Chapter 26: A Roll Call for Loyal Readers

Shang Lu said he was just a pathetic, insignificant, and helpless director of the workshop office. Including himself, there were only six people in the entire office. In the post-Advent era, where billions of people had died so casually, what could six people possibly accomplish? As a grassroots cadre at the 151 Nanshan Support Base, his job description was limited to patrolling the workshop, monitoring data, and flipping through "Lectures on Advanced Relativity," before simply waiting to die.

If he wanted to, he could at most "smoke, drink, and get a perm"—but the workshop system strictly forbade open flames, alcohol was prohibited on the base, and perms violated military appearance regulations.

See? He couldn't even smoke, drink, or get a perm.

How could he compare to Yu Qian?

Shang Lu sighed and sat down on the curb. The plaza under the streetlights was empty. His gaze drifted into the darkness beyond the reach of the light, lost in thought.

"Shang Lu, stop being so pessimistic," Bai Shu said, sitting down beside him. "You’re a top student from the Chengdu Institute of Automation."

"151 isn't exactly short on technical talent. Teacher Ji goes around tricking one person here and another there, calling them all over to be trained as his successors," Shang Lu said. "I must have had rocks in my head to buy into that."

Bai Shu laughed.

"Director Ji might genuinely want to train successors; it’s just that the pool of candidates is a bit broad."

"I wasn't exactly a standout at the Chengdu Institute. The Institute of Automation is full of elite talent. After graduation, they either stay at the institute or go to other research facilities. Only people with my mediocre level end up at front-line bases, doing low-tech, repetitive labor." Shang Lu turned his head to look at Bai Shu, his tone serious. "You’ve never been to the Chengdu Science City, have you?"

The young girl shook her head, knees pressed together, and gave a self-deprecating smile.

"My... my level is at the bottom of the barrel even in university."

"Chengdu Science City is a super-conglomerate, but its goal isn't profit; it’s technological breakthroughs. Tsinghua, Peking University, and even the Institute of Automation are now all subsidiaries of the Science City. The whole group has about 400,000 people," Shang Lu explained with gestures. "It has fully integrated all the resources and channels of universities and research institutes. It’s essentially a laboratory cluster of 400,000 people. Compared to it, university labs from before the Advent were as backward and inefficient as tenant farmers. But it’s also a place of immense pressure and tension. Whether you're a mentor or a student, everyone carries a heavy burden. There’s almost no time for you to learn and grow slowly; master’s students are used like post-docs."

"There is a core technical circle within the Science City called Factory 314. If the Science City is a massive, efficient machine for breakthroughs, then Factory 314 is its engine. It gathers the last remaining top-tier technical experts of humanity and is the birthplace and source of almost all giant mecha-related technologies," Shang Lu continued. "Those who can stand their ground at 314 are extraordinary people. I’m just a dropout who couldn't keep up. My technical projects failed every time, my grades were always at the bottom, so I ran away here to hide. It was too embarrassing to keep staying at the institute."

"It’s okay." Bai Shu patted his shoulder foolishly, smiling brightly. "I’m a bottom-tier student too!"

Shang Lu’s expression was neither a smile nor a frown.

"Better to be the head of a chicken than the tail of a phoenix," Bai Shu encouraged him. "Even if you weren't the best at the Institute of Automation, you’re here at 151 now, so you aren't at the bottom anymore!"

Long after, whenever Bai Shu recalled these words, she wished she could turn into the No. 099 Mobius Angel, twist time into a braid, and grab that silly girl by the throat before she could say such stupid things, shouting at her: How dare you!

How could you?

How could you pat Shang Lu on the shoulder and say, "It’s okay, I’m a bottom-tier student too"?

How could you believe his nonsense?

***

A gentle breeze stirred the calm, black surface of the Yinglong Lake Reservoir. In the center of the lake was a small sandy island, and across from it lay the abandoned Yinglong Lake Wetland Park. Thriving vegetation had almost completely engulfed all the ruins left by humanity. The bright, piercing light of the Red Lotus swept across the area; the ink-black water, the overgrown banks, and the woods entered the spotlight one by one. From Shen Jiang's perspective, she couldn't see anything unusual. If not for the report from the Riemann probes, no one would know that a lethal high-dimensional invader was hidden on the water's surface just a few hundred meters away.

