“…”
Faced with Zhang Yang’s question, the three of them fell briefly silent.
They looked at one another, not knowing how to answer.
They couldn’t very well say positron cannon and time-space text messages, could they?
That would be too stupid.
It would be giving away the secret outright.
“Time travel.”
Jiang Ran was the first to answer:
“These days, haven’t plenty of movies and science fiction novels invented time machines that can send people back to the past?”
“Once someone returns to the past and changes the original history, the subsequent course of history will also change accordingly, leading toward a different world line.”
“Take your example just now, Teacher Zhang. The present you is dissatisfied with being a teacher today, so you take a time machine back to the past, back to the moment when you failed the college entrance exam at eighteen.”
“Then you tell your eighteen-year-old self, who just failed the exam, that repeating a year and going back to school has no future, that the internet boom is about to arrive, and that you should head south to do business.”
“The eighteen-year-old you follows that advice, doesn’t repeat the year, and decisively heads south to Guangzhou. Then the world line completes a transition at that moment, jumping from World Line A to World Line B… The entire historical trajectory of the decades from when you were eighteen to now changes.”
“You wouldn’t be teaching at Donghai University, and we wouldn’t be your students. But perhaps you would already have become the CEO of a household-name internet company, or even the richest man in the Dragon Kingdom.”
…
Jiang Ran’s reasonable hypothesis filled Zhang Yang’s eyes with approval.
He patted Jiang Ran on the 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 recognition:
“For my general education course, I’ll have to give you a high score. You’ve studied very seriously.”
“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 quite right. As long as you change the choice made at some point in the past, you can alter established history, change the world line, and complete a world line transition.”
“In fact, it doesn’t even have to be the past. Different choices made at the present point in time can also lead the future onto different world lines.”
“For example, when you graduate from your undergraduate studies, do you choose to take the postgraduate entrance exam and go on to a doctorate? Or enter a large company to work? Or perhaps take the civil service exam?”
“Every different choice will lead your life toward a different world line.”
With the chalk, he drew four or five more parallel branches from the straight line representing World Line A, symbolizing the infinite possibilities of the future.
“However… no matter how you choose, no matter what kind of future you walk toward, don’t romanticize the roads you didn’t take.”
Teacher Zhang looked at those branches and smiled with emotion:
“Every choice, every kind of life, will have its successes and regrets. The most important thing is still to cherish the present and walk the road beneath your feet well.”
…
Seeing that the timing was about right,
Cheng Mengxue gave Jiang Ran a look, and he nodded.
It was time to bring up the biggest purpose of today, the question they cared about most.
“Um, Teacher Zhang.”
Cheng Mengxue raised her hand again:
“There’s something I’m curious about, which is…”
“【Once a world line transition occurs, is it possible for us to retain memories of the original history, the original world line?】”
“Using the example just now, if in the year you failed the exam at eighteen, you changed your choice and went south to do business, then in the future, when you’re sitting in the CEO’s office of a listed company, would you still retain the memories of being a teacher at Donghai University now?”
Jiang Ran and Qin Feng quietly exchanged a glance.
That’s right.
This was the real focus today.
This was what they wanted to know most.
They remained silent, waiting for Teacher Zhang’s answer.
“【Impossible.】”
Teacher Zhang did not hesitate at all.
Cheng Mengxue froze:
“Impossible?”
Teacher Zhang nodded:
“Impossible.”
His tone was decisive, leaving no room for doubt:
“【After a world line changes and transitions, even if one’s life is completely altered and the world undergoes earth-shaking changes, it is absolutely impossible for anyone to retain memories of the original world line.】”
“Why?” Jiang Ran asked.
“It’s not difficult to understand.”
Zhang Yang put down the piece of chalk, picked up the blackboard eraser, and pointed at the branching lines on the board:
“As I said just now, World Line A and World Line B cannot exist at the same time. So no matter what method is used to complete a world line transition, our history and past can only run along one of those world lines.”
“Therefore… suppose we jump from World Line A to World Line B. Do you think World Line A disappears?”
Zhang Yang looked at the three of them.
The three pondered for a moment, then nodded lightly.
“Wrong!”
Zhang Yang denied it emphatically:
“World Line A did not disappear. Rather, it never appeared in the first place! It never existed from the very beginning!”
He wiped away World Line A with the blackboard eraser and explained:
“If, after failing the exam at eighteen, I chose to head south to do business and embarked on World Line B, then all those things that should have happened on World Line A never happened. They never existed from the very beginning.”
“【So, a history that never existed in the first place, a world line that never existed in the first place, events that never happened in the first place… how could they possibly exist in memory?】”
…
Jiang Ran and the other two fell silent.
