Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Why the Universe Started from a Low Entropy State   We show that the inclusion of backreaction of massive long wavelengths
imposes dynamical constraints on the allowed phase space of initial conditions
for inflation, which results in a superselection rule for the initial
conditions. Only high energy inflation is stable against collapse due to the
gravitational instability of massive perturbations. We present arguments to the
effect that the initial conditions problem {\it cannot} be meaningfully
addressed by thermostatistics as far as the gravitational degrees of freedom
are concerned. Rather, the choice of the initial conditions for the universe in
the phase space and the emergence of an arrow of time have to be treated as a
dynamic selection.

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The categories of this paper are: atom-ph
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The categories of this paper are: nucl-ex
14
The categories of this paper are: math-ph
23
The categories of this paper are: solv-int
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The categories of this paper are: alg-geom
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The categories of this paper are: acc-phys
13
The categories of this paper are: quant-ph
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The categories of this paper are: q-alg
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The categories of this paper are: econ
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The categories of this paper are: funct-an
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The categories of this paper are: chem-ph
4
The categories of this paper are: cond-mat
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The categories of this paper are: hep-lat
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The categories of this paper are: adap-org
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The categories of this paper are: eess
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The categories of this paper are: q-fin