September 30th, the tritium tubes finally arrived.

After school, Bai Yang went straight to the Cainiao pickup station, retrieved the tritium tubes, and brought them home. They came in a small brown box containing white foam and packaging paper. Each tritium tube was only about two centimeters long, a delicate glass product, very fragile, emitting an ethereal green glow in the darkness.

All four tritium tubes had similar brightness. In a pitch-dark room, placing a tube on a textbook, you could see the text around it. One seemed slightly dimmer, though it might have been psychological – that was indeed the longest-used tube.

Bai Yang arranged the four tubes in sequence on the desk, then took down a small wooden photo frame from the bookshelf. The frame contained a tiny “Sunflowers” – a miniature photocopy of a knockoff of a reproduction of Van Gogh’s original.

Next, he dismantled the frame, removed the acrylic glass and the picture inside, and then used UV glue to attach the tritium tubes in predetermined order clockwise on the frame’s inner side, one tube per edge. After gluing, he exposed them to UV light to ensure they were firmly attached and wouldn’t fall off.

Finally, he replaced “Sunflowers” with “Hatsune Miku at Stalingrad,” carefully reassembled everything, and sealed the frame.

Turning off the room lights, Bai Yang could see the frame propped on the desk, the tritium tubes perfectly illuminating Hatsune Miku.

Mission accomplished.

Unless he told them, nobody would know this was a time indicator – they’d just think it was a picture.

Bai Yang packed the frame into the time capsule, stuffed pearl foam into the remaining spaces, and then used the wrench to tighten all the bolts. He shook it vigorously to ensure nothing would rattle violently inside.

At this point, Bai Yang’s time-slow delivery was completely ready.

All preparations were complete, now they just needed the right moment.

Earlier that evening while returning from picking up the package, Bai Yang had already done precise location scouting, finding four suitable backup spots for burying the time capsule.

Bai Yang let out a long breath and flopped onto his bed.

He chuckled – having completed such a major project, didn’t he deserve to praise himself a bit?

Awesome!

Awesome!

Niubility!

Bai Yang pulled out his phone to check the time – it was eleven-thirty PM. His planned operation time was 2 AM, so he set an alarm for then. The time capsule and shovel were under his bed, packed in a backpack… When the time came, he’d shoulder the pack and quietly go downstairs, dig a deep hole in the dead of night, and bury the time capsule. Bai Yang named this plan “Operation Community Garden,” with the key points being stealth! Stealth! And fucking stealth!

If he got caught by the community security guards, his reputation would be ruined for life.

He’d contact BG4MSR shortly to let her know he was burying the capsule tonight.

If she was willing to wait, she could wait until he finished burying it and came back to notify her. Bai Yang estimated he’d be done around 3 AM. If she didn’t want to stay up that late, he could tell her the exact location during tomorrow’s contact.

Bai Yang lay on his bed, watching his phone screen as time ticked away minute by second, getting closer and closer to 2 AM.

The youth’s leg dangled down, swaying gently beside the black backpack.

The backpack was bulging, its zipper not fully closed, with a shovel handle sticking out.

[Interview Excerpt – The Difficult Time-Slow Delivery:

Why is it called time-slow delivery rather than time-fast delivery?

The fast delivery means that after a package is sent out, its transport speed must be faster than you. If you have a package going from Hangzhou to Shanghai, delivered through major courier services or China Post within two days, that’s fast delivery.

But if you carry the package, walking step by step along the highway to your destination, arriving at the same time as the goods, that’s not fast delivery.

While spatial movement can be accelerated, temporal movement cannot.

When Bai Yang dug a deep hole in the lawn and placed the time capsule inside, filling it with soil, the capsule’s time flow rate wasn’t any different from his. There was no time tunnel in the hole leading directly to twenty years later. On the timeline, Bai Yang and the capsule moved at the same speed.

They advanced synchronously – tomorrow when Bai Yang checked, the capsule would still be there; next year it would still be there; ten years later it would remain there.

It didn’t move faster than you. To send it twenty years into the future, you had to spend twenty years.

Waiting for it to reach its destination would take an eternity.

Looking at the whole event from start to finish, for Bai Yang, the first-time-slow delivery was undoubtedly the most difficult. Being completely unfamiliar with the rules and mechanisms, like a blind man touching an elephant, he did much unnecessary work – although Bai Yang thought himself quite meticulous at the time, having considered all factors he could think of and avoided all possible interference, he still ultimately failed.

