The actor Daniel Radcliffe is on Broadway in a new play called “The Lifespan of a Fact”—perhaps the first-ever work of theatre in which a fact checker is a starring role. Radcliffe’s character is obsessive about his work, and he becomes locked in combat with a writer whose methods are unorthodox.  To get a taste of what fact-checking is really like, Radcliffe got lessons from Peter Canby and Parker Henry of The New Yorker, and then had to check a short piece himself: a review of a Mexican restaurant. Fact and opinion, he quickly learned, are not as easily separated as a layman might think. And in Pennsylvania, the reporter Eliza Griswold follows the route of a pipeline that carries fracking by-products through the back yards of some unhappy voters who think both parties are to blame.