Although it is very eye-catching, the dome itself does not like to be too public. Even if she could even have her own chauffeur if she wanted to, she would rather walk. The same is true in everyday life.

This is not for common reasons such as humility or low-key, but because by the nature of her personal preferences, it is difficult for her to take an interest in things that are not necessary. It has nothing to do with good morals such as frugality, it is simply a lack of interest in wasteful consumption.

Therefore, when she needs to take such a luxurious RV, she will inevitably feel a little awkward.

Turning his head to look at Haiyuan Mitsugui, he looked accustomed to it. Thinking about it, this is probably a matter of course, although my brother also has no habit of publicity, but I am afraid that he has been picked up more or less like this. After all, he is not usually used to flying by himself like himself.

Moving his body to the inside of the back seat, his usually relaxed behavior is a bit troublesome because he is wearing a yukata.

Suddenly, she noticed that there was a postcard in the seat she was about to sit in. A postcard from April 30.

Who left it in the car?

This thought only turned slightly in his mind, and he was driven out by the dome. In any case, two months have passed from the time on the postcard, and it is impossible for the car to have not been cleaned during this incident.

I'm afraid there is some other reason.

Dome picks up the postcard, which depicts a dark forest with only one path running through it. And at the end of this path, under the starlight, there is a silhouette of a little boy.

Above the starry sky is a text written:

"The Night of Valpurgis (note 1), the beginning of the birth of light and darkness."

("A night in Valperges?") ”）

For this term, Dome is surprisingly not unfamiliar. I remember that it was the legendary time of the year when witches and wizards gathered. At the first Solvay conference, Albert Einstein used the term to refer to a period of confusion in quantum mechanics. It was almost after this meeting that the H demon, who had been entangled with Einstein all his life, officially stepped onto the stage of history and opened a mythical era.

But obviously, this postcard can't have anything to do with the great scientist.

The pouting Dome flipped the postcard over, and on the back of the postcard, a fairy tale was written:

"On the last day of April, on a cold and extraordinary night, a lumberjack and his son came home through a dense forest, collecting the fallen firewood along the way, so they each walked on different paths. The forest is easy to get lost, so the lumberjack asks his son to take a path parallel to him.

However, when the child checked the lantern in his hand, he accidentally stepped on the flowers that Valperka had planted with his own hands. The Saturnalia was furious, and she called on the witches of the revelry to rule the land.

So, from where the boy stood, countless paths stretched out, but farther and farther away. The lumberjack shouted: 'Son, where are you?' Are you still on the same road as me? But the boy could only look at the starry sky above his head, and he could not go any further.

Whispers came from the forest, telling him that his father would never find him again. ”

It's very short, even a very simple story. Dome looked at the card, her expression a little stiff.

This story, which reads a little sad and even has some dark fairy tale overtones, is naturally the first time she has seen it. But for her, the secret hidden within her was all too familiar, and it was almost the mathematical basis of her abilities. Moreover, it is currently at odds with that H demon.

A title used by Albert Einstein to describe quantum mechanics is related to the mathematical foundations of general relativity? This strange feeling made her feel like she didn't know what to say.

(Huh?) Speaking of which...... ）

Suddenly, a thought crossed her mind.

If the story feels weird to her, isn't she weird herself?

As we all know, the theoretical basis for superpowers comes from quantum mechanics. But she seems to be an exception?

Although the level of competence has recently been increased through the correction of string theory, it is related to quantum mechanics. But for most of the previous period, the only basis for her abilities was general relativity, which was incompatible with quantum mechanics.

And this didn't affect her ability to use, not in the slightest.

In other words, within the school city, her ability seems to be a very unusual, even unusual case that can't be explained by the ability principle of other abilities?

"What's going on?"

Because her movements suddenly stopped, Mitsuki Umihara asked.

Dome handed over the postcard, and Mitsuki Umihara looked at the contents on it, unconsciously revealing some wonderful expressions.

"It's kind of interesting."

Although he is not as good as Dome Nai, his mathematical level is not bad either. And unlike Dome Nai, he was more knowledgeable than his sister in some ways.

