Extending Galactic Habitable Zone Modeling to Include the Emergence of Intelligent Life

Previous studies of the galactic habitable zone have been concerned with identifying those regions of the Galaxy that may favor the emergence of complex life. A planet is deemed habitable if it meets a set of assumed criteria for supporting the emergence of such complex life. In this work, we extend...

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Main Authors: Morrison, Ian, Gowanlock, M.
Format: Journal Article
Published: Mary Ann Liebert, Inc 2015
Online Access:http://hdl.handle.net/20.500.11937/72428
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author Morrison, Ian
Gowanlock, M.
author_facet Morrison, Ian
Gowanlock, M.
author_sort Morrison, Ian
building Curtin Institutional Repository
collection Online Access
description Previous studies of the galactic habitable zone have been concerned with identifying those regions of the Galaxy that may favor the emergence of complex life. A planet is deemed habitable if it meets a set of assumed criteria for supporting the emergence of such complex life. In this work, we extend the assessment of habitability to consider the potential for life to further evolve to the point of intelligence--termed the propensity for the emergence of intelligent life, fI. We assume fI is strongly influenced by the time durations available for evolutionary processes to proceed undisturbed by the sterilizing effects of nearby supernovae. The times between supernova events provide windows of opportunity for the evolution of intelligence. We developed a model that allows us to analyze these window times to generate a metric for fI, and we examine here the spatial and temporal variation of this metric. Even under the assumption that long time durations are required between sterilizations to allow for the emergence of intelligence, our model suggests that the inner Galaxy provides the greatest number of opportunities for intelligence to arise. This is due to the substantially higher number density of habitable planets in this region, which outweighs the effects of a higher supernova rate in the region. Our model also shows that fI is increasing with time. Intelligent life emerged at approximately the present time at Earth's galactocentric radius, but a similar level of evolutionary opportunity was available in the inner Galaxy more than 2?Gyr ago. Our findings suggest that the inner Galaxy should logically be a prime target region for searches for extraterrestrial intelligence and that any civilizations that may have emerged there are potentially much older than our own.
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spelling curtin-20.500.11937-724282018-12-13T09:32:29Z Extending Galactic Habitable Zone Modeling to Include the Emergence of Intelligent Life Morrison, Ian Gowanlock, M. Previous studies of the galactic habitable zone have been concerned with identifying those regions of the Galaxy that may favor the emergence of complex life. A planet is deemed habitable if it meets a set of assumed criteria for supporting the emergence of such complex life. In this work, we extend the assessment of habitability to consider the potential for life to further evolve to the point of intelligence--termed the propensity for the emergence of intelligent life, fI. We assume fI is strongly influenced by the time durations available for evolutionary processes to proceed undisturbed by the sterilizing effects of nearby supernovae. The times between supernova events provide windows of opportunity for the evolution of intelligence. We developed a model that allows us to analyze these window times to generate a metric for fI, and we examine here the spatial and temporal variation of this metric. Even under the assumption that long time durations are required between sterilizations to allow for the emergence of intelligence, our model suggests that the inner Galaxy provides the greatest number of opportunities for intelligence to arise. This is due to the substantially higher number density of habitable planets in this region, which outweighs the effects of a higher supernova rate in the region. Our model also shows that fI is increasing with time. Intelligent life emerged at approximately the present time at Earth's galactocentric radius, but a similar level of evolutionary opportunity was available in the inner Galaxy more than 2?Gyr ago. Our findings suggest that the inner Galaxy should logically be a prime target region for searches for extraterrestrial intelligence and that any civilizations that may have emerged there are potentially much older than our own. 2015 Journal Article http://hdl.handle.net/20.500.11937/72428 10.1089/ast.2014.1192 Mary Ann Liebert, Inc restricted
spellingShingle Morrison, Ian
Gowanlock, M.
Extending Galactic Habitable Zone Modeling to Include the Emergence of Intelligent Life
title Extending Galactic Habitable Zone Modeling to Include the Emergence of Intelligent Life
title_full Extending Galactic Habitable Zone Modeling to Include the Emergence of Intelligent Life
title_fullStr Extending Galactic Habitable Zone Modeling to Include the Emergence of Intelligent Life
title_full_unstemmed Extending Galactic Habitable Zone Modeling to Include the Emergence of Intelligent Life
title_short Extending Galactic Habitable Zone Modeling to Include the Emergence of Intelligent Life
title_sort extending galactic habitable zone modeling to include the emergence of intelligent life
url http://hdl.handle.net/20.500.11937/72428