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Quantum Mechanics: Symbolism of Atomic Measurements

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I presume I do not need to introduce Schwinger's list of credentials, including a nobel prize for QED alongside with Feynman and the third guy (I'm sorry, I never seem to remember his name). Schwinger has always had his own view of physics, much like Feynman, and in his books he usually follows that view. The consequence is a book on an old subject, such as QM, which includes many new viewpoints and ideas not found in other books, especially in use of action principles, of which Schwinger was a major proponent.

That being said, it should be stressed that you should not approach this book without taking a course or two in QM - Schwinger himself states so at the introduction. It would not only make the book hard to follow, but also make it pointless - the whole idea of reading this book is getting a fresh new perspective on QM.

For example, instead of stating the "axioms" of QM, Schwinger decides to examine physical experiments and try to see where these axioms come from. He is not always successful in doing that, but at the very least he should get every faithful reader to deeply ponder the foundations of QM. Instead of just writing down Schroedinger's equation and saying, "this is how our system evolves in time", he decides to take an action principle as his fundamental rule for time evolution and derive Schroedinger's equation from it. In short, he turns QM upside down - and gets away with it.

It is definitely worthwhile checking out this book, although many will not like the idea of doing things Schwinger's way - in a sense, the book's greatest strength is also its greatest weakness. You have been warned.

Schwinger died in 1994, and this book is largely a summation of his lecture notes for courses he gave at UCLA in the 80s. To a physicist who already knows the subject, there are still chances of gleaning insight from Schwinger's approach.

Keep in mind that the notes were for lectures to undergrads and grads. They are not reprints of his journal papers. The latter are somewhat notorious to generations of physics grads. Yes, Schwinger's work on QED was seminal. No physicist disputes that. But his papers were sometimes so hard to follow. Feynman's approach was considered much clearer, especially with his refactorings into what we now call Feynman diagrams. These gave an intuition often lacking from reading the analysis in Schwinger's papers.

Anyhow, the level of dissertion in this book is a lot clearer than in those papers. Rather surprising, to me at least. Because my acquaintance with Schwinger was through the journal papers. I never knew that he could write so clearly as he did here.

Schwinger has presented in the text the perfect way to do Quantum Mechanics. This book is actually transformed from lecture notes given by him for three quarters at UCLA in the mid-1980s. Just look at how he induses the general structure of quantum kinematics and establishes the dynamical principle - his quantum action principle, you would agree with me that it should be on the shelf of every physist, physics teacher and student.

This is a fascinating, illuminating, even exciting work. I'm giving it 5 stars, but with the caveat that occaisonally Schwinger's thought process merely left me confused. I'm sure that had he lived to finish the book those few snags would have been worked out with the editors.

One interesting feature is that, once he starts getting into applications,
derivations are worked out in great detail, which may make the book look more mathematically dense than it really is. It's all pretty accessible to anyone who has had undergrad QM. There are also tons of exercises (no solutions, though.) This would make a great supplement to a book like Sakurai's that takes a more deductive approach. I could even see a talented instructor using it as a primary text.

This is how quantum mechanics ought to be written and studied. By reading this book you will be learning from a true master!