Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Singularities In Scalar-Tensor Cosmologies   In this article, we examine the possibility that there exist special
scalar-tensor theories of gravity with completely nonsingular FRW solutions.
Our investigation in fact shows that while most probes living in such a
Universe never see the singularity, gravity waves always do. This is because
they couple to both the metric and the scalar field, in a way which effectively
forces them to move along null geodesics of the Einstein conformal frame. Since
the metric of the Einstein conformal frame is always singular for
configurations where matter satisfies the energy conditions, the gravity wave
world lines are past inextendable beyond the Einstein frame singularity, and
hence the geometry is still incomplete, and thus singular. We conclude that the
singularity cannot be entirely removed, but only be made invisible to most, but
not all, probes in the theory.

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The categories of this paper are: hep-ph
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The categories of this paper are: math-ph
13
The categories of this paper are: quant-ph
1
The categories of this paper are: cs
28
The categories of this paper are: alg-geom
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The categories of this paper are: nucl-th
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The categories of this paper are: adap-org
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The categories of this paper are: math
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The categories of this paper are: chem-ph
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The categories of this paper are: eess
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The categories of this paper are: funct-an
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The categories of this paper are: comp-gas
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The categories of this paper are: acc-phys
30
The categories of this paper are: q-alg
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The categories of this paper are: q-fin
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The categories of this paper are: dg-ga