Books: Pynchon's Comet

RATNER'S STAR by DON DeLILLO 437 pages. Knopf. $10.

A prime characteristic of the pure mathematician is an inability to speak in language that is intelligible to the layman. It follows that any novelist with a 14-year-old mathematical genius as his hero is probably looking for trouble. Ratner's Star, Author Don DeLillo's fourth book, has just such a hero—Billy Twillig—and its problems begin right there. Although Billy has won the only Nobel Prize ever awarded in his field, neither he nor DeLillo can explain much about the nature of "zorgs," Twillig's epochal discovery. Aside from his ineffable talent, Billy is just a...