Benford's latest novel in his Galactic Center series (Great Sky River, 1987) is strongest when it focuses on the crowded stellar masses, the whirling clouds of hot gasses, and the unimaginable forces that surround the ``Eater of All Things,'' the black hole at the center of our galaxy. Led by their ``Cap'n'' Killeen, the Bishop clan continues its flight from the frightful ``mechs,'' machine-creatures determined to exterminate all organic life. After near-mutiny and with the aid of the godlike ``Magnetic Mind,'' their ship, the Argo, plunges into a zone of tangled space- time hovering near the black hole, where the crew find a bizarre ancient human civilization that might hold the key to defeating the mechs. Alongside this epic plot runs the story of Toby, Killeen's son, and his growth from pouting adolescent to capable heir. Benford's cosmological vistas are stirring, but his depiction of future human culture is pallid: Although it's some 28,000 years from now, Bishops talk about clambakes, drink apricot brandy, and sample ``the authentic folk treat, Koca-Koola.'' This future world and its characters (except for Toby) have little depth, but when it comes to conjuring the marvels of space and the bizarre possibilities of high-energy physics, Benford is second to none.