Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Trans-Planckian redshifts and the substance of the space-time river   Trans-Planckian redshifts in cosmology and outside black holes may provide
windows on a hypothetical short distance cutoff on the fundamental degrees of
freedom. In cosmology, such a cutoff seems to require a growing Hilbert space,
but for black holes, Unruh's sonic analogy has given rise to both field
theoretic and lattice models demonstrating how such a cutoff in a fixed Hilbert
space might be compatible with a low energy effective quantum field theory of
the Hawking effect. In the lattice case, the outgoing modes arise via a Bloch
oscillation from ingoing modes. A short distance cutoff on degrees of freedom
is incompatible with local Lorentz invariance, but may nevertheless be
compatible with general covariance if the preferred frame is defined
non-locally by the cosmological background. Pursuing these ideas in a different
direction, condensed matter analogs may eventually allow for laboratory
observations of the Hawking effect. This paper introduces and gives a fairly
complete but brief review of the work that has been done in these areas, and
tries to point the way to some future directions.

16
The categories of this paper are: stat
22
The categories of this paper are: chao-dyn
37
The categories of this paper are: supr-con
17
The categories of this paper are: q-fin
20
The categories of this paper are: acc-phys
15
The categories of this paper are: nucl-ex
0
The categories of this paper are: hep-ph
9
The categories of this paper are: nlin
29
The categories of this paper are: funct-an
27
The categories of this paper are: comp-gas
14
The categories of this paper are: math-ph
33
The categories of this paper are: plasm-ph
23
The categories of this paper are: solv-int
11
The categories of this paper are: hep-lat
8
The categories of this paper are: hep-ex
1
The categories of this paper are: cs