80: Chapter 80 Noise Reduction

On the first day of his return, Jiang Lin did nothing at all.

He simply took a refreshing hot bath, ate happily, slept soundly, and walked round and round on the old street near the faculty building.

The old street was bustling. At the corner, a fried dough stick stall sizzled with hot oil, passing electric scooters blared harsh horns, and several retired old men argued fiercely over a game of Chinese chess under the shade of a tree.

Jiang Lin mingled in the crowd, listening to these noisy sounds and looking at those vibrant faces.

He needed this high-density information to fill the decades-long barrenness in his brain.

He was like a diver just salvaged from the deep sea, slowly adapting to normal atmospheric pressure in a decompression chamber.

Until the second day, the sense of weightlessness brought back from the Wasteland gradually faded, and the gap between his body and soul finally fit together seamlessly.

At eight in the morning, he put on his schoolbag and rode a bicycle to Jiangcheng University.

As for Jiangcheng No. 7 High School, he had asked for leave from his head teacher, Old Liu, yesterday.

Walking into Jiangda University through the familiar North Gate, he came to Building A of the School of Physics.

Last night, he opened the public course schedule of Jiangcheng University at home and selected a class.

The third session on Monday morning was Quantum Mechanics, taught by Associate Professor Zhao Mingyuan, located in Classroom A301.

During the last return, he came and went in a hurry and was too busy. Although he was at Jiangda University, he didn't feel much of the university atmosphere.

This time, he came to audit the class with a relaxed mindset.

When Jiang Lin walked to the Physics building, there were still ten minutes before class.

He took a slow walk around the slightly dim corridor on the first floor.

The Physics building was an old building constructed in the 1990s. The grayish-white terrazzo floor exuded a sense of age. The wooden handrails of the stairs had been polished glossy by generations of students, and walking on them, one could hear the hollow echo of the soles rubbing against the ground.

At the end of the corridor, there was a row of glass display cabinets against the wall, displaying the early scientific research achievements and historical evolution of the School of Physics of Jiangda University.

Inside were a few faded brass medals, several large group photos with yellowish edges, a few photocopied old papers, and some photos of distinguished alumni and old professors.

Jiang Lin stopped in front of the glass cabinet.

The old people in the photos wore the baggy suits common in the 1980s and 1990s, wore heavy thick-rimmed glasses, and stood beside extremely simple experimental benches.

In the background were old-fashioned oscilloscopes with green fluorescent screens, homemade power supply boxes with handwritten yellowish labels, and optical tables with bumped edges revealing the metal base color.

At that time, Professor Lu Zhixing pointed to an old instrument in the laboratory and said that the reason why some marginal directions of the School of Physics of Jiangda University could endure the bench-warming all the way to today was not because they suddenly secured tens of millions in major projects in a certain year, but because several generations before them passed down these habits bit by bit: how to set up the most basic experimental benches, how to use instruments standardly, how students should conduct basic training, and how to preserve the raw data of papers.

Through the glass, looking at those black-and-white photos, Jiang Lin's thoughts suddenly drifted far away, thinking of the Wasteland.

He thought of those remains that fell in the desert without successors.

In the glass cabinet of the Real World, although the things left behind by the old professors were old, they were still passed down in the classrooms of Building A, the laboratories of Building B, and the graduation theses of students generation after generation.

Even with impurities and losses, this river had not broken.

On the Wasteland, the heritage of civilization was left with only endless sandstorms and increasingly large systematic errors.

At nine fifty-five, Classroom A301 was already more than half full.

The undergraduate junior-year Quantum Mechanics class was never a public course used to boost GPA, let alone a slack class that could be skimped through by casually playing a couple of games in the back row.

The atmosphere in the classroom had a kind of oppressive focus.

Students in the front row spread out their textbooks early, with scratch paper densely covered with symbols pressed beside them.

Although someone in the back row turned on a computer, what was displayed on the screen was not web games, but rows of formulas, obviously reviewing the derivation process of the last class.

Jiang Lin walked in from the back door and chose an empty seat by the aisle in the last row to sit down.

Today he was wearing a black hooded jacket, a pair of dark trousers, and carrying an old backpack.

In this classroom full of college students, he was utterly unremarkable.

