Time travel paradoxes, path integrals, and the many worlds interpretation of quantum mechanics
Abstract
We consider two approaches to evading paradoxes in quantum mechanics with closed timelike curves. In a model similar to Politzer’s, assuming pure states and using path integrals, we show that the problems of paradoxes and of unitarity violation are related; preserving unitarity avoids paradoxes by modifying the time evolution so that improbable events become certain. Deutsch has argued, using the density matrix, that paradoxes do not occur in the “many worlds interpretation.” We find that in this approach account must be taken of the resolution time of the device that detects objects emerging from a wormhole or other time machine. When this is done one finds that this approach is viable only if macroscopic objects traversing a wormhole interact with it so strongly that they are broken into microscopic fragments.
 Publication:

Physical Review D
 Pub Date:
 June 2004
 DOI:
 10.1103/PhysRevD.69.124023
 arXiv:
 arXiv:grqc/0410035
 Bibcode:
 2004PhRvD..69l4023E
 Keywords:

 04.20.Gz;
 Spacetime topology causal structure spinor structure;
 General Relativity and Quantum Cosmology
 EPrint:
 no figures