My IQ has been increasing year by year.

The overhead ceiling fan speed was unknowingly adjusted to the third speed.

The wind turbine made a slight clicking sound as it turned, causing the few pages of draft paper on the table to rustle.

Chen Zhuo reached for an empty cup beside him and placed it on the corner of the paper, continuing to look down at the book "A Course in Theoretical Physics" in his hands. In late May, the air in Huizhou was already starting to feel sticky.

The school lockdown has lasted for quite some time now, and the initial tension has long been worn down by the monotony of day after day.

The students on the USTC campus are like frogs being slowly boiled in water, spending their days eating, sleeping, and hoping for some confirmation of the lockdown being lifted from the school radio station. Dormitory 215, however, is unusually quiet.

Chen Zhuo held a black fountain pen in his hand and wrote slowly and deliberately on the draft paper.

He needed to mentally review the Russian text in the book first, and then painstakingly reconstruct the derivation steps that the author habitually omitted, line by line, on paper. It was a rather physically demanding task.

The book is filled with endless partial differential equations and countless integral symbols.

Chen Zhuo didn't dislike these formulas, but he didn't particularly like them either. To him, it was like paving a smooth, straight road with tiny pebbles instead. He was used to point-to-point discrete algebra, used to that clean and efficient approach.

The mathematical method he was currently using, which required filling in the gaps bit by bit with infinitesimals to achieve a smooth transition, seemed somewhat tedious to him. But he said nothing, simply gripping his pen and meticulously reproducing the derivations omitted from the book on his scratch paper, line by line. He wrote steadily, the integral symbols on the scratch paper arranged neatly. When he encountered a step requiring approximation with higher-order infinitesimals, he paused, stared at the formula for two seconds, and then, following the logic in the book, diligently completed the rest.

"Oh my god..."

A sigh came from the side.

Wang Dayong sat at his desk, clutching his already messy hair, shoving the "Advanced Mathematics" workbook in front of him forward, and slumped back in his chair like a deflated balloon. "Is there something wrong with the last big problem in Real Analysis?"

He stared at the ceiling, irritably running his fingers through his hair.

"I've been calculating for over an hour, and the more I scale, the larger the error term becomes."

Chen Zhuo stopped writing. He had just finished deriving a continuous field integral from Landau's book, and the slight mental block hadn't completely dissipated. He picked up his cup, took a sip of water, and turned to look at Wang Dayong across from him.

"Where is it stuck?"

"An asymptotic integral of a high-dimensional space."

Wang Dayong pushed over a thick workbook along with its draft paper, pointing to a long string of formulas on it.

"I first used Lebesgue's control convergence theorem to try to move the limit to the integral sign, but the boundary conditions were not met. Then I started to use hard scaling and I used the Epsilon-Delta language to check its upper and lower bounds, but this higher-order error term could not converge at all. I wrote more than half a page of inequalities and it was all over."

Chen Zhuo took the draft paper.

The paper was covered with various inequalities with absolute values ​​and nested integral symbols.

Wang Dayong's foundation was very solid; every step of his analytical derivation was flawless. However, precisely because he was too orthodox, he got caught in an endless web of continuity. Chen Zhuo only glanced at it a few times before putting the draft paper aside and returning his gaze to the original problem.

Instead of picking up a pen to help Wang Dayong rewrite the inequalities, he gently tapped the integrand in the problem with his finger.

"Why do you insist on treating it as a continuous volume when performing the integral?"

Chen Zhuo's voice was very calm.

Wang Dayong was stunned for a moment.

"Isn't this the integration field? It's a continuous manifold space."

"That's how it appears on the surface."

Chen Zhuo pointed to the series of symmetrical constraints following the function.

"But look at its boundary. In this specific high-dimensional space, the essence of this integral is not to calculate a smooth volume." Chen Zhuo took a pen, drew a few points in the blank space, and then connected them with straight lines to form a simple grid. "Don't calculate continuous integrals; it's too convoluted."

Chen Zhuo talked as he drew.

