Causality paradoxes and nonparadoxes: Classical superluminal signals and quantum measurements

A potential causality paradox in quantum mechanics involving the measurement of a correlated system of two atoms that have moved far apart is constructed along the lines of a classical causality paradox involving the exchange of superluminal signals between distant observers. It is shown that the quantum measurement example does not lead to a paradox, but that the results have implications for the interpretation of quantum mechanics. The thought experiments presented have been used in undergraduate courses in special relativity and quantum mechanics.