ON CAUSAL LOOPS IN THE QUANTUM REALM

摘要

It is frequently argued that there is a tension between quantum theory and the special theory of relativity, but there are no conclusive arguments for their incompatibility. In this paper I consider two recent arguments for the impossibility of certain types of relativistic quantum theory on the grounds of causal paradoxes, due to Frank Amtzenius and Tim Maudlin. The structure of both arguments is (in effect) similar: if these alleged relativistic theories were true, closed causal loops could easily be constructed, but such loops would exclude the very possibility of these theories. I argue that Amtzenius's and Maudlin's lines of reasoning fail because they are based on untenable assumptions about probabilities in causal loops. I also argue that the consistency of the quantum theories under consideration depends on the interpretation of the probabilities they prescribe, and the question of their empirical adequacy requires metaphysical and empirical investigation into the nature of chances and frequencies in causal loops.