He changed Tiwat

Meeting the expectant gazes of the two, Han Fulai solemnly placed his hand on his chest, making the gesture most often used by their Yuehaiting secretary—he usually made this gesture when fooling the Seven Stars, such as a certain Yuheng Star—but this time it was not "fooling".

"What I'm about to say may be hard to understand, or it may sound very strange, but I hope... no, I ask that you two trust me unconditionally and believe every word I say. You could say that the key to everything lies in the 'heart of belief'—the value of a 'dream' lies in those hearts that believe in 'dreams'."

Both the shadow and the divine child nodded.

Han Fulai took a deep breath and said slowly, "As I just said, I need the General to slash the Divine Cherry Tree with a 'thoughtless strike' at the end of the exorcism ritual."

"But the purpose of this strike is not to cut the Divine Cherry Tree in two like the 'Musou Blade Hazama'. Nor is it 'destruction' in the usual sense."

"To be precise, the significance of this cut lies in 'wiping away'."

"I need the General to use the 'Unthinking Slash' to 'erase' this cherry tree corrupted by Evil Sun from Inazuma's 'timeline'—in the words of my world, this is called 'delayed-choice quantum erasure'."

Chapter 252 The Future Changes the Past [4k]

The so-called "delayed-choice quantum erasure" is a famous experiment on quantum mechanics on Earth.

It can be seen as a super-powerful upgrade of the "double-slit experiment", or it can be said to be one of the most "counterintuitive" experiments in quantum mechanics.

The basic "double-slit interference experiment" involves passing a beam of light through two parallel slits. Under normal circumstances, the light will appear as alternating bright and dark stripes on a piece of cardboard behind the slits, showing the ripple characteristics of water waves; however, if we install a phonograph behind one of the slits to observe the state of the light as it passes through the slit, it will appear as individual particles—that is, the "wave-particle duality" of light.

After conducting the "double-slit experiment," physicists summarized the pattern: when photons are observed, they exhibit particle-like properties (interference fringes disappear); when they are not observed, they exhibit wave-like properties (interference fringes appear).

After identifying the patterns, physicists naturally conducted more in-depth research. They began to wonder: what would happen if the "observation" were performed after the "appearance of interference fringes"?

For example, when a photon passes through a slit and hits the photosensitive plate, it still needs to travel the few meters along the way. Even traveling at the speed of light, it still takes a little bit of time.

What if people removed the photosensitive plate and replaced it with a camera before the photons hit it?

According to the principle of wave-particle duality, light appears as ripples when it hits a photosensitive plate before being observed, but it becomes particles when observed by a camera. If scientists are fast enough to remove the plate before the photons reach it, the photons will definitely change from waves to particles.

This is the origin of the "delayed selection experiment," where "delay" refers to the delayed observation.

People are preparing to "trick" and "ambush" the photon after it flies through the slit, laying an ambush to see if it will really suddenly change from a wave to a particle.

The idea is good, but the problem is that no scientist in the world has the "hand speed" to exceed the speed of a photon, so this experiment is simply impossible.

But just like 1+2=2+1, the process can be changed, as long as the result is the same. A clever person can always find a solution by changing their approach.

Therefore, the scientists designed the following experimental plan:

The experiment consists of a laser beam, two beam splitters, two mirrors, and two detectors.

A beam splitter is a thick piece of glass with silver plating on one side. It can split an incident beam of light into two beams, one of which is "reflected" and the other is "transmitted".

It divides the laser beam into two paths, one above the other, so that light traveling on different paths will enter different detection instruments.

In this way, scientists upgraded the "double-slit interference" device. The two paths, one above the other, are equivalent to two slits, and the second beam splitter in front of the detector is equivalent to a photosensitive plate, which can be mechanically controlled and removed at nanosecond speeds.

When a photon passes through beam splitter 1, there is a 50% chance that it will be "reflected" and travel along path 1; there is another 50% chance that it will be "transmitted" and travel along path 2.

This probability is theoretically "true random," and no one knows whether the photon will take path 1 or path 2.

In other words, the path information of the photon is kept secret; it is neither determined nor observed.

According to the wave-particle duality, a photon will appear as a wave when it is not observed, so it will "transmit" through the beam splitter like a wave and fly toward Detector 2.

Yes, that's exactly what the experiment showed. No matter how many photons the scientists emitted, as long as their path information was kept secret, they would always fly to Detector 2, and Detector 1 wouldn't receive a single photon.

Then scientists started "ambushing" photons.

