title: Environment-assisted invariance, entanglement, and probabilities in quantum physics.
abstract: I introduce environment-assisted invariance or envariance-a symmetry exhibited by correlated quantum systems and related to causality-and describe how it can be used to understand the nature of ignorance and, hence, the origin and interpretation of Born's rule for quantum probabilities.
authors.affiliation: Theory Division, MS B210, LANL, Los Alamos, New Mexico 87545, USA.
authors.forename: Wojciech Hubert
authors.initials: WH
authors.lastname: Zurek