"Hogwarts, with a total population of 1230, 80% of whom are students..."

"This is where the most cutting-edge knowledge of human civilization converges. In other words, it can be said to be an academy and research sanctuary standing at the very pinnacle of human civilization. Barring any unforeseen circumstances, Hogwarts' knowledge is at least two or three decades ahead of the rest of the world..."

"As everyone knows, Hogwarts is the safest place in the entire magical world, and even the world at large..."

"In order to protect the spark of civilization and safeguard underage wizards, Hogwarts has a complete system of law and order..."

On the speeding Hogwarts Express, Erina introduced the school to the first-year students who hadn't yet enrolled with a smile on her face. In the air, a slightly reduced three-dimensional holographic image of Hogwarts Castle gradually took shape.

And on the left breast of the girl's robe, there was a shiny silver letter "p" – the Hogwarts Prefect badge.

Prefect, is a student appointed by the Headmaster of Hogwarts School of Witchcraft and Wizardry or the Heads of each House, and is granted special rights and responsibilities. Each House will select a boy and a girl from the fifth year to serve as prefects, and they will continue to hold this position until they graduate. Therefore, each House will have 6 prefects at the same time, for a total of 24 in the whole school.

On the other hand, the Head Boy and Head Girl are usually selected from among the prefects and are not replaced.

Logically speaking, Erina was still a little short of the standard in terms of age and academic qualifications.

However, considering that Erina had completed all written exams from the first to fourth years in advance and received all As; in addition to simultaneously serving as assistant professor of Potions, Hogwarts head chef, and Hogwarts special consultant for curriculum reform; plus the advice of some school faculty members, Dumbledore and the four House Heads discussed and finally decided to appoint Erina as the new prefect in an exception.

Unlike the badges of other prefects, which are based on the representative colors of their respective Houses, Erina's is a bit more special.

As one of the few students with multi-house uniforms, the background color of the badge on her chest is not a single color, but is divided into four badges like the Hogwarts school badge with the pattern removed – however, the blue pattern that symbolizes Ravenclaw is still blank at this time, which makes Erina somewhat regretful.

Of course, this is also a matter of course.

After all, no matter from which aspect, Erina and Ravenclaw don't have much to do with each other.

Ravenclaw's common room welcomes any erudite and wise wizard, but that doesn't mean that wizards with extraordinary wisdom should belong here, even if Erina knows the secret of the knocker, she can't really become a Ravenclaw.

Unless... time goes back to the Sorting Hat threatening at the start-of-year feast a year ago...

"Erina? Oh, so you're in this compartment. Has the freshman induction not finished yet..."

Just as Erina was slightly distracted, the door of the compartment suddenly opened.

Then, a girl with thick brown hair walked in - Hermione Granger.

Hermione Granger first curiously looked at the little guys in the room, then turned her head to look at the white-haired ball of fluff. Before Erina could ask, she shrugged helplessly and took the initiative to explain.

"The room numbers you gave me earlier were wrong. One of them is Luna's compartment. After I lost at rock-paper-scissors, all the new students over there belong to her now, so I came over to see if there's anything I can help with?"

"Luna? Oh... that's right! I almost forgot, Luna is officially enrolling this year."

Erina looked at Hermione, who suddenly appeared at the door, was slightly stunned, and nodded in realization.

"In that case, it just so happens that my introduction is almost finished. Let me leave the following freshman trials to you. I only have two compartments left, and we'll go back together later."

"Yeah, yeah, yeah, Erina, go quickly. The boys should be almost finished."

"Remember--"

"I know, I know, don't worry!"

Hermione nodded quickly. Before Erina could finish speaking, she half-pushed and half-drove Erina out the door, patted her chest confidently, and replied excitedly - she had practiced for a long time for this day.

"Okay, then see you later..."

Bang!

As Erina's figure disappeared outside the door, the door of the train compartment closed again.

Only Hermione Granger and four bewildered first-year students remained in the room.

Hermione glanced at the confused freshmen, cleared her throat, straightened her face, drew her wand and waved it flexibly in the air, revealing a string of magical characters, while imitating Professor McGonagall's tone she said softly.

"Freshmen, welcome to Hogwarts - I am Hermione Granger from the second year of Gryffindor. I will take over the freshman admission trials and teaching work. According to Hogwarts tradition, before you are sorted into Houses, there is a small magical trial. Of course, don't worry, this will not affect your life at school afterwards..."

As Hermione spoke, a trace of nostalgia flashed in her eyes, and she smiled slightly.

"In the following time, I will teach you a basic spell that all wizards must master. From now until the train arrives at Hogsmeade Station, you have a whole day to practice--"

Her gaze roamed among the freshmen, raised her wand, and said with a smile.

"Now, please draw your wands and follow my movements to chant together..."

…………

At the same time.

