  A theory of everything should not only tell us the laws for matter, gravity,
and possibly boundary condition for the universe. In addition, it should
specify the relation between theory and experience. Here I argue for a minimal
prescription in extracting empirical predictions from path integrals by showing
that alternative prescriptions are unjustifiable. In this minimal prescription,
the relative probability for one experience is obtained by summing over all
configurations compatible with that experience, without any further restriction
associated with other experiences of the same or other experiential beings. An
application to Wigner's friend settings shows that quantum theory admits
objective predictions for subjective experiences. Still, quantum theory differs
from classical theory in offering individualized as opposed to collective
accounts of experiences. This consideration of experience in fundamental
theories issues several challenges to popular quantum interpretations, and
points to the outstanding need for a theory of experience in understanding
physical theories of everything.
