Saturday, November 07, 2015

Book Review: Quantum Mechanics

Leonard Susskind has published a couple of books based on his Theoretical Minimum lectures, one on classical mechanics and this one on Quantum Mechanics: The Theoretical Minimum, written with Art Friedman. I suppose I have a hundred or so books on various aspects of quantum mechanics, and I originally intended to just read through it like a novel, but guess what? It seems that I have forgotten quite a bit in the nearly half-century since I last studied QM. Anyway, I decided to read it carefully, going through every derivation and solving every problem, just like I was going to teach the book.

The textbooks I learned from long ago (Gottfried, Merzbacher, Pauling and Wilson) were fairly substantial volumes, but not like the massive tomes of Cohen-Tannouji and or even Shankar. Susskind has gone to the opposite extreme, just 364 pages, with large print and a spare selection of topics. The concept is to teach just the fundamentals, and teach them in as simple and clear a fashion as possible. Calculus and a bit of linear algebra is all the math required, and even it is presented in as simple and undemanding a fashion as possible. Problems are very simple and very focused on fundamentals.

This is not a book for traditional QM course. The would be instructor or student will look in vain for such classic topics as the hydrogen atom, scattering theory, perturbation theory and many other traditional subjects. Susskind instead devotes a great deal of time to measurement, quantum states and entanglement, explored via spin states. Later, he tackles the Schrödinger Equation and finally, the harmonic oscillator. The topics lost are important, but are more about the math than the physics.

This book is an excellent choice for anyone with a bit of math (calculus) and a desire to understand what quantum mechanics really is, especially if they don't feel up to the grind of Shankar et. al. It's also a good choice for someone who has taken one of those traditional courses, done the math, and still feels baffled about what it's really about, as well as a nice book for old guys who would like to relearn the fundamentals barely remembered.

I expect that it took 60-100 hours for this rather slow guy to work through the whole book, compared to the 6-10 times as much to go through, say, Shankar, in the same detailed way. Of course, YMMV.

I understood the old dictum that you don't really understand a subject until you have taught it a long time ago. I've never taught quantum.