolution of this paradox not only averted epistemological discord but also catalyzed the formalization of calculus as a coherent discipline, liberating it from heuristic constraints. That’s why ‘infinitesimal’ cannot be easily explained by ‘smaller than any number.’ It holds great significance and opened the entire mathematical era.”

“Such is the nature of Voyager’s system—every variable parsed, every outcome bound by exacting parameters. Madam Chen never uses her own experience and guesswork to decide what the spaceship should do. She only uses mathematical models to calculate probability distributions. So, under her leadership, our travels never encounter unexpected situations due to faulty decision-making—unlike previous generations of leaders who made mistakes.”

Ling Yi furrowed his brows, flipping the definition of that epsilon-delta² nonsense back and forth several times.

Lin Si finished teaching the knowledge he needed to pass on to the little one—he knew Ling Yi had an excellent memory, just lacking a bit of time to understand.

Ling Yi finally processed the information, raised his head, and asked a question Lin Si hadn’t expected.

“What are philosophy and theology?”

The boy’s expression was blankly earnest. He genuinely had no idea what those words meant.

After all, aboard this ship, science ruled everything.

Lin Si could almost answer all the bizarre, outlandish questions posed by a boy of his age, but this time, but now, he hesitated, the silence stretching awkwardly.

Finally, he muttered, “It’s the Zone 4.”

Ling Yi blinked. “You mean… the area we decommissioned?”

Lin Si replied, “Yes.”

Zone 4 was very small, especially next to the sprawling zones around it. Back when Voyager launched, it still claimed its own corner of the ship.

That’s where they’d housed the thinkers—philosophers, literary researchers, poets—anyone who studied the messy, unquantifiable parts of being human. They worked hand-in-hand with Zone 8, sifting through endless archives—sorting, labeling, building frameworks. All so that when humanity finally settled, they wouldn’t have to start from scratch.

As ship resources dwindled, Zone 4’s population kept shrinking until it became the smallest zone.

Then, during a crisis caused by a supernova explosion, Voyager jettisoned Zone 4 entirely—using its ejection to get a boost and escape the disaster.

Now, Zone 4 was rarely discussed. Ling Yi, raised entirely on Voyager, only knew soldiers and scientists. To him, the world had two kinds of people: scientists, and the people who kept them safe.

After Lin Si summarized Zone 4’s history, Ling Yi frowned. “So… how do you define it?”

—Lin Si’s lessons had stuck. The little one now knew to ask for definitions when encountering new concepts.

“It doesn’t have one,” Lin Si said. “They studied things that can’t be defined. Feelings, ideas… It’s not my area of expertise. You can look it up.”

Ling Yi nodded.

But all cats have strong insight and curiosity, and Ling Yi often behaved like one.

He blinked, “But I think human thoughts and emotions are easy to define.”

Lin Si raised an eyebrow. “Hm?”

“Like… I like you, and everyone here. And seeing Lin Si makes me happy—”

“You’ve only dealt with the basic emotions, not yet experiencing other types.” Lin Si cut in. “There will come times when you will like and resent someone at once. Or acknowledge something noble while knowing it’s selfish.”

Ling Yi shook his head.

Lin Si smiled faintly. “You’ll understand more when you’re older.”

Ling Yi couldn’t fully grasp it, but he was sharp.

He had often wondered what kind of experiences Lin Si had been through and had carefully observed Lin Si’s reactions to different things.

Lin Si works for the Voyager. He’s very serious, but he is indifferent to everything on the spaceship, which was a bit contradictory.

So, he hesitated and spoke, “Does Lin Si like and dislike the Voyager at the same time?”

Lin Si remained silent for a moment before responding, “I have never liked it.”

With that, Lin Si added, “Now, back to your calculus.”

Ling Yi gave a reluctant nod.

“Your calculations are rarely incorrect, but you lack innate mathematical talent,” Lin Si stated matter-of-factly. “My expectations remain modest—grasp the foundational concepts, but ensure you follow the proofs. I will consider that. Any objections?”

Ling Yi pouted, “No.”

Lin Si wasn’t being distant because it had been a long time since he had seen Ling Yi. He only spoke nicely when he was teaching him something.

And when teaching, he would always make things difficult for him!

It turns out that when he couldn’t see him, he thought too highly of him—Lin Si wasn’t likable at all!

Fortunately, Lin Si was called away. Finally freed from the math class, Ling Yi wandered aimlessly around Zone 6.

He hadn’t seen Bethy for a long time and missed her a bit, but he hadn’t run into her at all.

Eventually, he saw someone who wasn’t from Zone 6 around the corner of the hallway.

To be precise, it was two people.

Tang Ning’s mechanical keyboard was set aside, and he was sitting in the corner, playing with a red-dressed… little girl?

A golden-haired little girl in a complex and ornate red princess dress, about the height of his chest.

As he got closer, Ling Yi realized she was just a hologram.

Tang Ning held the girl’s hand lightly as the child in the red dress knelt halfway, eyes closed, her forehead pressed gently to his. Her other hand drifted through his hair—a gesture tender enough to soothe.

When his figure rounded the corner, the girl lifted her gaze.

“Tang Ning-gege,” Ling Yi heard the sweet voice of the little girl, “Your friend’s here.”

Tang Ning opened his eyes, saw Ling Yi, and greeted him, “Xiao Ling Yi.”

He then introduced the little girl to Ling Yi. “This is Vivian, an AI.”

Vivian lifted the hem of her dress and floated toward Ling Yi, pretending to take his hand. Since holograms lacked physical form, Ling Yi had to mimic the motion, his fingers curling around empty air as she “led” him to Tang Ning.

Vivian sat next to Tang Ning and rested her head on his shoulder.

“You know I never liked Lucia’s avatar,” Tang Ning remarked. “So I created Vivian instead.”

“Will she replace Lucia?”

Tang Ning shook his head. “No. Lucia chose her own appearance, and I won’t override that. Vivian isn’t as independent—her design is entirely my doing.”

Vivian sighed. “Vivian is a lower-level system than Lucia, Vivian is not happy.”

“I won’t create anything lower-level than my previous works,” Tang Ning said.

“Really?” Vivian immediately stopped looking disappointed and happily hugged his arm.

Tang Ning gave a measured nod. “Lucia’s advanced cognition stems from… unconventional parameters in her design. You, however, were coded from scratch. More streamlined. So you’re cleaner.”

Vivian’s hologram flickered with delight, as she nodded energetically “Vivian is very happy.”

Tang Ning’s hand drifted toward her golden hair—a reflexive gesture, though his fingers met only air. He withdrew, seizing the keyboard beside him. Balancing it on his knees, he synced it to the glowing interface and resumed typing lines of code.

Ling Yi remembered that he hadn’t played with Lucia in a long time.

Only the very lonely play with AIs.