Chapter 863: Qin King's Bone Reflection Mirror Secret

"Linear Algebra?" Zhao Ruizhi furrowed his brow, too surprised to be angry. Instead, he wondered what kind of divine skill or secret manual this was and why he had never heard of it.

Not just him, even Mi Li, who had read through the entire library of the Qin royal family back then, was completely bewildered. What in the world was linear algebra? Why didn't she know about it?

Only Bi Linglong seemed thoughtful, recalling past intelligence about Zu'an. He was an arithmetic teacher at Mingyue Academy, wasn't he? And he had visited the National Academy earlier, where even the usually arrogant teachers from the back mountain were deeply impressed by his profound knowledge. It must be that this "linear algebra" was one of the many skills he possessed.

Zu'an reconfirmed the inscription with Zhao Ruizhi, murmuring to himself, "'Dark clouds facing the Gate of Heaven' describes our situation before we landed on the island..."

However, the subsequent phrases involved ancient astrology, which Zu'an wasn't very familiar with. Fortunately, he had a "living encyclopedia" by his side.

He quickly consulted Mi Li, and only then did he roughly understand the secret within the inscription.

The Gate of Heaven (Tianmen) belongs to Jiao Xiu (Horn) among the Twenty-Eight Mansions. "Heavenly Sun" naturally refers to the sun. Historically, the "Golden Palace" generally refers to the dwelling of heaven and earth, and in ancient astrology, the Purple Forbidden Enclosure corresponds to this celestial dwelling.

Ancient astrology divided the sky into Three Enclosures and Twenty-Eight Mansions. The Three Enclosures are three vast stellar regions directly overhead, each containing many constellations and stars, named the Purple Forbidden Enclosure, Supreme Palace Enclosure, and Heavenly Market Enclosure.

Then, the constellations near the ecliptic were divided into twenty-eight regions, known as the Twenty-Eight Mansions. These Twenty-Eight Mansions are grouped into seven, and can also be divided into the Four Symbols (Azure Dragon, Vermilion Bird, White Tiger, and Black Tortoise) based on the four cardinal directions.

"Southern Star" likely refers to the Southern Dipper, the Dou Xiu (Dipper) among the seven northern mansions. "Jade Goad" (Yuheng) refers to the Yuheng star of the Big Dipper. For the Southern Star to revolve around the Northern Dipper is astronomically difficult to achieve under normal circumstances, which was why the emperor was so despairing earlier. However, since this stone slab now corresponds to the starry sky, it only requires aligning the respective symbols; there's no need to actually manipulate celestial phenomena.

"Hua Gai (Canopy) approaches Zi (Purple)" means the Hua Gai star in the Purple Forbidden Enclosure aligns with the Ziwei Emperor Star.

"Ya Yin (Elegant Sound) enters Zheng." In ancient times, "Ya Yin" referred to Xia Yin (Summer Sound), and since the Xia people were descendants of Xuanyuan (Yellow Emperor), this should refer to the Xuanyuan star among the constellations. "Zheng" refers to the Zheng star in the Heavenly Market Enclosure.

With Mi Li's help, Zu'an quickly deciphered the secret within the inscription. All that remained was to align the corresponding constellations.

This type of mechanism, where moving one pillar causes several others to rotate, could be easily brute-forced by random trial and error if it were simple. However, with such complex interconnections described on the inscription, random attempts would clearly be useless.

Although this ancient mechanism was intricate, it shouldn't be difficult for someone with a university education. It was essentially an applied problem in linear algebra.

He first ordered each pillar. Turning the first pillar once, he recorded how many times the other corresponding pillars rotated. For example, if the second pillar didn't turn, it was recorded as 0; if the third turned once, it was 1; if the fourth turned twice, it was 2, and so on. This could then be recorded as d1[1, 0, 1, 2...]ᵀ.

If the first pillar is rotated X1 times, the state of the pillars would become X1d1.

If the second pillar is rotated X2 times, the state of the pillars would become X2d2.

And so on, the final state of the pillars would be X1d1 + X2d2 + X3d3...

The result, `b`, is a determined constant, because by determining which patterns correspond based on the inscription's information, one can determine the final required rotation for each pillar compared to its initial position.

This is equivalent to solving a system of non-homogeneous linear equations, which allows solving for X1, X2, X3..., indicating how many times each respective pillar needs to be rotated to achieve the state described in the inscription.

Zhao Ruizhi watched Zu'an drawing symbols he had never seen before on the ground, finding them utterly incomprehensible, like reading a cryptic heavenly script.

He couldn't help but secretly glance at the others and found that both Bi Linglong and He Li, among others, had confused, bewildered expressions on their faces. His agitated state of mind instantly calmed down considerably.