They had no answer.
How were they supposed to answer that?
Teacher Zhang’s explanation was well-founded, logical, and inherently flawless.
And yet…
There just so happened to be Jiang Ran, this “exception,” this “BUG.” Who were they supposed to reason with about that?
However.
Since Teacher Zhang was so decisive, the three of them felt somewhat relieved and put their minds at ease.
If everyone in the world was normal, if none of them had Jiang Ran’s special constitution, none of them had memories from before the world line changed… then that instead meant their current situation was safe.
Ding-dong, ding-dong.
Two WeChat notification sounds rang from the phone on the lectern.
Zhang Yang looked at the screen and saw that it was a WeChat message from a teacher in the teaching and research office.
He put down the blackboard eraser and clapped his hands:
“You think it over first. I’ll reply to a message.”
With that, he picked up his phone and, without avoiding them, replied directly in front of the three of them.
It was a WeChat message from Teacher Meng in the teaching and research office:
【Teacher Zhang, do you still need the newly arrived lesson plan notebooks? I’ll have a student bring a few over to you.】
He directly opened the chat box and began replying.
Teacher Zhang’s typing keyboard was different from Jiang Ran and the others’. It was a nine-key keyboard.
For post-2000s like Jiang Ran, Cheng Mengxue, and Qin Feng, they all used full keyboards when typing on their phones.
Because they had grown up using large-screen smartphones and had never used button phones at all, naturally they had never come into contact with nine-key keyboards either.
Early button phones, led by Nokia, all used dial buttons for typing because of technological limitations.
Each number key from 1 to 9 corresponded to three or four English letters, and when typing, one had to press combinations of number keys in sequence.
Because each number key corresponded to multiple English letters, typing accuracy was not high. One often had to select characters one by one, which was very inconvenient.
However, nowadays input methods had become much smarter, and the accuracy of nine-key input had also gradually improved. At present, there was rarely any need to select characters; the input method would automatically arrange candidates based on context.
According to casual observation of those around them, most of the people who still insisted on using nine-key input were born in the eighties and nineties; while young people born after 2000 and 2010 basically all used full keyboards without exception.
Teacher Zhang truly was someone who had come all the way from the era of button phones. His thumb moved “swiftly” across the nine-key keyboard, muscle memory like touch-typing, pressing several digits—
28… 926…
!
The string of numbers engraved in his mind activated, and Jiang Ran instantly held his breath.
28926…
What a familiar number!
These were precisely the first few digits of that mysterious text message!
Teacher Zhang’s thumb continued to leap, pressing the two keys 53, and the input method’s candidate bar immediately produced the three Chinese characters 【不要了】.
After that, he rapidly pressed 943943, and the candidate bar produced the two Chinese characters 【谢谢】.
He tapped send.
The five Chinese characters 【不要了谢谢】 were sent in an instant.
Jiang Ran’s heartbeat quickened.
He raised his head and looked at Qin Feng and Cheng Mengxue.
The other two had the same shock and surprise in their eyes.
Nine-key…
They never would have imagined it!
The solution to that mysterious string of numbers was actually the nine-key input method!
Since the first five digits, 28926, represented the two words 【不要】… then what exactly did the later 9426494642 represent?
They only needed to try it and they would know!
“Teacher Zhang, we’ll be going first!”
Jiang Ran turned and ran.
“Eh, ah?”
Zhang Yang looked utterly baffled:
“You all understand it now? I can explain a little more to you.”
“Thank you, Teacher Zhang!”
Jiang Ran nodded in thanks:
“It’s mainly because we have another class later. We’ll come ask you for guidance another time!”
Suppressing their inner excitement, the three rushed straight out of the classroom door and arrived at the flowerbed outside the building.
“How did we not think of nine-key?”
“It was right under our noses!”
“I’ve never used a nine-key input method before!”
The three grumbled endlessly, regretting it too late.
But this really couldn’t be blamed on them.
For people their age, the nine-key input method truly was a blind spot in their knowledge.
“Hurry up and try it!”
Cheng Mengxue urged.
Jiang Ran nodded and took out his phone.
289269426494642.
This string of garbled numbers that had tormented him for so long and lingered in his mind had finally found its solution.
He adjusted his phone’s input keyboard to nine-key, then pressed the string of numbers in sequence:
Do… not… trust…
As the numbers were pressed one by one, the Chinese characters automatically formed from pinyin popped out in succession.
When he pressed the final number on the nine-key keyboard,
the three of them widened their eyes.
They looked at the sentence assembled in the input field—
【Do not trust Ha】