2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/213982We discuss how to embed quantum nonlocality in an approximately classical spacetime background, a question which must be answered irrespective of any underlying microscopic theory of spacetime. We argue that, in deterministic hidden-variables theories, the choice of spacetime kinematics should be dictated by the properties of generic non-equilibrium states, which allow nonlocal signalling. Such signalling provides an operational definition of absolute simultaneity, which may naturally be associated with a preferred foliation of classical spacetime. The argument applies to any deterministic hidden-variables theory, and to both flat and curved spacetime backgrounds. We include some critical discussion of Einstein's 1905 'operational' approach to relativity, and compare it with that of Poincare.30 pages. Minor changes. To be published in: "Absolute Simultaneity", eds. W. L. Craig and Q. Smith (Routledge, London, 2005)Quantum PhysicsGeneral Relativity and Quantum CosmologyHigh Energy Physics - Theorytext