That night, the three men tinkered with two spectrum analyzers until eleven, achieving nothing useful even as Mom finally lost her temper.

BG4MSR’s mysterious signal remained elusive. Though the signal in the IC-725’s headphones was as clear as a girl whispering in one’s ear, the analyzers in the living room remained stubbornly blind. Wang Ning repeatedly slapped the table, saying Old Bai must be playing tricks on him. This had to be Old Bai’s carefully designed scheme – he’d served as a communications technician in the military for over a decade, wasn’t he an encryption expert?

“You three old poles, are you ever going to finish? Do you know what time it is? Yang has class tomorrow morning!”

Mom issued the order to leave.

“Whatever else can wait until tomorrow!”

To Mom, anyone who dared interfere with Bai Yang’s studies and future deserved death. She’d kill whoever stood in the way – Bai Zhen, Wang Ning, and Zhao Bowen combined weren’t worth a thing.

Everyone knew Little Wen’s temper. In her younger days, she could make Bai Zhen kneel on the washboard. So Wang Ning and Zhao Bowen got up to leave, with Bai Zhen seeing them downstairs.

The spectrum analyzers would stay at Old Bai’s place for now – Wang Ning couldn’t carry them back alone anyway.

“What do you make of this?” Bai Zhen asked as they walked downstairs. “My son told me that girl lives twenty years in the future. In her era, she’s the only one left, everyone in the world is dead, with water buffalo and deer wandering freely in the streets.”

“Some days ago, Yang Yang came to my office asking about this. I thought he was writing science fiction,” Zhao Bowen said. “Never expected there’d be such a thing. It’s incredible to think about – what kind of disaster could make humanity extinct in just twenty years?”

“If you’re asking whether I believe it, I don’t,” Wang Ning shook his head. “This isn’t a movie.”

“But we can’t explain why we can’t catch BG4MSR’s signal while Yang Yang’s IC-725 can connect,” Zhao Bowen said.

“There are many possible reasons why we can’t catch the signal. Time travel is the most far-fetched one,” Wang Ning said. “I’m telling you it’s Old Bai’s setup. He found someone to help, hiding somewhere sending spread spectrum signals, all coordinating to put on a show. Just spread a normal signal into ultra-wideband, and it sounds exactly like background noise – even ghosts couldn’t tell the difference… Old Bai, am I right? How about tomorrow when we come back, we open up the IC-725 and take a look?”

“Your IC-725 can decode spread spectrum signals?” Bai Zhen countered. “Why would I go through all this trouble just to fool you? What benefit would I get from fooling you?”

“Then it’s your son fooling us – Little Yang’s setup.”

“If he had that ability, then we three have wasted all our years living as dogs,” Bai Zhen said. “He’d need to manually DIY, modify an amateur radio into military grade. Do you think that’s possible?”

“Based on this signal alone, I don’t believe BG4MSR lives twenty years in the future,” Wang Ning insisted.

“But he verified it,” Bai Zhen said.

“How did he verify?” Zhao Bowen asked. “The time capsule? The one mentioned before?”

“Yes, the time capsule,” Bai Zhen answered. “Bury the time capsule, then wait twenty years for the other side to dig it up.”

“How do you prevent faking?” Wang Ning asked.

“Tritium tubes.”

“Half-life?” Zhao Bowen immediately grasped the key point.

“Yes, using half-life to verify time,” Bai Zhen nodded. “When the other side dug up the time capsule, the tritium tubes were almost dark.”

Zhao Bowen and Wang Ning fell silent.

The half-life of radioactive elements cannot be accelerated – this was ironclad evidence.

Both thought simultaneously about how clever Little Bai was. If he had used other verification methods, they could find loopholes, but the tritium tube evidence was too solid, and unshakeable.

Just like antique dealers who exhaust every method to artificially age fake artifacts, inevitably exposed when faced with carbon-14 dating.

Zhao Bowen and Wang Ning could swing their 40-meter Occam’s Razor, slashing the unreliable time travel inference to pieces, but among those seemingly chaotic clues and speculations, Bai Yang had secretly buried a hard bone – this hard bone was the tritium tube. When Occam’s Razor hit the tritium tube, it immediately dulled and chipped, shocking both men’s hands numb.

The three reached the first floor, and Zhao Bowen and Wang Ning told Bai Zhen not to see them further.

