As soon as Wang Ning finished speaking, the 725 amateur radio station on the coffee table began radiating electromagnetic signals. It converted images into sound, then hid those sounds within radio waves that human ears couldn’t detect—whispers incomprehensible to humans, yet mysteriously containing an image. Converting images to sound might seem unimaginable to ordinary people, but for those who had mastered information encoding technology, information was information and carriers were carriers. Once you understood the essence of information, separating it from its carrier wasn’t particularly difficult.

From tens of thousands of years ago when humans first carved cave paintings with chisels, images served as carriers of visual information. They evolved from rock walls to clay tablets, to canvas, to paper, to photographic film, weathering countless years. The relationship between image and medium seemed eternal and unchanging—until the fires of the Industrial Revolution ignited. Information theory brought about a revolution in understanding. People could finally lift image data from two-dimensional planes and stuff it into sound, into electrical current, into light waves. From then on, any information could be broken down and compressed into any carrier.

Understanding the essence of information was, in a sense, a divine power.

By mastering information, humanity had taken another step toward divinity.

Bai Zhen sat watch before his laptop screen as the photo slowly scanned in from top to bottom. What did this feel like? Like scratching off a lottery ticket, scraping away strip by strip to reveal the image underneath.

At first, the signal reception was poor, showing only green snow static. Bai Zhen slightly adjusted the antenna direction before he could receive a clearer photo.

“How’s it going?” Wang Ning asked.

“Not bad,” Bai Zhen replied, “just a bit slow.”

A half-body photo of a Uganda black chimp—no, a baboon—was 15KB in size. The current transmission speed between the 725 and 705 radios in the living room experiment was only about 1000bps, or 0.1KB per second. Under ideal conditions, successfully transmitting such a photo would take 150 seconds—two and a half minutes.

But when were conditions ever ideal?

Radio was radio, after all, not cable or fiber optic. Using radio waves to transmit signals was convenient and simple, but you couldn’t expect it to be highly efficient. Among convenience, simplicity, and efficiency, you could only have two at once.

So amateur radio image transmission was unstable. In network engineering terms, there was severe packet loss. If the antenna wasn’t aligned perfectly, you’d get a strip of green snow static. Getting a complete, clear image in one transmission was impossible.

To ensure complete signal transmission, Wang Ning’s end would broadcast multiple redundant signals. His 725 would continuously cycle through sending the image in 150-second intervals until Bai Zhen could receive a complete picture. So to Bai Zhen, it was like repeatedly scratching lottery tickets on his Lenovo computer—getting his complete photo would be hitting the jackpot.

“Wait… there’s interference. Where’s it coming from?” Bai Zhen scratched his head, looking around. “Is it the switch? Hold on, Wang, let me try cutting the power.”

He immediately ran to flip the circuit breaker. When he cut the power, the room went completely dark.

“Power’s out?” Mom came out of the bedroom with her phone flashlight. “Why did it suddenly go dark?”

“Old Bai cut the power,” Wang Ning sat on the sofa, his chubby face lit by the CRT monitor’s green glow. “We’re doing an image transmission experiment.”

“Why cut the power just to experiment?” Mom asked.

“Interference,” Wang Ning answered.

The annoying electromagnetic interference of modern society was everywhere—the construction crane next door, the security guard’s intercom at the complex entrance, electric vehicles downstairs, and many inconspicuous small appliances in daily life, like household power switches. It was everywhere, surround-sound interference impossible to avoid. Bai Zhen could only cut his own home’s power—he couldn’t cut the neighbors’ power, much less the entire Meihua Mountain Villa complex. This was how the city’s electromagnetic environment had deteriorated.

Some old HAMs liked field operations… ah no, field setups, precisely for the clean, unobstructed environment. With good signal-to-noise ratios, they could hear a fly rubbing its hands on the other end of the radio waves.

After cutting power, Bai Zhen tried receiving the signal again.

“Any better?” Wang Ning asked.

“Nope!” Bai Zhen said, “Same crap.”

“Go find the complex’s main breaker,” Wang Ning said. “Cut power to the whole complex, that’ll fix the interference.”

“You want property management to skin me alive?”

“Hey, special circumstances call for special measures. Just tell them it’s an emergency power requisition—Unit 01 is using a positron cannon against the Fifth Angel on Purple Mountain. If we don’t get power, Rei will die.”

