  The search for extraterrestrial intelligence (SETI) is a scientific endeavor
which struggles with unique issues -- a strong indeterminacy in what data to
look for and when to do so. This has led to attempts at finding both
fundamental limits of the communication between extraterrestrial intelligence
and human civilizations, as well as benchmarks so as to predict what kinds of
signals we might most expect. Previous work has been formulated in terms of the
information-theoretic task of communication, but we instead argue it should be
viewed as a detection problem, specifically one-shot (asymmetric) hypothesis
testing. With this new interpretation, we develop fundamental limits as well as
provide simple examples of how to use this framework to analyze and benchmark
different possible signals from extraterrestrial civilizations. We show that
electromagnetic signaling for detection requires much less power than for
communication, that detection as a function of power can be non-linear, and
that much of the analysis in this framework may be addressed using
computationally efficient optimization problems, thereby demonstrating tools
for further inquiry.
