on 4 September 2004
Out of this World - Colliding Universes, Branes and other Wild Ideas of Modern Physics by Stephen Webb is a humble exercise in reminding one not to judge a book by its cover.
I was surprised by the difference between my initial judgment (by its title & cartoonish cover) and my evolving sense of appreciation for the depth & thoroughness this author brings to a general lay-audience. Stephen Webb provides a clear & accessible introduction to the most important subjects in fundamental physics while bridging the gulf between "gee wiz" popular science books (e.g. "Fabric of the Cosmos") and the deeper, more technical treatments that top out at the Undergraduate and Graduate level. Keep in mind this book is, strictly speaking, categorically qualitative (i.e. non-mathematical). The 11 chapters are subdivided into succinct & digestible sections with generous figures, tables and photographs (145 total) illustrating concepts of physical processes and the key physicists involved. A 14 page Glossary, 2 page Bibliography, and a fairly thorough 6 page index close out the book.
The scope of this book is grand and its broad range of subjects is covered in a concise no-nonsense, no-holds barred language. Group Theory & Gauge Symmetries, Special & General Relativity, Quantum Theory, the Standard Model of particle physics, Quantum Field Theories (Electroweak (QED) & Quantum Chromodynamics (QCD), Big Bang cosmology, and a fairly comprehensive coverage of Grand Unified Theories (GUTS), Supersymmetry (SUSY), Superstrings and M-Theory. All these subjects are put into proper historical context placing appropriate credit to the key physicists.
After an introductory chapter, Webb leads us through a profundity of symmetry principles in chapter 1: continuous & discrete symmetries, spatial & temporal translations, Noether's Theorem (symmetry & conservation laws: time-energy, rotation-angular momentum), mirror & parity symmetry, Lorentz transformations/invariance principles. The chapter concludes with a rather nice qualitative treatment on mathematical groups - introducing the reader to Special Orthogonal/Unitary (SO(N), U(1) & SU(N)) and exceptional Lie groups and their importance to symmetries in fundamental physics.
In chapter 2, the author crafts a beautiful real-world example of a practical application of both physics on a large scale (General & Special Relativity) and small scale (Quantum Mechanics: Planck scales, the Uncertainty principle and virtual interactions) by discussing how these "Twin Pillars of Physics" make the Global Positioning System possible.
Chapters 3 & 4 are my favorites. They quickly bring you through the way high energy physics produces and classifies the constituents of our Standard Model. The key concepts of units of energy, rest mass, Electric charge and spin; Fermions & Bosons, leptons, and the Quark model of Hadrons are fleshed out for our edification. Also, a fascinating aside reminds us that the World-Wide Web was created at the CERN accelerator facility in Europe and foretells of the next generation "Grid" global network system. Local Gauge Symmetry, Dirac field, QED, Feynman diagrams, perturbation & renormalization programs; the Strong interactions of SU(3)c Quark-Gluon, & color and the SU(2) X U(1) Electroweak plus Higgs unification close out chapter 4 with a nice ring. Chapter 5 is a quick but inclusive read where the fruits & faults of SU(5) GUTS and N=8 SUSY are aired out.
The early history of extra dimensions (1919 Kaluza-1926 Klein) and Edward Witten's 1981 eleven dimensional compact manifold paper are introduced in chapter 6. Chapter 7 brings us through the meat of Superstring Theories proper where Veneziano, Nambu, Susskind; Schwarz & Scherk; Calabi-Yau, Green, Witten, and Gross, Harvey, Martinec & Rohm ("Princeton String Quartet") are given due credit in the development of the Theory. Loop Quantum Gravity shows up in a one-page aside. The five types of consistent Superstring Theories are spelled out towards the end of the chapter.
Chapter 8 is titled "The Story of M". Here, Webb covers electromagnetic duality, monopoles & superconductors ('t Hooft, et. al), QCD again, heterotic SO(32), s and t duality and finally M-Theory itself. As with the rest of the book (and In the spirit of true scientific practice), the author includes both good arguments for and general criticisms against these theories. These pros & cons are given fair "air-time". D-BRANES and Black Holes are added to the mix in Chapter 9. Chapter 10 is a brisk cruise through the "Holographic Universe" principle via anti-de Sitter spacetime (AdS), Conformal field (CFT) and large-N theories.
The closing chapter (11) is a great synthesis & synopsis of some earlier travels through the lands of Quantum Fields, the Standard model of particle physics, symmetries & symmetry breaking; gravity waves & missing matter; extra dimensions, Strings, "Brane worlds", the Anthropic Principle, and "coming attractions" in high energy physics (HEP)...
All in all, this book is a substantial complement to my extensive library of physics multimedia. "Out of this World" undeniably meets my expectation for a great author to bridge the yawning gap we autodidacts crave to step across between purely pop-science to academic textbooks in the subject. I have to recommend this book to all seriously interested physics laymen who want a bigger & better picture of the way we humans strive to understand how the Universe ultimately works...
I'll read it several times and eventually pass my copy around when all this knowledge gestates & gels in my mind. Great work Webb!