Bai Yang sat in the darkness wearing a hoodie, a radio powered by a battery, desk lamp. The warm light pushed back the night into a small circle encompassing the desk, pencil holder, radio, and the youth’s face. He held the hand mic in one hand and a pen in the other, focusing intently as he wrote rapidly.

“Hm? No problem, just the lights went out. My dad and they cut the power,” Bai Yang pressed the PTT to speak. “They’re doing an image transmission experiment. Miss, let’s continue… Do you know Newton? Newton’s Law of Universal Gravitation, OVER.”

“Newton?” came the confused reply from the other end. “What’s Newton?”

“He was a person, English, a great physicist,” Bai Yang explained. “The F=G·(m1m2/r^2) your teacher wrote in the draft is the universal gravitation formula. Here F is gravitational force, G is the gravitational constant, the two m’s are the masses of celestial bodies, and r is distance. It means the gravitational force between two celestial bodies is directly proportional to the product of their masses and inversely proportional to the square of the distance between them, OVER.”

“Oh…”

The girl nodded, half-understanding.

Like a monk chanting sutras while she rang the bell—no need to understand, just nod along.

“I deduce your teacher was studying the relationship between Black Moon and Earth at the time, which is why he wrote these numbers and formulas on the draft paper,” Bai Yang said. “You just couldn’t understand them then, OVER.”

“I don’t understand them now either.”

“It doesn’t matter if you don’t understand—I can understand!” Bai Yang said confidently.

Bai Yang’s confidence and assurance had a reason. He was a high school senior about to take the college entrance exam.

He was currently at the stage of his life where his knowledge was most extensive, his thinking ability strongest, and his understanding spanning astronomy, geography, history, and politics.

“Let’s organize this data, Miss. Would you believe that just from this 1,200-kilometer figure, I can deduce Black Moon’s full picture?” Bai Yang said, “OVER.”

The girl paused, “Really?”

“Really,” Bai Yang nodded. “Miss, let’s first look at 1,200 kilometers, this number your teacher wrote on the Journey to the West draft. We think it’s Black Moon’s diameter, right?”

Ban Xia nodded.

This page of the Journey to the West draft had two numbers and two circles. The numbers were 1,200 and 3,476, marked beside the two circles. When interpreting this draft, Ban Xia and Bai Yang reached a consensus that these circles represented the White Moon and Black Moon, with 3,476 being the White Moon’s diameter and 1,200 being the Black Moon’s diameter.

“Do Black Moon and White Moon appear the same size to you?” Bai Yang continued asking, “Is that right, Miss? OVER.”

“Yes, they look the same size,” Ban Xia nodded.

“Then I can know how far Black Moon is from you…”

Bai Yang opened his calculator and quickly worked out calculations on paper.

He’d never been so diligent in his life, still doing math and physics even with the power cut. His mom said if he studied this hard normally, he wouldn’t need to kowtow from Purple Mountain to Xuanwu Lake to get into Nanjing University.

“Moon radius 1,737 kilometers.”

“Earth-Moon distance 380,000 kilometers.”

“Tangent should be 0.0045718…”

Half a minute later, Bai Yang had his answer.

“Miss, Black Moon is approximately 131,239 kilometers from you, OVER.”

Ban Xia was startled.

“How did you know that?”

“Angular size, Miss, simple calculation. White Moon and Black Moon appear the same size to you, so they have the same angular size when you look at them,” Bai Yang explained. “White Moon is 380,000 kilometers away with a 3,476-kilometer diameter. So with Black Moon’s 1,200-kilometer diameter, using trigonometry, it should be 130,000 kilometers from you, OVER.”

“That’s amazing.”

Ban Xia didn’t understand, but she thought it was amazing.

“Let’s continue calculating. Now that we know the Black Moon’s distance from Earth’s surface, we can calculate its orbital period—how long it takes to orbit Earth,” Bai Yang said rather proudly. Being praised by a beautiful girl was far more gratifying than compliments from his balding physics teacher. He wrote down formulas on his scratch paper, pressing forward with calculations, “Adding Earth’s radius, r should be 137,610 kilometers, G is the gravitational constant, we’ll use 6.67×10^(-11) Nm^2/kg… the formula T=√(4π^2r^3/GM), so T should be…”

Bai Yang held the hand mic, calculating and muttering simultaneously. The night room was silent except for the girl twenty years in the future listening intently.

