"Breathes there a history student with soul so dead, that he has not wondered what would have happened if?" asks Niven in his introduction to "All the Myriad Ways" in his N-Space. Niven believes that this question is the foundation of the interplay of ideas that attract young readers to his alternate history fiction. In the case of "All the Myriad Ways," he challenges the validity of the very concept of alternate histories by revealing the contradictions of physics that would be inherent in the concept. He humanizes the problem by having people act out the contradictions such as having Trimble shoot himself, and yet not shoot himself. It is an absurdity that the bullet would choose different directions to go in different timelines.

Niven asserts that alternate timeline stories are not actually science fiction, but fantasies "without fantasy trappings." By this, he means that the...