As the photons flew toward detector 2, they suddenly removed beam splitter 2, which served as the "photosensitive plate." Then, something strange happened: after the "photosensitive plate" was removed, the photons instantly changed from "waves" to "particles," hitting detectors 1 and 2 with a 50/50 probability that perfectly matched mathematical predictions.

In other words, after passing through beam splitter 1, the photons, which were originally "waves," were "changed" and became "particles" because humans removed the photosensitive plate.

It's as if the photon, which was in the form of a "wave," traveled back a few nanoseconds and appeared in the form of a "particle."

Once scientists put the photosensitive plate back on, that is, "erasing" the path information during the particle's flight, making the photon's flight path "unknown," it becomes a wave again and will only fly into detector number 2.

Later, scientists expanded the scale of this experiment to the Earth's orbit. Using ground-based telescopes and artificial satellites, they made the photons travel a distance of 3500 kilometers—even a photon takes 10 milliseconds to reach the "photosensitive plate" in the satellite.

10 milliseconds is an error range that a human can measure with a regular stopwatch, and it's also a very intuitive piece of data.

The experimental results are consistent with those at the nanosecond level—the "delayed selection experiment" can change the photon form 10 milliseconds in advance.

By the same token, even if a photon travels a distance of 1 million light-years, and then the "photosensitive plate" is removed at the last second, the photon will instantly change from a "wave" to a "particle," altering its past self.

This experiment completely violates the concept of "locality" in physics.

"Locality" is a fundamental law of classical physics, which means that the influence of anything is local and has a propagation speed.

Like dominoes, pushing the first domino in front of you can cause the hundredth domino, which is ten meters away, to fall. However, the fall does not happen instantly. The force of pushing the domino can only be transmitted to the hundredth domino, which is ten meters away, after the ninety-nine dominoes in the middle fall one after another.

The existence of these ninety-nine dominoes embodies the concept of "locality"—a falling domino can only affect dominoes within a certain range, and the force needs to be transmitted layer by layer, taking a certain amount of time to reach distant areas.

Human daily life is also built on this kind of "locality".

For example, if a mother calls her child to eat in the kitchen, the mother must speak first for the sound to travel through the air to the child's ears before the child can hear her; or, for instance, if the sun suddenly explodes, humans on Earth cannot immediately know about this explosion and must wait eight minutes—because it takes eight minutes for light to travel from the sun's position to Earth.

Similarly, "locality" applies to everything in human cognition: nothing in this world can happen "instantly".

There must be a cause before there is an effect, and the fastest speed from cause to effect is the speed of light—because there is nothing in nature that can exceed the speed of light.

The sun must have exploded first. Only after the light travels eight minutes through space to reach the human retina can we receive the information. Even if we placed a sensor inside the sun, it would still take eight minutes for the sensor's radio waves to travel back to Earth.

Humans will never know this at the moment the sun explodes.

Light needs time to spread, heat needs time to conduct, seeds need time to germinate, children need time to grow up... "Locality" is the sacred and inviolable "law of causality".

However, the "delayed selection experiment" overturned the concepts of "locality" and "causality".

Photons can change their form in an instant, exceeding the speed of light, and can even alter history from millions of years ago...

This is what quantum mechanics means by "the future changing the past".

The instruments and theories used in the "delayed choice experiment" are things that are difficult for the people of Teyvat to understand—in fact, even with the mathematical and physical foundation accumulated by Han Fulai, a modern university graduate, it would be very difficult to fully understand the experimental design.

Fortunately, he didn't need to make Shadow and Divine Child fully understand the principles of the experiment; all he needed was the conclusion of the experiment.

"In short, 'erasing' the Divine Cherry Tree can alter causality. Or rather—the future can change the past," he said to Shadow and Divine Child.

His "in short" statement simplified the tens of thousands of words of quantum mechanics paper and experimental data, only showing the conclusions to Shadow and God.

He could see the confusion on their faces, but he really couldn't explain the principles to two complete novices in quantum mechanics.

This is also why he requires the two of them to trust him unconditionally and believe every word he says.

He's like a middle school politics teacher now; there's no need for students to understand the political principles, just to memorize the knowledge points in the books.

As for whether those knowledge points are correct or not, students will naturally understand once they enter society and enjoy the blessings they have received.

Whoever can solve the problem, the people will follow. The people of Inazuma who raised the banner of rebellion against the shogunate five hundred years later understood this principle best.

The key is to instill in the Shadow and the Divine Child, especially the Shadow, the concept that "the past can be changed"—the "observer" must possess "will" and use "will" to change the world.

