In A Brief History of Time, Stephen Hawking appears before us as a silent, crablike figure a man who seems to be crumpling into himself. Hawking, of course, is the renowned physicist who was diagnosed with ALS (Lou Gehrig's disease) and, in 1988, became a celebrity with the publication of ''A Brief History of Time,'' his user-friendly theoretical riff on the origins of the universe.
In the movie, which is both a portrait of Hawking and a once-over-lightly summation of his ideas, Hawking, who no longer has the ability to speak, ''talks'' to us by punching out words on a synthetic voice machine. In the deliberate, metallic tones of a '50s sci-fi robot, he poses questions like ''Why do we remember the past and not the future?'' The movie confronts us with the arresting paradox of Hawking's presence, the notion of a man whose mental universe grows ever larger even as his physical world keeps shrinking.
Except that the film doesn't do enough with either half of the paradox. Directed by the ingenious documentarian Errol Morris (The Thin Blue Line), A Brief History of Time held out the promise of being an audacious, brain-bending experience. Instead, it's plodding and disappointingly conventional.
The details of Hawking's early life are fascinating he is described as the only ''normal'' member of an eccentric family but we soon lose any sense of him as a fleshed-out human being. The film is too intent on sanctifying his mind. And though Hawking's principal theory, which holds that the universe originated as a black hole in reverse, a dense concentration exploding outward in space and time, sounds like visionary fun to contemplate, the movie never develops it.
At one point, Hawking suggests that his cosmological obsessions may be nothing less than a new, secular vision of God. By the end of A Brief History of Time, his theories seem so scattered, hypothetical, and by his own admission contradictory that they don't leave us with a coherent new vision of anything.