As a three-dimensional creature, it is almost impossible to cross the barriers of the high-dimensional world.

Just as two-dimensional beings cannot perceive the existence of the three-dimensional world, without the help of scientific theories or special technical means, all they can observe is the projection of three-dimensional objects on the paper with the help of table lamps or other light sources, or a series of "strange properties" produced on the contact surface at the moment when the two are tangentially touched, or physical laws that are incomprehensible to two-dimensional creatures.

And all this is nothing more than the result of "interference".

Even if they are aware of their existence, it is almost impossible to stand in the position of low-dimensional beings and reverse this interference caused by the high-dimensional space to the low-dimensional space.

From this point of view alone, the existence of this kind of debris in four-dimensional space is somewhat similar to the existence of Z particles.

It's just that its existence is a little more complicated.

It is not some kind of substance that exists in the four-dimensional space, but precisely the space itself.

Therefore, it is theoretically impossible to cross this barrier.

Any physical attack is unlikely to have any effect on it, and even a megaton nuclear bomb that razes the ruins to the ground will not shake it in the slightest.

However, this does not mean that Lu Zhou is helpless.

The interior of the entire ruins is fragmented by fragments of the four-dimensional space, and all the passages here are continuous and constant in a topological sense. As for the change in position, it is only the distortion caused by the interference of the debris of the four-dimensional space on the three-dimensional space, which makes the tunnels mixed together like a disrupted puzzle.

And the reason why he couldn't cross the barrier in front of him was only because the "door" was not here. The inaccessible space in front of him was like a puzzle piece, which had been forcibly deducted from the complete pattern and thrown in an inconspicuous corner.

Now all he had to do was find the missing piece from the thousands of puzzles.

And, where it originally belonged.

If Xiao Ai was here, it would save him a lot of time, but this is the underground of Mars, and the only thing he can rely on is himself.

Thankfully, this is not a difficult task for the LV10 math grade.

Half an hour passed.

Finally found the missing puzzle piece, his eyes were locked on Lu Zhou, who was staring at the screen, and a smile finally appeared on his face.

“…… I didn't expect the answer to be so close at hand. ”

With a slight tap of his right hand on the wrist-mounted computer on his left arm, Lu Zhou reopened the communication module.

"See you later."

With that, he turned and left the spacious grotto, exiting the five-man arch and returning to where he had been.

Without any hesitation, Lu Zhou, who already had the answer in his heart, walked through the gray dust in the opposite direction with unhurried steps.

Soon, he came to the side of a bottomless cliff and stopped at the edge of the cliff.

If his reasoning was correct, this should be the location where the puzzle piece was cut off, and the inaccessible space he had seen in the grotto earlier belonged to it in the first place.

And if you want to get there, you can only go through this "door"!

It seemed that he had been watching his every move, and the voice that had disappeared for a long time appeared again, and spoke in his ear.

"Are you ready?"

Lu Zhou, who was about to take a step forward, stopped.

"What do you mean?"

"I mean, if it's too late to return it now."

Hearing this, Lu Zhou suddenly laughed and said in a joking tone.

"Are you willing to just let me go back?"

"It's not reluctant, for me it's just a little bit of a wait. Those observers are unlikely to leave me idle, and they will always send me the right individuals. ”

Lu Zhou: "Then since it doesn't matter, why do you persuade me." ”

"Because it's not an easy road, both for you and for me. I'm just offering you another option, and you can go back and live a happy and secure life, and the price doesn't have to be paid by you, and you don't even have a chance to see that far away. ”

There was a hint of demagogy in his voice.

Lu Zhou admits that it does sound tempting.

He has risen to the top of academia, and the pinnacle of power that a scholar can reach is nothing more than that. In the next few decades, even if he does nothing, he will be able to live the rest of his life happily, and there is no need to take such a big risk at all.

However......

"You're right, but since we've come this far," Lu Zhou continued, thinking about it, "If you go back like this, you'll still regret it." ”

"It's not a good thing to be too curious."

Lu Zhou smiled and said, "Really? I'm convinced now that you're not in the same league as the observers. ”

"Oh? Why. ”

Lu Zhou: "Because I remember that person said that curiosity is an enviable quality, and that quality has been abandoned by them for a long time. ”

"Hahaha, that's up to you. But you have to think clearly, once you've made your choice, there's no going back. ”

"I thought about that before I came here."

Saying this in a calm tone, Lu Zhou closed his eyes and pondered for a long time, then silently took off the wrist-borne computer on his left arm and threw it in the open space behind him.

Then, taking a deep breath and exerting all the courage of his body, he leaped towards the abyss that seemed to engulf all light, letting gravity pull it towards the boundless darkness.

The free fall lasted for three or four seconds.

Then, a magical scene happened!

The moment he was engulfed in the boundless darkness, the sensation of the world spinning crawled through every cell in his body.

As if the direction of gravity had been reversed for a split second, a massive inertia grabbed him by the shoulder, and then slammed it to solid ground.

"Ah......h

The painful tears were about to be squeezed out, and Lu Zhou, who felt like he had been hit by a truck, was gasping for breath while struggling to get up from the ground.

The moment he raised his head, a hint of ecstasy instantly appeared in his eyes.

The space in front of him at this moment was the grotto he had left before, and his position at this moment was the area that he could not pass through before—that is, the other side of the "wall".

Restraining the excitement in his heart, Lu Zhou took a deep breath and calmed himself down.

"Have I passed all the tests?"

"Sort of."

"What do you mean?"

This time, the voice didn't give any answer.

Just when Lu Zhou was confused about what to do next, the space around him suddenly lit up with a soft light. A crystal as flawless and transparent as a soap bubble appeared in front of him as if it appeared out of thin air.

If you look closely, there are tiny lines printed on the clear and transparent film. The lines are like projections of the ruins, corresponding to each tunnel in the ruins.

Curious about this miraculous phenomenon, Lu Zhou was about to reach out to touch it, but was stopped by the sound in his ears.

"Don't touch it with your hands!"

The hand stretched out into the air stopped, Lu Zhou took his hand back, stared at the flawless transparent spherical crystal for a long time, and then spoke.

"Don't touch it with your hands...... Should I touch it with something else? ”

"This is the fragment of the four-dimensional space, and all the changes in the ruins are caused by it."

The moment he heard this, Lu Zhou's eyes couldn't help but show an exclamation, and he couldn't help but ask, "How did you fold the four-dimensional space into such a ...... In perfect condition? ”

"It's not our technology," the voice said lightly, "folding the fragments of four-dimensional space into a three-dimensional sphere is something that only those observers can do." ”

Lu Zhou: "This is what the Void intends to give me?" A piece of four-dimensional space? ”

"No, it's just a key."

"Keys?"

"That's right, it can send you to the side of the treasure."

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