The other party found nothing.

He didn’t understand why. The only explanation before him at the time was that Ban Xia was lying, so after the first time capsule delivery failed, Bai Yang’s suspicion of Ban Xia reached its peak.

So what were you thinking then?

I asked.

Was the girl lying? Playing tricks on you?

The young man sitting opposite me pondered for a few seconds, then turned his head toward the window. I couldn’t see his eyes, only saw him nod:

That was my first reaction.

In the second half of 2020, during the October National Day holiday, the author first visited the person involved. By then, half a year had passed since everything ended.

Building 11 of Meihua Villa was an old building, eight stories tall without an elevator. Entering through the unit door, you could see rusty mailboxes on the wall and an old road bicycle parked against it. Climbing the stairs step by step, the eighth floor was at the top, with clotheslines strung in the corridor holding wet clothes.

I knocked on the iron door of unit 804, and a young man opened it – by then he was already a university student, wearing a simple black short-sleeve shirt, hair slightly disheveled, wearing slippers. The moment I saw him, I knew he was the person I was looking for, as this young man matched perfectly with the Bai Yang I had imagined. But he stared at me doubtfully for a while, perhaps wondering if this travel-worn man before him was indeed the writer who had chatted with him at length on WeChat last night.

Bai Yang led the author into his room, saying he was alone at home as his parents had left him to go traveling.

The room served as both study and bedroom, not very spacious – just enough room for two people to turn around.

The author’s attention was quickly drawn to a black behemoth on the bookshelf that looked like some kind of large radio.

Is that…

I asked.

The author had never seen the meritorious amateur radio that might have saved the world and couldn’t help being curious.

Ah, that’s not the 725.

Bai Yang smiled.

That’s the ICR8600, given to me by the Radio Commission. The 725 was taken by Nanjing University people for research.

When the interview touched on the first time-slow delivery, Bai Yang thought for a long while before posing a question to the author:

Teacher Tian Rui, what do you imagine time-slow delivery to be like?

I was taken aback.

What is time-slow delivery like? Probably dig a hole in the ground, bury something for twenty years, then have the other party dig it up?

Is it that simple? Bai Yang asked.

How complicated could it be? Isn’t it just that simple?

Well, Teacher Tian Rui, let’s consider a scenario, Bai Yang said. Suppose you live twenty years in the future, and I want to send you something. Right now I have an idea to bury the time capsule downstairs tonight, but before I bury it, I use the radio to tell you to go dig it up. Do you think you could find it?

I furrowed my brow, thinking carefully.

“Teacher Tian Rui, do you have this idea: for people twenty years in the future, what’s happening now is already history, so even though the capsule hasn’t been buried in this era, from the future person’s perspective it’s already been buried for twenty years?”

Bai Yang smiled.

I was taken aback, then nodded.

“That’s impossible because you simply can’t dig it up,” Bai Yang said. “I spent a long time exploring and experimenting, and summarized the first rule – what I call the First Law of Time-Slow Delivery: ‘The first prerequisite for successful time-slow delivery is that the sender must know the definite information about the package’s location, or in other words, the package’s state must be definite, including both spatial and temporal coordinates.'”

“On an operational level, this means the sender must bury the capsule before the prerequisites for time-slow delivery are met,” Bai Yang said. “Before it’s buried, its state is uncertain, and as long as uncertainty exists, time-slow delivery will likely fail.”

After saying this, Bai Yang added a summary:

“In short, attempting delivery before the capsule is buried is a non-starter, an automatic disqualification. Like in the example I just gave – even though I plan to bury the capsule tonight, there are ten thousand reasons that could delay it before I act, like changing my mind, or falling down the stairs and unfortunately breaking a bone.”

The author digested these words for a moment, then realized something:

“In your first time-slow delivery, you notified Ban Xia after burying the capsule, completely satisfying the conditions. Why did it still fail?”

Bai Yang let out a light sigh and posed another question:

“Teacher Tian Rui, imagine another scenario: you’re still living twenty years in the future, while I’m in the present. You use the radio to talk to me, telling me to bury the capsule somewhere, then you go dig it up… could you find it?”