Say, history.

(Huh?) ）

Pinching his fingers, he noticed something unusual on the postcard. Applying a slight telekinetic force to his fingers, suddenly the upper layer of the postcard "snapped" and opened, and a colorful sphere shimmered with star-like points of light, jumping out of the inside with the flipped card.

Of course, this is not some strange mechanism. The kind of ancient greeting card that will have a three-dimensional pattern erected after opening it must have been played by many people when they were children, right? This postcard, in fact, is something like this.

It's just that the complex structure is folded in a piece of paper that is not thicker than an ordinary postcard.,It's not something that can be seen outside of the school city.。 And this glowing speck constitutes the sphere of the image, which is not comparable to the rough "cardboard house". It's better to say that, in addition to the color, just from the appearance, it already looks like the three-dimensional star map in science fiction movies. When the card is opened, it "swells", and even that is very much like the universe itself.

I'm afraid that the material of this postcard is the same as the books in my study. As for those that glow on the spheres, they are supposed to be patterns on the surface of the postcard, with micro-power generation and storage modules that use solar energy to pass nanometers inside the fibers.

However, although it is generally possible to guess what is going on, even if the labor cost is excluded, these materials are not cheap except for the fiber itself. Haiyuan personally estimates that the cost price of this postcard alone may be enough to make people with abilities below LV.3 faint.

But there's a bit of tradition about it.

On the card at the bottom of the coloring ball, someone wrote a word by hand - "May 1st." Then, an upward arrow was drawn.

No matter how you look at it, it's all from my mother's handwriting.

"This kind of funny thing ......"

I'm afraid it's the kind of game their mother loves to play.

I wanted to say this, but he noticed that his sister's eyes seemed to brighten up all of a sudden, and Mitsuki Kaihara immediately took the words back.

Dome did have a reason to be interested, and she stretched out her finger and ran her finger along the longest red band of light on the orb.

It was the first ray of light at the birth of the universe, a panorama of cosmic microwave background radiation.

In other words, on this postcard, the entire universe was carefully engraved at the beginning of its existence.

Seeing that she seemed to like it very much, Mitsuki Umihara asked her to open her palm and put the unfolded postcard on her hand.

It looks like a girl is holding the entire universe in her hands. It's a wonderful look in every way.

"Miss, let me make a suggestion." From the driver's seat in the front seat, the voice of the driver, who made Mitsuki Kaihara a little concerned, said, "If you're ready, please fasten your seatbelt first." ”

"Ahh Yes. ”

Dome immediately folded his hands, enclosed the postcard's panorama of cosmic microwave background radiation in a narrow plane, and then fastened his seat belt as the driver instructed.

At this time, Mitsuki Haihara suddenly remembered something.

"By the way, I was forgotten by my mother just now. Now that you've seen Jinyi, I have something to ask you about her. ”

"Huh?"

The dome habitually tilted his head.

"You used to know Jinyi well, did she have a habit of writing a diary?"

"Keeping a diary? I don't know much about it. However, even if you had, you wouldn't write a diary in front of your friends, would you? ”

Not quite understanding the meaning of the question, she answered according to common sense. However, it is clear that Mitsuki Umihara is not too happy with this answer.

"I don't mean an ordinary diary, I mean a detailed diary. In other words, as long as something happens, it will find a way to record it as soon as possible. For example, use a mobile phone or mobile terminal to record anytime and anywhere. ”

Dome closed her eyes and recalled.

"No, that shouldn't be. At least I never saw one. ”

"Really......"

"Well, brother, what's wrong with that?"

"My position is not convenient to say anything. First of all, how is your relationship with beeeaters? ”

Although he was quite puzzled as to why the topic suddenly turned to the head of the bee-eater, Dome thought about it and answered honestly.

"It's not bad, but that's about it. It's friendly, but it's nowhere near the level of a good friend. ”

For some reason, the corners of Mitsuki Haihara's mouth twitched. It seemed like he wanted to say something, but in the end he didn't say it.

"If you have time, you can ask her what this behavior represents."

Mitsuki Haihara, who said so euphemistically, finally said "safe journey" and closed the car door.

_

The luxury RV is unusually smooth on the road of the school city.,Even in addition to the scenery of the rapid retreat outside the window.,It gives people the illusion that they are not moving forward.。

Night has fallen.,Shrouded in the school city.。 The stars, which are usually invisible due to the bustling light pollution, are now clearly visible today due to the fact that some of the lights are turned off during the fireworks show.

I remember never complaining that light pollution made it impossible for her to make astronomical observations, but this is probably one of the inevitable contradictions brought about by the development of science and technology.

Dome didn't care too much about this. Although it was a pity that she could not see the starry sky at night, she knew that the real starry sky was far from being comparable to what she saw on Earth.

You can't even observe it with the naked eye, you can only feel its splendor and magnificence in the mathematical model.

Thinking of this, she flipped through the postcard again. Even such an elaborate diorama cannot encapsulate the real starry sky, the real universe......

"Huh?"

Suddenly, she saw the bottom of the card holding the coloring ball, and on it was written a date in Juan Xiu's lettering - "May 1st".

Undoubtedly, it was the mother's handwriting. What is this to do?

Sometimes, my mother would often joke with her siblings in the form of puzzles. If they come up with the answer, they will also be rewarded. Although it should be just a fun game for their mother, the siblings are happy to use their mother's games as a pastime.

If you look closely, below this row of text, an arrow is drawn. The arrow is pointing straight down at you.

I guess it's not me, right? So......

Thinking about the second option in turn, Dome reached under his seat.

“！”

A safe with an electronic combination lock (only any numbers and mathematical symbols can be entered) was found under the seat.

The car is really luxurious, and even this kind of thing that has only been seen in movies is equipped.

No, that's not the point to be emotional. If it's the kind of game that mothers love, then there must be something in the safe as a reward. As for the password, she should have already been told.

The question is, what exactly is a password?

And just like that, Dome began to think about the mystery left by his mother. She was supposed to get to the place she had agreed with Mai Trin as soon as possible, and even hoped for a moment that the car would drive slower so that she would have enough time to crack the game.

=======================================

Note 1: The famous "Walpurgis Night", the following passage is said to be one of the legends about the night of Walpurgis, and I believe that everyone in this article should be able to see what is hidden in this story. But what I'm really trying to say here is this: the story is probably about a millennium before the establishment of non-Euclidean geometry.

What does this mean? Actually, it doesn't say anything. This story doesn't prove anything, and it doesn't build a theory. So strictly speaking, it can't belong to the category of mathematics, it's a story that belongs to the old mysticism. However, it can at least illustrate that human beings often start thinking about a problem much earlier than it ends up being an outcome.

Perhaps as most people know, non-Euclidean geometry is a concept that was not recognized until the 19th century, but this is not the case. In the field of science and mathematics, absolutely no achievement appears in a vacuum. A large number of historical studies have proved that mankind has been thinking about this problem for more than a thousand years before non-Euclidean geometry was established as an important branch of mathematics in the 19th century.

Unlike what many people think, the ancients were not ignorant. Many concepts in modern and even modern science have been thought about by humans since an unimaginable time. The results of these reflections are almost universally present in those legends that have survived to this day, in the occult. In the age when the tools of science were not yet formed, the occult was arguably the most preserved of scientific thought. Whether it's alchemy, astrology, or a lot of what we now become superstitious. Although the theorization of science has led to extraordinary achievements with the advent of scientific tools (especially mathematics), we no longer need to retrace those blank years, and we have long since buried the occult in the grave of history (it is undeniable that the occult should and has been eliminated). But I never thought that the occult was in the dustbin of history. It should be respectfully buried in the cemetery **** people who look back on history, not discarded like garbage). But when we pass by the cemetery of the occult, please pay that due respect. Because it is an undoubted spark of light in the confused and dark period of human exploration of science. Of course, after that, be sure not to stop. Because it is only a spark of the past worth remembering, not a truly glorious future.