Time is not a global perspective. The velocity of time is different under different gravitational fields and different systems of motion.

Velin potions have a point in time when they take effect. If you go back in time to an earlier point in time, you will go back as part of your memory about the fact that other experimenters drank the Velin potion at a later time. For the experimenter who drank the potion at a later time, his memory was erased by the actions of the other experimenters who went back in time.

Since there are definitions of "early" and "late", the question inevitably arises: what is the temporal precision that distinguishes "early" from "late"?

First of all, this precision is inevitable. In the view of quantum mechanics, time is not infinitely divisible. As long as it is a non-infinitely divisible unit, then there must be exactly the same point. This kind of sameness is not the same under a certain precision standard, but the same in the true sense. If the potion takes effect at exactly the same point in time between the two experimenters, there is no distinction between "early" and "late". In this case, the two experimenters arbitrarily tried to go back in time, but they were unable to clear the other's backtracking points. Wen Bing believes that in this case, one side may go back in time, which may cause both sides to bring their memories back to the point when the potion took effect. This phenomenon is defined by the Wenbing as "memory coexistence".

Since there is a point in time where there is no distinction between "early" and "late", there is a problem with accuracy. It is impossible to know whether the unit of time that distinguishes "early" and "late" is a Planck time, or a nanosecond, a millisecond, or even a second, or several seconds. If this unit of precision is large enough, "memory coexistence" can be easily achieved.

A large part of the fear of death is due to the limited length of life. Through the technology of going back in time, experiencing different lives dozens or even hundreds of times, most people will not have any regrets. But if someone tells you that you have experienced a different life hundreds of times, and it is only when you lose these memories that you will think that this is your first life, I am afraid that most people will not accept such a statement.

Looking back in time, compared with the first two methods of pursuing immortality by civil soldiers, it effectively avoided the problems of death caused by disease and the inability to live forever in the real world. But what doesn't change is that the flesh is fragile after all. Death from sudden accidents is still inevitable. Coupled with the restriction that time can only be retraced in a relaxed state, the risk of death from accidents is greater.

Therefore, in order to avoid this, Wen Bing must have a trusted friend who will drink the potion with him. When either party dies due to an accident, the other party can go back in time to the point in time before the accident occurred.

However, Wen Bing would never give this friend the right to drink the potion for a long time. Otherwise, this friend's behavior of going back in time for his own interests will affect the course of Wen Bing's life. As a result, a friend's act of drinking a potion can only occur once at the earliest point in time. For the sake of immediate interests, going back to a few years or even decades ago, I believe most people will think deeply.

This raises a new question. Once one party dies, the other party goes back in time, most likely back decades ago when they first drank the potion. Wen Bing and this friend he trusted, no one wanted to be the one who drank the potion late. The party who drank the potion late, no matter how many times the life experienced in time, as long as the party who drank the potion earlier went back in time, the party who drank the potion later would be emptied of all the memories of life. In other words, the party who drank the potion later was simply a tool for the party who drank the potion early to avoid accidental death.

Civilian soldiers who put their personal interests first will naturally have a way to deal with it.

The first method is not to tell the friend about the theory of time rewinding. As long as he can't figure out the pros and cons, he naturally won't be obsessed with drinking the potion first. And the civil soldiers gave him this opportunity to save each other's lives, and he will also be grateful to the civil soldiers.

The second way is to tell the friend about the theory of time rewinding. However, he drank the potion first and then went to this friend, pretending to let the friend drink the potion first and then drink the potion himself, and gained the trust of the friend through self-sacrifice. In fact, Wen Bing has an earlier time regression point, and every time he experiences a life, as long as he goes back to an earlier time regression point, his memory will not be erased, and his friends do not know about it.

And no matter which method it is, as long as Wen Bing himself can take the potion for a long time, he can save his friend's life by going back in time to a more recent point in time. Of course, this power cannot be given to his friends.

However, neither method 1 nor method 2 can avoid a problem: once you die, the power of life will be completely in the hands of your friends. Friends who have the ability to go back in time, just like alkanes, have immeasurable access to information. Once this friend discovers that Wen Bing is not honest with himself at all, and uses himself as a tool, as long as he has no intention of living, he can take Wen Bing to the grave together and get out of the cycle of time.

Even if this friend is also extremely afraid of death and trusts Wen Bing, every time he goes back in time, whether it is for himself or to resurrect Wen Bing, it may cause Wen Bing to lose decades of memories, and this problem is unavoidable.

