Implications of a search for intergalactic civilizations on prior estimates of human survival and travel speed

TL;DR

This paper models how searches for intergalactic civilizations influence estimates of human survival chances and expansion speeds, using anthropic reasoning to interpret survey results and test cosmological assumptions.

Contribution

It introduces a framework combining extraterrestrial civilization surveys with the Self Indication Assumption to update survival and expansion speed estimates.

Findings

Null survey results can significantly alter prior survival probability estimates.

The approach provides a testable prediction for the Self Indication Assumption in cosmology.

Survey outcomes influence the perceived maximum expansion speed of civilizations.

Abstract

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.