Five minutes later, the class bell rang.

Zhao Mingyuan strode onto the podium.

He was in his early forties, with a noticeable receding hairline. He wore a dark shirt that had been washed somewhat whitish, and a pair of rimless glasses on the bridge of his nose. The whole person had a dry, rigid temperament left behind by long-term dealings with blackboards, handouts, and referee reports.

He threw his thick handouts onto the podium, unscrewed his thermos cup and took a big gulp of wolfberry water, then turned around to pick up a piece of chalk, and forcefully wrote today's title in the upper left corner of the blackboard.

WKB Approximation: Turning Points and Connection Formulas

The chalk tapped crisp ticking sounds on the blackboard.

"In the last class, we talked about the WKB Approximation in the one-dimensional time-independent Schrödinger equation. Today we will continue moving forward."

Zhao Mingyuan turned around and scanned the whole class.

"Do not think of it as just a mathematical technique. Our focus today is when it fails, and after it fails, how to forcibly connect the solutions on both sides of the failure region."

Jiang Lin took out a blank notebook and a black pen from his schoolbag.

Zhao Mingyuan had already turned around and started a series of long derivations on the blackboard.

ψ ' ' ( x ) + k ² ( x ) ψ ( x ) = 0

k ( x ) = sqrt ( 2m ( E - V ( x ) ) ) / ℏ

...

The formulas on the blackboard unfolded one by one, and chalk dust danced up and down in the sunlight filtering through the window.

Jiang Lin did not take notes.

He was too familiar with these things.

Not just that version in Quantum Mechanics textbooks.

He had read that heavy classic by Bender and Orszag, read the more abstract and counterintuitive topological writings in Methods of Mathematical Physics, and even repeatedly used similar ideas in fluid mechanics and engineering heat transfer problems that seemed to have nothing to do with Quantum Mechanics.

Zhao Mingyuan's lecture speed was not fast.

As an experienced associate professor, he had to take care of the limited acceptance rhythm of this group of undergraduates.

Every time he derived a key physical condition, he would stop the chalk, turn around, and translate the physical meaning behind the symbols into plain language.

"Look at the blackboard, do not just stare blankly at this exponential term. The preceding amplitude term is equally important."

Zhao Mingyuan heavily tapped a row of formulas on the blackboard with the head of the chalk.

"I have taught several batches of students. Many people studying WKB Approximation for the first time only remember that phase integral in their heads, thinking that is everything. As a result, once the exam arrives and they encounter turning points, they are completely wiped out, having no idea why problems occur."

In the front row, a boy wearing glasses frowned and asked the person next to him in a low voice: "At the turning point, is it just substituting it in to make k = 0?"

The girl with a ponytail next to her wrote quickly on the scratch paper and replied in a lowered voice: "Yes, but it is not as simple as just substituting it in to equal zero. I previewed it last night and took a look, it seems the validity condition directly blows up at this place."

Zhao Mingyuan on the stage had already written out the final form of the WKB solution.

ψ ( x ) ≈ C / √ k ( x ) * exp ( ± i ∫ ^ xk ( s ) ds )

Immediately afterwards, he drew a smooth potential barrier curve freehand on the right side of the blackboard, marked the classically allowed region and classically forbidden region with different colored chalks, and drew two heavy crosses at the junction of the two.

Turning point.

"Alright, now the question comes." Zhao Mingyuan dropped the chalk in his hand, patted the chalk dust on his hands, "Dear future physicists, who can tell me why this approximate solution we worked so hard to derive cannot be used directly near the turning point?"

After Zhao Mingyuan finished asking, the huge Classroom A301 instantly fell dead silent.

The boy with glasses in the front row subconsciously wrote k = 0 on the scratch paper, his pen tip paused on the paper, and he stopped halfway through writing.

He vaguely felt something was wrong; this was too superficial.

A boy in the back row bumped his companion with his elbow and muttered in a low voice: "Because there is a square root of k in the denominator, and k tends to zero, so the amplitude term diverges."

The companion shook his head: "Since Teacher Zhao asks like this, it definitely goes beyond this. If you dare to stand up and say that, he will definitely pursue the root cause."

Zhao Mingyuan's gaze swept across the entire classroom like a searchlight.

