Recent content by Roman

spin is an angular momentum. not the orbital angular momentum, but another one. some books try to explain it with a particle that is "spinning" around its own axis. but it really doesnt. The best way to explain what it really is, I think is to treat spin like a property of a particle, like for...

a good introduction into electronic properties of graphene: http://arxiv.org/abs/0709.1163v2

Ising Model: https://www.physicsforums.com/showthread.php?t=197963

if you speak german, there is a good book about statistical physics: W.Nolting: Grundkurs Theoretische Physik 6 you can find there about 20 p concerning the Ising-Modell

because by building the Cooper-pairs electrons can reduse their energy. look at "Fermy - see - instability". to see the calculation look in any theoretical book about superconductivity

hi everyone, There are so many books about QFT, but what is in your oppinion the best book to learn quantum field theory?

hi, I would say yes, because: the Euler-Lagrange equations can be derived from the "action" integral. The solution of Lagrange equations minimises the integral

hello, this equation comes from lorentz transformations. just look in any book about special relativity

why isn't that correct? for example [L_i,L_j]_-\not=0 means that you can't exactly measure two components of angular momentum at the same time, the same for [x_i,p_i]_-\not=0. can you find a counter-example? so it is just a mathematical tool?

hello everyone, while studying QM you learn the physical meaning of commutating operators, namely they have simultaneous eigenstates. For observables it means, that they can be simultaneusly exactly mesured. What is the physical meaning of anticommuting and not anticommuting operators...

by the way, there is a book "Advanced Quantum Mechanics" from Sakurai (not Modern QM). does anyone has experience with it?

thank you for the link, Astronuc. I'm especially interested in quantum-liquid-theory, maybe there are any lecture notes on the web? i did a search and didnt find something, maybe someone is more lucky?

hello, do you have any experience with this book: Condensed Matter Physics, Michael P. Marder, Wiley & Sons. Is this good for the first contact to condensed matter physics, or can you recommend me another book?

then you have to start at 0

you are right. the ground state energy is for n=1. maybe it should be n_x, n_y, n_z \not=0. so you should try all combinations and find the lowest possible energy