"Damn it," Shen Jiang thought.

This wretched thing had actually hidden itself.

Just a moment ago, it was sweeping across the world with unchecked arrogance, but as soon as she, the Great Aunt, moved in to kill, it tucked its tail between its legs and started acting humble. Huh? Why stop being arrogant? Keep being arrogant.

That is the trickiness of the Angels; when they hide and remain silent, no one can track them.

It was a gloomy, pitch-black night. There were no moon or stars in the sky, and even the giant mecha couldn't see its own hand in front of its face.

"Have you heard that joke? A group of mice discussed how to deal with a cat. One mouse suggested setting up an early warning system by putting a bell on the cat. As long as the cat approached, the bell would ring. All the mice thought it was a great idea, but then another mouse asked: who’s going to bell the cat?" Shen Jiang stared straight ahead, rotating her wrists. "In the battlefield against the Angels, our greatest disadvantage is that we can't hang a bell around their necks."

"One-Six, No. 092 is near you," the Joint Command Center reminded. "It hasn't left this area."

"I know it's in front of me," Shen Jiang scanned the surroundings with sharp eyes. "Too bad, this ghost of a thing happens to be hovering over the lake, and there are no Riemann probes in the water. It's in our blind spot; this is a fog of war."

She had activated all observational and reconnaissance equipment, whether visible light, infrared, or other frequencies, but she couldn't find a trace of the No. 092 Lighthouse Angel. The thing had hidden itself, right there on the water's surface. It had likely shrunk its four-dimensional projection to an extremely small scale. The dust suspended in the air, or even oxygen molecules, were thousands of times larger than it. Trying to find it was like looking for a needle in a haystack.

Humans to Angels are like creatures on a piece of paper to humans. The two-dimensional creatures on the paper can only observe the shape of the human footprint on the paper. For the two-dimensional creatures, the footprint is the human's projection; when the human stands on their tiptoes, the projection area on the paper shrinks.

The No. 092 Lighthouse Angel was standing on its tiptoes, disappearing from human sight.

It was clearly a master ballet dancer; the contact area between its toes and the paper was small enough to be imperceptible.

The giant mecha remained in an attack posture, both palms open and pointed forward.

"Cave-One, I’m going in for a close-up observation," Shen Jiang said. "No matter what trickery it’s using, its mass is always there. If there's mass, I can grab it."

"Close-up observation is not advised," the Joint Command Center replied quickly. "One-Six, keep your distance, wait for the opportunity. It will move eventually."

"Play a waiting game with an Angel? They can stay here without eating or drinking for ten thousand years, while the Red Lotus might only have three minutes left. I have to find it quickly." Shen Jiang clicked her tongue. "I hope the research institutes in the rear hurry up and find a way to bell these things. I’ll personally volunteer to carry out the task, as long as we can measure the proper time flow of these bastards..."

Red Lotus took a step forward, its weapon systems retracted from standby, and its two forty-meter-long arms swept slowly through the air like a trawl net.

The giant mecha's arms were equipped with Riemann probes—sensitive detection devices. The four-meter-long arms spread out, forming a virtual net as they moved. No matter how small the Angel shrank, as long as the Riemann probes swept past it, they would catch this anomalous gravitational source.

But Red Lotus had lost its entire left arm in the previous action, which reduced Shen Jiang's search efficiency by half.

Red Lotus slowly stepped into the reservoir; the water soon reached its knees. The bottom was filled with soft silt, and every step sank deep. Red Lotus struggled to patrol along the lake shore. Yinglong Lake was a reservoir that was long from north to south and narrow from east to west. Shen Jiang maneuvered the giant mecha from the south end to the north end, then pivoted in a circle using its feet as the origin, its arms carving out a large circle with a radius of forty meters.

Shen Jiang felt a bit anxious.

Red Lotus had less than two minutes of normal operating time left.

