Likelihood of Contact Depends on the Lifetimes of Civilizations

If alien civilizations are anything like terrestrial civilizations, earthly beings may never encounter beings from outer space. Civilizations Beyond Earth contributor Alan J. Penny says our greatest chance for interaction will hinge on the longevity and attention span of an alien society — which must be long enough to give us a chance to interact.
To consider the number of extraterrestrial civilizations that may be out there and which we can detect by their emission of radio signals, we need to think about the likelihood that a star may host a planet with a civilization that can broadcast such signals.

But we also need to think about how long such civilizations last.

If all civilizations that broadcast do so for millions of years, we have a better chance of catching them at it than if they only last for thousands of years.

Previously, considerations of lifetimes have involved cultural matters, such as the stability of civilizations with nuclear arms, or physical matters, such as changes in the host stars. In my chapter we suggest a novel way that a civilization may end — a change in the genetic structure of the brains of the intelligent beings involved.

Starstruck: Cosmic Visions in Science, Religion, and Folklore; Spacefaring: The Human Dimension; Living Aloft: Human Requirements for Extended Spaceflight; and From Antarctica to Outer Space: Life in Isolation and Confinement.

Alan J. Penny, PhD, is honorary reader and visiting scientist in the School of Physics and Astronomy at the University of St. Andrews, where he researches stellar photometry of bright stars, extrasolar planets, and SETI. He is principal investigator of a team investigating the use of the LOFAR (LOw Frequency ARray) radio telescope for SETI. This project will determine LOFAR’s sensitivity and ability to discriminate against terrestrial sources when operating in SETI mode, and if it produces positive results, will proceed to observe nearby stars. Civilizations Beyond Earth was first published in September 2011. The collection was edited by Douglas A. Vakoch and Albert Harrison. Read earlier blog posts about the collection: Life Beyond Earth? Survey Says…, Extra-Terrestrial Life: Good or Bad News?, and A New Model for Interstellar Communication.

Douglas A. Vakoch is Professor in the Department of Clinical Psychology at the California Institute of Integral Studies, as well as Director of Interstellar Message Composition at the SETI Institute. He serves as Chair of both the International Academy of Astronautics (IAA) Study Group on Interstellar Message Construction and the IAA Study Group on Active SETI: Scientific, Technical, Societal, and Legal Dimensions. His books include Communication with Extraterrestrial Intelligence (CETI), Psychology of Space Exploration: Contemporary Research in Historical Perspective, and Ecofeminism and Rhetoric: Critical Perspectives on Sex, Technology, and Discourse.

Albert A. Harrison is Professor Emeritus in the Department of Psychology at the University of California, Davis. In addition to researching the societal dimensions of astrobiology and SETI, he studies human adaptation to spaceflight and spaceflight-analogous environments. His books include After Contact: The Human Response to Extraterrestrial Life; Starstruck: Cosmic Visions in Science, Religion, and Folklore; Spacefaring: The Human Dimension; Living Aloft: Human Requirements for Extended Spaceflight; and From Antarctica to Outer Space: Life in Isolation and Confinement. - See more at: