Close by planets that look unusually alike might be an indication of spacefaring alien life that has travelled between stars, researchers have recommended.

Astronomers trying to find extraterrestrial life are inclined to search for particular alerts, both within the type of “biosignatures” – molecules which are solely produced by organic processes – or “technosignatures”, irregular patterns of sunshine that will have been produced by applied sciences.

Each of those depend on assumptions about how life would possibly operate on one other world,…