Action at a Distance and the Observation Problem in Quantum Theory

Jerome Blackman

The relation between quantum theory and special relativity is peculiar. On the one hand it is close and essential. Steven Weinberg [1], for example, takes the position that the standard model is an inevitable consequence of the marriage of the two theories. On the other, the action at a distance implied by the famous paper by Einstein, Podolsky, and Rosen [2] is certainly contrary to the implications of special relativity in spite of the fact that it does not allow transmission of information. The setting of quantum theory is a Hilbert spaceH and a path inH whose development in time is governed by a one parameter group of unitary transformations while the setting for special relativity can be thought of as Minkowski space with the time development not absolute, but dependent on the inertial system of the observer. The problem is to show how these two very different viewpoints can be reconciled in a way that includes an explanation of the "action at a distance" conundrum.

Henry Mehlberg

Shreya Banerjee, Sayantani Bera, Tejinder P. Singh

Quantum nonlocal correlations and the acausal, spooky action at a distance suggest a discord between quantum theory and special relativity. We propose a resolution for this discord by first observing that there is a problem of time in quantum theory. There should exist a reformulation of quantum theory which does not refer to classical time. Such a reformulation is obtained by suggesting that spacetime is fundamentally noncommutative. Quantum theory without classical time is the equilibrium statistical thermodynamics of the underlying noncommutative relativity. Stochastic fluctuations about equilibrium give rise to the classical limit and ordinary spacetime geometry. However, measurement on an entangled state can be correctly described only in the underlying noncommutative spacetime, where there is no causality violation, nor a spooky action at a distance.

Alfred Landé

Stella Fillmore-Patrick

This thesis aims to legitimize the inclusion of action at a distance in scientific theories. I approach this task from two angles. In the first part, I show that action at a distance is a genuine metaphysical possibility. To do so, I examine how theorists in the history of science have justified their assumption of locality (and find these justifications inadequate), reconcile action at a distance with scientific explanation and show that it is not a threat to causation. In the second part, I consider an actual instance of action at a distance in nature: quantum nonlocality. Since action at a distance cannot be excluded through reason alone, if experience indicates action at a distance one may call it as such. I argue that action at a distance is the most viable theory by which to interpret quantum nonlocality.

Nicola Cufaro Petroni, Ph. Droz-Vincent, Jean Pierre Vigier