FOR MORE THAN HALF A CENTURY the eminent physicist Freeman Dyson has quietly resided in Princeton, N.J., on the wooded former farmland that is home to his employer, the Institute for Advanced Study, this country’s most rarefied community of scholars. Lately, however, since coming “out of the closet as far as global warming is concerned,” as Dyson sometimes puts it, there has been noise all around him. Chat rooms, Web threads, editors’ letter boxes and Dyson’s own e-mail queue resonate with a thermal current of invective in which Dyson has discovered himself variously described as “a pompous twit,” “a blowhard,” “a cesspool of misinformation,” “an old coot riding into the sunset” and, perhaps inevitably, “a mad scientist.”