Suspicion Chain's "Three-Body 2 Dark Forest"

Science fiction writer Liu Cixin mentioned this in his book "Three-Body 2: Dark Forest":

The dialogue in the novel helps us understand it easier. I believe everyone will read it after reading it. You will have a general understanding of this after selecting the excerpt. Please read the excerpt:

(The excerpt has been deleted to help everyone understand)

“Civilization probably sprouted in the universe billions of years ago. Judging from current signs, the universe It may have been crowded. No one knows how many empty spaces and unoccupied resources there are in the Milky Way and the entire universe."

"Isn't this right? "Apart from humans, no other alien life has been seen?"

"This is what we are going to say next. Give me a cigarette." Luo Ji fumbled for a long time before getting it from Da Shi. When he heard Luo Ji talking again, Shi Qiang found that he had already sat three or four meters away from him. "We need to put some distance between us. It will make it feel more like space." Luo Ji said, and then, He twisted the filter part of the cigarette and lit it. At the same time, Shi Qiang also lit a cigarette. In the darkness, two small sparks faced each other far away.

“Okay, in order to explain the problem, now we need to establish the most concise model of cosmic civilization: these two Mars represent two civilized planets. The entire universe is only composed of these two planets, and everything else is No, you delete everything around you. How do you find this feeling?"

"Well, this feeling is easier to find in this dark place."

"Now we call these two civilized worlds your civilization and mine respectively. The two worlds are far apart, let's say a hundred light years. You have detected my existence. But you don't know the more detailed situation, and I don't know at all. Know your existence.”

“Hmm.”

“Let’s define two concepts: goodwill and evil in science. They are not rigorous, so their meanings need to be limited: goodwill means not actively attacking and destroying other civilizations, while maliciousness is the opposite. "

"Is this the lowest goodwill?"

"You already know the existence of my civilization in the universe. Now please consider what choices you have for me. Please note that during this process, you must always keep in mind the axioms of universe civilization (namely: 1. Survival is the most important thing for civilization). Fundamental need. 2. Civilization continues to grow and expand, but the total amount of matter in the universe remains unchanged), and the environment and distance scale in space must always be considered."

"I choose to communicate with you. ?"

"If you do this, you have to pay attention to the price you pay: you expose your existence."

"Yes, this is not a small thing in the universe. "

"There are various levels of exposure: the strongest exposure is to let me know your precise coordinates in the interstellar world, the second is to let me know your general direction, and the weakest exposure is to just let me know But even the weakest exposure would make it possible for me to search and find you. Since you can detect my existence, it is certainly possible for me to find you. From a technological development perspective, it is only a matter of time. Question."

"But brother, I can take a risk to communicate with you. If you are malicious, then I am unlucky; if you are kind, then we can further communicate and finally join forces. A greater benevolent civilization."

"Okay, Da Shi, we have reached the key point. Now let's go back to the axioms of cosmic civilization: Even if I am a benevolent civilization, can I communicate at the beginning? How about judging that you are also kind?"

"Of course not, this violates the first axiom."

"So, what should I do after I receive your communication signal. What to do?"

"Of course you should first judge whether I am kind or malicious. If it is malicious, you destroy me; if it is kind, let's continue to communicate."

Luo Ji's side. The Mars rose up and moved back and forth. Apparently he stood up and paced, "It's possible on earth, but not in the universe. Let's introduce an important concept: chain of suspicion."

"It's a weird word."

"I only got this word at first, and she didn't explain it, but I finally guessed its meaning literally.

"

" Him? who is he? ”

“... Let’s talk about it later, let’s continue: If you think I am well-intentioned, this is not a reason for you to feel safe, because according to the first axiom, well-intentioned civilization cannot preempt others’ Civilizations also think of you as kind, so you still don’t know what I think of you, you don’t know whether I think you are kind or malicious; further, even if you know that I think of you as kind, I also know You imagine me to be kind, but I don't know what you think of me. What you think of me is pretty confusing, isn't it? This is the third level. This logic can be extended forward endlessly. ”

“I understand what you mean. ”

“This is the chain of suspicion. This kind of thing cannot be seen on earth. Human beings are of the same species, have similar cultures, live in the same interdependent ecological circle, and are very close to each other. In such an environment, the chain of suspicion can only extend one to two levels before being eliminated by communication. But in space, the chain of suspicion can stretch very long. ”

