Time capsule.

Bai Yang had wanted to buy one for a while now.

His plan was obvious: since BG4MSR claimed to be living in 2040 if Bai Yang could send a slow delivery across twenty years, and if she could receive it, it would prove she was telling the truth.

It sounded simple, but upon closer consideration, the practical implementation was full of difficulties. He needed to prevent cheating, forgery, lies, and loss, all within the capabilities of an ordinary high school student.

Order placed!

Bai Yang bought a small time capsule made of stainless steel, which came with two wrenches and a shovel, for sixty-eight yuan.

Expensive – his wallet would feel the pain for a while.

But what should he send?

What should go inside the time capsule?

Food? Medicine? Souvenirs? A letter?

No, none of these were important.

What mattered was a timer, a clock. Bai Yang needed a timepiece that could keep time. When the time capsule was dug up from the ground and the clock saw daylight again, it would tell people exactly how much time had passed.

No clock could remain stationary in a time capsule for twenty years and still function normally. Electronic quartz watches only had battery lives of five to ten years. Automatic mechanical watches didn’t need batteries and used tourbillons to wind their springs, but they relied on external movement for power – left stationary, their hands would stop.

What could he do?

With humanity’s current advanced technology, making a timer that could work continuously for twenty years would be a matter of minutes, but Bai Yang couldn’t do that. He was just an ordinary high school student with limited abilities and finances. His greatest resources were the shopping websites Taobao and JD.com.

Bai Yang tried searching for “timer” on Taobao, but most results were ordinary electronic clocks. Anyone could figure out they wouldn’t last twenty years in a time capsule. Bai Yang’s requirement sounded simple but was tricky to implement. He just needed a clock – no fancy functions required, just timekeeping. Listen to that – how simple! Isn’t keeping time a clock’s basic job?

But for how long?

At least twenty years.

That wasn’t so simple anymore. Even the simplest function becomes difficult when pushed to its limits. Bai Yang really couldn’t find a suitable option at the moment.

He sat in his chair, staring at his phone screen, deep in thought.

Twenty years was too long. In daily life, except for houses and furniture, few things were designed with a twenty-year lifespan in mind.

“Twenty years…”

Bai Yang muttered, frowning as he played with a coin in his hand.

It was a Morse code practice coin he’d bought when learning equal-amplitude transmission. It was about the size of a regular one-yuan coin, but both sides were engraved with Morse code and corresponding letters. It looked golden but was copper-plated stainless steel.

In the end, Bai Yang hadn’t mastered transmission. His father said practicing blindly like this would surely fail, developing bad habits that couldn’t be corrected. Bai Yang didn’t believe it, but he did fail. However, he wouldn’t admit it was his fault – he blamed the counterfeit Changshu K4 telegraph key he’d bought on Xianyu.

“Twenty years… how to endure through these twenty years?”

The question seemed uncomplicated at first glance.

Careful consideration revealed its sky-high difficulty.

When time itself becomes the roadblock before you, you’re facing the most powerful force in this world.

Since artificial constructs weren’t reliable, he could only pin his hopes on the world’s physical laws themselves – nature’s changes typically occurred on million-year scales, making twenty years merely the blink of an eye.

Bai Yang’s first thought was oxidation.

“Oxidation?”

Iron oxidation, or copper oxidation.

Iron oxidizes into ferric oxide, which is red; copper oxidizes into copper oxide, which is green.

If Bai Yang could utilize the color changes caused by metal oxidation, when BG4MSR dug up the time capsule, she would see the metal time marker inside the capsule.

Then Bai Yang would only need to ask her about the marker’s color – something that couldn’t be faked, and since she wouldn’t know what the color signified, she couldn’t lie either – to know if that girl was telling the truth.

“Would this method work?”

“No.”

Bai Yang shook his head.

It wouldn’t work.

The time capsule was strictly sealed, completely airtight – where would the oxygen come from?

Bai Yang’s second thought was evaporation.

He thought of the legend that Emperor Qin Shi Huang’s tomb was filled with mercury, with rivers and seas of mercury where boats could sail -, given mercury’s terrifying density, anyone could walk on water if they weren’t afraid of death. Mercury’s natural evaporation rate was extremely slow. If he put 0.5 grams of mercury in the time capsule, complete evaporation might take over ten years…

When BG4MSR opened the time capsule after twenty years, she would see – highly concentrated mercury vapor.

That wouldn’t work either.

That would be harming someone.

Bai Yang scratched his head.

This wouldn’t work, that wouldn’t work – what could he do?

Unfortunately, there wasn’t a second person present to discuss this problem with him. Two brains would be better than one. Bai Yang sat alone in his chair, wracking his brain. Too bad he was a primate mammal and not a large reptile, otherwise he might have grown a brain in his rear to help him think. In the silence, the small alarm clock on his desk ticked away. It was very late, and the rain seemed to still be falling outside.

That night, Bai Yang lay in bed unable to sleep, eyes wide open, staring at the ceiling in the darkness, his mind turning the problem over and over.

He hoped to find a method, a method that couldn’t be faked, unaffected by any external forces, unalterable by anyone, controlled only by the world’s iron laws – like trees dying and turning into coal, rocks being eroded to form caves – letting the world itself serve as a timer. Only this would qualify as ironclad proof.

That was easier said than done.

As a high school student, finding such a method was too difficult. Bai Yang thought silently, perhaps if it were someone else, someone older with more life experience, they might come up with a solution immediately. He was ultimately too young with too little experience… Would Yan-ge be able to think of a good method? Would He Leqin be able to think of a good method?

Young Master He had traveled widely since childhood, with more international trips than Bai Yang had provincial ones. Maybe he could think of something good?

Never mind, Bai Yang shook his head. He Leqin failed every physics test, and his chemistry scores were even lower than physics. He relied on Bai Yang and Yan-ge to save his daily homework. He spent all day obsessed with PUBG, Overwatch, Total War, Assassin’s Creed, Dark Souls, Euro Truck Simulator, Microsoft Flight Simulator, Half-Life… Half-Life was such a terrible translation, worthy of being called the worst among the top ten awful Chinese game translations… Who had translated it as “Half-Life”… What was Half-Life’s original name?

Bai Yang’s thoughts wandered.

Half-Life’s original name?

Seemed like it was half…

Half-life period?

Bai Yang started, suddenly sitting up in bed like a dying patient.

Half-life!