Thursday, July 02, 2015

Book Review: Fundamental Forces of Nature

Kerson Huang's Fundamental Forces of Nature: The Story of Gauge Fields is one of the rare examples a semi-popular physics book with lots of equations. It tells the story of the gauge revolution and the standard model with many words and a sprinkling of equations.

My own graduate work happened mostly before the gauge revolution in a department dominated by anti-field theory S-matrix people. My quantum field theory classes suffered from rather severe deficiencies in the book, the teacher, and, of course the student. Anyway, I didn't learn much. My work never used quantum field theory either.

From time to time I've tried to remedy this gross deficiency in my education, and I've accumulated a considerably library of QFT books in the process, but somehow I always seem to get distracted or run out of energy before I get to renormalization - which, in any case, was mostly smoke and mirrors when I was a grad student.

It's pretty hard for me to gauge (LOL) how much somebody innocent of physics would get out of this, but for me it was great. Huang is good at explaining ideas in words and he includes lots of pictures, but I think one should at least understand calculus if you want to follow the book. The idea of gauge as a fiber bundle over space-time is introduced with the electromagnetic field, and with it, the gauge covariant derivative. He shows how all the fundamental forces of particle physics take this form.

One of his overarching themes is the elimination of action at a distance from physics, via local gauge invariance.

The final chapters are mostly devoted to the ideas of fixed points and the renormalization group. I found the renormalization group material the most difficult to follow, perhaps because its the part I've never understood. For me, at least, the book has lots of pithy insights.

He throws in some more philosophical notions as well. Why gauge fields, for example, and why those particular gauge fields. He makes a nod to grand unified theories and string theory, but complains that they tend to make things more complicated rather than simpler. My favorite is the observation that the Feynman path integral is just the partition function of statistical mechanics with imaginary time, where time t = i hbar/T, where T is temperature.

This is not a textbook. There are no problems, no real derivations, and only the barest technical details. It is, though, a book that might be a bit of a guide for the perplexed student, wondering what it all means.