Do the laws of physics forbid the operation of time machines?

Synthese 169 (1):91 - 124 (2009)
We address the question of whether it is possible to operate a time machine by manipulating matter and energy so as to manufacture closed timelike curves. This question has received a great deal of attention in the physics literature, with attempts to prove no-go theorems based on classical general relativity and various hybrid theories serving as steps along the way towards quantum gravity. Despite the effort put into these no-go theorems, there is no widely accepted definition of a time machine. We explain the conundrum that must be faced in providing a satisfactory definition and propose a resolution. Roughly, we require that all extensions of the time machine region contain closed timelike curves; the actions of the time machine operator are then sufficiently “potent” to guarantee that closed timelike curves appear. We then review no-go theorems based on classical general relativity, semi-classical quantum gravity, quantum field theory on curved spacetime, and Euclidean quantum gravity. Our verdict on the question of our title is that no result of sufficient generality to underwrite a confident “yes” has been proven. Our review of the no-go results does, however, highlight several foundational problems at the intersection of general relativity and quantum physics that lend substance to the search for an answer.
Keywords General relativity  Time travel  Time machines  QFT on curved spacetime  Causality  Closed timelike curves
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DOI 10.2307/40271293
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References found in this work BETA
John W. Carroll, Laws of Nature. Philosophy and Phenomenological Research.
Frank Arntzenius, Time Travel and Modern Physics. Stanford Encyclopedia of Philosophy.

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Citations of this work BETA
Joachim Pfarr (2010). Closed Timelike Curves—Time and Again. Foundations of Physics 40 (9-10):1326-1332.
Cord Friebe (2012). Twins' Paradox and Closed Timelike Curves: The Role of Proper Time and the Presentist View on Spacetime. [REVIEW] Journal for General Philosophy of Science / Zeitschrift für Allgemeine Wissenschaftstheorie 43 (2):313-326.
Cord Friebe (2014). Don Ross, James Ladyman, and Harold Kincaid : Scientific Metaphysics. Journal for General Philosophy of Science / Zeitschrift für Allgemeine Wissenschaftstheorie 45 (2):387-391.

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