Jack Gladney the protagonist and narrator of the novel "White Noise" was an expert in what?

White Noise is the eighth novel by Don DeLillo, published in 1985. It won the U.S. National Book Award for Fiction. Set at a bucolic New England college known only as The-College-on-the-Hill, White Noise follows a year in the life of Jack Gladney, a professor who has made his name by pioneering the field of Hitler studies (though he hasn't taken German lessons until this year). He has been married five times to four women and rears a brood of children and stepchildren (Heinrich, Denise, Steffie, Wilder) with his current wife, Babette. Jack and Babette are both extremely afraid of death; they frequently wonder which of them will be the first to die.