The symbolic meaning of other universes changes throughout the novel. It begins as a representation of Ruprecht’s idealism and hope for the future. His quest to discover a path to a parallel universe takes up the bulk of his personal narrative arc. He sees it as the next step in scientific endeavor; hence, he closely studies the pioneering work of Professor Hideo Tamashi to inform his research.

After the death of Skippy, the symbolic meaning changes to represent regret and the desire to change the past. Skippy hints at this symbolic meaning in Part 1, Chapter 12 when asking Ruprecht if it’s possible to go back to the past and stop the future. Ruprecht yearns to discover a pathway to another universe where Skippy is alive, if not the spirit world where he can reach the ghost of Skippy. This resonates with the regrets of other characters throughout the novel, including Lori, who regrets her relationship with Carl, and Howard, who regrets giving up his life with Halley. Lori, meanwhile, reminds Ruprecht of the value of the present world when she quotes Paul Éluard to him, hinting that he could continue to pursue his research and move on.