"You've mapped the space you described directly into a discrete grid model. Those complex constraints are actually the connectivity relationships between vertices in this graph theory model." Wang Dayong leaned closer, looking at the points, his brow still slightly furrowed.

"What happens after you turn it into a discrete form?"

Write its adjacency matrix.

Chen Zhuo wrote a simple algebraic matrix symbol next to the grid.

"Once you construct this matrix, the asymptotic value of that troublesome high-dimensional integral is mathematically equivalent to the trace of this matrix raised to the power of n." Wang Dayong's eyes widened suddenly.

Find the trace of a matrix raised to the power of n...

Wang Dayong muttered to himself, his brain starting to work at lightning speed.

"This is equivalent to finding the sum of all eigenvalues ​​raised to the power of n. As n approaches infinity, which is the asymptotic limit, all other eigenvalues ​​can be ignored, and the final result depends only on the largest principal eigenvalue!"

What was originally a difficult analytical problem that required a lengthy, painful process of scaling down and approximating with countless infinitesimals has now been reduced to a simple calculation of linear algebraic eigenvalues. Even the processes of simplification and finding limits have been eliminated.

Wang Dayong gasped and snatched the draft paper and exercise book back.

He didn't even bother to sit down; he bent over and quickly wrote down the adjacency matrix on the table. In less than three minutes, the limiting constant that had been troubling him for over an hour was neatly written on the paper. "Awesome."

Wang Dayong looked at the simple number and shook his head in disbelief.

He turned his head and looked at Chen Zhuo with a look of astonishment as if he were looking at a monster.

"Brother Zhuo, how did you manage to see through those complex integral symbols and figure out at a glance that it's essentially an algebraic matrix?"

Chen Zhuo closed the pen cap and put it back in the pen holder.

"Because I don't like approximating with infinitesimals."

He leaned back in his chair, his tone tinged with a helpless honesty.

"Calculating continuous things is too much like manual labor. It's much more convenient to break them down into discrete points."

Wang Dayong nodded, seemingly understanding, then returned to his seat contentedly with his workbook, continuing to work on the next problem. Chen Zhuo turned his gaze back to his draft paper.

He looked at the two pages of field theory formulas he had spent half an hour deriving, and slightly moved his aching wrists. With a creak, the sound of the formulas rang out.

Chu Ge walked in yawning, his hair disheveled like a bird's nest, looking somewhat like a decadent young man.

"Does the fan in your room spin faster than the one in ours?"

As soon as Chu Ge entered the room, he grabbed a small stool, sat down in the center of the dormitory, closed his eyes, and felt the breeze overhead.

"Our big computer in room 216, if it's on for a long time, the case will be blasting hot air out. Lu Jia wouldn't let me open the door, saying that someone in the hallway was reciting English and disturbing his math problems. I just woke up, and I almost got steamed alive in the room." Wang Dayong turned around, glanced at Chu Ge's face, and laughed.

"If you hadn't said you just woke up, I would have thought you were getting ready to join the rock scene. Did you go and fix your boss's website again last night?" "Join the rock scene what?"

Chu Ge rubbed his face and sighed.

"The boss insisted that the inventory management page was loading too slowly and asked me to optimize it. I spent the whole night looking up database entries. If it weren't for the matrix mapping method that Brother Zhuo taught me last time, I'd probably still be writing nested loops right now."

As Chu Ge spoke, he opened his eyes and looked at Chen Zhuo, curiously glancing at the books on Chen Zhuo's desk.

"What are you researching now?"

Theoretical physics.

Chen Zhuo closed the book and finished the last sip of water in his cup.

"physics?"

Chu Ge curled his lip.

"Is this thing useful? Can you exchange it for money or eat it? If you ask me, the future definitely belongs to computers. With your brain that's good at writing low-level logic, if you work with me, we can earn back the money we spent on your computer in these two months."

Chen Zhuo couldn't help but laugh when he saw Chu Ge's money-obsessed expression.

"Writing too much code can cause hair loss."

Chen Zhuo pointed to Chu Ge's messy hair.

"If you keep going like this, when you start your second year of college, we'll have to scrape together money to buy you Bawang anti-hair loss cream."

"screw you."