He saw someone in the front row write k = 0 and stop the pen again, and students in the middle row turned to the second half of the handouts, obviously knowing the answer lay in the Airy function, but had not yet figured out the middle step clearly.

Finally, his sight crossed over numerous heads and landed on the window-side position in the last row.

Sitting there was a student who looked unfamiliar.

From the start of class until now, he hadn't flipped through a book or taken notes, but stared at the blackboard extremely calmly, looking as if he were watching a movie.

"That classmate in black clothes by the window in the back row, yes, it is you, you tell us about it."

In the undergraduate junior-year Quantum Mechanics class, whole-field silence in the face of the teacher's questions was a very normal thing.

The difficulty of this course was right there, and many students were not completely empty-headed, but knew that the concepts in their heads were a mess.

They were afraid that once they spoke, they would mix high-level vocabulary like turning points, divergence, Airy functions, and boundary matching into a mess and become a laughing stock.

However, Zhao Mingyuan had a habit in class: the more no one answered, the more he liked to call on those in the back row who didn't look like they were listening to the lecture but hadn't lowered their heads all along.

Moreover, in his impression, the back row could best expose whether a class had really been taught through.

Seeing that he was the one called, Jiang Lin showed no panic and stood up from his seat.

Looking at the potential energy curve drawn with red chalk on the blackboard, he replied.

"At the turning point, E = V ( x ₀ ) is satisfied, so the local wave number k ( x ) tends to zero. Under this limit, the amplitude term 1 / √ k in the WKB solution will diverge, which is the most intuitive mathematical problem."

Zhao Mingyuan raised his eyebrows slightly, did not interrupt, and motioned for him to continue with a gesture.

Jiang Lin paused for a second, and his tone remained calm: "But looking at it from a more essential perspective, the core premise of the WKB Approximation, which is its validity requirement, is that the local wavelength must change slowly enough in space. The commonly used criterion form is | k ' | / k ² ≪ 1."

Hearing this criterion, the boy with glasses in the front row was startled and subconsciously added this line of conditions on the edge of his scratch paper.

Jiang Lin continued: "For a simple turning point, K ( x ) tends to zero like ( x - x ₀ ) ^ ( 1 / 2 ), while k ' ( x ) instead shows a singular increase. Consequently, | k ' | / k ² does not become smaller, but diverges, and the asymptotic expansion of WKB loses control here."

This was a junior year classroom, and he did not continue pouring things into Stokes phenomenon, higher-order WKB, and uniform asymptotic expansion.

"If this is a simple turning point, that is, the derivative of potential energy V ' ( x ₀ ) ≠ 0, we can linearly expand the potential energy near x ₀ and approximate the Schrödinger equation in this local region into an Airy-type differential equation."

Speaking up to here, Jiang Lin's gaze finally moved from the blackboard to Zhao Mingyuan.

"Then, we use the two sets of asymptotic forms of the Airy function at positive and negative infinity as bridges: one set to match the oscillating solution of WKB in the classically allowed region, and the other set to match the exponentially decaying solution in the classically forbidden region."

"The extra phase of π / 4 in the connection formula in the textbook is not an empirical term patched up to piece together experimental data, but an inevitable result derived seamlessly from the asymptotic matching process of this Airy function."

The classroom fell into a strange silence.

The lethality of this sentence made several students in front who were taking frantic notes visibly stop their pens.

They could barely keep up with Jiang Lin's first half explanation about divergence just now.

But the last sentence directly connected the complex physical image, the properties of the differential equation, and the final phase parameters. This could no longer be summarized by a simple previewing very well.

"Good, very good, please sit down, classmate."

A trace of undisguised approval flashed in Zhao Mingyuan's eyes. He turned around and heavily tapped the blackboard.

"What this classmate just said was extremely thorough. Students, make sure to remember that condition for me emphatically. When studying Physics, never let the failure of WKB stop at such a superficial understanding that the amplitude term denominator is zero and looks bad. The truly fatal problem is that your approximation premise has collapsed."

Zhao Mingyuan picked up the chalk and heavily added the line of conditions | k ' | ≪ k ² in the center of the blackboard.

"There are two levels here: one is apparent mathematical divergence, and the other is underlying physical failure. The criterion mentioned by that classmate just now is much more useful than your blindly rote memorization of where the turning point is."