But if the phenomenon of memory coexistence is verified, everything becomes different. As long as the potion is injected at the same time, it can be retained every time you go back in time, and the memories of both parties can be retained. Civilians can also be honest with their friends, and every time either party decides to go back in time, they must first ask the other party's opinion. Because the other party will retain the memory before the rewind time, and know the behavior of the other party to go back in time.

Therefore, the experimental conclusions of the experiments to verify the phenomenon of memory coexistence must be absolutely reliable. The Soldier will be honest with a friend and inject potions at the earliest, creating an early memory co-existence time regression point. Of course, Wen Bing can secretly drink the potion once by himself and keep a backhand. But if a friend realizes this, he will understand that this point in time can be cleared, and his candidate can be replaced. When either party dies, the other party is in control as long as they do not want to live forever. Only absolute mutual trust and absolute equality can be maintained forever. Therefore, in the subsequent journey of life, if Wen Bing wants to create a new time regression point, he will also find friends to create this time point as a memory coexistence time regression point, so as to avoid the act of going back time to erase the other party's memory.

Therefore, if the phenomenon of memory coexistence does not exist, but due to the wrong conclusion of the experiment, the soldier and his friend are injected with the potion at the same time, and the soldier becomes the party that takes effect later, it will be the most unacceptable result for the soldier. In order not to generate the earliest and independent time regression point to cause mutual suspicion, Wen Bing could not verify the phenomenon of memory coexistence through another experiment. Therefore, for the confirmatory experiments of memory coexistence at similar time points, the experimental methods must be designed rigorously enough, and the experimental conclusions must be absolutely correct.

First of all, due to the need to verify whether the deceased subject can still coexist with the memories before death, the experiment requires the participant to die in a certain timeline. Therefore, it is impossible to find a willing experimenter under normal circumstances.

When faced with an experimenter who is forced to conduct an experiment, a large number of rules need to be developed to prevent the experimenter from transmitting information. At the same time, the phenomenon of memory coexistence should not be tested only in the case of two people. If the civilian soldiers want to get a higher guarantee of eternal life, the extremely low probability event of accidental death of two people at the same time should also be prevented.

If the experiment is conducted by three people, and the experimenter is free to rewind time, there will be a lot of variability. If the experimenter at the earliest point in time understands the purpose of the experiment as requiring three people to perform the correct action at the same time, as long as he goes back in time many times to obtain the information and then transmits the information to the other experimenter, the experiment will be successful even if the memory coexistence phenomenon does not exist. If two out of three people think of transmitting information and don't change the subject, even if memory coexistence does not exist, the success rate of the experiment will reach a fairly high value after a large number of experiments.

Therefore, first, the experimenter must be put into a state of extreme panic, and the tranquilizer must be artificially used to enter a state of relaxation. Simple bundling and the like, when encountering an experimenter with high psychological quality, you can also go back in time. Second, it is necessary to stifle any possibility of communication between experimenters. Even if the mouth is gagged, the experimenters make eye contact with each other, the fingers tap on the Morse code, etc., there is a risk of information transfer, especially for computer science students. Of course, this is also an overestimation of ordinary college students by Wen Bing, as a high-IQ person. But what the civilian soldiers want is foolproof. Third, communication cannot be severed by separating the three of them. Because it is necessary to inject the potion into three people at the same time through the separating needle, the effective time point of the potion is as close as possible.

Based on the above basic requirements and many other detailed considerations, the human centipede experiment was finally born. The absolute panic makes it impossible to retrace time on its own, and it is absolutely impossible to communicate without the operator's awareness, and the experimenter's position is suitable for injecting the Pyridium potion using a separating needle. Perhaps, with the wisdom of a civil soldier, he could have devised an experiment that was less bloody and less touching the bottom line. However, in order to make the conclusion absolutely reliable, and to create an experiment that absolutely breaks through the lower limit, so that Yongqi can know that Brother Shui has the ability and psychological quality to carry out other experiments based on this experiment alone, Wen Bing finally designed such an experiment.

This is why, if Yongqi monitors Brother Shui's experiments by becoming an experimenter, he must become an experimenter in position C. In the human centipede experiment, only the experimenter in this position does not have to experience death. Once Eternal Rider dies, things become completely out of control. And if it is attacked, it is also very likely that Yongqi will have his identity exposed due to the exposed circuit.

The occurrence or failure of the human centipede experiment is like a deliberately set Boolean value for judgment. Only if this value is true, it is possible for Wen Bing to listen to the experimental conclusions of any experiment given by Brother Shui. Without this premise, nothing is necessary.