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Wednesday, February 17, 2021
CONTINUITY: Interstellar Migration for Non-Grabby and Very Patient Aliens
A new paper on arXiv, “Minimal conditions for survival of technological civilizations in the face of stellar evolution” by Brad Hansen and Ben Zuckerman, examines how alien technological civilisations which developed around type G stars like the Sun might cope with the inevitable departure of their star of origin from the main sequence and the consequent end of habitability of their home planet.
A civilisation which emerged in the window of habitability of their planet comparable to humans on Earth (around a billion years of habitability remaining), and wishes to survive, but has no interest in broad-scale colonisation of other stars, might simply choose to wait until the motions of stars around the galaxy brings a suitable new star and planetary system close to their own. If the plan is to re-settle around a red dwarf star (the most abundant, by far, in the galaxy, and with lifetimes measured in trillions of years), waiting on a time scale of hundreds of millions of years (the details are complicated, as described in the paper) is likely to bring a suitable target star sufficiently close that travelling there using only techniques currently within our grasp (rocket propulsion and gravity assists by giant planets orbiting the original star) is possible in around 100 years, or two orders of magnitude faster than reaching a star with an average distance (around four light years) in our region of the galaxy.
Once ensconced around the new dwarf star, there would be no need for further migration for a timescale comparable to the expected habitability of the galaxy. The authors suggest how star systems in which such a migration might presently be possible might be identified, and suggest them as candidates in searches for techno-signatures such a migration might create. What the re-settled aliens might do when, a couple of billion years after they're settled in their new home, the advancing front of grabby aliens arrive, is not discussed.
Posted at February 17, 2021 11:55