Numbers and formulas flowed from the youth’s pen tip, streaming into rivers across the white paper surface.

In Bai Yang’s eighteen years of life and five years studying physics, these dragon-slaying skills that could “reach to heaven and seize the moon, or dive to the depths to catch leviathans” were being put to practical use for the first time.

Only in using them did Bai Yang realize what powerful tools he had mastered. These were the laws governing the universe’s operation, the base code of Universe Online. Every high school student had once built the grand edifice of classical physics in their mind, but few ever truly applied it, letting it weather and collapse with time.

“16 days!”

“Miss, Black Moon’s orbital period is 16 days. It orbits Earth once every sixteen days, OVER.”

“Incredible! How amazing, BG4MXH, how did you do that?”

Ban Xia could hardly believe it. She thought BG4MXH was performing magic.

He had never seen Black Moon—how could he know how long it took to complete an orbit?

“I didn’t do this alone—I stand on the shoulders of Newton, Kepler, and all the physicists in human history,” Bai Yang said. “And my physics teacher, who taught me the highest wisdom contained in all history’s most brilliant minds.”

“Then your physics teacher must be amazing!”

“I thank you on behalf of our physics teacher, Miss. Your teacher must have calculated all this back then too,” Bai Yang said. “Let’s continue. Now we know the Black Moon is 130,000 kilometers away, but I don’t understand—why does it orbit at 130,000 kilometers from Earth? OVER.”

Ban Xia froze, not understanding what this question meant.

Why orbit at 130,000 kilometers from Earth?

If Black Moon wanted to stay there, wasn’t that its freedom?

How could she possibly know why?

“Miss, Big Eye came from Black Moon, right? So why doesn’t Black Moon come closer to make it easier for Big Eye to descend?” Bai Yang raised a question Ban Xia had never considered. “130,000 kilometers—that’s no short distance. It would take quite a while to fly. Why not come closer? OVER.”

“Hmm… maybe there’s some special reason?” the girl pondered.

“Every phenomenon has a reason behind it,” Bai Yang said. “Miss, let’s consider this—maybe it can’t come closer because it can’t come closer. Maybe it stays in orbit 130,000 kilometers away because that’s as close as it can get, OVER.”

“Why?” Ban Xia asked. “Why can it only stay there?”

“Because a force restricts it,” Bai Yang answered. “A force that no one can resist restricts it, OVER.”

“What force?”

“Gravity, Miss, universal gravitation,” Bai Yang said. “The one force in this universe that can’t be unified or controlled. It restricts the Black Moon. If the Black Moon came too close, Earth’s enormous gravitational force would tear it to pieces. 130,000 kilometers is its safety zone—it can’t cross this red line. Those who cross this boundary will be shattered… This red line is called the Roche limit, OVER.”

“Assuming 130,000 kilometers is Earth and Black Moon’s Roche limit, we can work backward to find Black Moon’s density… Let me find the Roche limit formula! There’s fluid Roche limit and rigid body Roche limit…” Bai Yang frantically searched Baidu on his phone, pulling out a blank scratch paper. “I found it! I found it! Let me calculate—the formula is d=2.423R(ρ1/ρ2)^(1/3), Earth’s average density is 5507.85kg/m^3… So under fluid Roche limit Black Moon’s average density is 7.83kg/m^3, under rigid body Roche limit the average density is 1.09kg/m^3.”

“Miss, Black Moon’s average density is between 1.09kg/m^3 and 7.83kg/m^3.”

Ban Xia was somewhat dazed, not understanding what these numbers meant.

What did this density mean in practical terms?

The air we breathe daily has a density of 1.3kg/m^3. Nitrogen’s density is 1.26kg/m^3, oxygens are 1.46kg/m^3, and the densest gas, radon, is 9.73kg/m^3—meaning Black Moon’s maximum density wasn’t even as high as radon.

“What does this mean?” Ban Xia asked.

“It means either Black Moon is a gas satellite, actually just a mass of gas,” Bai Yang paused. “Or it has enormous internal cavities—it’s hollow.”