6 ms·

He seems to be like me: no matter how many times I read about quantum fields and quantum mechanics, I never seem to get it, and I read a different book on the s

by kolbe 7y ago

He seems to be like me: no matter how many times I read about quantum fields and quantum mechanics, I never seem to get it, and I read a different book on the same topic.

whatshisface 7y ago
You should read a book that presents classical mechanics in a simple way, then read both a book that presents classical fields and a book that presents classical mechanics in a complicated (modern) way, and then finally go back and read a book that is about quantum mechanics. Although QM textbooks usually begin with a deceptively elementary introduction, it's actually there as a compressed review of many semesters of learning that was expected to have taken place beforehand. I don't think anybody has ever picked up a book on QFT and understood it without first having learned the foundations.
- cambalache 7y ago
  For me the best way is to forget the physical motivations and the historical development during first encounter, I know it is controversial but it helps you to starts calculating fast and not get boggled in philosophical stuff. Take everything "on faith" then after you know how to work with the mathematical machinery, go back and study a different book, based on the historical development and with more physical intuition.
  - whatshisface 7y ago
    The list of prerequisites isn't really the historical motivation, in fact is almost impossible to find the historical perspective in textbooks. It's secretly a way of teaching math and concepts to students who do not already know them. If you already know all of the necessary math you can come in "sideways" like you are describing, and it is not that controversial. Granted you will have no idea about what's going on if you don't understand Newton's laws and friends.
    - cambalache 7y ago
      Plenty of books dedicate the first parts of the course to the experimental evidence of the need of a new theory, namely:the ultraviolet catastrophe of the blackbody radiation, the photoelectric effect, the unexplained stability of the electron position in an atom among others. From there you introduce, the Planck constant, the quantum of light concept, the de Broglie particle-wave duality and the Schrodinger equation and off you go. It is a pretty standard approach. As per the study of QM as a mathematical probabilistic theory you dont need Newtons Laws at all. The 5,6 postulates are pretty standard, and you take the position operator and the Hamiltonian definitions as part of them , no need to relate them to classical counterparts, at least until you prove the Ehrenfest theorem.

by kolbe 7y ago

He seems to be like me: no matter how many times I read about quantum fields and quantum mechanics, I never seem to get it, and I read a different book on the same topic.

whatshisface 7y ago

You should read a book that presents classical mechanics in a simple way, then read both a book that presents classical fields and a book that presents classical mechanics in a complicated (modern) way, and then finally go back and read a book that is about quantum mechanics. Although QM textbooks usually begin with a deceptively elementary introduction, it's actually there as a compressed review of many semesters of learning that was expected to have taken place beforehand. I don't think anybody has ever picked up a book on QFT and understood it without first having learned the foundations.

cambalache 7y ago
For me the best way is to forget the physical motivations and the historical development during first encounter, I know it is controversial but it helps you to starts calculating fast and not get boggled in philosophical stuff. Take everything "on faith" then after you know how to work with the mathematical machinery, go back and study a different book, based on the historical development and with more physical intuition.
- whatshisface 7y ago
  The list of prerequisites isn't really the historical motivation, in fact is almost impossible to find the historical perspective in textbooks. It's secretly a way of teaching math and concepts to students who do not already know them. If you already know all of the necessary math you can come in "sideways" like you are describing, and it is not that controversial. Granted you will have no idea about what's going on if you don't understand Newton's laws and friends.
  - cambalache 7y ago
    Plenty of books dedicate the first parts of the course to the experimental evidence of the need of a new theory, namely:the ultraviolet catastrophe of the blackbody radiation, the photoelectric effect, the unexplained stability of the electron position in an atom among others. From there you introduce, the Planck constant, the quantum of light concept, the de Broglie particle-wave duality and the Schrodinger equation and off you go. It is a pretty standard approach. As per the study of QM as a mathematical probabilistic theory you dont need Newtons Laws at all. The 5,6 postulates are pretty standard, and you take the position operator and the Hamiltonian definitions as part of them , no need to relate them to classical counterparts, at least until you prove the Ehrenfest theorem.