Stan Nadel sat with fellow historians around a lunch table as they introduced themselves one by one. His peers were greeted with warm nods and smiles, but when he stated his name, Mr. Nadel was met with surprise. The man across from him clapped his hand over his mouth.

"What the hell?" Mr. Nadel says he thought, recalling that moment. It was 1997, and he was attending a history conference in Oklahoma.

The lunch mate had graduated from a Ph.D. program at the University of Hawaii, a place Mr. Nadel had never visited. Perhaps the young man was familiar with Mr. Nadel's publications, he thought. Maybe he was a former colleague or a student.

It turned out, Mr. Nadel said, that the man had no connection to him at all. The stranger had recently accepted a one-year teaching appointment off the tenure track, which had prompted a colleague to warn him of Mr. Nadel's experience....