  We present a model where some proportion of extraterrestrial civilizations
expand uniformly over time to reach a cosmological scale. We then ask what
humanity could infer if a sky survey were to find zero, one, or more such
civilizations. We show how the results of this survey, in combination with an
approach to anthropics called the Self Indication Assumption (SIA), would shift
any prior estimates of two quantities: 1) The chance that a technological
civilization like ours survives to embark on such expansion, and 2) the maximum
feasible speed at which it could expand. The SIA gives pessimistic estimates
for both, but survey results (even null results) can reverse some of the
effect. The SIA-induced shift in expectations is strong enough to be regarded
as a falsifiable technological prediction, and a test of the SIA in
cosmological reasoning.

Cosmology and Nongalactic Astrophysics;General Relativity and Quantum Cosmology;Physics and Society