He didn’t leave time for the author to interject, continuing directly: “If you could dig it up, wouldn’t there be a paradox here? Look, Teacher Tian Rui – you live in the future, I live in the present. Your request is the cause, my burying the capsule is the effect. How can the cause occur after the effect? Wouldn’t that reverse causality?”

The author was now completely immersed in thought.

Bai Yang pushed the question in an even more absurd direction:

“Teacher Tian Rui, what if you dig a hole in an outdoor lawn, then use the radio to tell me to bury a capsule in the same spot – what would happen?”

“Would a capsule suddenly appear in the previously empty hole?”

The author grew increasingly astonished.

The question was indeed absurd, yet difficult to explain.

If I lived twenty years in the future, facing a white wall, and used the radio to traverse time telling Bai Yang to paint a picture on the same wall, what changes would occur to the white wall before my eyes?

Would a painting suddenly appear?

I shook my head, indicating I couldn’t figure it out, couldn’t explain it.

I could only wait for Bai Yang’s revelation.

“No need to explain,” Bai Yang revealed. “Because none of this would happen. There would be no paradox. You live twenty years later, use the radio to tell me to bury the capsule, but you won’t dig it up. You dig a hole and tell me to bury the capsule in the same location, that hole won’t change at all, it will still be empty.”

“So you’re saying if I live twenty years in the future, see a white wall, and use the radio to tell you to paint on that same wall, the wall I see still won’t show any changes?” I asked.

“Yes, it would still be a white wall,” Bai Yang nodded. “Nothing as bizarre as a painting suddenly appearing out of nowhere would happen.”

“Why is that?”

The author was quite puzzled.

No paradox – that made it slightly easier to understand, but why wouldn’t the wall show any changes? Where did the painting from twenty years ago go?

“The reason for this question, and the reason my first time-slow delivery failed, are the same.” Bai Yang sighed, suddenly becoming serious, and said to the author in a very solemn tone:

“Because it violates the Second Law of Time-Slow Delivery.”]

That night, Ban Xia stayed up with the radio until 3 AM. She wouldn’t go to sleep – at such a crucial moment, how could she sleep?

She didn’t want to wait a single moment.

The girl lay on the desk wearing headphones, listening to the faint electrical noise, like sitting by the seaside listening to endless waves. In that boundless sea of electromagnetic waves, Ban Xia stood on tiptoe looking out, hoping to see a ship’s mast appear on the horizon, bringing an important message.

After waiting for who knows how long, when that familiar voice finally came through the channel, Ban Xia suddenly became energized.

The other party was breathing heavily and got straight to the point, reporting the location:

“At the west end of the community square corridor, under the center tile!”

Ban Xia took off her headphones and ran out frantically.

At 3 AM, she brought a shovel and knife, diving into person-high grass. Meihua Villa’s community square was unrecognizable from its original state, the corridor Bai Yang mentioned submerged in wild grass. The teacher had warned her not to go in because there were snakes, including kraits, but Ban Xia couldn’t care less – her mind was completely focused on that tile.

Bai Yang’s location was accurate enough; Ban Xia quickly found that tile. Using the knife blade to probe the tile’s gaps, she found it was indeed loose.

She was immediately excited.

The girl forcefully pried up the tile, then swung the shovel to dig, getting more excited as she dug. What would it be?

Food?

But I don’t lack food.

Drinks?

Drinks probably wouldn’t preserve well for too long.

Medicine?

Pain medication would be good, give me lots of pain medication.

Ban Xia excitedly muttered to herself while digging forcefully, wielding the shovel like wind, but as she dug she realized something was wrong.

She had dug quite deep, but there was nothing.

Where was it?

Had she gotten the location wrong? Or had he remembered the location wrong?

Ban Xia started digging up the surrounding tiles.

Prying up the second adjacent tile, digging breathlessly to knee depth, she found nothing but stones.

Then the third tile.

The fourth.

Ban Xia pried up the corridor’s tiles one by one, then used the shovel to dig deep.

Nothing.

Nothing.

Nothing.

All nothing.

Why was there nothing?

That night Ban Xia frantically dug up half the corridor’s tiles, getting covered in mud, in complete disarray, her fingers bleeding, ultimately finding nothing.

She leaned exhaustedly against a corridor pillar, watching a ray of dawn rising between the high-rises, her gaze blank and desperate.