Andrew Marantz, a New Yorker staff writer, recently published his first book, Antisocial: Online Extremists, Techno-Utopians, and the Hijacking of the American Conversation. It reveals how the boundaries between technology, media, and politics have been erased, resulting in a deeply broken informational landscape—the landscape in which we all now live. For several years, Marantz has been embedded in two worlds. The first is the world of social-media entrepreneurs, who, acting out of naïvete and reckless ambition, upended all traditional means of receiving and transmitting information. The second is the world of the people he calls "the gate crashers"—the conspiracists, white supremacists, and nihilist trolls who have become experts at using social media to advance their corrosive agenda.