Craig argued (pls give your objections, clarifications, etc.) that suppose, on the other hand, that we reject the existence of causal connections between events occurring at A and B in favor of some interpretation according to which the photons at A and B are somehow correlated, but not causally connected. On this interpretation, the composite state consisting of the two photons with their respective measuring devices constitutes a single system, which is in a definite state (see Bohr 1964: 145–51). To affect the behavior of one photon via measurement is to disturb the whole system. When the wave function of a photon at A collapses, there is an immediate and correlated collapse of the wave function of its counterpart at B. But clearly, even though this interpretation denies the superluminal causal influence from A to B posited by the de Broglie-Bohm theory, it still just as effectively abrogates the relativity of simultaneity, since the collapse of the paired wave functions is simultaneous. Therefore, asseverations that such an interpretation would not run contrary to the received interpretation of SR because that theory prohibits only signals of superluminal velocities, not instantaneous correlations, are quite beside the
point.23 The point is that such correlations furnish the means of establishing relations of absolute simultaneity and a fundamental frame.24 As Maudlin points out
In Minkowski spacetime this theory of wave collapse no longer makes sense. The collapse can be instantaneous in at most one reference frame, leading to two possibilities: either some feature of the situation picks out a preferred reference frame, with respect to which the collapse is instantaneous, or the collapse is not instantaneous at all. (Maudlin 1994: 196; cf. pp. 137–38, 144)
The problem posed by instantaneous collapse of the wave function for relativity theory can be clarified by realizing that since, according to SR, simultaneity is relative to reference frames, the collapse of the wave function for spatially separated photons will itself become relative to a reference frame. The problem is that properties like polarization and spin are not relational,
but intrinsic properties of photons (Ryff 1992: 249). If the universe contained a single photon, it would have a definite polarization. Therefore the possession of such properties should not be made hyper-plane dependent. After surveying various attempts to integrate Bell’s Inequalities with relativity theory, Maudlin concludes that these attempts ‘‘entail such severe dislocations of our physical view that one must seriously consider whether our grounds for adhering to Relativity are really strong enough to justify such extreme measures’’ (Maudlin 1994: 239; cf. Eberhard 1978: 392–419). ‘‘Indeed, the cost exacted by those theories which retain Lorentz invariance is so high that one might rationally prefer to reject Relativity as the ultimate account of spacetime
structure’’ (Maudlin 1994: 220).