A tough call on first down, a matter of inches, potentially determines the Patriots’ fate in a crucial game. The referee tunes out the stadium chaos, puts on a pair of goggles, and enters virtual reality. He sees the field as a three-dimensional grid. He focuses on the yellow line indicating the distance needed for a first down. From his vantage point, the line slices through the tip of the ball. The referee signals a first down, backed by the kind of computer-generated accuracy that thrills engineers and silences critics.

This is not the NFL of the future. This is, technologically speaking, the NFL that is possible today.