The chalk fell, and the attention in the classroom was pulled back to the blackboard.

The ponytail-wearing girl in the front row turned her head and muttered in a low voice to the boy with glasses: "Oh my god, who is this person? This logical density in speech, is he some big shot running over to audit and review?"

The boy pushed his glasses, glanced out of the corner of his eye at the back row, and shook his head: "I don't know, he looks unfamiliar. He's probably a graduate student who came to ask Teacher Zhao questions."

Forty-five minutes later, the class bell rang.

The originally oppressive classroom suddenly moved like a thawing river.

The sound of zippers packing schoolbags and the screeching sound of dragging chairs rang into a piece.

Several top students in the front row immediately gathered in front of the podium with handouts, seizing the time to ask about homework and derivation details.

Jiang Lin did not go up to join the excitement. He closed the blank notebook, stuffed it into his schoolbag, shouldered it with one shoulder, and walked out quietly from the back door.

The corridor was bustling with people. It was during the break, and students from different classrooms poured out, appearing somewhat crowded.

The cork bulletin board on the wall was covered with colorful papers.

There were mobilization posters for the undergraduate mathematical modeling competition, huge posters of a certain academician coming to lecture, and a "Laboratory Safety Training and Asset Management Notice" printed on A4 paper.

Jiang Lin originally just wanted to go downstairs with the crowd, but inexplicably paused in front of that safety notice.

His gaze swept over several daily management items listed at the bottom of the notice.

High-voltage power supply use safety specifications.

Laser goggles wearing requirements.

Special gas cylinder storage and warehousing management.

Data storage and experimental notebook archiving.

Instrument reservation and artificial damage compensation system.

Below the last item, there was a supplementary note bolded in small size-4 Songti font.

Note: For high-value fragile consumables such as equipment probes, precision optical lenses, and high-speed data acquisition cards used by various research groups, please be sure to strictly register and use them according to the school's financial system. Damage must be reported to the mentor and go through the depreciation compensation process.

Jiang Lin stood in front of the bulletin board, staring at the words probes and acquisition cards for a full two seconds.

Just at this moment, two boys wearing white lab coats and access cards hanging around their necks walked down the stairs, discussing something fiercely while walking.

"That Tektronix current probe of your group broke again? Old Zhou didn't scold people?" The slightly taller boy on the left looked sympathetic.

"It can't be said that it's completely broken, it's just that the zero drift is severe, and the measured noise is even larger than the signal."

The greasy-haired boy on the right with dark circles under his eyes irritably grabbed a handful of hair, "Old Zhou said not to rush through the scrapping process yet, and asked me to contact the manufacturer to see if it can be repaired. The manufacturer side said that just mailing it back for testing and recalibration once would cost this much."

He gestured with a hand sign.

"How much?" asked the tall one.

"Round-trip shipping plus testing and labor fees, nearly ten thousand. If the core amplifier chip inside is burned out and needs to be replaced with a new one, replacing the entire line starts at sixty thousand."

The dark-circled boy sighed, "Sixty thousand, ah, even if I put in all my direct PhD student stipend for two and a half years, it wouldn't be enough. Old Zhou's face is as dark as dripping water right now, and my lab meeting this week is going to be the death of me."

The two didn't stay, walking past Jiang Lin's back with sighs, their voices quickly disappearing around the stair corner.

Sixty thousand!

Jiang Lin stood in place, stunned for a moment.

In the capital market, this might just be an insignificant ripple.

In the ledger of a wealthy family, this is merely the pocket change for a bag or a watch.

But in the scientific research system of the Real World, this is a weight that an ordinary student cannot bear, and the direct price tag of an instrument failure.

A current probe with decent performance, sixty thousand.

A high-speed data acquisition card capable of capturing high-frequency transient signals costs a few thousand for a cheap one, and tens of thousands for a better one.

A graphics workstation capable of running complex multi-Physics field simulation software starts at twenty to thirty thousand even if it is second-hand and custom-assembled.

In addition to these, there are enterprise-class hard drive arrays, uninterruptible power supplies, various industrial-grade sensors, digital oscilloscopes, logic analyzers, precision optical mounts, constant-temperature shockproof boxes, and even processing fees for various special materials and cloud data service fees...

