An earnest, hard-working, but problematic and obscure attempt to wed music, mysticism, and particle physics--from the author of The Wild Shore. In the 33rd century, many humans live in space on tiny bodies provided with heat, light, and gravity by ""whitsuns,"" products of the multidimensional ""discontinuity"" physics invented centuries ago by the remarkable Arthur Holywelkin. He also built a vast, mechanical, computer-controlled orchestra. Now directed by ex-addict Johannes Wright, the orchestra will embark from Pluto on a grand tour of the solar system. Wright fascinatedly probes ever more deeply into Holywelkin's life and deeds, oblivious to the plot being hatched against him by devious megalomaniac, weird cultist, and jealous rival Ernst Ekern. Inspired by writings supposedly left by Holywelkin but actually planted by Ekern, Wright evolves a transcendental composition which describes in music the deterministic physics calculated by Holywelkin. Then Wright contacts the Greys, a secretive, mystic cult who--maybe-have advanced beyond Holywelkin's physics, who--maybe--control the source of the life-giving whitsuns, and who--maybe--are manipulating plotter Ekern for their own unfathomable purposes. They tell Wright that his music not only recapitulates the past but actually predicts the future. So goes the grand tour--but exactly where is hard to say. Robinson does a respectable job of converting music into prose, and the narrative moves deftly and briskly. But neither plot nor drama accumulates much momentum; the characters loom large, but lack substance and motivation. Most irritating of all, Robinson risks ""dear Reader""-ing his audience to death. A fairly imposing enterprise, then, but not so much intriguing as elusive.