Count on Morris, physicist-cum-science writer, to provide clear exposition on the abstract, as he has done in books on light (Light, 1979), time (Time's Arrows, 1984), and, here, on cosmology. Morris's first chapters bring the reader up to date on elementary particles and the Big Bang, moving along to speculations on the dark matter, the furthest things in the universe, and other pursuits that take physicists out to what National Science Foundation physicist Roll Sinclair calls the ""frontiers"" of science. Morris borrows Sinclair's further defining phrases, the ""boundaries"" and ""edges"" of science, as well, while admitting that these distinctions blur. The latest superstring theories come under Morris's heading of scientific boundaries, as do questions about the origin of the universe. Finally, we reach the edges, where Morris further distinguishes between speculations that do not contradict conventional wisdom but are untestable, and speculations that are more philosophical than scientific. Both are to be distinguished from fringe or pseudoscience (a bag into which Morris would put Fritjof Capra, et al.). Speculations on the existence of tachyons (faster-than-light particles) or time travel through black holes or wormholes are legitimate and do not contradict recognized laws such as special or general relativity. However, they have not proved fruitful and so may suffer the fate of irrelevancy. The anthropic principle, on the other hand, leads ultimately to metaphysical theories invoking God or universe-by-design or else innumerable universes hostile to life. Morris concludes that these kinds of speculations are occurring more and more. After four centuries in which physics and biology grew by accreting to themselves what had been the domain of philosophy, we seem to be coming full circle again. ""Perhaps this kind of development is inevitable,"" Morris remarks--but you can hear the sigh behind his words.