Just as Qingmu exited Su Huilan's dream, the unconscious savage on the ground woke up.
In reality, their time in the dream was very short, at least in Alice's eyes, it was only a moment. She heard them talking about some strange things, like who entered whose dream, but she didn't dare to ask any questions and just watched curiously from the side.
Then, time seemed to stand still. For about two or three seconds, the cave fell silent, and even space seemed to freeze. Alice saw Qingmu and Su Huilan staring at each other, motionless, like two wax figures. She felt a chill and quickly stood up to add some dry branches to the fire.
At that moment, the savage lying on the ground awoke, his eyes filled with rage. He rolled over and grabbed Alice's foot, who was adding firewood to the fire.
Alice screamed in fright, not knowing what to do, when she heard a loud thud. The savage, who was trying to get up, was suddenly sent flying, his body crashing into the cave wall and tumbling down. It seemed he wouldn't be able to get up anytime soon.
She saw Qingmu, who had looked like a wax figure, lift one foot, and the slippers on his foot were still dangling there.
Su Huilan came over and hugged the still-shaken Alice, kissing her cheek and comforting her, "It's alright, Alice, don't worry, it's safe here."
"I'm fine." Alice's lips were pale, and her body trembled slightly.
The moment the savage grabbed her ankle, the pungent, fox-like odor filled her with extreme panic. She thought of Mrs. Larry, her heart clenched as if being squeezed, followed by anger and hatred.
She stared intently at the savage lying on the ground groaning, her eyes practically spitting fire.
Su Huilan sensed Alice trembling; it was anger emanating from the depths of her heart. She encouraged her, "Go."
Alice, her face tense, walked over and kicked the savage hard, cursing, "Beast! Animal!"
The savage on the ground rose up, like a trapped wild beast, and pounced fiercely on Alice.
With another loud thud, the savage flew out, crashed into the wall, and tumbled down.
Before anyone knew it, Qingmu had already positioned himself in front of Alice. He raised his right foot, his slippers dangling from it.
This kick was even harder than the previous one. The savage struggled twice and spat out blood all over the ground.
Alice grew bolder and went over again, kicking the savage hard in the groin. The savage was already badly injured, and this kick was the last straw. He grimaced in pain but had no strength to fight back.
Alice's face contorted in rage as she kicked and punched, then lunged at the savage, scratching his face with her nails as she screamed hysterically, though it was impossible to make out what she was saying.
The savage was left covered in wounds, his face and chest covered in blood. His eyes, which had initially been filled with anger and resentment, slowly turned into fear.
Alice was on the verge of madness; even Qingmu felt a chill run down his spine. He winked at Su Huilan: "That's enough, don't kill her."
Su Huilan went up and tried to pull Alice away, but she couldn't. Alice was still scratching and tearing wildly, even biting, as if she wanted to take revenge on this savage for all the suffering Mrs. Larry had endured.
Su Huilan had no choice but to hug her tightly, repeatedly saying in her ear, " Alice! Alice! Stop, Alice! Don't kill him, he's still useful, we still need to save Anderson!"
Alice stopped what she was doing when she heard Anderson's name, and sat on the ground in a daze for a long time. She turned around, glanced at Anderson, and then buried her face in Su Huilan's arms and sobbed.
The savage was still alive; Alice hadn't caused him any real harm. The real serious injury came from the kicks Qingmu gave him, which looked like he had quite a few broken bones.
Once Alice had calmed down, Qingmu and Su Huilan began researching how to hypnotize the wild man.
The island's natural Mental Power Field still existed, but after spending a whole day there, Qingmu was surprised to find that he had become quite accustomed to the existence of this energy field. Just like people from Tibet who feel itchy when they first leave the plateau, but after staying for a few days, they get used to the oxygen-rich air of the plains.
Su Huilan clearly shared the same feeling. She said, "The reason hypnosis is ineffective on the islanders is that they have adapted to the strong Mental Power Field on the island. Their consciousness is not sensitive to interference from Mental Power, just like bacteria develop tolerance to drugs. Too much penicillin becomes ineffective. Although we cannot yet determine whether the islanders' mental stance and our Mental Power are the same thing, I think they are essentially the same, at most the difference between ampicillin and amoxicillin. Once they develop tolerance to ampicillin, our use of amoxicillin on them will naturally be ineffective."
Although Qingmu felt that Su Huilan's analogy was problematic—for example, the principles of Mental Power and antibiotics are completely different and incomparable—he understood what Su Huilan meant and acknowledged that their current predicament was indeed as dire as it seemed. If this problem wasn't resolved, with just the two of them, plus the defenseless Alice and the injured Anderson, even if Crow returned and Petru and Hanran were unharmed, they would likely struggle to escape danger, let alone rescue Mrs. Larry.
He sensed the omnipresent Mental Power Field, thought for a moment, and said:
"You said this is an enclosed space surrounded by water, right?"
Su Huilan said, "It's not surrounded by water, but rather... a Klein Bottle."
" Klein Bottle?" Qingmu remembered Professor Mei mentioning this thing.
"This was discovered by the famous mathematician Felix Klein in 1882," Su Huilan explained. "You can imagine a bottle—a vase, a wine bottle, anything will do, as long as it's a normal bottle with a bottom and a mouth. First, dig a hole in the bottom of the bottle, then extend the neck of the bottle, imagining the neck of the bottle is as flexible as a water pipe, bend it, and insert the mouth of the bottle into the bottle from any position on the body, then connect it to the hole in the bottom. That's how you complete a Klein Bottle."
Imagine this bottle carefully. Its mouth and bottom are connected, so it is sealed. But from any point on the bottle, you can reach any point on either the inside or outside surface. In other words, there is no inside or outside. A sealed bottle, yet without an inside or outside. Put an insect in this bottle, and it can easily crawl out without needing to have the ability to pass through walls.
Of course, the Klein Bottle is actually a curved surface that can only be truly represented in four-dimensional space. I just described it from a three-dimensional perspective, and Klein also described it from a three-dimensional perspective, but what he was really describing was a four-dimensional thing. In three-dimensional space, its neck needs to pass through the surface of the bottle body to enter the interior of the bottle, that is to say, the position of the bottle itself in three-dimensional space is occupied by another part of itself.
However, if another dimension exists, it wouldn't need to pass through its own body; instead, the bottle's opening and bottom would connect through a fourth dimension. But we need to represent this in our three-dimensional space, so we have to make do and let it look like it's intersecting itself.
"You mean this island is a Klein Bottle?" Qingmu asked.
Su Huilan spread her arms and did an upward flip, saying:
"The sea outside the island appears to be a flat plane, but it is actually a distorted space. You can think of it as something that rolls up, like the body of a bottle. The island is the bottom of the bottle, and the lakes on the islands are the holes dug into the bottom. The bottle body, formed by the ocean, slowly closes in the sky to form the neck, passing through the fourth dimension and connecting with the hole at the bottom of the bottle, which is the lake on the island. This constitutes a complete Klein bottle."
This is why Alice returned to the lake after their voyage. Inside the Klein Bottle, the inside and outside are interconnected; it's a non-directional plane. The key is the hole at the bottom of the bottle and the book hole, which is the lake on the island. It is both the bottom and the top of the bottle.