Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Hawking's chronology protection conjecture: singularity structure of the
  quantum stress--energy tensor   The recent renaissance of wormhole physics has led to a very disturbing
observation: If traversable wormholes exist then it appears to be rather easy
to to transform such wormholes into time machines. This extremely disturbing
state of affairs has lead Hawking to promulgate his chronology protection
conjecture. This paper continues a program begun in an earlier paper [Physical
Review {\bf D47}, 554--565 (1993), hepth@xxx/9202090]. An explicit calculation
of the vacuum expectation value of the renormalized stress--energy tensor in
wormhole spacetimes is presented. Point--splitting techniques are utilized.
Particular attention is paid to computation of the Green function [in its
Hadamard form], and the structural form of the stress-energy tensor near short
closed spacelike geodesics. Detailed comparisons with previous calculations are
presented, leading to a pleasingly unified overview of the situation.

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The categories of this paper are: atom-ph
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The categories of this paper are: q-fin
3
The categories of this paper are: physics
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The categories of this paper are: ao-sci
1
The categories of this paper are: cs
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The categories of this paper are: econ
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The categories of this paper are: alg-geom
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The categories of this paper are: q-bio
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The categories of this paper are: plasm-ph
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The categories of this paper are: chao-dyn
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The categories of this paper are: quant-ph
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The categories of this paper are: hep-lat
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The categories of this paper are: dg-ga
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The categories of this paper are: eess
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The categories of this paper are: bayes-an
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The categories of this paper are: q-alg