Genius Playground

Faced with Zhang Yang’s question, the three of them fell briefly silent.

They looked at each other, not knowing how to answer.

They couldn’t just tell him about the Positron Cannon and Time SMS, could they?

That would be too foolish.

It would give away the secret right away.

”Time Travel.”

Jiang Ran was the first to answer.

”A lot of movies and sci-fi novels nowadays have invented time machines that let people go back to the past, right?”

”Once you go back to the past and change the original history, the subsequent historical trajectory will change in sync, leading to a different world line.”

”Take your example, Teacher Zhang Yang. Let’s say the current you is unsatisfied with your life as a teacher, so you take a Time Machine back to the past, to the moment you failed your college entrance exams at eighteen.”

”Then you tell your eighteen-year-old self who just failed his exams that studying for a retake is pointless. The internet boom is coming, and he should go south to start a business.”

”Your eighteen-year-old self follows this advice, doesn’t do the retake, and decisively heads south to Guangzhou. At that moment, the world line completes its jump, leaping from World Line A to World Line B... The entire historical trajectory of the several decades since you were eighteen changes completely.”

”You would no longer be teaching at East Sea University, and we wouldn’t be able to be your students. But perhaps you’d have become a famous internet entrepreneur, or even the richest man in Dragon Country.”

...

Jiang Ran’s reasonable hypothesis earned him a look of deep approval from Zhang Yang.

He patted Jiang Ran’s shoulder.

”Young man, which school are you from? What’s your name?”

”Teacher Zhang, my name is Jiang Ran. I’m from the School of Computer Science.”

”Very good.”

Zhang Yang’s tone was full of approval.

”I have to give you a high score for my general studies course. You’ve been studying very diligently.”

”Thank you, teacher.” Jiang Ran smiled.

Zhang Yang picked up the chalk again and looked at Cheng Mengxue and Qin Feng.

”Student Jiang Ran is correct. Just by changing a choice at a certain point in the past, you can alter established history, change the world line, and complete a Worldline Jump.”

”In fact, you don’t even need the ’past.’ Different choices made in the ’present’ can also lead the ’future’ to different world lines.”

”For example, when you graduate from your undergraduate studies, will you choose to take the entrance exams for graduate or doctoral programs? Or join a large corporation? Or maybe take the civil service exam?”

”Each different choice will lead your lives down a different world line.”

Using the chalk, he drew four or five more parallel lines branching off from the straight line representing World Line A, symbolizing the infinite possibilities of the future.

”However... no matter what you choose, no matter what kind of future you head towards, don’t romanticize the paths not taken.”

Teacher Zhang Yang looked at the branching lines and remarked with a wistful smile:

”Every choice, every life, will have its successes and regrets. The most important thing is to cherish the present and walk the path beneath your feet well.”

...

Seeing that the time was about right,

Cheng Mengxue gave Jiang Ran a look, and he nodded in return.

It was time to bring up their biggest goal for the day, the question they were most concerned about.

”Um, Teacher Zhang Yang.”

Cheng Mengxue raised her hand again.

”There’s something I’m curious about, which is...”

”Once a Worldline Jump occurs, is it possible for us to retain memories of the original history, the original world line?”

”Going back to the earlier example, if you had changed your choice and gone south to start a business the year you failed your exams at eighteen, would the future you, sitting in the CEO’s office of a publicly traded company, still retain the memories of being a teacher at East Sea University?”

Jiang Ran and Qin Feng quietly exchanged a glance.

’That’s right.’

’This is the main point of today.’

’This is what they most wanted to know.’

They remained silent, waiting for Teacher Zhang Yang’s answer.

”Impossible.”

Teacher Zhang Yang answered without any hesitation.

Cheng Mengxue was taken aback.

”Impossible?”

Teacher Zhang Yang nodded.

”Impossible.”

He was decisive, leaving no room for doubt.

”After a world line changes and jumps, even if your life is completely altered and the world has changed beyond recognition, it is absolutely impossible for anyone to retain memories of the original world line.”

”Why?” Jiang Ran asked.

”It’s not that hard to understand.”

Zhang Yang put down the piece of chalk, picked up the eraser, and pointed to the branching lines on the blackboard.

”As I said before, World Line A and World Line B cannot exist simultaneously. So, no matter what method is used to complete a Worldline Jump, our history and our past can only run on one of those world lines.”

”Therefore... let’s assume we jump from World Line A to World Line B. Do you think World Line A disappears?”

Zhang Yang looked at the three students.

After a moment’s thought, the three of them nodded slightly.

”Wrong!”

Zhang Yang refuted them emphatically.

”World Line A didn’t disappear—it never existed in the first place! It was non-existent from the very beginning!”

