According to the yo-yo's account, they had discovered this clue quite early on, but at that time their memory was not complete, because they were not truly resurrected, but rather absorbed and restored as a stream of information.
In fact, there was a similar scientific theory during the Earth Era that Lu Yuanming knew, called Poincare Recurrence.
According to this theory, the universe itself has no beginning or end because everything is boundless. Even if you died, all the particles that compose you, the string vibrations that contain all your information, and everything that includes you will eventually reconverge after an almost infinite amount of time. They'll reform into you and into the environment you once lived in, whether that be Earth, or your relatives, or your friends, or everything else you are familiar with. Everything will come back and be restored to its original state.
