Flat-Earth logic is by turns mesmerizing and maddening. There is no gravity, nothing to restrain it, but as a theory it explains fewer phenomena than the theory it seeks to supplant. In the corridor, I met a documentary filmmaker—there were several milling around at the conference—who had been following the flat-Earth community for months. His face bore a look of despair. “If you’re going to dismiss everything as a hoax, you’d better have something clear to replace it,” he said, his voice rising toward apoplexy. “If you tell me your car isn’t blue and I ask you, ‘Well, what color is your car?,’ don’t fucking tell me, ‘I don’t know, but it’s not blue.’ What color is your fucking car?!”

In 2012, Bachman had shown up at the home of a woman across town named Melissa Frost, claiming to be a New Yorker whose home had been destroyed in Hurricane Sandy. Overcome with pity, Frost let him in — and nearly lost her house. In an expensive and frightening ordeal that dragged on for months, Bachman slowly laid claim to the space, using his intricate knowledge of tenancy laws to stay one step ahead of her. He scuffed up the floors, kicked down the doors, and clogged the toilets with cat litter. “He went from being this cordial, polite person who understood he was a guest in my house,” Frost said in one of the articles, “to someone who was approaching me aggressively and flat-out saying, ‘This is my house now.’ ”

Marion Tinsley—math professor, minister, and the best checkers player in the world—sat across a game board from a computer, dying.

Tinsley had been the world’s best for 40 years, a time during which he’d lost a handful of games to humans, but never a match. It’s possible no single person had ever dominated a competitive pursuit the way Tinsley dominated checkers. But this was a different sort of competition, the Man-Machine World Championship.

His opponent was Chinook, a checkers-playing program programmed by Jonathan Schaeffer, a round, frizzy-haired professor from the University of Alberta, who operated the machine. Through obsessive work, Chinook had become very good. It hadn’t lost a game in its last 125—and since they’d come close to defeating Tinsley in 1992, Schaeffer’s team had spent thousands of hours perfecting his machine.

The night before the match, Tinsley dreamt that God spoke to him and said, “I like Jonathan, too,” which had led him to believe that he might have lost exclusive divine backing…’