Action and Passion at a Distance

Quantum mechanics permits nonlocality—both nonlocal correlations and nonlocal equations of motion—while respecting relativistic causality. Is quantum mechanics the unique theory that reconciles nonlocality and causality? We consider two models, going beyond quantum mechanics, of nonlocality— “superquantum” correlations, and nonlocal “jamming” of correlations—and derive new results for the jamming model. In one space dimension, jamming allows reversal of the sequence of cause and effect; in higher dimensions, however, effect never precedes cause. ∗To appear in Quantum Potentiality, Entanglement, and Passion-at-a-Distance: Essays for Abner Shimony, R. S. Cohen, M. A. Horne and J. Stachel, eds. (Dordrecht, Netherlands: Kluwer Academic Publishers), in press.