The first law of popular science is that a sense of the discipline can be conveyed without mathematical formalities. A dangerous assumption in any field, it's especially problematic when applied to the arcana explored in this cursory digest of cutting-edge physics. Webb, author of the well-received Where Is Everybody? Fifty Solutions to the Fermi Paradox and the Problem of Extraterrestrial Life, tackles the most intractable problems of general relativity, quantum mechanics, particle physics, cosmology, string theory, superstring theory, and the shadowy""M-theory"" that may lurk behind the others. It's an ambitious project, which Webb tries to hold together with the unifying theme of symmetry, a concept he feels infuses the truths of science with a""beauty"" comparable to the greatest works of art. Unfortunately, we're not talking Grecian urns here; the symmetries of avant-garde physics are the kind you find in ten- or eleven-dimensional space-time--that is, baffling abstractions that Webb admits are""difficult to describe, and probably impossible to visualize."" Physicists themselves can grasp such rarefied ideas only as the outcome of fiendishly difficult mathematics, and Webb can do little more than skate over them in a mixture of opaque jargon and inexact analogy that lay readers will still find incomprehensible after a few chapters. Occasionally an arresting result surfaces, like the notion that the universe might be a hologram, or that there might be a microscopic twin universe that shrinks as ours expands, or possibly a full-sized twin universe offset from ours by a fraction of an inch. But readers who lack the Ph.D-level training needed to make sense of these speculations may find that Webb's book alternately numbs and boggles the mind without really enlightening it. 143 illustrations.