Goldwirth, Dalia S. and Perry, Malcolm J. and Piran, Tsvi and Thorne, Kip S. (1994) Quantum propagator for a nonrelativistic particle in the vicinity of a time machine. Physical Review D, 49 (8). pp. 39513957. ISSN 05562821. http://resolver.caltech.edu/CaltechAUTHORS:GOLprd94

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Abstract
We study the propagator of a nonrelativistic, noninteracting particle in any nonrelativistic "timemachine" spacetime of the following type: an external, chronal spacetime in which two spatial regions V at time t and V+ at time t+ are connected by two temporal wormholes, one leading from the past side of V to the future side of V+ and the other from the past side of V+ to the future side of V. We express the propagator explicitly in terms of those for the chronal spacetime and for the two wormholes; and from that expression we show that the propagator satisfies completeness and unitarity in the initial and final "chronal regions" (regions without closed timelike curves) and its propagation from the initial region to the final region is unitary. However, within the time machine it satisfies neither completeness nor unitarity. We also give an alternative proof of initialregiontofinalregion unitarity based on a conserved current and Gauss’s theorem. This proof can be carried over without change to most any nonrelativistic timemachine spacetime and it is valid as long as the particle is not interacting with itself or any other quantum particle; it can, however, interact with an external field (gravitational or otherwise). This result is the nonrelativistic version of a theorem by Friedman, Papastamatiou, and Simon, which says that for a free scalar field quantummechanical unitarity follows from the fact that the classical evolution preserves the KleinGordon inner product.
Item Type:  Article 

Additional Information:  ©1994 The American Physical Society. Received 12 August 1993. It is a pleasure to acknowledge S. Coleman, J. Friedman, J. Hartle, and A. Strominger for enlightening conservations. We thank the Aspen Center for Physics for hospitality while much of this research was being done. This research was partially supported by the Center for Astrophysics (D.S.G.), by the Royal Society and Trinity College (M.J.P.), by the U.S.Israel BSF (T.P.), and by Caltech's Feynman research fund (K.S.T.). 
Group:  TAPIR 
Subject Keywords:  INTERACTING FIELDS; CAUCHYPROBLEM; CURVES; SPACETIMES; UNITARITY 
Record Number:  CaltechAUTHORS:GOLprd94 
Persistent URL:  http://resolver.caltech.edu/CaltechAUTHORS:GOLprd94 
Alternative URL:  http://dx.doi.org/10.1103/PhysRevD.49.3951 
Usage Policy:  No commercial reproduction, distribution, display or performance rights in this work are provided. 
ID Code:  5276 
Collection:  CaltechAUTHORS 
Deposited By:  Tony Diaz 
Deposited On:  09 Oct 2006 
Last Modified:  26 Dec 2012 09:04 
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