After a while, He Li, who was nearby, couldn't help but secretly glance at him too. He saw Zhao Ruizhi watching Zu'an draw those strange symbols, nodding slightly and continuously, as if deeply engrossed. He couldn't help but be full of admiration, thinking, "The Emperor truly lives up to his title; he can even understand this!"

After a while, Zu'an finally stood up. "Done!" he announced.

He then went to the array of stone slabs, recalling the answers he had just calculated, and rotated the corresponding pillars several times.

As expected, after rotating them in his calculated sequence, all the patterns aligned perfectly!

Immediately afterward, a series of rumbling sounds echoed from beneath, clearly indicating that the mechanism had begun to operate.

The entire stone slab suddenly emitted a glow. Then, these rays of light rapidly ascended, and all the luminous pearls previously placed in the hollows lit up.

A beam of light traveled between the luminous pearls, finally striking a specific spot on the stone slab. That section of the slab clearly had a slight incline.

But after a while, nothing happened. Zhao Ruizhi frowned, "What's going on?"

He didn't rush to blame anyone, because all previous signs indicated that Zu'an's solution was correct. Was something still missing?

He pondered for a long time but had no clue, so he simply looked at Zu'an. As emperor, he naturally didn't need to do everything himself; troublesome matters could be left to his subordinates to figure out.

Zu'an was also puzzled. Everything had gone smoothly, so why had nothing appeared?

Just then, Mi Li's voice suddenly rang out: "Do you remember the last sentence on the stone tablet we found?"

"'The moon, as a noble person, enters the center...'" Zu'an silently recited the sentence. He noticed that the stone slab where the light beam shone had a slightly sunken groove. The shape of the groove seemed like a mirror.

A thought struck him. He pulled out the Qin King's Soul-Illuminating Mirror that he had found earlier in the treasure vault of the Celestial Measuring Jade Moon Dragon. As expected, its shape perfectly matched.

After Zu'an had obtained this mirror, he had tried various methods to activate it, but unfortunately, it had remained like a lifeless object from beginning to end, showing no reaction whatsoever.

But at this moment, as the beam of light shone onto the mirror, the previously silent mirror suddenly burst forth with brilliant light, like a small sun, making it impossible to look at directly.

A bright beam of light shot out from the mirror's surface, soaring into the sky and striking some unknown point on the third immortal island.

Then, something astonishing happened. A bright yellow beam of light, over a zhang wide, slowly spread down from the third immortal island.

Yes, it unrolled like a carpet. Soon, the light reached the second immortal island.

Immediately afterward, from the direction of the second immortal island facing them, another bright yellow beam of light spread towards them, quickly embedding itself near the array of stone slabs and forming a transparent bridge of light between the two islands.

Once this bridge of light had formed, the bright light from the luminous pearls on the stone slab slowly faded, and the Qin King's Soul-Illuminating Mirror also returned to its normal state.

Zu'an quickly put it away. This was clearly a treasure, and he couldn't bear to leave it here.

Zhao Ruizhi glanced at him, clearly realizing that Zu'an's mirror was extraordinary. He was about to seize it and then eliminate Zu'an, but then he remembered what Zu'an had just said, and having witnessed his ability to decipher those "ghostly" symbols, he thought, "This guy is indeed good at solving these mechanisms. It's better to wait for now. Who knows, I might still need him later."

Suppressing his murderous intent, he was the first to walk onto the light bridge.

At first, he was a bit cautious, but he soon realized that although the light bridge looked transparent and intimidating, stepping on it felt like solid ground. There was no fear of falling.

"Is this the method of immortals?" Zhao Ruizhi's gaze towards the distant palace grew increasingly fervent. His figure transformed into a blur, and he quickly ascended to the second island.

Seeing this, He Li and the others quickly followed. After all, there might be immortal fortunes ahead, and who wouldn't want a share?

Zu'an, meanwhile, secretly lamented. He had just tried to close the light bridge to make the emperor fall to his death, but unfortunately, neither the pearls nor the pillars could be moved; they were completely unmovable, as if welded in place.

"Never mind, I'll find another opportunity later," Zu'an thought, and then he also took Bi Linglong onto the light bridge.

Bi Linglong was utterly astonished along the way, excitedly looking all around the light bridge.

In his previous life, Zu'an had seen such scenes countless times in various wuxia and xianxia TV shows and games, so it was nothing new to him.

He silently took out the Qin King's Soul-Illuminating Mirror. It seemed to have been activated just now; what functions did it have?

Unfortunately, after studying it for half a day in his hand, it still looked completely ordinary, with no discernible difference.

"Was it just my imagination?" Zu'an frowned.

Just as he was about to put the mirror away, Bi Linglong suddenly came up to him and asked, "What are you looking at?"

At this moment, Zu'an was holding the mirror, and Bi Linglong was standing behind it, looking at him with a puzzled expression.

Zu'an looked down at the mirror's surface, and two streams of nosebleed immediately gushed out.