In the Real World, behind every parameter table, every probe, and every piece of code lies a clearly priced industrial cost.

Taken individually, each of these expenses can be given a reasonable explanation.

But if they are all combined, it is by no means an excuse that a high school student's breezy words about buying some study materials and hobby toys can cover.

Jiang Lin knew very well that if he went home now and told Jiang Jianguo that he needed sixty thousand yuan to buy a probe, his father would most likely be silent for a few seconds, then flip out his bank card and ask, "Is it enough?"

Parents' love is unreserved.

But precisely because of this, Jiang Lin absolutely cannot open this mouth again.

Some money can be given by the family; that is the selfless backing of parents for their children.

But some systems are destined to be gold-swallowing behemoths.

Once he decides to pull up a hard-core technology defense line of his own in this comfortable world, he must find an independently blood-supplying pump for this system.

He cannot suck dry his parents' blood to nourish his own ambition.

Jiang Lin turned around and walked out of the gate of Teaching Building No. 3.

The spring sunshine was still bright.

He walked east along the main road of the campus, passing through a row of tall phoenix trees, beneath which were densely parked students' electric bikes and shared bicycles.

At the end of the main road was Physics Building Block B, the core experimental building cluster of the School of Physics at Jiangda University.

Jiang Lin stood at the intersection without walking in.

He didn't want to go to the laboratory to find Professor Lu Zhixing today, nor did he want to squeeze himself back into any existing academic narrative.

On the department bulletin board by the road, various administrative and academic notices were posted.

Notice on the Conclusion Acceptance of Key Projects of the National Natural Science Foundation.

Supplementary Explanation on the Blind Review Stage of Doctoral Graduate Dissertations.

Poster for the academic report on Friday afternoon.

The topics on the posters, some were very close to his current direction, and some were very far.

Characteristic Analysis of Plasma Turbulence.

Nonlinear Dynamic Evolution in Complex Systems.

Parameter Inversion and Reconstruction Based on Sparse Observation Data.

Machine Time Allocation and Usage Training for High-Performance Computing Platforms.

Jiang Lin looked at these titles printed in boldface.

In the eyes of ordinary people, these terms were dry and boring.

But in Jiang Lin's eyes, these words were like locked steel gates.

Behind every door, what was locked inside was not purely Physics knowledge.

Behind the doors were connections, funding flow, equipment procurement rights, laboratory key permissions, access passwords for core data, authorship sequence in top journals, cumbersome ethical approvals, and malicious questioning and difficult replication by peers.

Modern science had long since been a heavy industry.

The Wasteland had given Jiang Lin endless time and immunity for trial and error, allowing him to build a theoretical palace belonging only to himself in his brain.

But the Real World would not give anyone the privilege of bypassing this set of organizational costs.

If you want to turn blueprints into physical objects in reality, you must abide by the rules of capital and industry.

Jiang Lin stood quietly at the intersection for a while, until the class bell echoed in the campus again.

Continuing to audit classes in the afternoon.

By the time he returned home, the sky had not completely darkened.

The afterglow of the setting sun penetrated through the window, dyeing the living room floor orange-yellow.

Mother was chopping vegetables in the kitchen, and hearing the commotion of the door opening, she poked her head out and asked, "You're back?"

Jiang Lin took off his sneakers, straightened them on the shoe rack, and said in a natural tone, "Yeah, went to Jiangda University to wander around today and audited a few classes."

"Oh, did you go find Teacher Lu?" Mother asked casually.

"No, just randomly found a few classrooms to listen in." Jiang Lin said while changing into slippers.

Mother gave an "oh" sound and asked no more.

The range hood in the kitchen soon emitted a low roar, and the kitchen knife fell on the wooden cutting board, making a crisp clatter.

The sound was regular, trivial, and filled with the atmosphere of life.

Jiang Lin returned to his bedroom, put down his schoolbag, and pressed the power button of the computer mainframe.

After the screen lit up, he skillfully created a new Excel spreadsheet.

The spreadsheet was renamed as: [Initial Budget for Study and Experimental Supplies V1.0]

He created six pages in the worksheet tab bar at the bottom.