“Hey, Old Wang, Old Zhao,” Bai Zhen called to their backs. “If this is real, what then?”

“Then I better hurry and withdraw my housing fund, stop paying pension insurance too,” Wang Ning said. “Twenty years later I’ll have just retired, won’t even get to enjoy one good day before the world ends.”

Zhao Bowen scratched his head, looked around, and muttered: “If this is real, then we’ve got big trouble… From every angle, every meaning, big trouble.”

“BG4MSR, BG4MSR, let’s stop here for tonight. Uncle Zhao and Uncle Wang have left. We’ve been at it all evening with no results, and I have class tomorrow,” Bai Yang prepared to end the contact and get ready for bed. “Have to wake up at 6:30, first period is terrible English class, OVER.”

“They didn’t find anything?”

“The only discovery is that only I can receive your signal – nobody else can,” Bai Yang answered. “Uncle Wang is the Radio Commission director. Tonight he even called other HAMs who weren’t asleep yet, and had them try monitoring 14255, but they couldn’t hear anything either, OVER.”

“Why is it like this?”

“I don’t know either,” Bai Yang shook his head. “They’re still looking for the reason, OVER.”

“Hmm… will you come back tomorrow night?” the girl asked.

“Of course,” Bai Yang said. “But tomorrow I have evening self-study, so it’ll be a bit later than tonight. You can wait for me on 14255, OVER.”

“BG4MXH, what’s evening self-study?”

“Evening self-study is when you have to stay at school doing homework even after afternoon classes end, all the way until 10 PM. It’s a great psychological trauma inflicted on young people, OVER.”

“BG4MXH, is this also part of school?”

“Yes, BG4MSR, this is also part of the school, a harsh trial that every child in this era must experience while growing up,” Bai Yang said. “Countless people have fallen during this process. Just imagine, an innocent, naive young person, having seven or eight teachers assign homework every night! How inhumane, how unbearably painful – this is purgatory, this is a slaughterhouse! OVER.”

“Seven or eight teachers! You have seven or eight teachers!”

The girl’s tone was envious.

“Is that the point? BG4MSR, the point is purgatory! Slaughterhouse!”

Slaughterhouse?

The girl became frightened again.

“Does everyone have to go to school?”

“Everyone must go to school. It’s called compulsory education, OVER.”

“What do they teach in school?” the girl asked. “Do they also teach archery, shooting, and wilderness survival? A teacher once told me that before the Black Moon came, schools taught combat, restraining techniques, wrestling, and shooting. They even had tests. BG4MXH, in your monthly exam you mentioned, did you test combat and shooting?”

Bai Yang wondered which school her teacher graduated from.

Are we really in the same world?

“Our exams… test Chinese, math, English, plus physics, chemistry, biology,” Bai Yang said. “Everyone sits in classrooms, answers with pens, then gets ranked by scores. You probably can’t understand – thousands of students fighting until their heads bleed for a score ranking. Everyone studies desperately, desperately studies, all for that tiny number on the test paper. One number bigger than heaven, one number deciding your fate. You definitely can’t imagine it, OVER.”

“Thousands of students, so many people, isn’t that wonderful?”

The girl’s tone was envious again.

“Is that the point? The point scores! Fighting until heads bleed for scores!”

Fighting until heads bleed?

The girl continued to be frightened.

“BG4MSR, in exams, mentally normal people don’t want too many competitors, so fewer people is better, OVER.”

“No, more people is better, OVER.”

“Why?” Bai Yang asked.

“No reason, just more people is better,” Ban Xia said. “There should be millions of people, tens of millions of people. This world should be full of people, that would be good, OVER.”

Bai Yang scratched his head.

“BG4MSR, I should go to sleep,” Bai Yang yawned, looking at the alarm clock. “Oh no… it’s 11:30, why do I always lose track of time chatting with you? I need to sleep, sister. You don’t have school but I do. Good night, 73.”

“You’ll come back tomorrow night?”

“I will, OVER.”

“Promise?”

“Promise!”

Ban Xia put down her headphones.

She spread out the old letter paper on the desk again, staring blankly at the writing on it. How strange, how incomprehensible… The person she just talked to was a living, breathing young man, who could laugh and play and breathe, so full of vitality and life force. But why, when she took off the headphones, did he immediately become someone who died long ago?