Starting as a Wallfacer, his defection to the Three-Body Problem shocked the world.

"I told you long ago that this place is incredibly weird, but you guys still insisted on coming here." Shi Qiang took out a cigarette from his pocket, lit it, and handed one to Luo Ji, who was standing next to him.

Upon seeing this, Principal Liu instinctively took a half step back to avoid being choked by the smoke from the two men's cigarettes.

“Luo Congmin is watching over the Earth Alliance, and we can’t really help much anyway. We’re going to come here anyway, so we might as well come and take a look beforehand.” Luo Ji smiled as he looked at the glass in the corridor. From here, they could directly observe the entrance to the Erbart Cluster in the distance through the window.

He knew a little about Lin Xuan's previous conversation with Number Three. The so-called final battlefield was like a glowing black hole.

"How did the Administrator Civilization create this thing? It's like a subspace, isolating the entire Elbart Cluster from the main universe. Wouldn't you consider this a more advanced form of dark space?" Luo Ji pointed to the darkness in front of him. He was speaking to himself, clearly not expecting any valuable response from the two people beside him.

"Dr. Luo Ji, it's been a long time."

As the group was talking, Zhang Beihai entered through the hatch, followed by Dongfang Yanxu, Chu Yan, and a group of high-ranking members of the Human Alliance. Among them were many familiar faces from the Red Coast Base years ago. After all, to ensure the complete success of the plan, Lin Xuan couldn't allow Zhang Beihai to go alone after that incident.

The appearance of the three at the same time was not surprising to Shi Qiang and Principal Liu. They had been unofficial members of the Human Alliance before returning to the Earth Alliance, so they naturally knew that the Human Alliance's losses were not as great as imagined. However, Luo Ji was different. Back on Earth, due to his identity, it was inconvenient for him to meet with his old friend. Later, he didn't mention it, and Liu Chang and Shi Qiang naturally couldn't say anything either. Therefore, he was the only one present who was somewhat shocked to see Chu Yan and the others.

After all, in his eyes, these people had all disappeared for various inexplicable reasons back then. Even if they were still alive, they should no longer be alive, just like Zhang Beihai's first wife and children, who did not choose to use the immortality potion and died naturally over time.

"I'm sorry we have to meet under these circumstances. If Mr. Lin Xuan were still here, we could probably find a nice spot in our little house on Earth for a picnic, and I'd have Zhang Xiang cook some food to welcome you all." Luo Ji looked at Zhang Beihai and smiled with some relief.

"Unfortunately, it's impossible now. You can't go back to Earth, and even if you did, there probably wouldn't be any scenery to see. If we really have to say, we can only live in igloos like the Inuit people."

“This is not your fault, Dr. Luo Ji.” Zhang Beihai pointed to the connecting bridge, indicating that the other party should walk and talk.

"I never imagined that the Earth would change so much."

"Actually, it wasn't a big deal. It's just that Mr. Lin Xuan had a bit of an accident. Before he left, Di Lian was no different from before."

"That's a pity, but it's good that you're here. Otherwise, our Human Alliance fleet would probably have plunged headlong into the trap that Bi Yunfeng set for us, which would have been a real problem."

As soon as Zhang Beihai said this, Luo Ji couldn't help but glance at him, and immediately, a subtle smile appeared on the faces of the two old foxes.

"You're just fooling yourself." Luo Ji found it amusing. If Zhang Beihai had really entered the solar system without any precautions, he wouldn't have chosen to paralyze the Earth Alliance's defense equipment first at the outset.

This is as absurd as you coming home and instead of taking out your keys, you swing a sledgehammer and smash the security door. It's likely that even the Star Ring Group's sabotage is part of their plan.

"I have a question that I've actually wanted to ask you guys for a while now." Luo Ji hesitated for a moment before steer the conversation back on track.

"I heard from Shi Qiang that you encountered other observers. Could you tell me more about it?"

Zhang Beihai didn't hide anything and recounted what happened on Green Star. Although Luo Ji had heard Shi Qiang and the others talk about these conversations many times, he discovered something different when he heard Zhang Beihai's retelling.

"In other words, the Dark Forest Theory has actually been deciphered in a higher level of civilization, and these civilizations may have even reached a preliminary cooperative relationship?"

"Sort of... but we'll probably have to wait until we meet Mr. Lin Xuan to find out the specifics."

Luo Ji stroked his chin: "Actually, when I first conceived of the Dark Forest Theory, I had already considered this kind of thing, but that doesn't mean the Dark Forest Theory is inapplicable, but rather that a condition has been broken."

"What conditions? Do you mean the chain of suspicion?" Zhang Beihai asked doubtfully. "We have studied the conjecture about the technology tree before. Whether the dependency theory can completely lock down a civilization's technology tree is still a mystery. After all, the last civilization that claimed to be able to block technology is now an interstellar citizen. Even if we do come across a reasonable way to block it, we have to be extra careful."

But Luo Ji shook his head.

"No, I won't include the unknown in my assumptions. What I mean is, there are probably civilizations that have already reached the limits of this universe... or rather, the limits of the dimensions of this universe."

Zhang Beihai's thinking was no less advanced than Luo Ji's; he simply understood the point immediately.

"The universe's resources are finite, so there is competition between civilizations. But what if a civilization's resources have reached their maximum capacity?"

"Yes, that's what I mean. Of course, this is just my guess." Luo Ji nodded.

"Just like those cultivation novels, if, and I mean if, the theory of the technology tree holds true, then all civilizations should theoretically have a technological ceiling. Once this ceiling is reached, they either cannot advance any further, or they need certain conditions to continue. In short, if the theory holds true, then the first condition that must be met is that technological development has an upper limit."

"But having an upper limit is not enough. After all, Qin Shi Huang knew that immortality was impossible, and he still spent a lot of resources searching for a way to live forever. So, the best condition is that all civilizations know the method to advance to the next level, but due to some unknown situation, they are unable to advance to the next level of civilization, or rather, they dare not."

Luo Ji's conjecture was bold, but it also best fit the current situation. During this period, the Human Alliance had eliminated many civilizations in the outside world, and at the same time, it was hunted down by many advanced civilizations. However, the more they developed, the more they realized this bottleneck—a bottleneck from the enemy.

Back when they were only a Level 0 civilization, the technology they displayed when they encountered the Trisolaran civilization was completely incomprehensible. When the Sophons first appeared, humanity's fear of the unknown was almost ingrained in everyone's bones.

But now, although the enemy's weapons are becoming more and more powerful, they are at least still within their comprehension and do not have that oppressive feeling that transcends dimensions.

This also shows that they are getting closer to the upper limit of the world's technology tree. If such an upper limit really exists, then some of their previous guesses are also valid.