On the visible size and geometry of aggressively expanding civilizations at cosmological distances

TL;DR

This paper models the observable size and distribution of large, rapidly expanding civilizations in the universe, predicting their potential visibility from Earth based on various expansion scenarios.

Contribution

It provides a detailed analysis of the shape, size, and sky coverage of observable domains of advanced civilizations expanding cosmologically.

Findings

Median domain size is about 1% of the celestial sphere.

Observable domains are typically within a gigalight-year from Earth.

Most scenarios predict at least one domain covers a significant sky fraction.

Abstract

If a subset of advanced civilizations in the universe choose to rapidly expand into unoccupied space, these civilizations would have the opportunity to grow to a cosmological scale over the course of billions of years. If such life also makes observable changes to the galaxies they inhabit, then it is possible that vast domains of life-saturated galaxies could be visible from the Earth. Here, we describe the shape and angular size of these domains as viewed from the Earth, and calculate median visible sizes for a variety of scenarios. We also calculate the total fraction of the sky that should be covered by at least one domain. In each of the 27 scenarios we examine, the median angular size of the nearest domain is within an order of magnitude of a percent of the whole celestial sphere. Observing such a domain would likely require an analysis of galaxies on the order of a Gly from the Earth.