“Aliens could colonize the galaxy without using spaceships”
In an article published in the International Journal of Astrobiology, scientist Irina K. Romanovskaya proposes that the search for extraterrestrial intelligence (SETI) may have a better chance of success by including the search for migratory extraterrestrial civilizations.
For example, extraterrestrial civilizations may abandon their home planetary systems when faced with existential threats. One of the ways to do this is to travel on free-floating planets.
Free-floating planets can offer space and resources, as well as protection from space radiation, for very large populations embarking on interstellar travel.
It is technically impossible that huge starships – also called world ships – can offer the same.
Extraterrestrial civilizations may also use free-floating planets to send biological or post-biological species to study interstellar space, stars, and planetary systems.
Or to establish their colonies in various planetary systems to preserve and expand their civilizations even before they face existential threats on their home world.
In her article, Romanovskaya discusses how extraterrestrial civilizations can travel on free-floating planets that are bypassing their home planetary systems, or can travel on planet-like objects ejected from their planetary systems by dying host stars.
Alternatively, extraterrestrial civilizations may use propulsion systems and gravitational assist events to convert objects equivalent to our Sedna in the Oort cloud into a means of interstellar transportation.
Romanovskaya points out that with little starlight reaching free-floating planets, aliens could use controlled nuclear fusion as a power source, and could live in subterranean habitats and oceans to shield themselves from space radiation.
That would also prepare them for the colonization of oceans in planetary systems.
Following their approach to planetary systems, the aliens could transfer from their free-floating planets to selected Oort cloud objects that would carry them inland and to the parent planets of the systems to be colonized.
Or, planetary systems could capture those free-floating planets. Then aliens would colonize such planetary systems.
To discover aliens on free-floating planets, Romanovskaya proposes looking for certain technological signatures—electromagnetic emissions produced by alien technologies on and around free-floating planets—and, in some cases, finding coincidental signs of terraforming that may be indicating a process. of colonization.
If astronomers detect technological signatures produced on a free-floating planet without detecting the planet itself, they could misinterpret the origin of the signals.
For example, on August 15, 1977, astronomers detected the famous Wow! in the constellation of Sagittarius. Forty-five years later, scientists continue to hypothesize why the signal was detected only once.
According to Romanovskaya, if aliens sent a Wow! of an undetected floating planet and the planet moved away from the line of observations, the signal would not be detected again along that line.
Therefore, astronomers should look for free-floating planets along the lines of observations of unusual and potentially artificial signals from space.
Romanovskaya proposes that there may be a very small chance that in the past few billion years, free-floating planets with intelligent extraterrestrial species have traveled into our stellar neighborhood, and discusses different ways to search the solar system and beyond for their artifacts. nearby planetary systems.
Today, somewhere in space, hundreds of light-years from Earth or closer, migratory intelligent biological species or artificially intelligent post-biological beings may be traveling on free-floating planets and looking for a new home.
Romanovskaya recommends that the search for such space travelers, the Search for Migratory Extraterrestrial Intelligence (SMETI), should be part of our search for intelligent life in the universe.