May 30, 2022 I Paul Seaburn

Hitchhiking ETs May Not Need Spaceships to Colonize the Galaxy

One of the most famous and beloved science fiction novels is “The Hitchhiker's Guide to the Galaxy.” Without spoiling the plot for the few who haven’t read it (when you’re done here, go get a copy), the hitchhiking is done in a spaceship and it turns out to be an effective way to get around the galaxy. A physicist and astronomer proposes that real hitchhiking might actually be an effective way for extraterrestrials to cruise the Milky Way and other galaxies – but not by jumping into the door of spaceships piloted by sympathetic captains with an empty seat. She proposes a mode of free (-ish) transportation that more resembles hobos riding in empty boxcars (ask your grandpa for an explanation) – hitchhiking on free-floating planets as they pass by. Will this really work? Has it already?  

Waiting for a planetary Uber?

“Some free-floating planets may host simple life forms and deliver them to planetary systems. I propose that free-floating planets may enable interstellar travel of extraterrestrial civilizations and technologies, delivering them to planetary systems. Extraterrestrial civilizations' biological species, post-biological species or their technologies become Cosmic Hitchhikers when they ride free-floating planets to reach, explore and colonize planetary systems.”

In a paper published in the International Journal of Astrobiology, Irina K. Romanovskaya (also known under her married name Irina Mullins), a Professor of Physics and Astronomy at Houston Community College, explains her Cosmic Hitchhikers hypothesis. Since the search for extraterrestrial intelligence (SETI) and the search for extraterrestrial artifacts has so far been unsuccessful, Romanovskaya proposes that the problem lies in where astronomers are looking. Most SETI searches look for biological or technical signatures on planets in the habitable or Goldilocks zone around planets with stars similar to our own. That approach is based on the assumption that advanced civilizations ae building huge spaceships using a process that generates huge amounts of industrial activity and pollution. Romanovskaya thinks some advanced civilizations might see this as too challenging or time-consuming. However, they could be smart enough to see a hitchhiking alternative.

“Free-floating planets can provide constant surface gravity, large amounts of space and resources. Free-floating planets with surface and subsurface oceans can provide water as a consumable resource and for protection from space radiation.”

The idea makes sense so far. In addition to exploration. Romanovskaya sees a free-floating planet as a good means for repopulation – placing biological species on the traveling rock to deliver life forms to start again on a new space rock. And, of course, a civilization needing to evacuate its planet for whatever reason would probably be far too large of a spaceship, so a passing free-floating planet would be perfect. This all sounds viable … assuming this intelligent civilization can tolerate extremely slow travel to their destination. What if they want or need a quick getaway?

“Technologies can be used to modify the motion of free-floating planets. If controlled nuclear fusion has the potential to become an important source of energy for humankind, then it may also become a source of energy for interstellar travelers riding free-floating planets.”

Did Romanovskaya just drop a subtle hint that humans might want to keep an eye out for free-floating planets in the near future? Possibly. Using nuclear fusion to give a free-floating planet some added velocity is an interesting idea, especially if the planet is a small one or even a large asteroid. She also suggests another very humanlike use for a free-floating planet – as a place to relocate unwanted populations, like the way the British populated Australia with prisoners. And, if a civilization doesn’t want to staff the free-floating planet with life forms, she suggests equipping it with smart machines, probes, robots and other forms of technologies.

Could some advanced civilization already be traveling through our galaxy on a free-floating planet? Romanovskaya thinks so and offers ways to find them.

“Unexplained emissions of electromagnetic radiation observed only once or a few times along the lines of observation of planetary systems, groups of stars, galaxies and seemingly empty regions of space may be technosignatures produced on free-floating planets located along the lines of observation; the search for free-floating planets is recommended in regions where unexplained emissions or astronomical phenomena occur.”

Unexplained one-time emissions like the famous “WOW!” signal could be coming from flyby civilizations. Romanovskaya suggests looking away from the location of such signals under the assumption that they’re from a planet on the move. If the culture is looking for another star system to settle in, she proposes following a path to it to look for a reoccurrence of the signal or a technosignature. She also thinks a good location would be a solar system with an Oort cloud of asteroids that could be used as smaller free-floating space rocks to get around shorter trips. That leads to another interesting suggestion – these civilizations might encounter other similar civilizations in a new star system and convince some members to join them on the free-floater while dropping off those tired of traveling.

Cosmic hitchhiking on a free-floating planet is indeed an interesting concept that just might work. It would certainly make packing for the trip easier.

Paul Seaburn

Paul Seaburn is the editor at Mysterious Universe and its most prolific writer. He’s written for TV shows such as "The Tonight Show", "Politically Incorrect" and an award-winning children’s program. He's been published in “The New York Times" and "Huffington Post” and has co-authored numerous collections of trivia, puzzles and humor. His “What in the World!” podcast is a fun look at the latest weird and paranormal news, strange sports stories and odd trivia. Paul likes to add a bit of humor to each MU post he crafts. After all, the mysterious doesn't always have to be serious.

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