He promptly erased World Line A with the eraser and explained:

”If I had chosen to go south and start a business after failing my exams at eighteen, thus taking World Line B, then the events that were supposed to happen on World Line A would have never occurred. They would have been non-existent from the start.”

”So, a history that never was, a world line that never was, events that never happened... how could they possibly exist in memory?”

...

Jiang Ran and the other two were silent.

They were speechless.

’How could they refute that?’

Teacher Zhang Yang’s explanation was well-reasoned and logical, utterly unassailable.

But...

...there just had to be an ”exception,” a ”BUG” like Jiang Ran. Who could they possibly explain this to?

However,

Since Teacher Zhang Yang was so adamant, the three of them felt a sense of relief and could relax a little.

If everyone in the world was normal, if no one else had Jiang Ran’s special constitution and retained memories from before the world line changed... then that would actually mean their current situation was safe.

DING DONG, DING DONG.

The phone on the lectern chimed twice with a WeChat notification sound.

Zhang Yang glanced at his phone screen and saw it was a WeChat message from a teacher in his department.

He put down the eraser and clapped his hands.

”You guys think about it for a bit. I need to reply to a message.”

With that, he picked up his phone and, without any attempt to hide it, began replying right in front of the three of them.

It was a WeChat message from Teacher Meng of the department:

[Teacher Zhang, do you still need the new lesson plan notebooks? I can have a student bring a few over to you.]

He opened the chat window directly and started to reply.

Teacher Zhang Yang’s keyboard layout was different from Jiang Ran’s group; he used a T9 number pad.

People born in the 2000s like Jiang Ran, Cheng Mengxue, and Qin Feng all used a full QWERTY keyboard for typing on their phones.

Because they had grown up using large-screen smartphones, they had never used feature phones with physical buttons and had naturally never encountered a T9 number pad.

Early feature phones, led by brands like Nokia, all used the dial pad for typing due to technical limitations.

Each number key from 1 to 9 corresponded to 3-4 letters, and typing required pressing a combination of number keys in sequence.

Because each number key corresponded to multiple letters, the typing accuracy wasn’t high. You often had to select characters one by one, which was very inconvenient.

But now, input methods have become more intelligent, and the accuracy of T9 input has gradually improved. It’s now rare to have to select characters, as the input method automatically arranges candidates based on context.

According to anecdotal evidence, most people who still insist on using T9 input are from the 80s and 90s generations, while the younger generations from the 2000s and 2010s almost exclusively use full QWERTY keyboards.

As expected of someone who came up from the era of feature phones, Teacher Zhang Yang’s thumb flew across the T9 pad. It was like muscle memory, like touch-typing, as he pressed a series of numbers—

28... 926...

!

The string of numbers etched into his mind was activated. Jiang Ran instantly held his breath.

28926...

’Such a familiar number sequence!’

These were the first few digits from that mysterious text message!

Teacher Zhang Yang’s thumb continued to dance, pressing the 5 and 3 keys. The three words ”Don’t need it” immediately appeared in the input candidate bar.

Next, he quickly pressed 943943, and the two words ”thank you” appeared in the candidate bar.

He hit the send button.

The five-word message, ”Don’t need it, thank you,” was sent in an instant.

Jiang Ran’s heart began to race.

He looked up at Qin Feng and Cheng Mengxue.

The same shock and excitement were reflected in their eyes.

’The T9 keypad...’

’Who would have thought!’

The solution to that mysterious string of numbers was the T9 input method!

Since the first five numbers, 28926, represent the two words for ”don’t want”... what did the following 9426494642 mean?

They just had to try it to find out!

”Teacher Zhang, we have to go!”

Jiang Ran turned and bolted.

”Eh? Huh?”

Zhang Yang was completely baffled.

”Did you guys understand everything already? I can explain a bit more.”

”Thank you, Teacher Zhang!”

Jiang Ran nodded his thanks.

”It’s mainly because we have another class. We’ll come find you for more guidance later!”

Suppressing their excitement, the three of them rushed out of the classroom and over to a flower bed outside the building.

”How could we not have thought of the T9 keypad?”

”It was right under our noses!”

”I’ve never used a T9 keyboard in my life!”

The three of them grumbled, full of regret.

But they couldn’t really be blamed.

For people their age, the T9 input method was truly a blind spot in their knowledge.

”Hurry up and try it!”

Cheng Mengxue urged.

Jiang Ran nodded and took out his phone.

289269426494642.

The solution to this string of gibberish numbers that had tormented him and lingered in his mind for so long had finally been found.

He switched his phone’s input method to the T9 number pad and then pressed the string of numbers in order:

Don’t... be... lieve...

As he pressed the numbers one by one, the Chinese characters automatically formed from the Pinyin jumped out one after another.

When he pressed the last number on the T9 keypad,

The three of them stared with wide eyes,

looking at the sentence that formed in the input bar—

[Don’t believe Ha]