Page 1: Professional Books and Literature Database Subscriptions.

Page 2: Basic Computing Equipment and Storage.

Page 3: Electronic Measurement and Signal Analysis Equipment.

Page 4: Machining Tools and Basic Consumables.

Page 5: Data Services and Commercial Software Licensing.

Page 6: Advanced Instruments That May Be Needed in the Future But Deferred from Purchase.

He clicked on the second page, his fingers tapping on the keyboard, and began to input specific entries.

Second-hand graphics workstation host, dual server-grade CPUs, ECC memory at least 256G.

Enterprise-class high-capacity mechanical hard drives, at least four pieces, forming a RAID array for data redundancy.

High-power UPS uninterruptible power supply.

Dual-screen high-color-gamut monitors.

Next was the measurement equipment on the third page.

USB protocol logic analyzer.

High-bandwidth simple portable oscilloscope.

Multi-channel voltage/current data logger.

Low-ESR solid capacitors, precision ceramic capacitors, ferrite magnetic rings of different frequency bands.

High-precision temperature and humidity logger.

Three-axis acceleration sensor.

Small high-sampling-rate data acquisition module.

...

At the very bottom of the table, there were a few items he set in gray font.

High-bandwidth passive current probes, high-voltage photoelectric isolation probes, NI high-end PCIe data acquisition cards, second-hand vibration-isolation optical platform accessories...

Looking at those gray rows, his eyes narrowed slightly.

That conversation heard in the corridor of the Physics building at Jiangda University today, that number about sixty thousand, made these gray items extremely glaring on the screen again.

He deleted them not because he wouldn't use them in the upcoming plan.

Simply because his current balance sheet could not support the expenses of these items even if they were second-hand goods.

Jiang Lin pressed the shortcut keys to sum up the estimated amounts of the first four pages.

In the cell at the lower right corner of the screen, a six-digit total amount popped up.

He looked at that number for a few seconds, then dragged the table to the right, finding a column he had preset earlier —— [Parent-Explainable Expenses].

Jiang Lin leaned his body backward, leaning against the back of the chair.

The sound of TV news broadcasting came from the living room outside the door; his father had gotten up.

Jiang Lin suddenly thought of how the last time he made the excuse of buying study materials, his father didn't even look at the list, only asking if the money was enough.

That unhesitating trust was never an ATM that could be infinitely overdrawn.

Nor was it a fig leaf for him to cover up his grand plan.

He moved the mouse and decisively deleted the entire column of [Parent-Explainable Expenses] directly.

Then, at the end of the table, he created a new page.

The page title was named: [Independent Funding Sources].

Then he opened the browser and typed a few words into the search box.

Online technical part-time jobs.

Mathematical modeling proxy writing, taking orders.

Science and engineering papers, computing outsourcing.

Scientific research drawing, proxy data writing.

Pressing the enter key, the page instantly popped up a massive amount of information.

Most of these web pages were filled with tempting advertising slogans, and the prices were also marked very eye-catchingly.

Jiang Lin expressionlessly clicked open a page ranked near the front, glanced through it quickly for thirty seconds, and then unhesitatingly clicked the cross in the upper right corner to close it.

Clicking open another post leaving a WeChat ID, taking a glance, and closing it again.

The academic gray industry on the internet was even more rampant than he imagined, and the demands were written extremely nakedly.

"Urgent order! Revision for a Zone 2 journal, requests modification of the model, conclusions must reach a significance level, price negotiable."

"Need a writer familiar with Python, adjust the data trend according to the target results I give, don't look at the process, only look at the charts."

"Graduation thesis data bottom-line guarantee, guaranteed revision until passing blind review, final payment upon completion."

Jiang Lin's gaze lingered for an instant on the words adjust data according to the target results on a certain web page.

Then, he moved the mouse and directly killed the entire process of the search page.

He was indeed very short of money, but not so short of money that he had to knead error bars like plasticine back and forth.

After a brief thought, Jiang Lin put his hands back on the keyboard.

This time, he changed to a completely different set of search terms.

Not papers, not academia, but things closest to capital itself.

Data anomaly detection, prize competition.

Financial time series, data cleaning, challenge.

Quantitative factor replication, bounty platform.

Backtesting systems, data leakage detection, crowdsourcing.

