Customer Reviews

Lectures on Quantum Mechanics

5 star:		(6)
4 star:		(1)
3 star:		(3)
2 star:		(0)
1 star:		(0)

 

 

This is a very important book. In it Dirac reviews his modified Hamiltonian formalism, including constraints, so that systems which do not have a proper hamiltonian can be canonically quantized anyway. For Dirac sustains that one only knows how to quantize a system when it has a Hamiltonian. So, if the system doesn't have one, what is a guy to do? He teaches how to generalize the canonical formalism and construct an effective Hamiltonian which is sufficient to do the job. These ideas gave origin to a flow of papers dealing with the matter, and to several good books. Still, Dirac's original lectures are the best introduction, in my opinion. Not to be confused with the famous "Principles of Quantum Mechanics" , the great expository classic. This book I am reviewing is more of a research document.

The concept of 'quantization' has acquired multiple meanings in mathematical physics, since the foundation of quantum mechanics in the 1920ties. I refer to the papers of Heisenberg, Schrodinger, and Dirac which made precise the variables: states, observables, probabilities, the uncertainty principle, dual variables, and the equations of motion. This was also when the wave-particle question received a more precise mathematical formulation, and resolution. Perhaps best known are the equation of Schrodinger, giving the dynamics of systems of quantum mechanical particles, and Dirac's equation for the electron. All three of the pioneers won the Nobel Prize at a young age;-- Schrodinger was a little older than the other two (Heisenberg and Dirac were both born in 1902.) In 1932, John von Neumann showed, surprisingly at the time, that Schrodinger's formulation is equivalent to Heisenbergs matrix mechanics, and von Neumann turned quantization into a field of mathematics. Von Neumann was a contemporary, but trained in mathemetics. His 1932 book "Mathematical Foundations of Quantum Mechanics" was reprinted by Princeton University Press in 1996. Occasionally the link to the foundations of physics have been missed: Reed and Simon quote Edward Nelson: "First quantization is a mystery, and second quantization is a functor." Dirac's lovely little book represents a set of lectures Dirac gave in 1964 at Yeshiva University, at a time when the great master could take advantage of hindsight. The Dover edition didn't appear until 2001. The clarity of Dirac's presentation is truely compelling (no mystery at all!). Very little background is required on the part of the reader. Dirac begins with the Hamilonian method, and then passes to quantization in terms of physics. The mathematics of quantization on curved (and flat) surfaces is clearly presented in the second part of the book. Dirac's ansatz for relativistic theory is Lorentz invariance, and the equations of motion arise naturally as extensions of the 'classical' theory. The Lorentz-invariant action integrals are central, and Dirac covers the Born-Infeld electrodynamics in the last chapter. In total the book is only 87 pages, but Dirac is the master of effective and consise exposition. He also firmly believed that, as a rule, the beauty of the mathematics involved is a good indication that the equation is right for physics. Readers who enjoy popular books by the pioneers in science might like to check out Schrodinger's "What is Life?" reprinted by Cambridge University Press 2002, with a Preface written by Roger Penrose, and a lovely set of biographical sketches, written by Schrodinger, and translated by his granddaughter Verena. And there is a lovely book edited by Pais, Jacob and Atiyah, "Paul Dirac: The Man and his Work" , Cambridge U Press, 1998. ---Review by Palle Jorgensen, July 2003.

My three star review is no criticism of Dirac - after all, he is the pioneer of the theory of Hamiltonians with constraints and as such deserves all the credit that is due. However I would like to redirect you to Henneaux and Teitelboim's book on quantization of gauge systems since they have done much to clarify the mathematics behind the theory and I think give a better introduction to the field than Dirac's dated book.

The famous author talks about the difference between Hamilton and Lagrange equations. That is a non-linear model, but with a certain approximation we can linearize it. That likes useful with the Brackets of Poisson. In this way the mathematical problem achieves a significative thecnics. When we transfer those conditions on a surface, it is very important to consider the flat case. Today because the string theory is hard to proof, we must return to the old physics of 70 years.

Dirac explicates as the theory of Hamilton is better than that of Lagrange for having a modern approach to the quantum physics. The use of probabilistic thecnics allows to semplify the Schroedinger and Maxwell equations, such that we can linearize non-linear conditions. A typical strategy for this is the use of Poisson brackets.

This book may be beautiful for those who love history of science
I find it inaccessible and much a modern approache facilitates a thourough understanding of this advanced topic
Feynman and other writers as wellas those describing Feynmans achievements are far better reads.

Very simple and light book about foundations of quantum mechanics. No one should expect any enhancement of knowledge. It is interesting title from rather historical point of view.

If you have 5 books on Quantum mechanics already and are a big fan of Dirac, then this is O.K.
The book is a set of lectures that are not for beginners
( the audience was best and brightest professors at Yeshiva.)
I get the personal feeling that Paul Dirac should have read more Klein on group invariants,
more Weyl on gauge theory, and more Cartan on Lie Algebra theory,
but there is no doubt that he knew what he was talking about
and was the master of field quantization. Just not showing well here...

From the master himself: Paul Dirac. Very sharp, to-the-point and complete overview of the Quantum Theory. But from Dirac's point of view it's an interesting angle to review things.

I have no doubt: this is a necessary book for those who love quantum mechanics.