Avi Loeb has a chip on his shoulder. For years, the Harvard astrophysicist has been trying to find aliens. He’s in the middle of trying to record the entire sky with an international network of telescopes and recently travelled to Papua New Guinea to find out if a meteor detected in 2014 was actually part of an interstellar spaceship. Meanwhile, academics and pundits snipe at him in the media, and he’s sick of it. “I hear that the scientists say: ‘Why would you go to the Pacific Ocean? It’s a waste of time, waste of energy.’ And I say: ‘I’m...