That evening, the time capsule he ordered from Taobao arrived.

A brown cardboard box cushioned with white pearl foam. When opened, it looked similar to a thermos flask liner – cylindrical with a shiny stainless steel exterior, but much more robust. It measured twenty centimeters in length with a diameter of about eight or nine centimeters, standing about as tall as a mineral water bottle when upright. Both ends had caps secured by eight bolts each.

The time capsule came with two wrenches and a shovel – a complete set of equipment that had arranged everything for you from sealing the coffin to nailing it shut to burial.

After removing all the bolts from one side with the wrench and taking off the cap, you could see rubber sealing rings pressed against the cap rim and an empty interior. The time capsule had a volume of only 0.6 liters – Bai Yang could fit his clenched fist inside, reaching up to mid-forearm.

This was the smallest size time capsule. The next size-up cost over eighty yuan and the largest was over two hundred. Bai Yang was too poor to afford those.

Could this thing stay buried underground for twenty years?

Bai Yang gently tapped the time capsule’s exterior. The smooth stainless steel reflected the light. He tried squeezing it harder but couldn’t dent it. Pretty solid.

Not like a soda can.

He suspected it was just made from a section of thick seamless steel pipe – cut a ten-centimeter diameter stainless steel pipe into segments, each segment becoming a time capsule just by adding caps on both ends secured with bolts. Very simple structure, with no fancy technology involved.

Damn, selling this thing for sixty-eight yuan – that’s easy money.

Bai Yang thought if he couldn’t find a job in the future, he’d sell time capsules on Taobao.

Starting from today, counting forward twenty-one years would be the era of BG4MSR – if she lived in that era. According to the girl, Earth would face an extinction-level catastrophe during these twenty years, wiping out all of humanity. Bai Yang found it hard to imagine what kind of disaster could destroy human civilization. The Great Flood from the Bible? Even an asteroid impact shouldn’t be that thorough.

He weighed the slightly heavy stainless steel capsule in his hand, unsure if it could survive. The capsule manufacturer probably designed it just as a commemorative novelty item, never imagining it would shoulder the great responsibility of protecting human civilization’s relics against a world-ending super disaster.

But this was the best equipment Bai Yang could get his hands on.

What should he put in this capsule?

Due to the limited volume, he couldn’t fit much inside – besides the tritium tube serving as a time indicator, Bai Yang hoped to include some useful items.

He sat in his chair, looking around the room.

Food?

Such a small capsule couldn’t hold more than a few compressed biscuits, at most two cup noodles – couldn’t even fit one Master Kong Pickled Cabbage Beef Noodle.

Drinks?

Even more impossible. Liquids were hard to preserve, and if they leaked the whole capsule would be ruined. Besides, she wasn’t short on water. Bai Yang shook his head.

What about medicine? The apocalyptic world probably lacked medicine.

“Mom! Where do we keep the medicine?” Bai Yang put on his slippers, opened his door stepped onto the wooden floor, and called out to the living room.

“Under your bed.” Mom was watching TV on the sofa. “What do you need medicine for?”

“Just checking.”

Bai Yang pulled out a plastic basket from under his bed containing the family’s regular medicines: Tiger Balm, Fengyoujing, dexamethasone cream, along with norfloxacin, cefixime, ibuprofen, and amoxicillin. He packed the medicines into a plastic bag and stuffed them into the time capsule. Perfect fit.

Alright, he’d send her some medicine.

Let her taste some bitterness.

Bai Yang was satisfied. Modern pharmaceutical industry products were quite stable. Although the instructions stated twelve or thirty-six-month expiration dates, they could last many years if kept away from light, water, and high temperatures. They should still be usable after twenty years.

Besides the time indicator and medicine, what else?

Bai Yang looked at the remaining space in the time capsule, then pulled out a fruit hard candy of unknown age from his desk drawer and tossed it in.

He’d send one candy too.

Can’t just give bitterness, need to give some sweetness too.

Finally, for a sense of ceremony, he should write a letter.

So Bai Yang took out a white piece of paper, uncapped his pen, hesitated for a few seconds, then began writing:

“Dear Miss BG4MSR:

By the time you read this letter, I will be dead.”

It sounded like a hero’s final words to family and friends before sacrificing himself to save the world in a movie – somewhat grandiose, unexpectedly impactful.

Of course, according to the girl’s words, he would indeed be dead in twenty years, with only one person left in the whole world.

“This is a letter from the deceased, crossing twenty years of endless time to reach your hands. As I write this letter, you may not yet be born, and by the time you receive it, I will no longer be in this world.

What is a world with just one person like? A Fuzimiao, Xinjiekou, Nanhang Affiliated Middle School, and Yueyahu Park without people, a Nanjing without people – there must be no college entrance exams, no math test papers, no ‘Small Problem Grinding’ workbooks.

Also, I want to know how I died. If you receive this letter, I hope you can tell me my cause of death, and others’ causes of death too, if you know.”

Writing letters to people from the future seemed absurd no matter how you looked at it, but Bai Yang remembered that the great scientist Hawking had once done a similar performance art piece. In 2009, he held a party for future humans, secretly choosing a room as the venue, but only announcing the party invitation the day after it ended – if future humans could travel through time, they could arrive at the party venue the day before the announcement was made.

The result was unsurprising – Hawking waited alone in that room all night. Whether future humans could not traverse time or simply hadn’t seen Hawking’s announcement was unknown. Would Bai Yang’s letter be received by the future human?

“Of course, if my death was too tragic, please use your discretion and don’t tell me too directly, to avoid causing me too much mental stress. In twenty years I won’t even be forty years old – just thinking about the world losing such a promising young talent fills me with deep regret.

Wishing you good health, may you never forget to bring an umbrella when it rains, and may you never bite into ginger when eating yellow braised chicken. 73.”

Bai Yang paused, then signed off:

“BG4MXH, currently connecting with you from twenty years ago.”

Once the tritium tube arrived, he would seal it together with the letter in the time capsule.

Then bury it underground, letting it wait quietly for twenty years.