Signal-locality in hidden-variables theories

We prove that all deterministic hidden-variables theories, that reproduce quantum theory for a 'quantum equilibrium' distribution of hidden variables. predict the existence of instantaneous signals at the statistical level for hypothetical 'nonequilibrium ensembles'. This signal-locality theorem generalises yet another property of the pilot-wave theory of de Broglie and Bohm, The theorem supports the hypothesis that in the remote past the universe relaxed to a state of statistical equilibrium (at the hidden-variable level) in which nonlocality happens to be masked by quantum noise. (C) 2002 Published by Elsevier Science B.V.