Of course, not every student can listen to a teacher's lecture. Although he asked Shadow and Divine Child to believe him, no one can lie to their own conscience.

In order to give them the "will" to change the world, he had to instill this idea more deeply into their hearts, so that they would genuinely believe that they could change the past and change the world.

Whether it succeeds or not depends on Teacher Han's eloquence.

Han Fulai forcibly ignored their confusion and continued, "I know you can't believe this conclusion right now, but facts always speak louder than words. This 'suddenly appearing' divine cherry tree represents the existence of this fact—Inazuma's history has already been altered once by Raiden Shin, using this divine cherry tree."

“Think back carefully. If this Divine Cherry Tree did not exist, the ley lines of Inazuma would have been contaminated by the ‘Dark Calamity,’ and Inazuma would have been destroyed before the General could return from Kanria.”

"But things just happen so coincidentally. There is a sacred cherry tree in Inazuma that has been there for thousands of years. It has never played any role in these thousands of years, at most allowing greedy foxes to make wine and eat petals... But when the 'Dark Calamity' came, it suddenly gained the ability to absorb filth—as if it had been waiting here for thousands of years, just to show its power at that moment and protect Inazuma."

Ying's expression changed from blank to thoughtful.

The suddenly appearing Divine Cherry Tree did indeed protect Inazuma during the "Dark Calamity" and continued to suppress the disasters left behind by the "Dark Calamity" in the years that followed—it seems that it really only existed for the "Dark Calamity" and had only this one purpose.

Ying still remembers that she once launched the "Hunting for Famous Things in the World" for her sister, searching for rare and precious tea sets from all over the world.

The artisans of Inazuma sent tea sets made of all sorts of rare and precious materials to the castle tower, including wooden, pottery, stone, and even all sorts of inexplicable materials.

Even rare minerals from the deep lava abyss of Liyue were crafted into "Yohen Tenmoku Tea Bowls" and delivered to her—but the Thunder Cherry Trees of Inatsuki's homeland, and the Divine Cherry Trees of Narukami Shrine, seemed to have never been used as materials by artisans.

Similarly, in the past few thousand years, Inazuma has never produced any utensils made from the branches of the Divine Cherry Tree, such as a Divine Cherry Tree sword sheath or hilt...

The "Lightning Five Transmissions" technique requires the use of "evil spirits" to create swords, and the branches of the Divine Cherry Tree are an excellent material to counteract "evil spirits." Logically speaking, someone should have thought of using the Divine Cherry Tree's ability to absorb filth to create these items.

However, the truth is, no.

As far as a tree is concerned, the use of the sacred cherry tree seems too "professional".

"Also, the 'Great Purification of Divine Cherry Trees' ritual appeared quite suddenly." Han Fulai then turned his gaze to the priestess. "Priestess, you are the priestess of Narukami Shrine, in charge of all the festival rituals of Inazuma. But besides the 'Great Purification of Divine Cherry Trees,' has Narukami Shrine passed down any other festival rituals that use the divine cherry tree?"

His question stumped the divine child.

As the chief priest of the shrine, Inatsume knew all the rituals of the festivals that had been passed down for thousands of years by heart. But no matter how hard she racked her brains, she couldn't find a single ritual that used the sacred cherry tree other than the "Great Purification of the Sacred Cherry Tree".

Even using branches of the Divine Cherry Tree as a "talisman" to suppress the "evil spirit" of Hachiyū Island was a use she only discovered after becoming the High Priestess. Prior to that, only during the "Dark Calamity" era did Master Saigu temporarily create the "True Meaning of Kagura" she held using branches of the Divine Cherry Tree…

But this shouldn't be happening.

In the princess's memory, the sacred cherry tree was truly a sacred tree planted by Narukami himself on the day he came to Inazuma, and it held unparalleled symbolic significance for the people of Inazuma...

Then Inazuma should also have some kind of rituals performed for this sacred tree.

For example, a "Divine Cherry Blossom Festival" like the "Radiant Splendor Festival"... However, the truth is, there isn't one.

If we consider the history of Inazuma as a light novel, and the "Dark Calamity" as the great demon that the protagonist must face—

The so-called "divine cherry tree has existed for thousands of years" is more like a "background setting" to make its existence seem less abrupt.

Because Inazuma was unable to resist the "Dark Calamity" Demon King, the author temporarily added the setting that Inazuma "possesses a divine cherry tree that can fight against filth," giving the protagonist a weapon that can fight the Demon King.

