E.T. may not phone. Earthly conjecture on extraterrestrials is constrained by human behavior, achievement and science fiction, says British science writer Philip Ball. Speculation about space beings hasn’t evolved much since the first sci-fi novel in 1657, and it may be limiting the alien-hunting SETI program. The recent suggestion that unusual light fluctuations from star KIC 8462852 might be the passing shadow of a massive energy collector built by alien engineers sparked a media frenzy. But how likely is it that “they” would construct — or even want — something we’ve determined they need?