SPACEWARPS

English astrophysicist Gribbin (Timewarps, White Holes, etc.) proves once again that he is a lucid and fluent expositor to lay readers. But there is some sleight-of-hand here. In this volume, says Gribbin, he wants to dwell on the anomalies of space in an Einsteinian universe: matter disturbs the smooth flatness of the terrain, producing the gravity wells or warps predicted by general relativity theory. However, these are but foils that allow Gribbin to introduce those major distortions of space—wells that close in upon themselves: the black holes. Once they are encountered and possible candidates detailed, they provide a springboard by which to describe white dwarfs and other assemblages of compacted matter, along with the evolution of stars. The material covered, in the end, is much the standard fare we meet in other contemporary surveys of cosmology/astrophysics—including Gribbin's. A new wrinkle, possibly, is his idea that the present universe may be a black hole turned inside out. Whether or not the universe will continue to expand ad infinitum, or contract back to the ultimate singularity that was the Big Bang, becomes food for thought on the amount of mass in the universe. Some calculations suggest that perhaps 90 percent of the mass may be undetectable—black holes not near enough to perturb visible masses. Some authorities, Gribbin admits, find this an off-putting thought: astronomers, after all, like to think that their domain is investigatable. Apparently such conjectural invisibility does not daunt Gribbin (a theorist), nor one of his most admired contemporaries, Stephen Hawkins, who has spawned a theory of miniblack holes. As a variation on Gribbin's and other recent popularizations, the book is fine—just remember you may have read it elsewhere already.