Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Galactic Gradients, Postbiological Evolution and the Apparent Failure of
  SETI   Motivated by recent developments impacting our view of Fermi's paradox
(absence of extraterrestrials and their manifestations from our past light
cone), we suggest a reassessment of the problem itself, as well as of
strategies employed by SETI projects so far. The need for such reevaluation is
fueled not only by the failure of searches thus far, but also by great advances
recently made in astrophysics, astrobiology, computer science and future
studies, which have remained largely ignored in SETI practice. As an example of
the new approach, we consider the effects of the observed metallicity and
temperature gradients in the Milky Way on the spatial distribution of
hypothetical advanced extraterrestrial intelligent communities. While,
obviously, properties of such communities and their sociological and
technological preferences are entirely unknown, we assume that (1) they operate
in agreement with the known laws of physics, and (2) that at some point they
typically become motivated by a meta-principle embodying the central role of
information-processing; a prototype of the latter is the recently suggested
Intelligence Principle of Steven J. Dick. There are specific conclusions of
practical interest to be drawn from coupling of these reasonable assumptions
with the astrophysical and astrochemical structure of the Galaxy. In
particular, we suggest that the outer regions of the Galactic disk are most
likely locations for advanced SETI targets, and that intelligent communities
will tend to migrate outward through the Galaxy as their capacities of
information-processing increase, for both thermodynamical and astrochemical
reasons. This can also be regarded as a possible generalization of the Galactic
Habitable Zone, concept currently much investigated in astrobiology.

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The categories of this paper are: math
5
The categories of this paper are: gr-qc
29
The categories of this paper are: funct-an
10
The categories of this paper are: q-bio
37
The categories of this paper are: supr-con
11
The categories of this paper are: hep-lat
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The categories of this paper are: hep-ph
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The categories of this paper are: atom-ph
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The categories of this paper are: cmp-lg
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The categories of this paper are: comp-gas
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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: econ
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The categories of this paper are: q-alg
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The categories of this paper are: stat
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The categories of this paper are: alg-geom