  The transition from classical to quantum mechanics rests on the recognition
that the structure of information is not what we thought it was: there are
operational, i.e., phenomenal, probabilistic correlations that lie outside the
polytope of local correlations. Such correlations cannot be simulated with
classical resources, which generate classical correlations represented by the
points in a simplex, where the vertices of the simplex represent joint
deterministic states that are the common causes of the correlations. The `no
go' hidden variable theorems tell us that we can't shoe-horn correlations
outside the local polytope into a classical simplex by supposing that something
has been left out of the story. The replacement of the classical simplex by the
quantum convex set as the structure representing probabilistic correlations is
the analogue for quantum mechanics of the replacement of Newton's Euclidean
space and time by Minkowski spacetime in special relativity. The nonclassical
features of quantum mechanics, including the irreducible information loss on
measurement, are generic features of correlations that lie outside the local
correlation polytope. This paper is an elaboration of these ideas, and its
consequences for the measurement problem of quantum mechanics. A large part of
the difficulty is removed by seeing that the inconsistency in reconciling the
entangled state at the end of a quantum measurement process with the
definiteness of the macroscopic pointer reading and the definiteness of the
correlated value of the measured micro-observable is only apparent and depends
on a stipulation that is not required by the structure of the quantum
possibility space. Replacing this stipulation by an alternative consistent
stipulation resolves the problem.