Chu Ge touched his hair and chuckled.

"I call this sacrificing myself for the cause. Once the lockdown is lifted, I'll treat you all to barbecue in the back alley, as much as you want."

Upon hearing the word "barbecue," Wang Dayong swallowed hard.

"When will this school lockdown end? I'm getting sick of eating the same few dishes in the cafeteria every day. I could eat a plate of edamame like it was meat." "Soon."

Chu Ge leaned back in his chair and crossed his legs.

"This morning I heard from Lu Jia that the neighboring provinces seem to have started to lift the alert one after another. It should be within the next few weeks. Final exams are coming up soon, and the school can't keep us locked up until summer vacation."

Wang Dayong's face fell again when the final exams were mentioned.

"Don't mention exams to me. I haven't even finished reviewing more than half of my advanced calculus textbook yet."

Wang Dayong looked at the books on the table with a worried expression.

"How's Lu Jia's revision going?"

"he?"

Chu Ge rolled his eyes.

"He got up at 6:30 in the morning and sat at the table, memorizing Marxist philosophy all morning. In the afternoon, he started calculating linear algebra. I really admire his concentration. If it weren't for the sound of him turning the pages keeping me awake, I wouldn't have come to your room for refuge."

The group chatted casually.

Most of it was just idle chatter, complaining about the weather, speculating about when the lockdown would end, or discussing which cafeteria lady's hands weren't shaking so much. Chen Zhuo occasionally chimed in with a word or two; he didn't think this kind of idle talk was a waste of time.

After spending hours deriving formulas, listening to these casual complaints is a great way to relax.

The overhead fan continued to whir.

As Chu Ge talked, his eyelids started to droop again, and his head slumped down little by little.

"I can't take it anymore, I need to go back and catch up on some more sleep."

Chu Ge stood up, stretched, and his bones cracked a few times.

"When you go out for dinner tonight, remember to kick me in room 216. I'm not setting an alarm."

"Go ahead, go ahead."

Wang Dayong waved his hand.

"I'll tell Lu Jia to keep his math problems quiet so as not to disturb your rest, the big boss."

"If he listened to me, he wouldn't be Lu Jia."

Chu Ge muttered something, then sauntered out of dormitory 215, closing the door behind him.

The dormitory fell silent again.

Wang Dayong took a deep breath and plunged back into the sea of ​​advanced mathematics problems.

Chen Zhuo glanced at the clock on the wall; it was 4:15.

He glanced at the closed "Course in Theoretical Physics" on the table, but didn't open it again. He had already completed his task for today regarding the quantities and derivations of continuous field theory. As for the remnants of partial differentials and differential equations in his mind, while not unpleasant, they definitely needed to be cleared away.

Chen Zhuo stood up, moved the chair back a little, bent down, and pulled the black rectangular box out from under the bed.

Hearing the noise, Wang Dayong looked up from his workbook and glanced at the violin case in Chen Zhuo's hand.

"Going to play the violin?" Wang Dayong asked.

"Um."

Chen Zhuo nodded and casually patted the dust off the violin case a couple of times.

"Let's go sit in the activity center for a while."

"Okay, go ahead. I'll try to finish the exercises for this chapter before you get back."

Chen Zhuo, carrying his violin case, pushed open the door and walked out of the dormitory.

It was the hottest time of the afternoon, and the sunlight shining on the windowpane at the end of the corridor was dazzling.

On the blackboard in the lobby on the first floor, various prevention and control regulations for this period were still written in chalk, the writing already somewhat blurred. The dormitory supervisor sat in a rocking chair by the entrance, holding a palm-leaf fan in his hand, listening to the Huangmei opera on the radio with his eyes closed. Chen Zhuo walked out of the dormitory building, a gust of hot wind blowing in his face.

The trees on campus have grown lush and green, providing a large shade over the main road.

There weren't many students on the road; occasionally a few people would hurry by on their bicycles, making a slight rustling sound as they drove on the asphalt.

Everything was peaceful.

There were no major incidents, and no problems that needed to be solved immediately.

Time marches on, step by step, with these rhythmic footsteps.