Alien civilisations that have terraformed a number of planets might be detectable from afar
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Nearby planets that look unusually alike might be a sign of spacefaring alien life that has travelled between stars, researchers have recommended.
Astronomers looking for extraterrestrial life are likely to look for particular indicators, both within the kind of “biosignatures” – molecules that are solely produced by organic processes – or “technosignatures”, irregular patterns of gentle that might have been produced by applied sciences.
Both of these depend on assumptions…