There is a round hole on the opposite bulkhead. In the Dark Forest, the second novel of Three-body, which was mentioned at that time, Ike was lying on the bed of his cabin when he suddenly saw a round hole on the opposite bulkhead, about one meter in diameter, and the overlapping part of the Hawaiian scenery hanging on the wall disappeared. Originally, many bulkheads inside the spacecraft are deformable, and doors can automatically appear in any position, but this round hole will not appear, and the bulkheads in the middle-level officer dormitory are all non-deformable metal walls. Ike looked carefully and found that the edge of the round hole was as smooth as a mirror.

Three-body is a sci-fi novel series created by Liu, which consists of Three-body, three body 2: Dark Forest and three body 3: Death and Eternal Life.