# S-Matrix, String theory, Matrix mechanics and Quantum Mechanics

I'm trying to learn theoretical physics up to string theory. I know linear algebra, calculus 1+2, complex analysis. I know the basics of homology, homotopy, group theory and differential geometry. Now I'm starting to read a first introduction to QM, which is this PDF: http://arxiv.org/abs/1007.4184 . And I read a lot on physics exchange on these topics. My main goal is to get a good sense of string theory and maybe that I can solve some basic problems. Now I did read that the historical background of string theory is the S-Matrix(which I guess has to do with the matrix formulation of QM).

Should I first learn this approach to QM and then switch to S-Matrix and finally string theory? Or just completely skip these topics(S-Matrix and Matrix Mechanics) and learn string theory in an ordinary style?(like in the usual literature, which I assume is not taught with the S-Matrix model).

Edit/ I know usual mechanics, theoretical mechanics(Lagrangian and Hamiltonian too) and a bit electromagnetism, but didn't do much problems on these topics, but I know the concepts.

• Parts of this question (v2) seem to be primarily opinion-based. – Qmechanic Dec 30 '13 at 14:35
• I'm not sure about the details, but I think understanding string theory would be easier when one learns from the origins up. And yes, I obviously asked for an opinion. – user117640 Dec 31 '13 at 14:34

## 1 Answer

You should first learn QM (Quantum Mechanics) (Sakurai is good considering your math background, but you may want to use Griffiths too). Then you can learn Quantum Field Theory (QFT) (Schroeder is pretty standard here). From there you can move onto String Theory.

It's tough to answer your question without knowing your background in physics. Like math, but perhaps even more so, physics is built up from the ground with each level expanding upon the previous one. If you don't have a solid foundation yet, it's best you start at the very beginning with a calculus based Newtonian Mechanics and Electrostatics text. You can refer to the undergrad curriculum of colleges to get a sense of progression.

• Thank you for the answer :) I edited my post, which now includes my physics background. – user117640 Dec 29 '13 at 21:59
• Following what I said in my first paragraph should be fine. Though, most of the actual physics is contained in the problems. From my experience (and from many others) you learn far more when working out problems compared to any other form of study. – mcFreid Dec 29 '13 at 22:13