Quantum mechanical 'Backward in Time'? Comments, Answers, and the Causal   Indistinguishability Condition
  We discuss a number of comments on quant-ph/9801061, and propose to introduce the concept of 'Causal Indistinguishability'. The incompatibility between Quantum Mechanics and Nonlocal Causality appears to be unavoidable: upholding of Quantum Mechanics by experiment would mean to live with influences backward in time, just as we are now living with such faster than light. 
Antoine Suarez (Center for Quantum Philosophy, Zurich)