Final answer:
The statement made by Sakurai is related to the interpretation of wavefunctions and their overlap in quantum mechanics. According to the Copenhagen interpretation, a particle exists in a superposition of states when not observed, and its wavefunction collapses into a specific position state when observed.
Step-by-step explanation:
The statement made by Sakurai is related to the interpretation of wavefunctions and their overlap. In the Copenhagen interpretation of quantum mechanics, a wavefunction describes the probability distribution of a particle's position.
When an observer is not looking or when a measurement is not being made, the particle exists in a superposition of states. However, when an observer looks or detects the particle, the wavefunction collapses into a specific position state. This interpretation suggests that the particle is everywhere until it is observed.