The result web pages of this search group became much more stern in style.

Gone were those fancy pop-up ads and the vulgar titles of easily earning ten thousand a month.

More of them were official announcements from quantitative investment platforms, hard-core discussion posts in geek technical communities, large paragraphs of all-English technical documents, archived pages of past data competitions, and some half-dead forums with low activity but extreme professionalism.

Holding the mouse, Jiang Lin searched page by page.

He was not looking for the most profitable way in the world.

The most profitable things in financial markets are always insider information and capital volume, not technology.

He was looking for an entrance.

An entrance that does not require reviewing academic resume, does not require showing one's face to sign contracts, and only requires using absolute technical strength to submit cleaning results and algorithmic reports in exchange for legitimate remuneration.

Seven-twenty-three in the evening.

Jiang Lin slid his fingers, and the image on the screen stopped in front of an inconspicuous page.

The UI design of this website was very crude, even somewhat like a product from ten years ago.

But right in the center of the page, below the title bar, hung a line of bold characters.

[Minute-Level Market Data Anomaly Detection Challenge (Phase III)]

Base bonus: 8,000 RMB.

Additional terms: Excellent contestants whose report logic is extremely rigorous and who can provide general audit scripts can sign a subsequent long-term part-time data audit cooperation agreement with the platform.

Jiang Lin's line of sight moved down, quickly skimming over the lengthy disclaimer, and landed on the core task description.

Task description: The organizer will provide desensitized minute-level market quote slice samples of the past five years from a certain market (containing a large amount of dirty data).

Contestants must use algorithms to accurately identify the abnormal fluctuation data segments among them, missing patterns caused by exchange interface issues, and underlying fields suspected of inconsistent forward/backward-adjustment calibers, and submit the cleaned dataset and method description report.

Scoring criteria are jointly determined by anomaly label recognition accuracy, consistency of cleaned fields, retained sample proportion, and manual report review.

A hidden test set is additionally set up to detect the stability changes of the cleaned data in benchmark factor replication experiments.

Next was the specific description of the data dictionary.

Timestamp.

Desensitized target code.

Open price.

High price.

Low price.

Close price.

Trading volume.

Trading turnover.

Suspension flag bit.

Re-adjustment flag bit.

Division of training window and testing window.

Jiang Lin looked at these lines of words representing the beating pulse of the capital market on the screen, looking at the so-called opening, closing, trading volume.

Suddenly, a strong and absurd sense of familiarity surged from the bottom of his heart.

This sense of familiarity had nothing to do with finance, wealth, or even the elite narrative of Wall Street.

This was his familiarity with those temperature sensors that went on strike in extreme cold storms.

It was his familiarity with radiometers undergoing zero drift due to cosmic ray interference.

It was his familiarity with Poisson noise generated by cameras under absolute dark fields due to thermionic transitions.

It was his familiarity with optical mounts slowly undergoing thermal expansion and contraction deformation during the alternation of day and night temperature differences, causing all interference readings to bias to one side the next morning.

Many people say data does not lie.

Jiang Lin proved with bloody lessons on the Wasteland that this sentence was utterly wrong.

Data often lies.

Not only does it lie, but it also disguises itself as truth to guide you toward destruction.

A more accurate physical expression should be that data will absolutely honestly record all problems during the operation of a complex system, including the laws of the system itself, the defects of the measuring instruments, the interference of the environment, and the loss of the transmission channel.

It's just that humans often mistakenly believe that data only records that part of the ideal state they want in their minds.

In this desensitized financial time series, those so-called abnormal fluctuations, missing data, and inconsistent calibers were, in Jiang Lin's eyes, nothing more than the noise floor, probe drift, and transmission packet loss generated by quantity-price detectors in this complex system named the market.

The mathematical structure and physical essence behind them were identical to the mess he had handled for decades on the Wasteland.

Outside the bedroom door, mother's voice penetrated through the door panel, carrying the aroma of food.

"Jiang Lin, come out to eat."

"Coming."

He didn't immediately close this crude webpage.

The mouse cursor hovered over the blue [Download Dataset (3.4 GB)] button at the very bottom of the page.

Beside the button, there was also a line of small red countdown text.

Distance to submission deadline: 4 days.