Researcher describes how extraterrestrial civilizations could colonize the galaxy even if they don't have starships

Astronomers have been looking for extraterrestrial civilizations in planetary systems for sixty years. In the paper published by the International Journal of Astrobiology, Cambridge University Press, and titled " extraterrestrial civilizations and interstellar colonization: Implications for SETI and SETA", the author proposes that the search for extraterrestrial intelligence may have consequences.

extraterrestrial civilizations may leave their home planetary systems when faced with threats. There are ways to ride free-floating planets. Space and resources can be offered by free-floating planets, as well as protection from space radiation, for large populations embarking on interstellar travel. Huge starships, also called world ships, are not likely to be able to offer the same.

Extraterrestrial civilizations may use free-floating planets to send biological or post-biological species to survey space, stars, and planetary systems, or to establish colonies in several planetary systems to preserve and expand their civilization even before they face threats at home.

In her paper, Romanovskaya talks about how extraterrestrial civilizations may hitch a ride on free-floating planets that are outside their home planetary systems, or they may ride planet-like objects ejected from their planetary systems by dying host stars. extraterrestrial civilizations may use gravity assist events to convert Oort-cloud objects of their planetary systems into free-floating planets and ride them among the stars.

With little starlight reaching free-floating planets, extraterrestrials could use controlled nuclear fusion as the source of energy, and they could be protected from space radiation. They would be prepared for colonization of oceans in planetary systems.

Because free-floating planets cannot sustain their oceans forever, extraterrestrial civilizations would ride free-floating planets to reach and colonize planets around stars. The extraterrestrials could transfer from their free-floating planets to selected Oort-cloud objects of the planetary systems that would carry them towards the major planets of the planetary systems. Such free-floating planets could be captured by the planetary systems. The extraterrestrials would colonize the planetary systems.

To find extraterrestrials riding free-floating planets, Romanovskaya proposes to search for certain technosignatures, such asmagnetic emissions produced by extraterrestrial technologies on the free-floating planets and in their vicinity.

Astronomers could misinterpret the origin of technosignatures if they did not detect them on a free-floating planet. The famous Wow! signal was detected in the constellation Sagittarius. Scientists are hypothesizing why the signal was only detected once.

If extraterrestrials sent the Wow! signal from a free-floating planet and it moved away from the line of observations, it would not be detected again. Astronomers should search for free-floating planets along the lines of observations of unusual and potentially artificial signals coming from space.

There is a chance that extraterrestrial intelligent species may have traveled in our stellar neighborhood over the last few billions of years, and Romanovskaya discusses different ways to look for their artifacts in the solar system and nearby planetary systems.

Near or far away from Earth, intelligent biological species or post-biological beings with artificial intelligence may be riding free-floating planets and looking for a new home. The search for space travelers should be part of our search for intelligent life in the universe.

More information: Irina K. Romanovskaya, Migrating extraterrestrial civilizations and interstellar colonization: implications for SETI and SETA, International Journal of Astrobiology (2022). DOI: 10.1017/S1473550422000143 Journal information: International Journal of Astrobiology Citation: Researcher describes how extraterrestrial civilizations could colonize the galaxy even if they don't have starships (2022, May 26) retrieved 26 May 2022 from https://phys.org/news/2022-05-extraterrestrial-civilizations-colonize-galaxy-dont.html This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.