...When the light novel authors of "Yaedo" encounter a story that can't be explained, they will come up with this kind of "deus ex machina".

Thinking about it this way, this divine cherry tree is just a "deus ex machina" concept!

Chapter 253 The Pen to Rewrite History Has Always Been in Your Hands [4k]

Seeing the change in their expressions, Han Fulai knew that they had begun to actively consider the suspicious points about the Divine Cherry Tree and the possibility that "Inazuma's history was once changed by Raiden Shin".

The cheesy films of this era had only just begun to touch upon the suddenly appearing divine cherry tree, and were in a state of "half-believing, half-doubting" about its existence. On one hand, she doubted whether her memories might be wrong, and on the other hand, she thought that as long as the divine cherry tree could protect Inazuma, it didn't matter if it appeared out of thin air...

The Divine Child, however, always believed that the Divine Cherry Tree had existed in Inazuma "since ancient times," even though the movie had once told her that the Divine Cherry Tree didn't exist before. Subconsciously, she still felt it might be a problem with the movie's memory. After merging with the Divine Cherry Tree, she even read the leyline records, confirming that the Divine Cherry Tree had appeared in Inazuma three thousand years ago…

Human thinking tends to be based on the idea that "existence is justification." Because the unknown can cause anxiety, people tend to ignore it and even make baseless "fill-in-the-blank" attempts to justify it. In short, they want to transform the "unknown" into something that is "nothing strange" or "has always been the case."

Since the Divine Cherry Tree is already standing right in front of us, it seems pointless to think about how it came to be. It's better to accept its existence and make good use of it; that would be more efficient.

Few people are willing to think, "Just because it's always been this way, does that mean it's right?"

This is why this cherry tree, which appeared as if by divine intervention, has existed for five hundred years without anyone questioning it.

But once a seed of doubt is planted in a person's heart, that person will find all sorts of doubts that they had previously overlooked.

Han Fulai's words had already planted seeds of doubt in Ying and Shenzi's hearts.

Doubt is the prerequisite for understanding the essence of the world.

Without doubt, there will never be the motivation to explore.

When people try to understand and change the world, the first step is always to raise doubts.

"I think you now realize how abrupt the existence of the Divine Cherry Tree is."

Han Fulai reached out and stroked the trunk of the Divine Cherry Tree.

His fingers felt the rough texture of the bark; every crisscrossing groove on the Divine Cherry Tree seemed to contain the vicissitudes of thousands of years of history—but he knew it was fake.

"This tree actually exists in Inazuma, yet it does not exist in Inazuma. It is everywhere, yet it is nowhere."

These words were spoken in a mysterious and cryptic manner, and sounded completely contradictory, but the divine child was surprisingly able to understand their meaning.

“I remember you said before that Her Highness, like this divine cherry tree, has become a higher-dimensional being, and we, who live in a lower-dimensional world, cannot contact her…”

"If the Divine Cherry Tree was indeed planted by His Highness to protect Inazuma during the 'Dark Calamity,' and was the key that changed Inazuma's history—then its essence is actually something that exists 'outside the world,' right?"

"The cherry blossom tree that we see and touch is only one side of it, just like characters in a novel looking at the outside world through the pages of a book, never seeing the real thing clearly, right?"

Han Fulai turned back to look at Shenzi with some surprise—as expected of the "Editor-in-Chief"? Although what Shenzi said was all based on imagination in light novels, it went straight to the heart of the matter.

Moreover, the divine child's conjecture gave him a hint, making him think of how to give the divine child and the shadow the "will" to "change the past in the future".

“Yes, that’s exactly right.” Han Fulai smiled. “The continent of Teyvat we are on is a world enveloped by a ‘false heaven.’ The fate of every mortal on this continent is controlled by the ‘fate system’ of Sky Isles.”

"Then let's think of the world we live in as a light novel."

“I, the Divine Child, the General, and your sister, Princess Shin... we are all characters in a novel. 'The Dark Calamity' is a plot point in a novel.”

"In the original plot of this novel, Inazuma would be destroyed by the 'Dark Calamity.' But Princess Shin, with her visionary foresight, saw through the plot's development and wants to save Inazuma, whom she deeply loves. Please consider, what method will she use?"

“The characters in the novel…want to change the history in the novel…” Lei Movie paused for a moment.

Han Fulai's analogy may seem strange at first glance, but upon closer examination it is quite apt—after all, even the "Seven Rulers of the Mortal World" are nothing more than "chess pieces" under Sky Island, and the fact that the "Heart of God" is made in the shape of a "chess piece" is itself a symbol.