Next to Hogwarts Castle, Academy City, Zone A.

"Lumos!"

Accompanied by the clear incantation, a soft white light appeared at the end of the wand.

Then, like a light catkin, it floated out of the wand, swaying in the air.

"Unbelievable, you shattered the beliefs of those guys in the Vatican for life... creating light out of thin air with just your mind, is this the legendary magic? It's so amazing! So interesting!"

Kolmogorov said with admiration as he looked at the light ball in front of him, gesticulating wildly.

As the last batch of scholars to evacuate from the former Soviet Union, if one put aside the series of transfers and placements yesterday afternoon, strictly speaking, this was almost Kolmogorov's first official contact with the magical world.

"This is just the most superficial magic. Any wizard can easily cast it."

Gellert Grindelwald grinned and replied elegantly, with a hint of well-hidden contempt in his eyes.

If it weren't for Erina's request, and the fact that these Muggles had used their once-a-month right to seek the most advanced wizarding wisdom to solve some problems that had plagued them for a long time, he wouldn't have bothered to come.

"Is there anything else? This ball of light can last all day, you can study it slowly..."

Grindelwald glanced at the group of startled Muggles, took out a contract and placed it on the table, knocking it lightly.

"If there's nothing else, please sign and confirm this letter of commission - and write down the contents of your research topic, otherwise, that little girl won't acknowledge it..."

According to the agreement he had discussed with Erina, whenever he completed an "sss-level" academic commission, he could make a reasonable request to Erina—this included even some not-so-excessive requests.

Of course, if he took on the task and failed to complete it in more than half a month, then he owed Erina a wish.

"Uh, wait, Mr. Apokalypse... there's one last small step, a small detail that needs to be completed."

Kolmogorov scratched his cheek a little embarrassedly, gesturing with his thumb and index finger.

The middle-aged scholar suddenly stood up and exchanged an excited look with several colleagues around him. Together, they pushed four or five mobile blackboards filled with various numbers and formulas in front of Gellert Grindelwald.

"You see, you are now using magic to create light in a three-dimensional world. According to what you said before, wizards only need to use their thoughts to complete it when casting magic. You also know that light has speed..."

"That's right, so? Do you need me to help you calculate it?"

Grindelwald frowned impatiently, glancing at the blackboard in front of him.

Kolmogorov drew a large cross arrow on it, with time written on one side and space written on the other, and drew a long graph from the zero point outward, marked with a string of numbers.

"No, no, we already know the speed of light..."

Kolmogorov rubbed his hands and looked at Grindelwald expectantly.

"This is the space axis, this is the time axis, you might as well imagine the light spot you created as a line traveling fast on it. I remember you said before that magic can produce different wavelengths, I mean beams of different colors..."

"That's right, it's not difficult, so what color light spot do you want?"

Grindelwald raised his eyebrows slightly, and said slowly, raising his wand.

Kolmogorov shook his head quickly and pointed to the long line of formulas and graphs beside him.

"No, don't be so complicated—first take a close look at these formulas and inferences, and then try to exchange the time axis and space axis in your mind, and let the speed of light return to zero. In short, cast a light spot to see what effect it will have..."

???

Grindelwald's wand froze, and he turned his head with a confused expression.

If it were a transfiguration charm, or a slightly more advanced *Lumos* charm, he would be very clear.

But...

Transforming the space axis and the time axis? Making the speed of light return to zero?

What was this Muggle talking about... some kind of strange foreign language?

Looking at the silent wizard, Kolmogorov blinked and explained after thinking about it.

"Well, that's right, it's actually flattening this light cone—this shouldn't be difficult for you to understand, right? It's actually just thinking about it, this conceptual thing, it may only be possible to reproduce with magic after careful thought."

"???"

The corners of Grindelwald's mouth twitched. After a few seconds of silence, he said slowly,

"About this matter, I need to prepare a little bit. Magic is not as simple as you think. How about you change the request today? For example, help you become a few years younger temporarily, or..."

"Sorry, Mr. Apokalypse, if it's about personal needs, we don't need it."

Kolmogorov sighed a little disappointedly, and thought about it and said.

"Why don't you go to Academy City B and take a look? I remember Mr. Alexei and the others over there also seem to have a simple little problem that needs to be solved. They seem to want to know why measurement destroys quantum wave functions--"

"...I see, I understand."

Grindelwald raised his hand, crossed out the [Lumos Charm Improvement Commission], and said expressionlessly.

If there were no surprises, he should now start considering how to fulfill the little girl's wish.

No wonder Albus had a strange look on his face after hearing that he had accepted the commission. The ideas in these Muggles' heads are so crazy. Fortunately, he doesn't have to take Muggle classes this year like those poor students.

Hopefully, those little guys at Hogwarts won't cry too loudly this year...

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