“This means that whether you or I are a well-intentioned civilization or a malicious civilization, the result will be the same? ”

“Yes, this is the most important characteristic of the chain of suspicion: it has nothing to do with the social form and moral orientation of the civilization itself. Just regard each civilization as the points at both ends of the chain, regardless of where the civilization is.” Whether they are benevolent or malicious inside, they will become the same thing after entering the network formed by the chain of suspicion. "

"But what if you are much weaker than me, and you are not a threat to me, so I can always communicate with you, right? ”

“No, this will lead to the second important concept: technological explosion. She didn't have time to explain this concept, but it was much easier to speculate than a chain of suspicion. Human civilization has a history of five thousand years, and the history of life on earth lasts billions of years. However, modern technology was developed in three hundred years. From the perspective of the time scale of the universe, this is not a development at all, but an explosion! The possibility of technological leaps is the explosive buried inside every civilization. If it is ignited by internal or external factors, it will explode with a blast! The earth is three hundred years old, but there is no reason to think that human beings are developing the fastest among civilizations in the universe. It is possible that the technological explosion of other civilizations is even more rapid. I am weaker than you. After receiving your exchange of information and learning of your existence, a chain of suspicion between us was established. During this period, I could have a technological explosion at any time and be far ahead of you. , become stronger than you. You must know that on a cosmic scale, hundreds of years are just a blink of an eye, and my knowledge of your existence and the information obtained from communication may be the best fuse for the technological explosion. So, even if I am just an infant civilization or a budding civilization, it is still full of dangers for you. "

Shi Qiang looked at the sparks in the darkness over Luo Ji in the distance and thought for a few seconds, then looked at his cigarette butt, "Then, I can only remain silent. "

"Think about it, is this right? "

They were both smoking cigarettes. As the sparks brightened from time to time, the two faces alternately emerged in the darkness, as if they were two deep-thinking gods in this simple universe.

History Qiang said: "No, if you are stronger than me, since I can find you, then you will be able to search for me one day, so there will be another chain of suspicion between us; if you are weaker than me, but it may happen at any time When technology explodes, it becomes the first situation. To sum up, firstly, letting you know my existence; secondly, letting you continue to exist is dangerous to me and violates the first axiom. "

"Da Shi, you are really a very clear-minded person. "

"My mind can still keep up with you at the beginning.

Luo Ji was silent for a long time in the darkness. His face appeared in the dim light of Mars two or three times before he said: "Da Shi, this is not the beginning. Our inference has ended." . "

"The end? Didn't we get anything out? What about the picture of cosmic civilization you mentioned? ”

“After you learn of my existence, communication and silence are not acceptable, and you have only one choice left. ”

In the long silence, both sparks were extinguished, without a trace of wind, and the darkness became as sticky as asphalt in the silence, blending the night sky and the desert into one. In the end, Shi Qiang just Say one word in the darkness: “Fuck! ”

“Extrapolate your choice to billions of civilizations among hundreds of billions of stars, and the big picture will emerge. Luo Ji nodded in the darkness and said.

"This... is too dark..."

"The real universe is so dark." Luo Ji stretched out his hand and waved it, feeling it like stroking a swan's seal The texture of darkness, "The universe is like a dark forest, and every civilization is a hunter with a gun, sneaking in the forest like a ghost, gently pushing aside the branches blocking the road, trying hard not to make a sound with his footsteps, even his breathing. Be careful...he must be careful, because there are hunters like him everywhere in the forest. If he finds another life, whether it is a hunter or not, whether it is an angel or a devil, whether it is a delicate baby or a tottering old man. , whether it is a fairy-like girl or a god-like god, there is only one thing that can be done: shoot and eliminate them. In this forest, other people are hell and an eternal threat. Any life that exposes its existence will be destroyed. will be wiped out soon. This is the picture of cosmic civilization, and this is the explanation of Fermi's Paradox."

To put it simply, I am good, I don't understand you, and you certainly don't understand either. Get to know me. So if I don't fire, you fire. Because survival is paramount, I'll fire on you first.

But some people think that the chain of suspicion may not be established.