"This stubborn thing couldn't have run off, right? Theoretically, it can move an infinite distance along the ω-axis. Who knows, it might already be tens of thousands of kilometers away from us by now."

As everyone knew, the three-coordinate orthogonal system used to describe three-dimensional space was (x, y, z), with the three axes perpendicular to each other. The four-dimensional space occupied by the Angels had a four-axis coordinate system (x, y, z, ω), with all four axes perpendicular to each other. In the eyes of an Angel, there was one extra direction in this universe. Theoretically, if it moved far enough along the ω-axis, it could completely depart from the human universe.

Assuming the No. 092 Lighthouse Angel really had run tens of thousands of kilometers along the ω-axis, humanity would have no way of determining if it had any velocity components on the other axes. If they were lucky, it was just running along the ω-axis with zero velocity on the other three, meaning the Lighthouse Angel's coordinates in the human universe would remain unchanged. It would still be in the Earth's inertial frame, and its projection would still be at 106.72° E, 29.50° N at Yinglong Lake Park. Staying here and guarding might eventually pay off, though there was no telling how many years it would take.

If they were unlucky, the thing was running wild in four-dimensional space, with velocity components on every axis. Then, no one could accurately predict its position. Perhaps the next time it returned, it would appear out of thin air in the Sichuan Basin, completely bypassing the defense line—and then all of humanity would be doomed.

However, no phenomenon of Angels appearing out of thin air had been observed so far. People believed that when all Angels moved, their velocity components and movement distance on the ω-axis were infinitely close to zero.

(This was the only reason humanity hadn't gone extinct yet.)

So some believed that Angels were actually trapped by the membrane of this universe, like a group of flies stuck on a giant piece of flypaper. Of course, that was a discussion for another time.

***

"Could it be higher up?" Shen Jiang looked up and scanned the area with optical radar. "Maybe it isn't as obedient as other Angels and doesn't listen to the atmospheric electric field..."

"One-Six, pay attention, we have a situation," the Joint Command Center suddenly warned. "Infrared signal alert."

"Yeah, I see it." Shen Jiang bit her lip and smiled.

Finally, it showed itself. It had given her quite a chase.

Several hundred meters away, above the lake, a tiny point of light glowed faintly. It hovered at the same height as Red Lotus's head, dark red in color, like a firefly.

It flickered, like a dying candle swaying in the wind.

It was hard to imagine that this was the very thing that had easily cleaved through Red Lotus's shield and body two hours ago.

"It better be a point-source mass so I can apply the Schwarzschild metric. Don't make it too complicated."

"Is there anything we can do to help, One-Six?"

"If you can calculate the Christoffel symbols for every point in the tens of millions of cubic meters of space above the lake for me, then I'll thank you."

Shen Jiang clenched her fists.

Establish basis vectors.

Calculate principal curvatures.

Calculate Gaussian curvature.

Measure precession with the gravity gyroscope.

The complex and massive calculation results flowed down like a waterfall from above her head, running along the spherical cockpit to her feet. The calculation core inside Red Lotus's head was constructing model functions according to the girl's logic. Shen Jiang controlled the calculation paths and function models on the cockpit walls with her eyes; one thought was enough to delete, reject, or increase the weight—Reject! Reject! Reject! Reject! Reject, reject, reject, reject, reject, reject!

The data appearing before the pilot was only one-billionth of what the supercomputer was processing. This was the world's most powerful computing tool, solving the world's most complex problem.

"Take it out before this thing expands. Strike while it’s sick and finish it off. Weapon systems self-check, ready."

Shen Jiang maneuvered Red Lotus to take a step forward, but at that moment, a red warning popped up.

She froze.

"Damn it."

"One-Six, what's the situation?"

"Countdown hit zero, lower limb joints severely damaged, locked up." Shen Jiang looked up. "I can't move anymore."

She stared at the flickering No. 092 Lighthouse Angel hundreds of meters away. Its faint red light suddenly intensified, becoming piercing and sharp. The Joint Command Center was shouting in the channel about Riemann probe alerts. Shen Jiang licked her lips, sweat beading on her forehead: "Damn it, these 151 guys are such jinxes. Why are their other countdowns never this accurate?"