The search for life beyond Earth has long inspired all and some — and eyerolls in others. But in recent years, new reporting has made it clear that there really have been hard-to-explain encounters between humans and something that may be operating technology that seems straight out of science fiction. One scientist who’s taking the search seriously is Harvard astrophysicist Avi Loeb, who joined GBH’s All Things Considered Friday. He’s the leader of the new Galileo Project, which will be looking into space for possible evidence of extraterrestrial civilization. What follows is a lightly edited transcript.