On the Quantum Stability of the Time Machine

Abstract

In a number of papers it has been claimed that the time machine are quantum unstable, which manifests itself in the divergence of the vacuum expectation value of the stress-energy tensor $⟨\mathbf{T}⟩$ near the Cauchy horizon. The expression for $⟨\mathbf{T}⟩$ was found in these papers on the basis of some specific approach \cite{Fro,KimT}.\par We show that this approach is untenable in that the above expression firstly is not derived from some more fundamental and undeniable premises, as it is claimed, but rather postulated and secondly contains undefined terms, so that one can neither use nor check it. As a counterexample we cite a few cases of (two-dimensional) spacetimes containing time machines with $⟨\mathbf{T}⟩$ bounded near the Cauchy horizon.

LaTex, 12 pages, no figures

References in corpus (1)

• Quantum Complex Scalar Field in the Two-Dimensional Spacetime with Closed Timelike Curves and a Time-Machine Problem

Cited by in corpus (32)

• Hyperfast Interstellar Travel in General Relativity
• Surface stresses on a thin shell surrounding a traversable wormhole
• Can the Universe Create Itself?
• A new time-machine model with compact vacuum core
• Formation of closed timelike curves in a composite vacuum/dust asymptotically-flat spacetime
• A Self-Consistent Vacuum for Misner Space and the Chronology Protection Conjecture
• The time travel paradox
• Models for Chronology Selection
• Exotic solutions in General Relativity: Traversable wormholes and 'warp drive' spacetimes
• Traversable wormholes: the Roman ring
• An Exact String Theory Model of Closed Time-Like Curves and Cosmological Singularities
• The reliability horizon for semi-classical quantum gravity: Metric fluctuations are often more important than back-reaction
• Time Machines Constructed from Anti-de Sitter Space
• Quantum time machine
• Causal paradoxes: a conflict between relativity and the arrow of time
• The thermal and two-particle stress-energy must be ill-defined on the 2-d Misner space chronology horizon
• Divergences in the Effective Action for Acausal Spacetimes
• Nonorientable spacetime tunneling
• Lectures on Faster-than-Light Travel and Time Travel
• Quantum Field Theory in Curved Spacetime (2nd Edition)
• Quantum field theory and time machines
• Holography of time machines
• The time traveler's guide to the quantization of zero modes
• Ring wormholes and time machines
• Chronology Protection in Generalized Godel Spacetime
• Wormhole Time Machines and Multiple Histories
• Recurrence metrics and the physics of closed time-like curves
• Evaporation induced traversability of the Einstein--Rosen wormhole
• Particle Creation Near the Chronology Horizon
• The CWKB Method of Particle Production Near Chronology Horizon
• Special Theory of Relativity in Curved Space Time
• Curvature effects in special relativity