  Wigner's friend experiment and its modern extensions display the ambiguity of
the quantum mechanical description regarding the assignment of quantum states.
While the friend applies the state-update rule to the system upon observing an
outcome of her measurement in a quantum system, Wigner describes the friend's
measurement as a unitary evolution, resulting in an entangled state for the
composite system of the friend and the system. In this respect, Wigner is often
referred to as a "superobserver" who has the supreme technological ability to
keep the friend's laboratory coherent. As such, it is often argued that he has
the "correct" description of the state. Here we show that the situation is more
symmetrical than is usually thought: there are different types of information
that each of the observers has that the other fundamentally cannot have - they
reside in different "bubbles" (in Calvalcanti's terminology). While this can
explain why the objectivity of the state assignment is only relative to the
bubble, we consider more elaborated situations in form of a game in which the
players can switch between bubbles. We find that, in certain circumstances,
observers may be entitled to adopt and verify the state assignment from another
bubble if they condition their predictions on all information that is in
principle available to them.
