The Limit of Questions (Limit of Life in the original Japanese version) is a theory among the scientists in the Eureka Seven series that too many sentient lifeforms in a given space will collapse reality. According to the theory, this will result in a black hole that will tear through space and absorb the entire planet. It is brought up in the final episode of Eureka Seven: AO by Renton as he explains the appearance of the Scub Coral in the alternative universe to his son, Ao, and a few others.